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Variation in parasite communities and health indices of juvenile Lepomis gibbosus across a gradient of watershed land-use and habitat quality
... Among the variety of biological communities that are able to reflect the habitat variability in freshwater ecosystems, fish parasites are regarded as having great potential [9]. Overall, the assessment of parasites and host traits could be used as an appropriate model to provide valuable insights into the effect of co-invaders on native communities (see Lymbery et al. [10] for a seminal review). ...
... According to animal use and care regulations, each individual minnow was euthanized before examination. The euthanasia protocol consisted of an overdose of clove oil, followed by severance of the spinal cord (adapted from Chapman et al. [9]). After euthanasia, specimens were measured for Standard Length (SL, to the nearest 1 mm). ...
... Genus was the lowest practical taxonomic level reached for two parasite taxa (Table 1). According to Poulin [33] and Chapman et al. [9], taxonomic genera provide enough information to assess the ecological roles within the fish-parasite relationship (e.g., definitive/intermediate host, monoxenous/heteroxenous parasites). ...
Biological invasions are of special conservation concern in the Iberian Peninsula and other regions with high levels of endemism. Environmental variability, such as the seasonal fluctuations of Mediterranean streams, is a key factor that affects the spread of aquatic species in novel habitats. Fish parasites have a great potential to reflect such changes in the habitat features of freshwater ecosystems. The aim of this study consisted of seasonally analysing the health status and parasitological traits of non-native fish in Iberian waters. In particular, a strongly invasive population of Languedoc minnow Phoxinus septimaniae (leuciscid species native to southeast France) was assessed in Tordera Stream (north-eastern Iberian Peninsula, Mediterranean conditions). Fish were sampled in April, July, and October 2023 by electrofishing. Health status (external/internal organs) was significantly better in autumn (HAI = 28.8) than spring (HAI = 35.6). Life-cycle complexity was higher in spring (LCI = 1.98), whereas parasite abundance and Shannon diversity were significantly lower in autumn (TA = 19.6 and H' = 2.15, respectively). In October (more 'benign' environmental conditions in Iberian streams), minnows could display elevated foraging activity, with fish increasing their health condition and level of parasite resistance/tolerance. Overall results showed a particular seasonal profile of health and parasite infra-communities that allow this minnow species to thrive under highly fluctuating habitat conditions. This information could help environmental managers to control non-native fish in Mediterranean streams.
... Overall, the persistence of a parasite species and its population in an ecosystem is determined by the weakest link in the chain: the most sensitive and specific host, or the most delicate parasite life stage. According to theory and recent findings, the diversity of heteroxenous parasites with complex (multihost) life cycles (e.g., Digenea, Cestoda, Acanthocephala) is thus more likely to decrease in stressful environments than the diversity of monoxenous parasites (Box 2; e.g., Monogenea, Microsporidia) ( [2,[7][8][9][10] and references therein). In contrast to heteroxenous parasites, monoxenous parasites might in fact benefit from the presence of stressors, for example, if stressors impair the host's defence against pathogens [11]. ...
... Additionally, an increase in environmental stressors can favour populations of tolerant host species, while populations of more sensitive species disappear. The resulting higher host population density increases the likelihood of transmission of monoxenous parasites between hosts [7,12]. Furthermore, specialist parasites will rely on hosts with large and stable populations, as they are not able to switch to other host species, and therefore face a higher risk of secondary extinction [13]. ...
... In contrast, functional and resilient ecosystems are characterised by high habitat diversity and species richness (e.g., [22]), which should also be mirrored by a high parasite diversity as the association between parasite and host species richness suggests [23,24]. More specifically, there is an indication that parasite species richness is low and total abundance is high in stressed ecosystems, while parasite abundance decreases and diversity increases under conditions with absent or low stressor impact (Box 2; [7]). Based on these findings, the idea of parasites as indicators of biodiversity or 'ecosystem health' was developed [12,25,26], as high parasite diversity is always dependent on diverse and complex interactions among free-living species [23]. ...
Anthropogenic stressors are causing fundamental changes in aquatic habitats and to the organisms inhabiting these ecosystems. Yet, we are still far from understanding the diverse responses of parasites and their hosts to these environmental stressors and predicting how these stressors will affect host-parasite communities. Here, we provide an overview of the impacts of major stressors affecting aquatic ecosystems in the Anthropocene (habitat alteration, global warming, and pollution) and highlight their consequences for aquatic parasites at multiple levels of organisation, from the individual to the community level. We provide directions and ideas for future research to better understand responses to stressors in aquatic host-parasite systems.
... Fish were allowed to acclimatise for a 30-min period by swapping water between the laboratory aquarium and the transportation tank, before being completely released into the aquarium. Minnow were individually euthanised by immersion in an overdose solution of anaesthetic (dropwise addition of clove oil) for 5 min (adapted from Chapman et al., 2015), followed by severance of the spinal cord. Immediately after euthanasia, fish were measured for SL (±1 mm). ...
... Moreover, HAI helps to complement data on parasite infra-communities (see details below in Section 2.5) as a proxy of tolerance (Blanchet et al., 2010;Råberg et al., 2007) and it can also reveal the effect of poor physiological conditions over short periods (e.g. YOY fish, see Chapman et al., 2015). Specifically, skin (fins and scales), eyes, and gills were externally examined for abnormalities. ...
... Parasites were identified using the keys/databases in Brewster (2016), Bruno et al. (2006), and Illán-Aguirre (2012). For particular parasite taxa, family or genus were the lowest practical taxonomic levels, since these categories provide enough information to assess the ecological role of parasites as potential bio-indicators (Chapman et al., 2015;Poulin, 1997). After examination and counting, specimens were deposited in the Parasitological Collection of the Department of Basic Medical Sciences, San Pablo-CEU University (Boadilla del Monte, Spain). ...
Invasive fishes are a major environmental issue at the global scale, particularly for their impacts on freshwater ecosystems via the mechanisms of hybridisation, competition, predation, and disease transmission. This is of special conservation concern on the Iberian Peninsula due to the high level of endemism. With the aim to improve our knowledge on the invasion process of non‐native fishes, the present study consists of analysing key biological traits potentially related to their colonisation capacity: morphology, parasite communities, and genetic diversity.
A non‐native population of Languedoc minnow Phoxinus septimaniae (leuciscid species native to south‐east France) was assessed in Tordera Stream (north‐eastern Iberian Peninsula). Fish were sampled in mid‐May (reproductive period) 2018 and 2019. Biological traits were compared between colonising and resident individuals from stream reaches of intermittent and perennial flow, respectively.
After adjusting for fish size/body mass with analysis of covariance, body condition and health status (external and internal examination) tended to be better in the intermittent reach. Parasite load (number) and diversity (Shannon index) were significantly higher in the perennial reach. Fish development was also more stable in colonising minnow, as detected by low levels of fluctuating asymmetry for the eye diameter and the length of pectoral fins (adjusted for bilateral character size). Genetic diversity (microsatellite markers) was lower in resident minnow. Minnow genetic homozygosity (index of internal relatedness) was positively associated with parasite load and developmental instability (high fluctuating asymmetry levels).
Our results show that colonising minnows display particular profiles of morphological, parasitological, and genetic traits that apparently allow these individuals to increase their dispersal capacity to survive and reproduce in harsher environmental conditions. The potential mechanisms may be related to a wider physiological tolerance, better immune response, parasite resistance/tolerance, and genetic diversity in colonising specimens.
Such information reveals the specific traits of successful fish invaders under a seasonal colonisation dynamic. These data are relevant for environmental managers, to predict and identify areas vulnerable to invasion, in order to establish monitoring programmes for early detection, which will help to reduce the spread of non‐native fish populations.
... It can be suggested that the successful survival of the oviparous and viviparous monogeneans in the highly turbid, small-sized and shallow water of Telbanah Drain may indicate an adaptation to environmental degradation. According to [31], the diversity of parasitic species seems to decrease as watershed size becomes smaller and habitat quality decreases. However, overall abundance of parasites, mainly determined by fluctuations in the prevalence and intensity appears to increase under these circumstances. ...
... The author added that decreasing habitat availability may increase the density of the host population, leading to the exposure of a greater number of fish individuals to secondary or intermediate host(s) as habitat necessities overlap. Many authors reported that large-sized streams show higher parasite diversity [66,67,31]. In this respect, increased growth and diversity of parasite populations may be correlated with the complexity of the habitat and connectivity of greater ecosystems [31]. ...
... Many authors reported that large-sized streams show higher parasite diversity [66,67,31]. In this respect, increased growth and diversity of parasite populations may be correlated with the complexity of the habitat and connectivity of greater ecosystems [31]. ...
One tool to obtain data on the health of the aquatic ecosystem is the use of bioindicators or biomonitors. The present study aimed to test the validity of the oviparous and viviparous monogeneans of the Nile catfish, Clarias gariepinus as a tool for monitoring some aquatic ecosystems in the Nile Delta, Egypt. Three differing-water quality ecosystems were studied during the period from October 2015 to September 2016: Damietta Branch of the River Nile, Ammar Drain (Drain No. 2) and Telbanah Drain. Obtained data revealed that the studied monogenean species varied greatly in their numbers on the catfish host, with the oxygen-poor, pungent smell, highly turbid, dirty, shallow and small-sized Telbanah Drain was the most hospitable habitat for these parasites (4907 out of 7098 worms). This deteriorated waterway stored the highest amounts of Ca +2 , Mg +2 and N 2. On the other hand, the relatively deeper, larger and agriculturally polluted water of Ammar Drain showed the highest levels of pH, EC, TDS, HCO 3 − , SO 4 +2 , Cl − , Na + , K + and P, and accommodated 1704 monogenean worms. All the monogeneans responded similarly to environmental parameters, however Macrogyrodactylus clarii was highly sensitive to water temperature whereas Gyrodactylus sp. was highly sensitive to TDS. The highly transparent, oxygen-rich, much deeper, and larger River Nile showed the lowest infestation levels (487 worms). The highest number of monogenean worms was attained by the most dominant oviparous Quadriacanthus aegypticus (3058 worms), followed by Quadriacanthus clariadis (1786 worms) and Quadriacanthus kearni (1375 worms). The dominant Q. aegypticus attained the highest infection variables (prevalence, mean intensity and abundance) at Telbanah Drain and Ammar Drain. Macrogyrodactylus congolensis recorded the greatest number (549 worms) among viviparous monogeneans. A total of 146 worms was scored for Macrogyrodactylus clarii, however Gyrodactylus rysavyi recorded 96 worms on the skin and 71 worms on the gills. The satellite monogeneans, Gyrodactylus sp. and Paraquadriacanthus nasalis recorded 14 and 3 worms, respectively. The present findings revealed that only Quadriacanthus species are good biomonitors and sensitive pointers of environmental fluctuations in the aquatic ecosystems; these organisms apparently proliferate in polluted water and stressed fish.
... That complexity requires to be explored from different perspectives and on different components of biota. Among a variety of organisms used as bioindicators of environmental impact produced by urbanization, parasites are increasingly utilised as shown by recent research on different host taxa, particularly on stream fishes (Blanar et al., 2016;Bhuthimethee et al., 2005;Chapman et al., 2015;de Aquino Moreira et al., 2015;Iwanowicz et al., 2016;Machut and Limburg, 2008), possibly based on the demonstrated responsiveness of parasites to anthropogenic stress and their applied bioindication value in an environmental sense (Sures et al., 2017). As for research on streams in general, most studies on parasites of stream fishes as bioindicators has also dealt with comparisons between urbanized and natural areas, or along urbanization clines represented by different localities, but little effort has been made on understanding urban impacts along a urban river continuum (Barger and Esch, 2001;Blasco-Costa et al., 2013). ...
... Anthropogenic-induced environmental perturbations on parasitic organisms at both the population and the community level include domestic and industrial sewage, eutrophication, acidification, pesticides, thermal stress, hydrological changes and ultraviolet light (Marcogliese, 2005). Indeed, most of them are normally related to urban development and can act simultaneously; consequently, the mechanisms driving differences in parasite community dynamics are often not well understood (Chapman et al., 2015). Therefore, although it may be possible to determine the degree of impairment accurately, it is difficult achieving the same level of certainty regarding the causes and, consequently, matching a response to the responsible stressor can be very difficult (Allan, 2004). ...
... Human actions at the landscape scale are a principal threat to the ecological integrity of lotic ecosystems, impacting habitat, water quality, and the biota via numerous and complex pathways (Allan, 2004). These systems are currently among the most threatened environments in the world and are degrading more rapidly than terrestrial ecosystems (Chapman et al., 2015). Consequently, there is a peremptory need to monitor and mitigate their degradation in an increasingly urbanized world. ...
Parasites have proven to display high responsiveness to anthropogenic stress, having, therefore a considerable value as bioindicators. We analysed the variability in the structure of parasite populations and assemblages of the poeciliid Cnesterodon decemmaculatus caught at partially urbanized stream along a unidirectional gradient with the aim of evaluating their utility as indicators of the effect of urbanization. A total of 209 fish were examined for parasites; some physical parameters of the stream, including the percentage of urbanization (UR) were also recorded. Data were analyzed at the levels of parasite populations and assemblages discriminated by host sex. Fish condition factor was negatively affected by UR, possibly related to flashing hydrology, but it was not related to parasite abundance. Different combinations of variables explained the distribution of parasite populations and assemblages along the creek, with UR being recurrently identified among the best predictors of parasite loads at all levels of analyses. Whereas densities of mollusc first intermediate hosts were considered of little relevance for parasite distribution, distribution of definitive hosts, as well as the presence of pollutants and increased flashiness in urbanized sections of the creek were retained as possible explanations to the observed patterns. As these factors can act simultaneously, the mechanisms driving differences in parasite dynamics of urban streams are difficult to individualize, but the effect of urbanization on both hosts and parasites was clearly identified. Parasites found, with abundances clearly related to UR, can be considered as good ecological indicators, since they are broadly distributed in the region, easy to observe and count, their prevalence and abundance allow reliable quantitative comparisons and are sensitive to variations of environmental stress and/or ecological conditions at small spatial scales. Consequently the susceptibility of fish-trematode systems to variations in both biotic and abiotic stressors makes them a promising tool for detecting urbanization-related disturbances in streams.
... Therefore, we have used data from our survey to characterise helminth communities in this host species. Furthermore, a recent study of parasite communities in the same host from its native range in Canada (Chapman et al. 2015) provides the opportunity to compare helminth communities in native and non-native habitats of this fish species. ...
... The infection parameters and the parasite community terminology follow Bush et al. (1997). The prevalence criteria 10% and 50% were adopted for identifying rare, intermediate and common species as used by Chapman et al. (2015) for parasite communities of the same host in Canada. The significance of seasonal dynamics in mean intensity, mean abundance and species richness was assessed using Kruskal-Wallis H test. Several parameters of helminth communities were calculated (Magurran 1988). ...
... The present description of helminth communities in L. gibbosus and the data on metazoan (parasitic worms and unionid glochidia) parasite communities in the same host species in Canada (Chapman et al. 2015) allow comparisons of structural parameters of helminth communities in this host species in its native and invasive geographical range (Table 7). The data from the native range in Ontario (Chapman et al. 2015) were based on a single sample for each of the three localities studied in June 2012. ...
A helminthological survey of the alien Pumpkinseed Sunfish, Lepomis gibbosus (L.), from the Lake
Atanasovsko Wetlands, Bulgarian Black Sea coast, is based on the examination of 107 host individuals
studied in spring, summer and autumn of 2012 and 2013. Six helminth species are recorded: metacercariae
of Posthodiplostomum centrarchi Hoffman, 1958 with prevalence (P) 8.41%, mean intensity (MI) 1.88
and mean abundance (MA) 0.16; monogeneans Onchocleidus similis Mueller, 1936 (P 31.78%, MI 4.41,
MA 1.40) and O. dispar Mueller, 1936 (P 3.74%, MI 1.00, MA 0.04), both specific parasites of centrarchids;
adult liver nematode Schulmanela petruschewskii (Shulman, 1948) (P 3.74%, MI 17.74, MA 0.66);
larvae of nematodes Spiroxys contortus (Rudolphi, 1819) (P 10.28%, MI 2.90, MA 0.30) parasitic as
adults in pond turtles and Contracaecum sp. (P 1.87%, MI 1.00, MA 0.02) parasitic as adults in fish-eating
birds. Though L. gibbosus harbours three alien parasites (P. centrarchi, O. similis and O. dispar), there
is no evidence for spillover infections in fishes in the Lake Atanasovsko Wetlands. However, its negative
impact on native populations might be by parasite spillback (participation in life cycles of native parasites
in fishes, reptiles and birds). Helminth component communities and infracommunities studied have lower
species richness, diversity and abundance compared to those in the host’s native range, which is consistent
with the Enemy Release Hypothesis.
... Hence, each parasite species in a parasite community in a host population will reflect the presence of various organisms in the environment that support the parasite's life cycle. Therefore, close interactions between fish host characteristics (size, age, sex, food habit, trophic level, life mode, density, etc.), the environment (temperature, climate, season, etc.), and the level of parasite infection have been well documented in diverse fish species from a variety of habitats (Poulin and Fitzgerald 1987;Rohde et al. 1995;Mamani et al. 2004;Marcogliese et al. 2006;Lopes et al. 2009;Violante-González et al. 2009;Rohlenová et al. 2011;Bittencourt et al. 2014;Tavares-Dias et al. 2014, Alcântara andChapman et al. 2015). However, there are only a few studies on the parasite communities and diversity in fish from the Amazon. ...
... Species diversity characterized by the Berger-Parker index expresses the proportional abundance of the most abundant species, i.e. I. multifiliis (Table 3) Pinto et al. 2015;Chapman et al. 2015). The presence of a great diversity of parasites depends on the host species and on other factors related to the host and environment. ...
... Variations in endoparasite communities and diversity may be determined by variables such as a shift in host diet or the volume of food consumed, ontogenetic changes in immunocompetence, modification in the probability of contact with and infection efficiency of potential intermediate hosts, and parasite life-history strategies. Moreover, parasites and intermediate host invertebrates may respond to environmental changes in different ways from individual to community and infracommunity level (Poulin and Fitzgerald 1987;Rohde et al. 1995;Violante-González et al. 2009;Rohlenová et al. 2011;Tavares-Dias et al. 2014, Alcântara andPinto et al. 2015;Chapman et al. 2015). Therefore, most of these factors may be related to the community structure of parasites in our population of S. jurupari. ...
Assessment of biodiversity is fundamental for the understanding of ecological interactions, but fish parasites were neglected in biodiversity estimates for a long time. The aim of this paper was to investigate the diversity of parasites in Satanoperca jurupari in the Amazon River system in Brazil. Of the fish examined, 90.0% were parasitized by one or more species of protozoans and metazoans, and a total of 3,110,094 parasites were collected. Ichthyophthirius multifiliis, Piscinoodinium pillulare, Sciadicleithum juruparii, Clinostomum marginatum, Posthodiplostomum sp., Genarchella genarchella, Argulus multicolor and Ergasilus coatiarus were found. However, I. multifiliis and P. pillulare were the most prevalent, abundant and dominant parasites, while A. multicolor and G. genarchella were the least prevalent and abundant parasites. The parasites had an aggregate dispersion, but E. coatiarus and the endoparasite species had a higher aggregation pattern. The species richness of parasites varied from 1 to 8 species per host, the Brillouin index varied from 0.32 to 1.09 and evenness varied from 0.01 to 0.47. The host size did not influence the diversity indices and the abundance of parasites, which did not affect the body condition of the hosts. Satanoperca jurupari is a new host for G. genarchella. © 2017, Instituto Nacional de Pesquisas da Amazonia. All Rights Reserved.
... the fish based on the methods of Adams et al. (1993) and Chapman et al. (2015) with some modifications. ...
... To evaluate the health of the fish, we calculated the infection percentage using the methods of Bush et al. (1997) and Margolis et al. (1982). In this study, we assessed the health assessment index score (HAIS) of the fish by modifying the methods of Adams et al. (1993) and Chapman et al. (2015). To collect blood samples, we collected fish from the sampling sites, euthanized them with 10% ethyl alcohol, and kept the fish designated for blood sampling in an aquarium to reduce stress. ...
The ramifications of anthropogenic activities on the environment and the welfare of aquatic life in lakes worldwide are becoming increasingly alarming. There is a lack of research in the Indian Himalayas on fish biomarker responses to stressful aquatic conditions and the use of environmetric modelling in GIS. Our research evaluates the environmental health of urban lakes in multiple basins using multi-biomarker endpoints (13 features) in Schizothorax niger and hydrochemical characterization (9 features) of water. The study covers 31 grids, each at a distance of 1 km². This study demonstrated a statistically significant (P = 0.001) increase in white blood cells (WBC), mean cell size (MCH), helminth infection, and health assessment index score (HAIS) score in fish from a highly eutrophic cluster or basin compared to a reference cluster, which is indicative of environmental stress in fish. Based on hydrochemical similarities, the lake water datasets were divided into three categories using hierarchical cluster analysis (HCA). In the PCA analysis, the first three principal components were responsible for 78.1% of the data’s variance. The first principal component (PC1) accounted for 57.4% of the variance and had a strong positive loading from ammonia, total phosphate, pH, nitrates, and total alkalinity for water quality parameters. Additionally, PC1 had a favourable loading from WBC, helminth infection (%), and the health assessment index score (HAIS) for biological endpoints. These findings are in alignment with the results of the multivariate analysis. The trophic state index (TSI) showed a significant (P < 0.05) increase in Cluster 1, which includes the peripheral areas of Hazratbal and Gagribal side (> 70), compared to the reference cluster. The multiple regression model indicates that ammonia, phosphate, and nitrate significantly impact the general health of fish (R² > 0.7). A novel methodology for monitoring water quality fluctuations across different basins and clusters is presented in this study. By integrating fish health biomarkers and GIS technology, we have developed a comprehensive approach to evaluate the overall well-being of aquatic habitat. This technique may prove beneficial in the management of urban lentic water bodies in the Kashmir Himalayas and other comparable water systems around the globe, while also supporting sustainable practices.
... In this study, we addressed the effects of aquatic pollution on common carp by assessing the uptake of pharmaceutical compounds and their effect on biometric parameters, parasite community composition, and parasite abundance, using a partial cross-over semiexperimental approach. While changes in parasite community composition, diversity, and species richness have previously been used as an indicator of environmental impact [47], Marcogliese et al. [48] suggested that parasite communities may not be sensitive enough to detect the effects of low to moderate pollution, or that the effects may be overshadowed by those of natural environmental variation. In our study, the less polluted control site was characterized by higher parasite diversity and equitability and lower dominance. ...
... In our study, the less polluted control site was characterized by higher parasite diversity and equitability and lower dominance. This corresponds to findings reported from a range of other freshwater ecosystems, e.g., [47,[49][50][51], and supports the indication value of parasite communities in partially controlled natural studies. The parasite community of carp restocked into the treatment pond (C-T) from the control pond (C-C) adapted quickly to the new environmental conditions and, after six months exposure, matched the composition of those carp in the treatment pond. ...
The response of parasite communities to aquatic contamination has been shown to vary with both type of pollutant and parasite lifestyle. In this semi-experimental study, we examined uptake of pharmaceutical compounds in common carp (Cyprinus carpio L.) restocked from a control pond to a treatment pond fed with organic pollution from a sewage treatment plant and assessed changes in parasite community composition and fish biometric parameters. The parasite community of restocked fish changed over the six-month exposure period, and the composition of pharmaceutical compounds in the liver and brain was almost the same as that in fish living in the treatment pond their whole life. While fish size and weight were significantly higher in both treatment groups compared to the control, condition indices, including condition factor, hepatosomatic index, and splenosomatic index, were significantly higher in control fish. Parasite diversity and species richness decreased at the polluted site, alongside a significant increase in the abundance of a single parasite species, Gyrodactylus sprostonae. Oviparous monogeneans of the Dactylogyridae and Diplozoidae families and parasitic crustaceans responded to pollution with a significant decrease in abundance, the reduction in numbers most likely related to the sensitivity of their free-living stages to pollution.
... Then, Pomphorhynchus laevis abundance could be affected by fish population diversity, becoming less abundant when the fish population is not dominated by potential hosts like S. cephalus. Our results are also in agreement with Chapman et al., (2015), who found that parasite diversity increased while abundance decreased within healthy ecosystems. For example, increased abundance of Helminth parasites, Posthodiplostomum spp. ...
... and Actinocleidus sp. indicated poor environmental health (Chapman et al., 2015). In the Arc River, Pomphorhynchus sp. ...
Acanthocephalans' position in food webs, in close interaction with free-living species, could provide valuable information about freshwater ecosystem health through the viability of the parasites' host populations. We explored Pomphorhynchus laevis cystacanths' and adults' intensities of infection, and the prevalence of infected hosts respectively in their Gammarus pulex intermediate hosts and Squalius cephalus definitive hosts in a Mediterranean river. First, we analysed the relationship between P. laevis intensity of infection, its two hosts populations and the other acanthocephalan species found (Pomphorhynchus tereticollis and Polymorphus minutus). Second, we characterised the influence of bacteriological, physicochemical and biological water parameters on these acanthocephalans, and their intermediate and definitive hosts. This research highlights that P. laevis infection was closely related to their two preferential hosts population in the river. Moreover, P. laevis intensity of infection was positively correlated with organic pollution in the river but negatively correlated with biodiversity and with ecological indexes of quality. Pomphorhynchus laevis could thus benefit from moderate freshwater pollution, which promotes their tolerant intermediate and definitive hosts.
... Then, Pomphorhynchus laevis abundance could be affected by fish population diversity, becoming less abundant when the fish population is not dominated by potential hosts like S. cephalus. Our results are also in agreement with Chapman et al., (2015), who found that parasite diversity increased while abundance decreased within healthy ecosystems. For example, increased abundance of Helminth parasites, Posthodiplostomum spp. ...
... and Actinocleidus sp. indicated poor environmental health (Chapman et al., 2015). In the Arc River, Pomphorhynchus sp. ...
... Some fish parasites have been found to be zoonotic and may, therefore, pose a risk to the consumers [7,8]. The community structure and species abundance of parasites of fish vary with regards to environmental conditions, quality and pollutants [9]. This has led to the successful application and use of parasites as bioindicators of habitat degradation and water quality [10][11][12][13]. ...
... Monogeneans: monoxenous gill infecting ectoparasites are very sensitive to changes in dissolved oxygen, because they infest the gills and are exposed to the environment throughout their life [9]. Some monogenean parasites have been documented to decrease in abundance when the water quality deteriorates and dissolved oxygen levels decrease [32,33]. ...
PurposeParasite infections may lead to mortalities in fish; therefore, destabilizing the biodiversity and ecosystem functions. Swamps such as the Lorwai Swamp are important water sources, and information on the parasite species infecting Oreochromis nilotocus baringoensis in the hot springs of Lorwai Swamp which have a distinct genetic makeup from their counterparts in Lake Baringo is lacking. The purpose of this study was to provide a knowledge base on the parasite species infecting O. niloticus baringoensis in these springs, facilitate their comparison with those in Lake Baringo and determine their relationship with selected water quality parameters.Methods347 fish were collected and standard parasitological procedures were used to examine the presence of parasites. Physico-chemical parameters were measured in situ and water samples were collected for chlorophyll-a determination and nutrient analyses in the laboratory using standard methods. Relationship between parasitic infections and selected water quality parameters was determined by PCA using SPSS version 22.ResultsTwo parasite species were common in all sites: Cichlidogyrus sclerosus and Clinostomum sp. Some parasites correlated positively with some parameters; Amirthalingamia macracantha and Contracaecum sp. with nitrogen compounds. Others like Clinostomum sp. and Tylodelphys sp. correlated negatively with dissolved oxygen.Conclusion
Results from this study showed that there were both positive and negative relationships between some water quality parameters and the prevalence of recovered parasites. O. niloticus baringoensis from Lake Baringo also recorded high parasite prevalence and this calls for sensitization of the public on the risks that may arise from the consumption of undercooked infected fish.
... In addition to the lethal effects of angling, fish captured and released by anglers are often subjected to sublethal stressors (a negative factor impacting an organisms' health) that alter physiology, which have the potential to alter fish behavior and ultimately reproductive fitness (Barton & Iwama 1991;Chopin and Arimoto 1995;Wendelaar Bonga 1997;Chrousos 1998;Cooke et al 2002aCooke et al , 2002bRapp 2009). Increased amounts of hooking, fighting, and handling leads to increased stress on fish, which ultimately compromises potential immune system responses, allowing the fish to become more susceptible to infestation by diseases and parasites (Landsberg et al. 1998;Khan 1999;Lafferty and Kuris 1999;Hoffman 1999;Lafferty and Kuris 2004;Marcogliese 2004;Hill 2008;Pracheil andMuzzall 2009, 2010;Bauer 2010;Wisenden et al. 2012;Chapman et al. 2015). A positive relationship between stress caused by catch-and-release events and parasite intensity has been documented, with a direct increase in parasite intensity due to elevated levels of stress (Wedemeyer and Goodyear 1984;Landsberg et al. 1998;Hoffman 1999;Lafferty and Kuris 1999;Altman and Byers 2014). ...
... Increased amounts of hooking, fighting, and handling leads to increased stress on fish, which ultimately compromises potential immune system responses, allowing the fish to become more susceptible to infestation by diseases and parasites (Landsberg et al. 1998;Khan 1999;Lafferty and Kuris 1999;Hoffman 1999;Lafferty and Kuris 2004;Marcogliese 2004;Hill 2008;Pracheil andMuzzall 2009, 2010;Bauer 2010;Wisenden et al. 2012;Chapman et al. 2015). Interactions between fish and parasites are extremely common and fish can be infected by numerous parasites (Hoffman 1999). ...
I wanted to determine if catch-and-release angling increased larval trematodes in small (50-160 mm) bluegill (Lepomis macrochirus). I used angling effort as a proxy for amount of catch-and-release angling. I assumed bluegill assessed, due to their size and age, experienced catch-and-release events. I assessed larval trematode intensity, black spot (Crassiphiala bulboglossa) and white grub (Posthodiplostomum minimum centrarchi), in 750 bluegill. The first objective was to quantify the association between angling effort and reservoir area. Angling effort and reservoir area were positively correlated. The second objective was to determine if angling effort, reservoir area, bluegill age, and total length affect larval trematode intensity. I hypothesized that angling effort would positively affect larval trematode intensities, allowing larval trematode intensity to be an index of angling effort. Reservoir area, bluegill age, and total length were influential on larval trematode intensity; reservoir area and total length were negatively correlated, and bluegill age was positively correlated with larval trematode intensity, whereas angling effort was both negatively and positively correlated with larval trematode intensity. The third objective was to determine if angling effort, reservoir area, bluegill age, total length, and larval trematode intensity affect condition of bluegill. I hypothesized that increased angling effort and increased larval trematode intensity, and associated stressors from both variables, would decrease condition of fish. Reservoir area, total length, and larval trematode intensity were influential on condition factors, and angling effort and bluegill age were partially influential; reservoir area, bluegill age, and larval trematode intensity were positively correlated with three condition factors (viscerosomatic and hepatosomatic indices, and Fulton's condition factor), whereas the angling effort and total length were positively and negatively correlated with condition factors. Overall, the effects of catch-and-release angling activities provide limited support for the hypotheses I put forth, indicating that larval trematode intensity is not a viable indicator of angling effort. iv ACKNOWLEDGEMENTS
... In addition to the lethal effects of angling, fish captured and released by anglers are often subjected to sublethal stressors (a negative factor impacting an organisms' health) that alter physiology, which have the potential to alter fish behavior and ultimately reproductive fitness (Barton & Iwama 1991;Chopin and Arimoto 1995;Wendelaar Bonga 1997;Chrousos 1998;Cooke et al 2002aCooke et al , 2002bRapp 2009). Increased amounts of hooking, fighting, and handling leads to increased stress on fish, which ultimately compromises potential immune system responses, allowing the fish to become more susceptible to infestation by diseases and parasites (Landsberg et al. 1998;Khan 1999;Lafferty and Kuris 1999;Hoffman 1999;Lafferty and Kuris 2004;Marcogliese 2004;Hill 2008;Pracheil andMuzzall 2009, 2010;Bauer 2010;Wisenden et al. 2012;Chapman et al. 2015). A positive relationship between stress caused by catch-and-release events and parasite intensity has been documented, with a direct increase in parasite intensity due to elevated levels of stress (Wedemeyer and Goodyear 1984;Landsberg et al. 1998;Hoffman 1999;Lafferty and Kuris 1999;Altman and Byers 2014). ...
... Increased amounts of hooking, fighting, and handling leads to increased stress on fish, which ultimately compromises potential immune system responses, allowing the fish to become more susceptible to infestation by diseases and parasites (Landsberg et al. 1998;Khan 1999;Lafferty and Kuris 1999;Hoffman 1999;Lafferty and Kuris 2004;Marcogliese 2004;Hill 2008;Pracheil andMuzzall 2009, 2010;Bauer 2010;Wisenden et al. 2012;Chapman et al. 2015). Interactions between fish and parasites are extremely common and fish can be infected by numerous parasites (Hoffman 1999). ...
I wanted to determine if catch-and-release angling increased larval trematodes in small (50-160 mm) bluegill (Lepomis macrochirus). I used angling effort as a proxy for amount of catch-and-release angling. I assumed bluegill assessed, due to their size and age, experienced catch-and-release events. I assessed larval trematode intensity, black spot (Crassiphiala bulboglossa), and white grub (Posthodiplostomum minimum centrarchi), in 750 bluegill. The first objective was to quantify the association between angling effort and reservoir area. Angling effort and reservoir area were positively correlated. The second objective was to determine if angling effort, reservoir area, bluegill age, and total length affect larval trematode intensity. I hypothesized that angling effort would positively affect larval trematode intensities, allowing larval trematode intensity to be an index of angling effort. Reservoir area, bluegill age, and total length were influential on larval trematode intensity; reservoir area and total length were negatively correlated, and bluegill age was positively correlated with larval trematode intensity, whereas angling effort was both negatively and positively correlated with larval trematode intensity. The third objective was to determine if angling effort, reservoir area, bluegill age, total length, and larval trematode intensity affect condition of bluegill. I hypothesized that increased angling effort and increased larval trematode intensity, and associated stressors from both variables, would decrease condition of fish. Reservoir area, total length, and larval trematode intensity were influential on condition factors, and angling effort and bluegill age were partially influential; reservoir area, bluegill age, and larval trematode intensity were positively correlated with three condition factors (viscerosomatic and hepatosomatic indices, and Fulton’s condition factor), whereas the angling effort and total length were positively and negatively correlated with condition factors. Overall, the effects of catch-and-release angling activities provide limited support for the hypotheses I put forth, indicating that larval trematode intensity is not a viable indicator of angling effort. Advisor: Kevin L. Pope
... Here, we explored the relationships between behaviour, parasite density and body condition in wild-caught pumpkinseed sunfish, Lepomis gibbosus. Pumpkinseed sunfish can be infected by numerous parasitic worms including trematodes, cestodes and nematodes in the wild (Chapman et al., 2015) and have been used in previous studies to measure aspects of trappability, boldness, exploration and cognition (Thambithurai et al., 2022;Thelamon, 2023;Wilson et al., 1993). In Laurentian lakes where this study was conducted, sunfish are commonly infected by at least two species of trematodes (e.g. ...
... Regarding the establishment of L. sceleratus in this investigated area of the Mediterranean Sea coast, it might be attributed to the high rate of water pollution recorded through our previous investigation on the water quality of this area revealing severe water deterioration and concluded a strong positive relationship between isopod prevalence and water pollution. The same conclusion was provided by Ashmawy et al. (2018) and Chapman et al. (2015). In the present study, the record of isopod infestation among the invasive pufferfish L. sceleratus from the Egyptian Mediterranean Sea coast indicated the role of this invasive fish in transmitting parasites such as isopods and perhaps other types of pathogens to the Egyptian marine water resources and consequently to the native fish species (Mahmoud et al. 2023). ...
With the opening of the Suez Canal in 1869, many changes have occurred in the Mediterranean Sea ecosystem so became a home to many invasive Lessepsian marine species that have migrated from the Red Sea. About 500 marine species including pufferfish have immigrated and rapidly established a population in the Mediterranean Sea causing significant impact on its ecosystem and fisheries sector. The parasitic fauna of these pufferfish has scarcely been studied in the Mediterranean Sea and also in their native habitat. During this surveillance study on the invasive pufferfish species from the Egyptian Mediterranean coast, the female cymothoid isopod Elthusa raynaudii was detected from the branchial cavity and also in the buccal cavity of 23.9% of the examined Lagocephalus sceleratus. The isolated isopod species was firstly identified and described through electron microscopy and molecular phylogeny based on the sequences of mitochondrial 16S rRNA gene. Additionally, the description of eggs, embryonic stage, and manca of E. raynaudii was firstly provided. The pathological impact on the infested fish tissues was investigated and revealed curling and loss of secondary gill lamellae in addition to mucous exudates in between the gill filaments and granuloma formation in the gill arch. The study provided the first report of L. sceleratus as a new host for the isopod E. raynaudii collected from the Egyptian Mediterranean coast as a new locality record. The role of the Lessepsian invasive pufferfish in transmitting parasites to the native fish species was discussed.
Graphical Abstract
... Riparian habitat quality (RHQ), an indicator of riparian habitat status, is reported to be closely associated with catchment LULC and can be regarded as a composite indicator of LULC (Gomes et al., 2021). Considering that LULC strongly affects water quality parameters (Zhang et al., 2019a), it is understandable that degraded riparian habitat leads to the deterioration of river water quality (Chapman et al., 2015). However, understanding the relationship between RHQ and water quality parameters remains limited. ...
... Functional diversity reflects the intensity of land development around the surveyor's neighborhood [4,48,49]. The approach was to calculate the entropy of information on eight types of POI facilities within 800 m of the community (restaurants, companies, leisure areas, schools, hospitals, government, buildings, and shopping) and to reflect the intensity of land development in the vicinity of the surveyors' residential areas. ...
The built environment, as perceived and felt by human beings, can shape and affect residential satisfaction. From the perspective of municipal administrators, understanding the building environment and its relationship with people’s residential satisfaction is crucial to improving people’s living environment. This study examines the correlation between built environment elements and residential satisfaction using the consideration of spatial heterogeneity of such a correlation. Machine vision technology is introduced to quantify the design dimension of the built environment. The method of multiscale geographically weighted regression is used to evaluate the relationship between built environment and residential satisfaction and to analyze the spatial heterogeneity in the influencing effects. This empirical study draws on 399 collected samples from the residents of Zhengzhou, China. The results show that elements of the built environment, including street space design features, have a significant effect on people’s residential satisfaction in Zhengzhou City. The factors of functional diversity and distance to the city center show spatial heterogeneity in influencing effects on residential satisfaction. The results of this study could help municipal managers to improve people’s residential satisfaction in Zhengzhou City through the development of urban renewal policies.
... Higher dominance in the helminth component community in 2020-2021 is related to the higher relative abundance of two taxa: the nematode Pseudoterranova sp. and the acanthocephalans of the genus Corynosoma (Table 1). In general, the increase of dominance in the parasite community of fish is connected to less favourable environmental conditions (Chapman et al., 2015). ...
Helminth community of the Antarctic black rockcod, Notothenia coriiceps, was examined using the fish samples collected in 2014—2015 (106 specimens) and 2020—2021 (78 specimens) in the water area of the Argentine Islands, West Antarctica. In total, 30,951 helminth specimens were collected and identified. We analyse the helminth infra- and component communities and investigate possible changes in the main parameters of helminth communities of N. coriiceps during the six-year
period. Thirty species of helminths from five taxonomic groups were recorded: one species of Monogenea, 5 of Nematoda, 4 of Cestoda, 9 of Trematoda, and 11 of Acanthocephala. Notothenia coriiceps was found to be the definitive host of 18 helminth species; 12 species parasitize it in the larval stage using N. coriiceps as the second intermediate or paratenic host. The proportion of larval helminths in the samples was lower in 2014—2015 (73.4%) than in 2020—2021 (81.4%). The number of dominant helminth species (infection prevalence >50%) increased from seven in 2014—2015 to nine in 2020—2021. In helminth infracommunities, the species richness was similar in two samples. On the other hand, we found significantly higher helminth abundance in the
infracommunities from the sample collected in 2020—2021. In the helminth component community, the diversity indices (Shannon, Simpson, Pielou, Berger-Parker) evidenced higher evenness and lower domination in the sample collected in 2014—2015 compared to the sample collected in 2020—2021. Lower evenness in 2020—2021 was due to the larger relative abundance of larval Pseudoterranova sp. and Corynosoma spp. We suggest a deeper investigation of the role of separate helminth species in the component community changes, as well as further monitoring of component community parameters as prospective directions for future studies of helminth communities of N. coriiceps in West Antarctica.
... For example, playas surrounded by agriculture are subject to tillage and runoff that contains erosional sediments and agrochemicals, relative to those surrounded by grassland (Haukos & Smith, 1994). Such disturbances are suggested to have ecological consequences on aquatic organisms (e.g., in terms of parasitism, community structure, etc.) (see Chapman et al., 2015). ...
We compared the prevalence and intensity of Arrenurus sensu stricto water mite parasites on Enallagma civile Hagen in Selys, 1853 (Zygoptera: Coenagrionidae) from 10 freshwater wetlands (playas) in two different land-cover contexts in western Texas from 2006-2007. Vulnerability to parasitism may be a consequence of disturbance, so we predicted that the more natural form of regional land cover (grasslands) surrounding playas should be associated with a lower water mite load than more disturbed land cover (tilled croplands). Additionally, we examined Arrenurus occurrence and intensity of infection by host sex. Overall prevalence was 38.46% of 130 damselflies sampled having mites; this varied by land-cover type but with opposite trends between years. Overall average parasite load was ~11 water mites per infected host (range: 1-40 mites); intensity was significantly higher in hosts from cropland playas in 2006, but there was no difference by surrounding land cover in 2007. Although there were consistent trends in both years of more males being parasitized than females, the highly uneven distribution of parasites on hosts and differences in average mite load between years generated variability that obscured any statistically significant patterns. Thus, land-cover context surrounding playas, but not host sex, had an impact on parasite load in one of the two years of our study. Future work is needed to identify the mechanisms by which land cover may affect water mite-odonate host-parasite relationships as well as the role of the odonate assemblage as a whole in dispersal of parasites in a temporally dynamic wetland network.
... For example, YOY spottail shiners were 100% infected with 6 species and 6.1 parasites/fish at Iˆles de la Paix, and 7 species and 30.3 parasites/fish at Iˆle Dorval (Marcogliese et al., 2006). Juvenile pumpkinseed (Lepomis gibbosus) collected from 3 streams in southern Ontario were infected with 14-16 parasite species and total mean abundance ranged from 14 to 37 parasites/fish at each locality (Chapman et al., 2015). Perch (Perca fluviatilis) fry from Lake Constance, Germany, were infected with 12 parasite species at 8 and 12 wk posthatch (Behrmann-Godel, 2013). ...
The round goby (Neogobius melanostomus) is an invasive species that has become one of the most abundant fish in the St. Lawrence River, Quebec, Canada over the past 15 yr. Since its introduction, the round goby has acquired a number of native parasites, yet little is known about the dynamics of parasite recruitment. To examine this question, young-of-the-year and juvenile round gobies were collected monthly from 2 localities in the river (Îles de la Paix, Île Dorval) from June through November 2012. At Îles de la Paix, round gobies (n = 180) were infected with 3 species of parasites, all larval stages (Diplostomum spp., Tylodelphys scheuringi, Neoechinorhynchus tenellus). Prevalence of the digenean Diplostomum spp. varied from 3.3 to 13.3%, and mean abundance from 0.03 to 0.53 from June through September, with a maximum in August. The digenean T. scheuringi was seen only in August, at a prevalence of 10.0% and a mean abundance of 0.53. The acanthocephalan N. tenellus was observed in June, August, and September, prevalence ranging from 3.3 to 10.0% and mean abundance from 0.03 to 0.27. Maximum infection for all 3 species occurred in August. All infected fish were ≥44 mm in total length (TL). Fish infected with more than 1 parasite species were >60 mm TL. No round goby (n = 178) was infected at Île Dorval. This study demonstrated that the invasive round goby starts to acquire parasite infections in the St. Lawrence River in the first year of life and may contribute to the transmission of some parasites within this ecosystem.
... Sunfishes are also hosts to a range of parasites (Margolis and Arthur, 1979). In particular, trematodes causing black spot disease are common in many populations of sunfishes (Chapman et al., 2015). The trematodes that cause black spot disease have a complex life cycle requiring two intermediate hosts, typically a snail and a fish, with a piscivorous bird or mammal as the final host (Hunter and Hunter, 1938). ...
Wild animals have parasites that can compromise their physiological and/or behavioural performance. Yet, the extent to which parasite load is related to intraspecific variation in performance traits within wild populations remains relatively unexplored. We used pumpkinseed sunfish (Lepomis gibbosus) and their endoparasites as a model system to explore the effects of infection load on host aerobic metabolism and escape performance. Metabolic traits (standard and maximum metabolic rates, aerobic scope) and fast-start escape responses following a simulated aerial attack by a predator (responsiveness, response latency, and escape distance) were measured in fish from across a gradient of visible (i.e. trematodes causing black spot disease counted on fish surfaces) and non-visible (i.e. cestodes in fish abdominal cavity counted post-mortem) endoparasite infection. We found that a higher infection load of non-visible endoparasites was related to lower standard and maximum metabolic rates, but not aerobic scope in fish. Non-visible endoparasite infection load was also related to decreased responsiveness of the host to a simulated aerial attack. Visible endoparasites were not related to changes in metabolic traits nor fast-start escape responses. Our results suggest that infection with parasites that are inconspicuous to researchers can result in intraspecific variation in physiological and behavioral performance in wild populations, highlighting the need to more explicitly acknowledge and account for the role played by natural infections in studies of wild animal performance.
... Interactions between parasites and their hosts influence the life-history traits of individuals (from metabolism to mortality; SeppÄnen et al., 2009;Masud et al., 2020) and these interactions are an essential part of maintaining ecosystem health (Marcogliese and Cone, 1997;Palm and Rückert, 2009;Lefèvre et al., 2009;Cable et al., 2017). This is supported by community level studies showing that habitats suffering environmental contamination have reduced parasite diversity (Marcogliese and Pietrock, 2011;Chapman et al., 2015). Although many investigations have assessed the impact of single environmental stressor impacts on host pathogen dynamics (e.g., Ackerman et al., 2006;Wysocki et al., 2007;Smallbone et al., 2016), few have taken a multi-stressor approach. ...
Chemical pollutants are a major factor implicated in freshwater habitat degradation and species loss. Microplastics and glyphosate-based herbicides are prevalent pollutants with known detrimental effects on animal welfare but our understanding of their impacts on infection dynamics are limited. Within freshwater vertebrates, glyphosate formulations reduce fish tolerance to infections, but the effects of microplastic consumption on disease tolerance have thus far not been assessed. Here, we investigated how microplastic (polypropylene) and the commercial glyphosate-based herbicide, Roundup®, impact fish tolerance to infectious disease and mortality utilising a model fish host-pathogen system. For uninfected fish, microplastic and Roundup had contrasting impacts on mortality as individual stressors, with microplastic increasing and Roundup decreasing mortality compared with control fish not exposed to pollutants. Concerningly, microplastic and Roundup combined had a strong interactive reversal effect by significantly increasing host mortality for uninfected fish (73% mortality). For infected fish, the individual stressors also had contrasting effects on mortality, with microplastic consumption not significantly affecting mortality and Roundup increasing mortality to 55%. When combined, these two pollutants had a moderate interactive synergistic effect on mortality levels of infected fish (53% mortality). Both microplastic and Roundup individually had significant and contrasting impacts on pathogen metrics with microplastic consumption resulting in fish maintaining infections for significantly longer and Roundup significantly reducing pathogen burdens. When combined, the two pollutants had a largely additive effect in reducing pathogen burdens. This study is the first to reveal that microplastic and Roundup individually and interactively impact host-pathogen dynamics and can prove fatal to fish.
... They argued that the entropy index only relates to the land-use evenness rather than land-use diversity. Shannon diversity index is a commonly used and valid method to measure land-use mix diversity [30][31][32][33]. The landuse mix degree function as given below: ...
Previous studies have mostly examined how sustainable cities try to promote non-motorized travel by creating a walking-friendly environment. Such existing studies provide little data that identifies how the built environment affects pedestrian volume in high-density areas. This paper presents a methodology that combines person correlation analysis, stepwise regression, and principal component analysis for exploring the internal correlation and potential impact of built environment variables. To study this relationship, cross-sectional data in the Melbourne central business district were selected. Pearson’s correlation coefficient confirmed that visible green ratio and intersection density were not correlated to pedestrian volume. The results from stepwise regression showed that land-use mix degree, public transit stop density, and employment density could be associated with pedestrian volume. Moreover, two principal components were extracted by factor analysis. The result of the first component yielded an internal correlation where land-use and amenities components were positively associated with the pedestrian volume. Component 2 presents parking facilities density, which negatively relates to the pedestrian volume. Based on the results, existing street problems and policy recommendations were put forward to suggest diversifying community service within walking distance, improving the service level of the public transit system, and restricting on-street parking in Melbourne.
... Land-use mixed degree can be defined as the diversity of land use type. Shannon diversity index is a commonly used and valid method to measure land-use mix diversity [25][26][27][28]. The land-use mix degree function as given below: ...
Previous studies have mostly examined how sustainable cities try to promote non-motorized travel by creating a walking-friendly environment. Such existing studies provide little research that identifies how the built environment affects pedestrian volume in high-density areas. This paper presents a methodology that combines person correlation analysis, stepwise regression, and principal component analysis for exploring the internal correlation and potential impact of built environment variables. To study this relationship, cross-sectional data in the Melbourne central business district were selected. Pearson’s correlation coefficient confirmed that visible green index and intersection density were not correlated to pedestrian volume. The results from stepwise regression showed that land-use mix degree, public transit stop density, and employment density could be associated with pedestrian volume. Moreover, two principal components were extracted by factor analysis. The result of the first component yielded an internal correlation where land-use and amenities components were positively associated with the pedestrian volume. Component 2 presents parking facilities density, which negatively relates to the pedestrian volume. Based on the results, existing street problems and policy recommendations were put forward to suggest diversifying community service within walking distance, improving the service level of the public transit system, and restricting on-street parking in Melbourne.
... Aquatic ecosystems suffer not only from the impacts of fish farming, but also chemical and organic pollution from other sources, such as the release of domestic sewage, agriculture or mining waste into untreated water bodies, which alter the population dynamics in natural environments (Audry et al., 2004;Quinatto et al., 2018;Zhang et al., 2019). Fish and their parasites respond to these changes and can be used as signalling organisms for these impacts (Chubb, 1979;Blanar et al., 2009;Chapman et al., 2015;Bezerra et al., 2019). ...
Fish farming is becoming an increasingly popular agricultural activity, and water quality in these environments is a major concern. Fish parasites, such as monogeneans, respond to changes in abiotic conditions, either with an increase or decrease in population. This study aimed to identify gill monogeneans and analyse their relationships with abiotic factors during the ontogenetic development of Nile tilapia over the fish culture cycle in Mato Grosso do Sul, Brazil. Fish were sampled monthly for eight months, and a total of 200 fish were collected. The physical and chemical water parameters were measured and correlated with the abundance of each monogenean species. Over the fish culture cycle, the physical and chemical parameters fluctuated, and the water quality decreased. The parasites found included Cichlidogyrus tilapiae, Cichlidogyrus thurstonae, Cichlidogyrus sclerosus, Cichlidogyrus halli and Scutogyrus longicornis. The abundances of all species showed significant differences during ontogenetic development (body size) and C. tilapiae, C. sclerosus, C. thurstonae and S. longicornis were correlated with changes in abiotic conditions. However, C. halli was not significantly correlated with any of the evaluated physical or chemical parameters. Understanding how different monogenean species respond to changes in the physical and chemical parameters of water during a production cycle can prevent peaks in abundance and subsequent sanitary problems.
... It was shown that fish parasites reflect the condition of the ecosystem health in several ways. First, by temporal changes in the parasite community structure (usually the species diversity decreases while the abundance increases) (Gelnar et al. 1997;Dušek et al. 1998;Chapman et al. 2015) or through their special body functions (e.g. an ability to store high levels of pollutants, metals and organic compounds from the ambient environment). This study demonstrates another potential for certain parasitic species to be used as indicators of impending environmental problems: through the enumeration of body deformities exceeding the common level of phenotypic variability. ...
A comparative study on the strobilar morphology of the tapeworm Proteocephalus percae (Müller, 1780) (Cestoda), a parasite of the perch Perca fluviatilis (L.), showed a high percentage of abnormally developed parasite individuals. The evaluation of biological samples showed seven types of morphological abnormalities, mostly related to reproductive organs of the model tapeworm species. The most commonly identified deformity was an incomplete segmentation of the strobila. A malformed ovary, which is a structural anomaly linked with proglottization and maturation of the strobila, was also shown to be rather frequent. Offish hosts (P. percae) were collected from two localities with different levels of heavy metal pollution, the highly contaminated water reservoir Ružín and a control locality, the water reservoir Palcmanská Maša, which belongs to the European network of protected areas in Slovakia. Tapeworm abnormalities occurred more frequently in individuals from the contaminated environment (29.9%) compared with individuals from the control site (4.9%). The concentrations of heavy metals found in the parasites and their fish hosts from the heavily polluted reservoir support our assumption that the occurrence of abnormalities could be linked with the destructive effect of toxic substances. The present study also demonstrates that the enumeration of body deformities exceeding the common level of phenotypic variability of particular parasitic species could potentially be used as an indicator of environmental problems.
... Parasites respond to ecosystem disturbances, and as such they can provide valuable information about a system's quality, integrity and health in response to pollutants and other stressors (Sures et al. 2017 and references therein). The composition and diversity of parasite communities may be used to characterise ecosystem health and integrity (Marcogliese 2005;Nachev and Sures 2009;Chapman et al. 2015). Pollution may affect parasite infection in fish directly, by its Section Editor: Guillermo Salgado-Maldonado Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00436-020-06819-9) ...
The composition and diversity of parasite communities are useful tools to characterise ecosystem health and integrity. Environmental disturbances may affect parasite infection in fish directly, by their effects on the free-living stages, or indirectly, on the intermediate hosts. Slimy sculpins, Cottus cognatus, a small fish inhabiting cold waters of North America, have been considered as sentinels due to their limited mobility, often occupying relatively small areas throughout their lives and thus reflecting the local environment. Ninety-six specimens of C. cognatus were sampled from four tributaries of the Athabasca River to assess patterns of helminth parasite community structure in this fish and to study the composition and diversity of its parasite communities in relation to water quality. The localities included single samples from High Hills, Horse and Dunkirk rivers, and two from the Steepbank River. Twelve metazoan parasite species were found, most of them being larval forms. Significant differences occurred in the structure and composition of parasite assemblages of sculpins from the tributaries, although similarities were observed in connected and nearby sites. Parasite communities were influenced mainly by a combination of local environmental conditions, distance and connectivity, and were separated based on the distribution and abundance of autogenic and allogenic parasites. Water quality appeared to influence the distribution of trematode species that use gastropods as intermediate hosts, while proximity and connectivity of sites led to sharing allogenic parasite species in slimy sculpin.
... Many of the studies that examine the interaction between host and parasite in urbanized ecosystems have been conducted with human pathogens [16], consider a single host and a single parasite [17], or a single contaminant and landscape factor. Further, linking the regional process of urbanization to local transmission and diversity of parasite communities has yet to reveal consistent patterns [18][19][20]. One potential explanation for the absence of consistent results is that urbanization differentially affects parasite species: the size and direction of effect is contingent upon parasite life history. ...
This study examined the relationship between urbanization and parasite community structure in the estuarine fish, Fundulus heteroclitus. We measured landscape and physicochemical factors associated with urbanization at 6 sites from 4 collection periods. Concurrently, we quantified the metazoan parasite community in F. heteroclitus collected at those sites, with 105 fish studied per site during the 4 collection periods. Parasite community composition differed among sites. Host size was the most important variable for direct life-cycle parasite assemblages and indirect life-cycle parasites at the individual fish level, while landscape and physicochemical factors determined the structure of indirect life-cycle parasite assemblages at the population scale. Variation in the prevalence and intensity of infection of two indirect life-cycle parasites, Lasiocotus minutus and Glossocercus caribaensis, were the primary parasites that drove differences across sites. Variation in the presence/absence of these indirect life-cycle parasite species was associated with sediment Ni concentrations, patch density, and marsh size. Our data support the hypothesis that urbanization, acting at both landscape and physicochemical scales, can have a significant impact on parasite community structure. This, however, varied by parasite life history: there was little effect of urbanization on the prevalence and intensity of direct life-cycle parasites, but significant variation was detected for indirect life-cycle parasites. This study demonstrates how anthropogenically driven landscape change influences fine-scale population dynamics of parasites.
... The present study assessed the responses of ectoparasites and endoparasites to heavy metals in fish exposed to several parasites, and it reflected the environmental condition of the habitats that the host fish live in. Parasitic levels were high at less polluted sites (Nachev and Sures, 2009;Chapman et al. 2015). However, the infection and abundance of some parasites showed a clear relationship with increase in pollution. ...
Pollution of the ecosystem is a source of concern and wide attention globally. In this study, samples of water was collected and 50 fish samples of Carangoides bajad to assess the rate of water pollution of the coastal area of Rabigh on the coast of the Red Sea and that is due to its closeness to industrial activities. Concentrations of some heavy metals were assessed and was estimated as follows Zn> Fe > Pb (81 > 15.1 > 12.6 μg/l, respectively) using atomic absorption spectrophotometer (Model AA-7000, Shimadzu, Japan). Using a light microscope, different types of endoparasites and ectoparasites were recognized in the chosen infected fish; in addition, a histological examination was conducted for some targeted organs (gills, intestines, liver). The results revealed that 40 fish were infected with subclass Copepoda Hatschekia (intensity 2); digenean parasites Bucephalus margaritae (intensity 4.36), Plagioporus ira (intensity 3.09), and Tergestia bengalensis (intensity 2.33); and Anisakis physeteris (intensity 12.57). The results revealed many histopathological changes which demonstrate the presence of potential risks on consumers due to pollution of the aquatic ecosystems. Therefore, continuous monitoring of these pollutants is an essential matter to ensure the safety of aquatic organisms and humans that rely on these aquatic resources.
... Prevalence of neascus-type trematodes in central stonerollers was consistently different between two streams in Tennessee, attributed to abiotic factors (Ferrara and Cook, 1998). Chapman et al. (2015) found that around 30% of pumpkinseed (Lepomis gibbosus) near Cornwall Ontario had black spot parasites whereas Cone & Anderson (1977) examined pumpkinseed in Ryan Lake, Ontario, and found that the prevalence was at or near 100% for age-1 and older fish. Nearly 60% of fathead minnows (Pimephales promelas) contained black spot parasites in a lake in Minnesota ( Wisenden et al., 2012). ...
1. Evidence of black spot inducing trematode pathogens was seen in four fish groups.
2. Prevalence of black spot symptoms were more common in southern Ontario, CA.
3. Results do not seem biased by citizen scientists compared to biogeography.
4. Citizen science data can provide novel insights for disease ecology.
5. A novel and preliminary venture into the utility of online photo databases.
... However, there is speculation that total parasite burdens may increase due to pollutants compromising host immunity (Poulin, 1992;Overstreet, 1997;MacKenzie, 1999;Marcogliese, 2004). Additionally, parasite diversity has been shown to be inversely related to ecological disturbance (Huspeni and Lafferty, 2004;Chapman et al., 2015). In a study of salt marsh restoration, the prevalence and diversity of trematodes parasitizing the California horn snail (Cerithideopsis californica) increased in response to habitat restoration. ...
Many contaminants persist in the environment for decades or more, influencing ecosystem health. Environmental contamination with mercury (Hg) is a particular concern due to its ability to biomagnify in food webs and its lethal and sub-lethal effects in exposed organisms. Despite the known impacts of anthropogenic contamination, there remains a need for data on wildlife exposure to Hg and other contaminants, and the effects of exposure on wildlife health. The objectives of this study were to: 1) quantify differences in concentrations of mercury and other trace elements among three sympatric semiaquatic mammals of different assumed trophic position: North American river otter (Lontra canadensis), raccoon (Procyon lotor), and North American beaver (Castor canadensis), 2) compare trace element concentrations between animals captured on the Savannah River Site (SRS) in South Carolina, USA, where known inputs of Hg and other trace elements have occurred, and reference sites in South Carolina (SC) and Georgia (GA), USA, and 3) investigate the relationship between host trace element concentrations and endoparasite communities. River otters, beavers, and raccoons were sampled from the SRS, SC, and GA to quantify trace element concentrations in liver tissue and quantify endoparasite communities. Both species and sampling location were important factors determining hepatic trace element concentration, however, there was no consistent trend of elevated trace element concentrations among animals sampled on the SRS. Only Hg demonstrated biomagnification based on assumed trophic position, with river otters having the highest Hg concentrations among the sampled species. Additionally, the results suggest a possible relationship between host hepatic mercury concentration and endoparasite abundance, while hepatic selenium concentration may be related to endoparasite diversity. These findings further demonstrate how wildlife can accumulate anthropogenic contamination, although future research is needed to determine the mechanisms contributing to patterns observed between endoparasite communities and the contaminant concentrations of their mammalian hosts.
... Fishes tend to exhibit rapid and easily measurable changes to physiology or demography in response to the environment and are therefore early indicators of ecosystem health (e.g. Chapman et al. 2015;Jeffrey et al. 2015;Lennox et al. 2018a). Moreover, fishes range from primary consumers to apex predators and are critical to nutrient cycling and material and process subsidies (Polis et al. 1997;Holmlund and Hammer 1999). ...
Drought is a constant and important consequence of natural climatic processes and most freshwater fishes have adaptations to counter its effects. However, a changing global climate coupled with increasing human demand for water is reducing the availability of fresh water to fishes and contributing to more frequent and intense drought around the globe. A clear understanding of how fishes, fish habitat, and fisheries are affected by extended drought is needed to help resolve conflicts over water. We therefore identify key questions and research themes to promote the conservation of freshwater fishes as drought increases in length, frequency and severity. (1) How does drought affect fish habitat? (2) What is drought tolerance in fishes? (3) What are drought refuges for fishes? (4) What kills fish during drought? (5) What is the nature of species succession in drought-stricken waters? (6) What are the long-term consequences of drought to fishes? (7) How does climate change affect drought-fish interactions? (8) How does drought influence fisheries? Our limited ability to provide answers to these questions indicates that fish diversity and abundance worldwide is threatened by drought. Planning, including collection of long-term data, is necessary so that conservation and water re-allocation strategies can be implemented in a timely manner to maintain habitats necessary to support biodiversity during drought periods. Without increased understanding of physiological and behavioural factors that determine the tolerance of fishes to drought, it will not be possible to establish realistic targets for management and restoration of populations and species confronting increasing drought frequency and severity.
... The infection parameters and related terminology are as defined by Bush et al. (1997). The prevalence criteria 10% and 50% were adopted for identification of rare, intermediate and common species (Chapman et al. 2015). The significance of seasonal dynamics (mean intensity, mean abundance and species richness) was assessed by applying the Kruskal-Wallis H test. Parameters describing helminth communities were calculated following Magurran (1988): for component communities, these were Shannon's Diversity Index (H') and Simpson's Dominance Index; for infracommunities, we calculated the number of helminth species per fish, the number of helminth individuals per fish (both as the mean ± standard error, range and median) as well as values of Shannon's Diversity Index (H') and Simpson's Dominance Index. ...
During a helminthological survey carried out during the spring, summer and autumn of 2012–2013, a total of 186 specimens of the Caucasian dwarf goby Knipowitschia caucasica (Berg) from Lake Atanasovsko, Bulgaria, were examined. Of these, 171 specimens were infected, with a prevalence (P) of 91.94%, mean intensity (MI) of 35.80 and mean abundance (MA) of 32.91. Four helminth species were recorded: the trematodes Aphalloides coelomicola Dollfus, Chabaud & Golvan, 1957 in the body cavity (P 59.14%, MI 8.64, MA 5.11) and Paratimonia gobii Prévot & Bartoli, 1967 from the intestine (P 58.60%, MI 35.82, MA 20.98), the monogenean Gyrodactylus bubyri Osmanov, 1965 from the skin, fins and gills (P 50.54%, MI 13.46, MA 6.80) and the nematode Contracaecum sp. (third-stage larvae) from the body cavity (P 1.61%, MI 1.00, MA 0.01). Based on their total prevalence values, A. coelomicola, P. gobii and G. bubyri are recognised as common species and Contracaecum sp. is considered a rare species at the component community level. The helminth component communities and infracommunities studied are characterised by a smaller species richness than those recorded in the same host species from two other (brackish) localities in the Black Sea basin.
... The infection parameters and related terminology are as defined by Bush et al. (1997). The prevalence criteria 10% and 50% were adopted for identification of rare, intermediate and common species (Chapman et al. 2015). The significance of seasonal dynamics (mean intensity, mean abundance and species richness) was assessed by applying the Kruskal-Wallis H test. Parameters describing helminth communities were calculated following Magurran (1988): for component communities, these were Shannon's Diversity Index (H') and Simpson's Dominance Index; for infracommunities, we calculated the number of helminth species per fish, the number of helminth individuals per fish (both as the mean ± standard error, range and median) as well as values of Shannon's Diversity Index (H') and Simpson's Dominance Index. ...
During a helminthological survey carried out during the spring, summer and autumn of 2012–2013, a total of 186 specimens of the Caucasian dwarf goby Knipowitschia caucasica (Berg) from Lake Atanasovsko, Bulgaria, were examined. Of these, 171 specimens were infected, with a prevalence (P) of 91.94%, mean
intensity (MI) of 35.80 and mean abundance (MA) of 32.91. Four helminth species were recorded: the trematodes Aphalloides coelomicola Dollfus, Chabaud & Golvan, 1957 in the body cavity (P 59.14%, MI 8.64, MA 5.11) and Paratimonia gobii Prévot & Bartoli, 1967 from the intestine (P 58.60%, MI 35.82, MA 20.98), the monogenean Gyrodactylus bubyri Osmanov, 1965 from the skin, fins and gills (P 50.54%, MI 13.46, MA 6.80) and the nematode Contracaecum sp. (third-stage larvae) from the body cavity (P 1.61%, MI 1.00, MA 0.01). Based on their total prevalence values, A. coelomicola, P. gobii and G. bubyri are recognised as common species and Contracaecum sp. is considered a rare species at the component community level. The helminth component communities and infracommunities studied are characterised by a smaller species richness than those recorded in the same host species from two other (brackish) localities
in the Black Sea basin.
... Native L. gibbosus is known to host over 100 parasite species, with monogenean and digenean parasites being the most common in terms of species richness (Hoffman, 1999) and abundance (e.g. Chapman et al., 2015). ...
Metazoan parasite communities of Lepomis gibbosus (Centrarchidae), one of the most successfully introduced fish species in Europe, were studied at two isolated ponds (Knielingen, Tropfen) along the Upper Rhine in Germany. Nine parasite taxa were observed, including North American species co-introduced to Europe (ancyrocephalid monogeneans, diplostomid trematodes), circumpolar species infecting L. gibbosus in both their native and non-native ranges (bothriocephalid cestodes) and locally acquired parasitic nematodes. Both parasite communities consisted predominantly of North American species. Acquisition of local parasites was not observed at Tropfen, where the fish community comprised just two species, with L. gibbosus dominant. Low prevalence and abundance of acquired parasites was found at Knielingen, which supported a diverse fish community. At Tropfen, a high abundance of the North American parasite Posthodiplostomum centrarchi probably contributed to the lower condition index, hepatomegaly and splenomegaly observed. Due to low local parasite competency, L. gibbosus appears to have no significant impact on parasite dynamics in affected habitats.
... The infection parameters and related terminology are as defined by Bush et al. (1997). The prevalence criteria 10% and 50% were adopted for identification of rare, intermediate and common species (Chapman et al. 2015). The significance of seasonal dynamics (mean intensity, mean abundance and species richness) was assessed by applying the Kruskal-Wallis H test. Parameters describing helminth communities were calculated following Magurran (1988): for component communities, these were Shannon's Diversity Index (H') and Simpson's Dominance Index; for infracommunities, we calculated the number of helminth species per fish, the number of helminth individuals per fish (both as the mean ± standard error, range and median) as well as values of Shannon's Diversity Index (H') and Simpson's Dominance Index. ...
Acta Zoologica Bulgarica 70 (2): 225-240 - -
During a helminthological survey carried out during the spring, summer and autumn of 2012–2013, a total
of 186 specimens of the Caucasian dwarf goby Knipowitschia caucasica (Berg) from Lake Atanasovsko,
Bulgaria, were examined. Of these, 171 specimens were infected, with a prevalence (P) of 91.94%, mean
intensity (MI) of 35.80 and mean abundance (MA) of 32.91. Four helminth species were recorded: the
trematodes Aphalloides coelomicola Dollfus, Chabaud & Golvan, 1957 in the body cavity (P 59.14%, MI
8.64, MA 5.11) and Paratimonia gobii Prévot & Bartoli, 1967 from the intestine (P 58.60%, MI 35.82,
MA 20.98), the monogenean Gyrodactylus bubyri Osmanov, 1965 from the skin, fins and gills (P 50.54%,
MI 13.46, MA 6.80) and the nematode Contracaecum sp. (third-stage larvae) from the body cavity (P
1.61%, MI 1.00, MA 0.01). Based on their total prevalence values, A. coelomicola, P. gobii and G. bubyri
are recognised as common species and Contracaecum sp. is considered a rare species at the component
community level. The helminth component communities and infracommunities studied are characterised
by a smaller species richness than those recorded in the same host species from two other (brackish) localities in the Black Sea basin.
... Chronic endocrine stress, however, renders individuals prone to disease through immunosuppression (Pickering and Pottinger, 1989). Indeed, Chapman et al. (2015) observed high abundance of parasites on fish living in degraded habitats relative to individuals from more pristine habitats. Stress and parasitism are both factors that have been linked to increases in metabolic demand, elevating the standard metabolic rate of infected individuals (Santos et al., 2010). ...
Freshwaters are among the most imperiled ecosystems on the planet such that much effort is expended on environmental monitoring to support the management of these systems. Many traditional monitoring efforts focus on abiotic characterization of water quantity or quality and/or indices of biotic integrity that focus on higher scale population or community level metrics such as abundance or diversity. However, these indicators may take time to manifest in degraded systems and delay the identification and restoration of these systems. Physiological indicators manifest rapidly and portend oncoming changes in populations that can hasten restoration and facilitate preventative medicine for degraded habitats. Therefore, assessing freshwater ecosystem integrity using physiological indicators of health is a promising tool to improve freshwater monitoring and restoration. Here, we discuss the value of using comparative, longitudinal physiological data collected at a broad spatial (i.e. watershed) scale (i.e. macrophysiology) as a tool for monitoring aquatic ecosystem health within and among local watersheds to develop timely and effective management plans. There are emerging tools and techniques available for rapid, cost-effective, and non-lethal physiological sampling and we discuss how these can be integrated into management using fish as sentinel indicators in freshwater. Although many examples of this approach are relatively recent, we foresee increasing use of macrophysiology in monitoring, and advocate for the development of more standard tools for consistent and reliable assessment.
... Posthodiplostomum minimum is one of the most widely reported fish parasites and they have been subject to evaluation as measures of environmental health (Chapman et al. 2015) and parasite ecology studies (Lane et al. 2015). The present study describes the first microsporidian parasite associated with P. minimum and the first described Ovipleistophora species associated with a trematode. ...
Microsporidia are diverse opportunistic parasites abundant in aquatic organisms with some species hyperparasitic in digenean parasites. In the current study, we describe a unique microsporidian parasite, Ovipleistophora diplostomuri n. sp. that has a tropism for both the bluegill sunfish Lepomis macrochirus , and its digenean parasite Posthodiplostomum minimum . Though the microsporidium first infects a fish, the subsequent infection causes hypertrophy of the metacercarial wall and degeneration of the P. minimum metacercariae within the fish tissue. Genetic analysis placed this species within Ovipleistophora and ultrastructural characteristics were consistent with the genus, including the presence of dimorphic spores within sporophorous vesicles. Meronts did not have a surface coat of dense material, which has been previously reported for the genus. This is the first Ovipleistophora species described that does not have a tropism for ovary. Genetics demonstrated that O. diplostomuri n. sp. groups closely within fish microsporidia and not other species known to be hyperparasitic in digeneans, suggesting that it evolved from fish-infecting microsporidians and developed a secondary tropism for a common and widespread digenean parasite. The high genetic identity to Ovipleistophora species demonstrates the close relationship of this unique microsporidian with other microsporidia that infect ovary.
... Ecological Indicators 81 (2017) 503-513 Fish samples, caught by fishermen using traditional gear (nets), were transported to the laboratory for further investigation, and morphometric indices, including total length (TL), standard length (SL), and body weight (BW) as well as the sex of each fish specimen were estimated. The length-weight relationship, condition factor (Fulton's index), and gonadosomatic index (GSI) were determined according to the following equations: Length-weight relationship: W = aL b (Le Cren's, 1951) Condition factor/Fulton's index: K = W/L 3 × 10 5 (De Vlaming et al., 1982) Gonadosomatic index: (GSI) = Gonad weight/body weight × 100 (De Vlaming et al., 1982) The Health Assessment Index Score (HAIS) of fish was determined according to Adams et al. (1993) and Chapman et al. (2015), and HAIS was based on the examination of internal and external organ abnormalities. A scoring method (ranging from 0 to 30 for each organ category) was used to calculate the combined single HAIS for each fish. ...
Endoparasitic infections vary significantly across altered aquatic ecosystems, making these organisms ideal for the biomonitoring of degraded environments. To assess the biomonitoring potential of the Caryophyllaeid tapeworm Adenoscolex oreini and the possible impact of water quality on fish species, a study was carried out in three lakes with marked eutrophication and pollution gradients. The A. oreini infection level in three host fish species of the genus Schizothorax and corresponding fish health status were determined. The pattern of cestode infection varied significantly in the three fish species across the pollution gradient. The prevalence of infection in two fish species (Schizothorax esocinus and S. curvifrons) was significantly greater (P < 0.05) in the eutrophic lake than in the reference lake, whereas in S. niger, the maximum was reached in the hypereutrophic lake. The estimated marginal mean intensity and other infection indices varied significantly (P < 0.05) across the inter- and intra-pollution gradients of lakes. Multivariate statistical analysis results revealed maximum cestode infection in the eutrophic lake. An altered seasonal pattern was observed in the highly stressed lake. The gonadosomatic index (GSI) and condition factor values were significantly greater in fish collected from the reference lake than in those collected from the other lakes. A significant negative relationship between GSI and cestode prevalence was observed in the hypereutrophic lake as compared to least eutrophic lake. These findings indicate that infection indices of the Caryophyllaeid tapeworm and health attributes of fish can act as surrogates for the environmental quality of deteriorated lentic water bodies of the north-western Himalayan region, which is currently undergoing environmental degradation.
... Ecological Indicators 81 (2017) 503-513 Fish samples, caught by fishermen using traditional gear (nets), were transported to the laboratory for further investigation, and morphometric indices, including total length (TL), standard length (SL), and body weight (BW) as well as the sex of each fish specimen were estimated. The length-weight relationship, condition factor (Fulton's index), and gonadosomatic index (GSI) were determined according to the following equations: Length-weight relationship: W = aL b (Le Cren's, 1951) Condition factor/Fulton's index: K = W/L 3 × 10 5 (De Vlaming et al., 1982) Gonadosomatic index: (GSI) = Gonad weight/body weight × 100 (De Vlaming et al., 1982) The Health Assessment Index Score (HAIS) of fish was determined according to Adams et al. (1993) and Chapman et al. (2015), and HAIS was based on the examination of internal and external organ abnormalities. A scoring method (ranging from 0 to 30 for each organ category) was used to calculate the combined single HAIS for each fish. ...
Endoparasitic infections vary significantly across altered aquatic ecosystems and therefore, these organisms are ideal for biomonitoring of degraded environments. To assess the biomonitoring potential of the Caryophyllaeid tapeworm Adenoscolex oreini and the possible impact of water quality on fish species, a study was carried out in three lakes with marked eutrophication and pollution gradients. The A. oreini infection level in three host fish species of the genus Schizothorax and fish health status, were determined. The pattern of cestode infection varied significantly in the three fish species across the pollution gradient. The prevalence of infection in two fish species (Schizothorax esocinus and S. curvifrons) was significantly greater (P < 0.05) in the eutrophic lake than in the reference lake, whereas in S. niger, it was the maximum in the hypereutrophic lake. The estimated marginal mean intensity and other infection indices varied significantly (P < 0.05) across the inter- and intra-pollution gradients of lakes. Multivariate statistical analysis indicated that cestode infection in the eutrophic lake was the maximum. An altered seasonal pattern was observed in the highly stressed lake. The gonadosomatic index (GSI) and condition factor values were significantly greater in fish collected from the reference lake than those collected from the other lakes. A significant negative relationship between GSI and cestode prevalence was observed in the hypereutrophic lake but not in the least eutrophic lake. These findings indicate that infection indices of Caryophyllaeid tapeworm and health attributes of fish can act as surrogates for the environmental quality of deteriorated lentic water bodies of the north-western Himalayan region, which is currently undergoing environmental degradation.
... fish) were found to reflect the ecological condition of habitats where the host occurs. For example, Nachev & Sures [125] and Chapman et al. [126] reported higher parasite diversity at less polluted sampling sites, whereas the composition of the parasite fauna and the abundance of some parasites showed a clear relationship with the pollution gradient. Furthermore, various studies demonstrate, for example, that toxic pollution reduces the diversity of heteroxenous parasites, whereas parasites with direct life-cycles (monoxenous) are less affected (e.g. ...
Environmental parasitology deals with the interactions between parasites and pollutants in the environment. Their sensitivity to pollutants and environmental disturbances makes many parasite taxa useful indicators of environmental health and anthropogenic impact. Over the last 20 years, three main research directions have been shown to be highly promising and relevant, namely parasites as accumulation indicators for selected pollutants, parasites as effect indicators, and the role of parasites interacting with established bioindicators. The current paper focuses on the potential use of parasites as indicators of environmental pollution and the interactions with their hosts. By reviewing some of the most recent findings in the field of environmental parasitology, we summarize the current state of the art and try to identify promising ideas for future research directions. In detail, we address the suitability of parasites as accumulation indicators and their possible application to demonstrate biological availability of pollutants; the role of parasites as pollutant sinks; the interaction between parasites and biomarkers focusing on combined effects of parasitism and pollution on the health of their hosts; and the use of parasites as indicators of contaminants and ecosystem health. Therefore, this review highlights the application of parasites as indicators at different biological scales, from the organismal to the ecosystem.
Abstract Considering that changes in the biodiversity of parasite communities can be used as indicators of ecosystem health, the aim of this study was to investigate the potential use of Geophagus brasiliensis parasites as bioindicators of environmental changes. We established three sample points in the Iguaçu River, each presenting different degrees of environmental impact. Out of the 69 G. brasiliensis specimens analyzed, 32 (46.3%) were parasitized by at least one parasite. We collected a total of 56 specimens of endoparasites belonging to the phylum Nematoda. Fishes collected in point 3 presented a significantly higher abundance of nematode species (moderately degraded) (Kruskal-Wallis2;69 = 8.62; p = 0.01) and species compositions between points were significantly different (F = 6.95, p = 0.002). No significant difference in relative condition factor (Kn) among the points (F2;66 = 2.54; p = 0.08) or correlation in Kn and abundance of nematodes (rs = 0.1; p = 0.4) were indicated. The results presented in this study indicate that the parasitic community of G. brasiliensis is characterized by low diversity in polluted locations, which explains the absence of certain parasite species and the occurrence of nematode species with varied responses to the pollution gradient.
Coastal lagoons are key ‘transitional’ aquatic environments for biodiversity conservation. Ecological indicators are useful tools for the management of water resources in the European Union. Among different biological communities, fish are a very sensitive tool to assess environmental integrity. Indeed, their parasites can be used as complementary indicators of habitat quality. Yet there is still a deep lack of information on ecological assessment using fish (along with their parasites) for coastal lagoons, particularly for the Iberian Peninsula.
The aim of the present study was to assess the use of fish morphology and their parasite communities as ecological indicators of anthropogenic impact within the Mar Menor coastal lagoon (SE Spain), a Mediterranean area of special conservation concern for European/Iberian biodiversity.
Fish samples (black‐striped pipefish Syngnathus abaster and marbled goby Pomatoschistus marmoratus ) were collected in August 2022 from the Littoral (high level of nutrient enrichment) and Barrier habitats. Physical status (both external and internal indices), asymmetry (level of developmental instability), parasite load, diversity and life‐cycle complexity were compared between habitat types.
Body condition and mainly the health assessment index were better in the Barrier habitat. Except for pectoral fins in pipefish, the fluctuating asymmetry was statistically greater in the Littoral habitat (i.e. with eutrophication leading to poorer fish development). The parasite load was higher in the Littoral habitat for both host fish species. However, the diversity and life‐cycle complexity of parasite communities were statistically lower in the Barrier habitat (a structurally simpler environment) only for gobies.
This study demonstrates an elevated potential for certain fish morphological and parasitological traits to be considered as good ecological indicators of environmental health. This could help environmental managers and policy makers to design effective monitoring programmes to detect impacts within valuable areas for conservation, such as the Mar Menor coastal lagoon.
Gymnogeophagus is a genus of fish from the family Cichlidae present in freshwaters from Southern South America, and the knowledge on its parasite communities is rather scarce. Therefore, the present study evaluated, for the first time, the parasite community of G. balzanii. Fish were collected in the Pantanal wetlands, State of Mato Grosso do Sul, Brazil and analysed for metazoan parasites. Ten taxa (larvae and adult) were found including Nematoda (3), Digenea (5), Copepoda (1) and Monogenea (1). All taxa were aggregated within the host population, few showed high prevalence and all had low abundance. The parasite community was composed by few specialists and several generalist and characterised by low richness, diversity and, consequently high dominance of few species and low evenness. These characteristics are typical of isolationist parasite communities. The predominance of larval forms indicates that G. balzanii occupies a lower position within the food chain, acting as an important link for trophic relations. Host length and weight were strong determinants in the parasite community, making fish sex also important since males were significantly longer and heavier than females. Generally, the parasite fauna did not influence host body condition, indicating no apparent debility. Presence of Clinostomum metacercariae is important for human health issues.
The present study aimed to describe the infective larval stage of Physaloptera sp. parasitizing Leptodactylus macrosternum and the microscopic lesions of these larvae in the stomach wall. Forty-five specimens of L. macrosternum were collected during the rainy season in May 2018, in the municipality of Petrolina, sub-middle São Francisco region, state of Pernambuco, Brazil. Twenty-seven infective larval stage (L3) specimens of Physaloptera sp. were collected attached in the stomach mucosa of 11 specimens (24.4%) of L. macrosternum. No other larval stages (L4) or adult of Physaloptera was found among the necropsied hosts. The stomach’s L3 attachment site showed macroscopic and histological lesions such as hyperaemic and ulcerated sites, mucous tunic necrotic regions, and inflammatory infiltrate eosinophilic. This is the first morphological study of Physaloptera infective larvae parasitizing L. macrosternum, and the first record of this paratenic host in the Caatinga biome. Additionally, it is also the first histopathological study of lesions caused by infective larvae of Physaloptera in this host species.
National parks promote the protection of the ecological environment and global biodiversity conservation. However, the changes in land use obviously damages the natural habitat, leading to habitat fragmentation and degradation. Land use changes affect ecosystem service value (ESV) and its spatial distribution. In this study, a framework for the assessment of regional spatial patterns in land use/cover changes (LUCC) and ESV was established; the framework relies on the application of a classical spatial autocorrelation model. Remote sensing data for Hainan Tropical Rain Forest National Park (HNTRFNP) were used as a test case for the autocorrelation model approach to analyzing spatial patterns in ESV. Across HNTRFNP, ESV averaged 6201.44 million USD, with high ESV seen in aquatic and forested areas. Furthermore, land use types in HNTRFNP showed spatial autocorrelation (P < 0.05), though the extent varied among types. Forests and water exhibited the most aggregation. The ESV showed significant spatial autocorrelation (P < 0.05). High ESV clusters occurred in primary tropical rainforests (i.e., Bawangling, Jianfengling, Wuzhishan, and Yinggeling) and aquatic areas (i.e., Changhua river, Daguangba reservoir, Nandu river, Taiping reservoir, Xiaomei reservoir, and Wanquan river tributaries). Low ESV areas occurred in villages and surrounding farmlands. There was a negative correlation (P < 0.05) between land use intensity and ESV. In conclusion, to heighten the ESV of HNTRFNP, we should return farmlands to forest, carry out relocation projects in key areas, and construct migration corridors to expand key species habitat.
Wild animals have parasites that can compromise their physiological and/or behavioural performance. Yet, the extent to which parasite load is related to intraspecific variation in performance traits within wild populations remains relatively unexplored. We used pumpkinseed sunfish (Lepomis gibbosus) and their endoparasites as a model system to explore the effects of infection load on host aerobic metabolism and escape performance. Metabolic traits (standard and maximum metabolic rates, aerobic scope) and fast-start escape responses following a simulated aerial attack by a predator (responsiveness, response latency, and escape distance) were measured in fish from across a gradient of visible (i.e. trematodes causing black spot disease counted on fish surfaces) and non-visible (i.e. cestodes in fish abdominal cavity counted post-mortem) endoparasite infection. We found that a higher infection load of non-visible endoparasites was related to lower standard and maximum metabolic rates, but not aerobic scope in fish. Non-visible endoparasite infection load was also related to decreased responsiveness of the host to a simulated aerial attack. Visible endoparasites were not related to changes in metabolic traits nor fast-start escape responses. Our results suggest that infection with parasites that are inconspicuous to researchers can result in intraspecific variation in physiological and behavioral performance in wild populations, highlighting the need to more explicitly acknowledge and account for the role played by natural infections in studies of wild animal performance.
Species introductions often coincide with loss of genetic diversity and natural enemies. Anthropogenic translocation of the North-American pumpkinseed Lepomis gibbosus (L., 1758) (Centrarchidae) and its further spread have resulted in recent species establishment in most European countries. This study determines genetic differentiation of non-native European pumpkinseed populations and identifies how their genetic structure relates to the distribution and abundance of parasite species. Microsatellite analysis indicated presence of three genetic lineages, which were well supported by discriminant analysis based on parasite abundance data. The first lineage clustered pumpkinseed populations from northern and southern France and showed high allelic richness, heterozygosity and parasite richness. The second included populations along the “Southern invasion corridor” connecting the rivers Rhine, Main and Danube. The fish exhibited low to high genetic and parasite diversity and generally high parasite abundance. The third lineage clustered populations with low genetic and parasite diversity, located in Portuguese reservoirs and water bodies along the upper Elbe. Parasite species richness was significantly associated with host microsatellite heterozygosity and allelic richness, a trend partially affected by richness of North-American parasites. Furthermore, our results indicate that parasite community composition may serve as a useful biological tool to discriminate non-native fish populations and their inter-relationships.
The fish health status and parasitic infection in paddy fields are understudied in Borneo. This study was done to compare the prevalence and abundance of parasites on freshwater fishes in the upstream and downstream rivers of paddy fields. Parasite study on freshwater fishes was done by collecting live fish samples using ten minnow traps with baits at each site in Serian and Padawan, Sarawak, from October 2017 until March 2018. A total of 120 freshwater fishes were examined during this study period. Cold anaesthesia was applied on live samples prior to ectoparasite and endoparasite microscopic screening, which involved scraping of outer body mucous and removal of fish intestines, respectively. No ectoparasites were recovered from the fish samples. A total of 19 (15.83%) fishes from Cyprinids were infected with endoparasites. From these, 58 individuals of endoparasites were recovered. Two groups of parasites, namely Nematoda (Cucullanus sp.) and Trematoda (unidentified), were recovered from the fish intestines. From this study, there was a significant difference between the upstream fishes and downstream fishes in their endoparasite infection at both Triboh Village (p = 0.035) and Annah Rais Village (p = 1.445 × 10-6) using two samples t-test. The endoparasite abundance in fish was higher in the streams where there was less human disturbance. This study may serve as a baseline study on the parasitic infections of freshwater fishes in streams near paddy fields or other agricultural area in Sarawak.
Man's activities have had profound, and usually negative, influences on freshwater fishes from the smallest streams to the largest rivers. Some negative effects are due to contaminants, while others are associated with changes in watershed hydrology, habitat modifications, and alteration of energy sources upon which the aquatic biota depends. Regrettably, past efforts to evaluate effects of man's activities on fishes have attempted to use water quality as a surrogate for more comprehensive biotic assessment. A more refined biotic assessment program is required for effective protection of freshwater fish resources. An assessment system proposed here uses a series of fish community attributes related to species composition and ecological structure to evaluate the quality of an aquatic biota. In preliminary trials this system accurately reflected the status of fish communities and the environment supporting them.
Humans have dramatically altered landscapes as a result of urban and agricultural development, which has led to decreases in the quality and quantity of habitats for animals. This is particularly the case for freshwater fish that reside in fluvial systems, given that changes to adjacent lands have direct impacts on the structure and function of watersheds. Because choices of habitat have physiological consequences for organisms, animals that occupy sub-optimal habitats may experience increased expenditure of energy or homeostatic overload that can cause negative outcomes for individuals and populations. With the imperiled and threatened status of many freshwater fish, there is a critical need to define relationships between land use, quality of the habitat, and physiological performance for resident fish as an aid to restoration and management. Here, we synthesize existing literature to relate variation in land use at the scale of watersheds to the physiological status of resident fish. This examination revealed that landscape-level disturbances can influence a host of physiological properties of resident fishes, ranging from cellular and genomic levels to the hormonal and whole-animal levels. More importantly, these physiological responses have been integrated into traditional field-based monitoring protocols to provide a mechanistic understanding of how organisms interact with their environment, and to enhance restoration. We also generated a conceptual model that provides a basis for relating landscape-level changes to physiological responses in fish. We conclude that physiological sampling of resident fish has the potential to assess the effects of landscape-scale disturbances on freshwater fish and to enhance restoration and conservation.
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Parasite communities tend to be dissimilar in hosts that are geographically, phylogenetically, ecologically and develop-mentally distant from one another. The decay of community similarity is a powerful and increasingly common method of studying parasite beta diversity, but most studies have examined only a single type of distance. Here, we evaluate distances based on the phylogeny, ecology, spatial proximity and size of hosts, as predictors of the similarity of parasite communities in individual hosts, host populations and host species. We surveyed parasites in six species of fish collected simultaneously from six localities in the St. Lawrence River, Canada, and species in a common group of larval parasites were discriminated using DNA sequences from barcode region of cytochrome c oxidase I. Distances based on the habitat use patterns of host species were good predictors of short-term, ecological similarity of parasite communities, such as that operating at the scale of the individual host. The genetic distance between host species was associated with almost all types of similarity at all scales, particularly qualitative and phylogenetic similarity of parasite communities at the level of populations and meta-populations of hosts. The trophic level, diet, spatial proximity and size of hosts were poor predictors of parasite community similarity. The increased taxonomic resolution provided by molecular data increased the explanatory power of regression models, and different factors were implicated when parasite species were distinguished with DNA barcodes than when larval parasites were lumped into morphospecies, as is commonly practiced. Environmental conditions have long been used to predict the species composition of local communities (Whittaker 1956), but variation in species composition can also be explained with neutral processes (Hubbell 2001). For exam-ple, species composition follows the 'first law of geography' (Tobler 1970), with greater resemblance among communi-ties that are close together than among those that are further apart, which is consistent with the effects of environmental gradients, and/or historical or neutral processes (Nekola and White 1999). However, the rate at which the similar-ity of communities decays with spatial distance provides an intuitive way of examining beta diversity that can be compared across studies, shedding light on underlying mechanisms, including suggesting a role for environmental gradients (Soininen et al. 2007, Locke et al. 2012). Decay in ecological similarity can also be measured in non-spatial dimensions, such as through time (Korhonen et al. 2010). Spatial decay in similarity is well documented among parasite communities (Locke et al. 2012). The similarity of parasite communities also decays along dimensions reflect-ing attributes of populations and species of hosts, or of their environment (Seifertová et al.
The recently proposed index of biotic integrity (IBI) was evaluated for several watersheds throughout the midwestern United States. Five of the community metrics comprising the IBI depend on the number of fish species present and must be adjusted for changes in expected species richness with stream size or zoogeography. We use basic relationships of fish species richness versus stream size, calculated from historical fish community data for seven watersheds, to define lines of maximum species richness. These lines are used to predict attributes of “excellent” fish communities, the basis of comparison for assigning scores to 5 of 12 IBI metrics. When zoogeographic and stream-size factors were accounted for in assigning scores, the IBI accurately reflected watershed and stream conditions. As partial tests of the IBI, we found that the index conforms to knowledge of biologists familiar with several watersheds, is independent of stream order in homogeneous watersheds, and is not biased upwards in generally degraded watersheds. Furthermore, analysis of undisturbed fish communities in Illinois and Kentucky support criteria set for percentages of omnivorous individuals and insectivorous cyprinids expected in excellent fish communities. Comparison of maximum species richness lines reveals two groups of similar fish communities, those in woodland streams (Illinois, Michigan, and Kentucky) and those in Great Plains streams (Nebraska, North and South Dakota). We suspect similarities result from ecological factors relating to physical habitat and biotic interactions, rather than from factors such as geologic and climatic history.
Man's activities have had profound, and usually negative, influences on freshwater fishes from the smallest streams to the largest rivers. Some negative effects are due to contaminants, while others are associated with changes in watershed hydrology, habitat modifications, and alteration of energy sources upon which the aquatic biota depends. Regrettably, past efforts to evaluate effects of man's activities on fishes have attempted to use water quality as a surrogate for more comprehensive biotic assessment. A more refined biotic assessment program is required for effective protection of freshwater fish resources. An assessment system proposed here uses a series of fish community attributes related to species composition and ecological structure to evaluate the quality of an aquatic biota. In preliminary trials this system accurately reflected the status of fish communities and the environment supporting them.
Parasite communities were examined from spottail shiners (Notropis hudsonius (Clinton, 1824)) collected from nine localities in the St. Lawrence River around the Island of Montréal and downstream from its municipal effluents in June and September 1998–2000. A total of 30 taxa were found, the most common being Diplostomum spp. Parasite communities were dominated by digeneans, most of which were larval stages that infect birds as definitive hosts. Mean abundance of the most common parasites varied among localities and years. Component community and mean infracommunity species richness fluctuated within and among years at the various localities. Similarity analyses demonstrated that parasite component communities from the different localities could be partitioned according to season, year, and water mass. Canonical correspondence analysis demonstrated that the parasite component communities from the different localities could be distinguished clearly, indicating that the fish in the different localities compose separate populations or stocks. Year, season, and water mass correlated most strongly among the species–environment relationships. The abundance and distribution of parasite species appeared to be subtly influenced by environmental contaminants and urban effluents, leading to slight reductions in parasite diversity. However, the parasite species composition at the various localities more clearly reflected the local food-web structure and biodiversity in terms of the distributions of various invertebrate groups, piscivorous fish, and waterfowl along the St. Lawrence River.
Parasite communities in four study lakes in 1986 reflected the influences of eutrophication, pollution, and habitat fragmentation. Discriminant analyses of communities at the individual host level revealed two major axes. One contrasted communities in a lake affected by chemical pollution from a pulp mill with those from two eutrophic, less polluted lakes. Changes in the density of intermediate hosts, direct effects on ectoparasites, and impaired immune systems were regarded as important mechanisms. The second contrasted communities in an oligotrophic, unpolluted lake with those from the two eutrophic lakes and was more complex, reflecting habitat fragmentation (the absence of glochidia and some digeneans) and pollution or eutrophication, probably mediated by the same mechanisms as above. Changes in some index parasites in Lake Vatia monitored in 1994, following 8 years of reduced pollutant loading, supported our conclusion that parasite faunas in Lake Vatia in 1986 involved the effects of pollution.
There is growing recognition that opportunities exist to use physiology as part of the conservation and management of populations
and ecosystems. However, this idea has rarely been extended to the field of restoration ecology. Physiological metrics (e.g.,
gas exchange, energy transfer and metabolism, stress response, nutritional condition, gene expression) from a range of taxa
can be used to understand the function of ecosystems as well as the factors that influence their structure. Such knowledge
can assist the development and implementation of effective restoration strategies that recognize the role of habitat quality
on organismal performance. Furthermore, physiological tools can be used to monitor the success of restoration projects during
their implementation and as part of postproject monitoring. The often rapid response of physiological metrics provides more
immediate information, enabling an adaptive approach to restoration, than can usually be obtained if the focus is solely on
population- or ecosystem-level metrics. Greater integration of physiological responses into ecological restoration will provide
practitioners with fundamental scientific information needed to design, implement, and monitor restoration activities to aid
in repairing ecosystems around the globe.
Aims In ecology and conservation biology, the number of species counted in a biodiversity study is a key metric but is usually
a biased underestimate of total species richness because many rare species are not detected. Moreover, comparing species richness
among sites or samples is a statistical challenge because the observed number of species is sensitive to the number of individuals
counted or the area sampled. For individual-based data, we treat a single, empirical sample of species abundances from an
investigator-defined species assemblage or community as a reference point for two estimation objectives under two sampling
models: estimating the expected number of species (and its unconditional variance) in a random sample of (i) a smaller number
of individuals (multinomial model) or a smaller area sampled (Poisson model) and (ii) a larger number of individuals or a
larger area sampled. For sample-based incidence (presence–absence) data, under a Bernoulli product model, we treat a single
set of species incidence frequencies as the reference point to estimate richness for smaller and larger numbers of sampling
units.
Roach (n = 81) caught on 23 May, 1992 from oligotrophic, unpolluted Lake Peurunka were kept in cages over a 2-week period before moving half of the fish to nearby Lake Vatia, which is influenced by pulp mill effluents. Refore moving the fish gill parasites were examined from 9 fish; 5 Dactylogyrus species, Gyrodactylus sp. and Paradiplozoon homoion were found, the main components of the infracommunities being dactylogyrids. Afterwards, 5 fish from each lake were studied weekly between 1 July and 17 August. Metazoan parasites were recorded from gill arches divided into 4 sections along the dorso-ventral axis. D. crucifer, D. nanus, D. micracanthus and D. suecicus occurred in both lakes throughout the study. Gyrodactylus sp., Ergasilus briani and P. homoion occurred in low numbers in both lakes. Differences between the lakes were seen in the prevalence of D. micracanthus which was higher in Lake Vatia and significantly increased abundances of D. crucifer, D. nanus and D. micracanthus in Lake Vatia. Abundances of other Dactylogyrus species remained, on average, at the same level in both lakes. No change during the experiment was recorded in the location of the two most common species, D. crucifer and D. nanus, on the host gills in either of the lakes, both species favouring the 2nd and 3rd gill arches and especially the inner parts of the gills. The apparent lack of competition between the 2 most common Dactylogyrus species indicates that no limitation of resources on roach gills occurred. This was also confirmed by the increased overlapping indices with increasing abundances between the two most common species in Lake Vatia.
Running waters are perhaps the most impacted ecosystem on the planet as they have been the focus for human settlement and are heavily exploited for water supplies, irrigation, electricity generation, and waste disposal. Lotic systems also have an intimate contact with their catchments and so land-use alterations affect them directly. Here long-term trends in the factors that currently impact running waters are reviewed with the aim of predicting what the main threats to rivers will be in the year 2025. The main ultimate factors forcing change in running waters (ecosystem destruction, physical habitat and water chemistry alteration, and the direct addition or removal of species) stem from proximate influences from urbanization, industry, land-use change and water-course alterations. Any one river is likely to be subjected to several types of impact, and the management of impacts on lotic systems is complicated by numerous links between different forms of anthropogenic effect. Long-term trends for different impacts vary. Concentrations of chemical pollutants such as toxins and nutrients have increased in rivers in developed countries over the past century, with recent reductions for some pollutants (e.g. metals, organic toxicants, acidification), and continued increases in others (e.g. nutrients); there are no long-term chemical data for developing countries. Dam construction increased rapidly during the twentieth century, peaking in the 1970s, and the number of reservoirs has stabilized since this time, whereas the transfer of exotic species between lotic systems continues to increase. Hence, there have been some success stories in the attempts to reduce the impacts from anthropogenic impacts in developed nations. Improvements in the pH status of running waters should continue with lower sulphurous emissions, although emissions of nitrous oxides are set to continue under current legislation and will continue to contribute to acidification and nutrient loadings. Climate change also will impact running waters through alterations in hydrology and thermal regimes, although precise predictions are problematic; effects are likely to vary between regions and to operate alongside rather than override those from other impacts. Effects from climate change may be more extreme over longer time scales (>50 years). The overriding pressure on running water ecosystems up to 2025 will stem from the predicted increase in the human population, with concomitant increases in urban development, industry, agricultural activities and water abstraction, diversion and damming. Future degradation could be substantial and rapid (c. 10 years) and will be concentrated in those areas of the world where resources for conservation are most limited and knowledge of lotic ecosystems most incomplete; damage will centre on lowland rivers, which are also relatively poorly studied. Changes in management practices and public awareness do appear to be benefiting running water ecosystems in developed countries, and could underpin conservation strategies in developing countries if they were implemented in a relevant way.
Environmental stressors can predispose fish to mortality from infectious disease. This study examined the effects of two factors, water quality and physical crowding, on the responses of fish to viral infection. Juvenile largemouth bass Micropterus salmoides were experimentally inoculated with largemouth bass virus (LMBV), an emerging pathogen in the family Iridoviridae. In separate experiments, fish were exposed to various concentrations of nitrate (0, 40, 200, and 400 mg/L) and were housed at either high or low population densities. Survival time, viral load (quantity of virus in tissues), and body condition were measured as outcomes. Nitrate, as well as other water quality parameters such as ammonia, nitrite, and pH, affected mortality rates and viral loads in complex ways. Paradoxically, increased nitrate concentrations were associated with reduced mortality rates in juveniles exposed to LMBV. In general, rapid fluctuations in the concentrations of dissolved toxins had greater impact on sensitivity to viral infection than did persistently high levels of these toxins. Fish housed at high density experienced increased mortality rates, elevated viral loads, and reduced body condition compared with fish held at low density. These results demonstrate that both physiochemical and social environmental stressors can affect the survival and condition of largemouth bass infected with LMBV.
1. Stream ecosystems are increasingly impacted by multiple stressors that lead to a loss of sensitive species and an overall reduction in diversity. A dominant paradigm in ecological restoration is that increasing habitat heterogeneity (HH) promotes restoration of biodiversity. This paradigm is reflected in stream restoration projects through the common practice of re‐configuring channels to add meanders and adding physical structures such as boulders and artificial riffles to restore biodiversity by enhancing structural heterogeneity.
2. To evaluate the validity of this paradigm, we completed an extensive evaluation of published studies that have quantitatively examined the reach‐scale response of invertebrate species richness to restoration actions that increased channel complexity/HH. We also evaluated studies that used manipulative or correlative approaches to test for a relationship between physical heterogeneity and invertebrate diversity in streams that were not in need of restoration.
3. We found habitat and macroinvertebrate data for 78 independent stream or river restoration projects described by 18 different author groups in which invertebrate taxa richness data in response to the restoration treatment were available. Most projects were successful in enhancing physical HH; however, only two showed statistically significant increases in biodiversity rendering them more similar to reference reaches or sites.
4. Studies manipulating structural complexity in otherwise healthy streams were generally small in scale and less than half showed a significant positive relationship with invertebrate diversity. Only one‐third of the studies that attempted to correlate biodiversity to existing levels of in‐stream heterogeneity found a positive relationship.
5. Across all the studies we evaluated, there is no evidence that HH was the primary factor controlling stream invertebrate diversity, particularly in a restoration context. The findings indicate that physical heterogeneity should not be the driving force in selecting restoration approaches for most degraded waterways. Evidence suggests that much more must be done to restore streams impacted by multiple stressors than simply re‐configuring channels and enhancing structural complexity with meanders, boulders, wood, or other structures.
6. Thematic implications : as integrators of all activities on the land, streams are sensitive to a host of stressors including impacts from urbanisation, agriculture, deforestation, invasive species, flow regulation, water extractions and mining. The impacts of these individually or in combination typically lead to a decrease in biodiversity because of reduced water quality, biologically unsuitable flow regimes, dispersal barriers, altered inputs of organic matter or sunlight, degraded habitat, etc. Despite the complexity of these stressors, a large number of stream restoration projects focus primarily on physical channel characteristics. We show that this is not a wise investment if ecological recovery is the goal. Managers should critically diagnose the stressors impacting an impaired stream and invest resources first in repairing those problems most likely to limit restoration.
Hosts can protect themselves against parasites by actively reducing parasites burden (i.e. resistance) or by limiting the
damages caused by parasites (i.e. tolerance). Disentangling between tolerance and resistance is important for predicting the
evolutionary outcomes of host-parasite interaction. Dace (Leuciscus leuciscus) are often parasitized by the ectoparasite Tracheliastes polycolpus which feeds on (and destroys) fins, reducing thus the host’s condition. We tested the hypothesis that genetically-based variation
in ectoparasite tolerance exists in a wild dace population. We found that moderately heterozygous dace, which are less resistant
than highly heterozygous or homozygous dace, tolerated better the effect imposed by T. polycolpus for a given parasite burden. However, tolerance also varied upon environmental conditions, suggesting that genetic and environmentally-based
variation exists for both resistance and tolerance in this natural host-parasite system. Moreover, a negative genetic correlation
may exist between tolerance and resistance, and hence several evolutionary outcomes are possible in this interacting system.
KeywordsResistance-Inbreeding-Heterozygosity-fitness correlations-Ectoparasite-Co-evolution-Arm race-Genetic correlation-Virulence-Pathogenic effects-Environmental effects-Rivers-Pathogens-Microsatellites
The species-area relationship of the island biogeography theory was calculated for macroinvertebrates in 22 coastal, adjacent streams. A z-value of 0.19 was obtained. The low z-value was probably a consequence of the short distances between streams as well as high dispersal rates. In addition, a cluster analysis based on the dissimilarity of species assemblages showed that stream size was of prime importance in categorizing the streams. To a smaller extent water quality affected the community structure in the streams.
Effective management of our natural resources requires an understanding of ecosystem structure and function; effectively, an ecosystem-based approach to management. Parasites occur, albeit cryptically, in almost all ecosystems, yet they are usually neglected in studies on populations and communties of organisms. Parasites can have pronounced or subtle effects on hosts affecting host behavior, growth, fecundity, and mortality. Furthermore, parasites may regulate host population dynamics and influence community structure. Many parasites have complex life cycles and depend for transmission on the presence of a variety of invertebrate and vertebrate intermediate hosts. Often transmission involves predator–prey interactions. Thus, parasites reflect the hosts position in the food web and are indicative of changes in ecosystem structure and function. Parasites can provide information on population structure, evolutionary hypotheses, environmental stressors, trophic interactions, biodiversity, and climatic conditions. I use examples from diverse freshwater and marine systems to demonstrate that parasites should be incorporated into research and monitoring programs to maximize information gathered in ecosystem-based studies and resource management.
There are good reasons for focusing on parasites in the search for indicators to monitor the effects of pollutants on marine organisms. Firstly, there are more parasitic than free-living species. Secondly, in parasites with complex life cycles, the different stages have widely differing requirements, so that each stage must be assessed separately, thereby greatly increasing the number of potential indicators. Thirdly, many parasites have delicate free-living transmission stages which are highly sensitive to environmental change. A reduction in their levels of infection will serve as an early warning that changes are occurring. Conversely, other parasites are highly resistant to environmental change and will respond by increased levels of infection. As a general rule, infections with endoparasitic helminths tend to decrease, while infections with ectoparasites tend to increase, with increasing levels of pollution.
Numerous studies have indicated that aquatic pollution affects parasite populations and communities. However, the responses of individual taxa and functional groups to specific contaminants, and their effect sizes, have yet to be assessed quantitatively. We began by summarizing general trends in the literature, and found that reports of significant changes in parasitism were most commonly observed in response to eutrophication and metal contamination. Among parasite taxa, significant changes were most commonly reported for acanthocephalans, digeneans and microparasites. We then conducted a quantitative meta-analysis of the effects of pollution on parasitism in aquatic animals. We calculated signed standardized effect sizes (as Cohen's d) for all published studies that provided the necessary descriptive statistics, and compared them among major contaminant types (pesticides, hydrocarbons, polychlorinated biphenyls, pulp mill effluent, metals, sewage, eutrophication, and acidification) and parasite taxa (Acanthocephala, Cestoda, Digenea, Monogenea, Nematoda and microparasites). Effect sizes were not significantly different from zero for many parasite/contaminant interactions, and tended to be highly variable within individual taxa. However, consistently strong, significant negative effects were noted in Digenea and Monogenea, especially in response to metal pollution. Significant effect sizes were typically negative, indicating that pollutants have negative effects on parasite populations. Contaminants also had a slightly negative effect on community richness. When parasites were grouped into heteroxenous (with >1 obligatory host in life cycle) vs. monoxenous (1 obligatory host in life cycle) taxa, the latter were more susceptible to a wide range of pollutants. Similarly, directly exposed (external parasites and the free-living transmission stages of internal parasites) and freshwater taxa were more susceptible to a wider range of pollutants than indirectly exposed (internal parasites) and marine taxa. This meta-analysis represented a first attempt to consider the size of the effect of pollution on parasites, and highlighted the potential of susceptible parasite taxa, communities, and functional groups for use in the biological assessment of pollution. For instance, our results indicate that freshwater monogeneans and digeneans are good candidates as potential biological indicators of pollution in aquatic ecosystems.
Previously published multidisciplinary studies in the Miramichi and Bouctouche rivers (New Brunswick, Canada) noted significant changes in fish health parameters, including elevated tissue levels of organic contaminants and a wide range of physiological disturbances, in mummichog Fundulus heteroclitus (L.) from a site on the Miramichi River that received bleached kraft pulpmill and municipal effluent. The present study reports differences in the abundance of individual parasite species, as well as parasite infracommunity and component community composition, in mummichog from both rivers. These differences were evaluated in relation to host (size, condition, immune function, tissue organochlorine contaminant levels) and environmental (faecal coliform counts, salinity, temperature) data derived from the previously published studies. Overall, 18 parasite species were identified, the most common of which were Ascocotyle sp. larv., Ornithodiplostomum sp. larv., Posthodiplostomum sp. larv., and Proteocephalus filicollis (Rudolphi, 1802). There were broad differences in parasite community structure and composition between rivers and within rivers, the most prominent pattern being a pronounced difference between sites in the upper and lower estuary of each river that was likely driven by salinity. Mean infracommunity richness was also positively related to faecal coliforms (considered here as a surrogate measure of eutrophication via municipal sewage), and both were highest at the most polluted site. We noted no other significant relationships. Thus our data suggest that the parasite communities in these two estuaries were primarily structured by large upstream/downstream ecological gradients in salinity, and secondarily by eutrophication due to pollution by municipal and industrial effluents. Overall, our results highlight the value of coordinated multidisciplinary studies for understanding the factors that shape parasite abundance and community structure.
Parasite communities in four study lakes in 1986 reflected the influences of eutrophication, pollution, and habitat fragmentation. Discriminant analyses of communities at the individual host level revealed two major axes. One contrasted communities in a lake affected by chemical pollution from a pulp mill with those from two eutrophic, less polluted lakes. Changes in the density of intermediate hosts, direct effects on ectoparasites, and impaired immune systems were regarded as important mechanisms. The second contrasted communities in an oligotrophic, unpolluted lake with those from the two eutrophic lakes and was more complex, reflecting habitat fragmentation (the absence of glochidia and some digeneans) and pollution or eutrophication, probably mediated by the same mechanisms as above. Changes in some index parasites in Lake Vatia monitored in 1994, following 8 years of reduced pollutant loading, supported our conclusion that parasite faunas in Lake Vatia in 1986 involved the effects of pollution.
Late summer myxozoan infra- and component communities parasitizing 73 Notropis hudsonius at 5 sites on the St. Lawrence River upstream and downstream from the island of Montreal are described from study of histological sections of individual fish. Community membership included Myxobolus sp. A (intracellular in striated muscle fibers), Myxobolus sp. B (intracellular in striated muscle fibers), Myxobolus sp. C (brain), and Thelohanellus notatus (Mavor, 1916) Kudo, 1929 (loose connective tissue), all of which are histozoic myxobolids displaying strict tissue specificity for trophozoite development. Mean infracommunity richness in fish at the separate localities was estimated to be 0.4 +/- 0.5 to 1.3 +/- 0.7, with a maximum richness of 3 in any 1 fish. Component community richness in host samples was 2 to 4. It is argued that these are relatively high levels of diversity for freshwater fish parasites but that the values are probably conservative because of the study of only portions of individual fish. The percentage of fish infected with myxozoans of any species and infracommunity richness was significantly greater below the island of Montreal compared with above it. It is suspected that increased oligochaete populations at these sites, resulting from sewage-caused organic enrichment of sediments, may have accounted for the observed increased prevalence of infection.
Selected features of the responses by fish to helminth parasites are discussed and comparison is made where appropriate with mammals. These include: (i) Factors influencing host specificity and consideration of the mechanisms that underpin the restriction of some parasites in their host spectrum, (ii) How fish leucocytes kill helminth larvae, with emphasis on the role of released oxygen (ROS) and nitrogen (RNS) free radicals from macrophages, (iii) Immune evasion strategies used by fish helminths, including invasion of immunologically privileged sites, encystment, adsorption of host proteins on the parasite surface, and high surface membrane turnover, (iv) Potential immunogens for vaccination and use for immonodiagnosis of infection, and (v) Natural and induced protection against helminths, with emphasis on the potential for future vaccination strategies.
Approximately 30 species of larval and adult parasites were collected from 549 centrarchid fish and 7718 gastropod molluscs from an oligotrophic and two eutrophic lakes in southwestern Michigan. The distribution pattern indicates that centrarchids from the oligotrophic lake harbor a wide range of species of adult parasites and a comparatively smaller number of larval forms, many of which complete their life cycles in predatory fish. On the other hand, bass and sunfish from the two eutrophic lakes harbor a proportionately larger number of larval parasites, most of which culminate their life cycles in fish-eating birds and mammals. A trophic hypothesis, based on the nature of predatorprey relationships in each of the two types of ecosystem, is proposed to explain the distribution patterns of parasites.
Parasite communities tend to be dissimilar in hosts that are geographically, phylogenetically, ecologically and developmentally distant from one another. The decay of community similarity is a powerful and increasingly common method of studying parasite beta diversity, but most studies have examined only a single type of distance. Here, we evaluate distances based on the phylogeny, ecology, spatial proximity and size of hosts, as predictors of the similarity of parasite communities in individual hosts, host populations and host species. We surveyed parasites in six species of fish collected simultaneously from six localities in the St. Lawrence River, Canada, and species in a common group of larval parasites were discriminated using DNA sequences from barcode region of cytochrome c oxidase I. Distances based on the habitat use patterns of host species were good predictors of short-term, ecological similarity of parasite communities, such as that operating at the scale of the individual host. The genetic distance between host species was associated with almost all types of similarity at all scales, particularly qualitative and phylogenetic similarity of parasite communities at the level of populations and meta-populations of hosts. The trophic level, diet, spatial proximity and size of hosts were poor predictors of parasite community similarity. The increased taxonomic resolution provided by molecular data increased the explanatory power of regression models, and different factors were implicated when parasite species were distinguished with DNA barcodes than when larval parasites were lumped into morphospecies, as is commonly practiced.
The health assessment index (HAI) is an extension and refinement of a previously published field necropsy system. The HAI is a quantitative index that allows statistical comparisons offish health among data sets. Index variables are assigned numerical values based on the degree of severity or damage incurred by an organ or tissue from environmental stressors. This approach has been used to evaluate the general health status offish populations in a wide range of reservoir types in the Tennessee River basin (North Carolina, Tennessee, Alabama, Kentucky), in Hartwell Reservoir (Georgia, South Carolina) that is contaminated by polychlorinated biphenyls, and in the Pigeon River (Tennessee, North Carolina) that receives effluents from a bleached kraft mill. The ability of the HAI to accurately characterize the health offish in these systems was evaluated by comparing this index to other types of fish health measures (contaminant, bioindicator, and reproductive analysis) made at the same time as the HAI. In all cases, the HAI demonstrated the same pattern offish health status between sites as did each of the other more sophisticated health assessment methods. The HAI has proven to be a simple and inexpensive means of rapidly assessing general fish health in field situations.
Parasites occur in nearly every population. They often interact in complex ways with other stressors. In some cases, the interaction may lead to a disproportionately negative effect on the host population. In other Cases, the stressor may ameliorate the effects of parasitism. Here we illustrate intersections of four types of environmental stressors with infectious diseases: First, pollutants may increase parasitism by increasing host susceptibility or by increasing the abundance of intermediate hosts and vectors. Pollutants can also decrease parasitism if infected hosts suffer differentially high mortality, parasites are more susceptible to pollution than their hosts, or if pollutants negatively affect intermediate hosts or vectors. These effects vary depending on the particular parasite and pollutant that interact. Second, habitat alterations such as impounding water or development can affect both intermediate host and vector populations such that the abundance of their attendant parasites is either increased or reduced. Third, fisheries can impact populations already stressed by disease. However, they may act to lower the density of a host population below the threshold for sustained transmission to such an extent that the parasite population can no longer persist. Fourth, introduced species may introduce new diseases to susceptible native populations or they may gain an advantage if they invade without the parasites from their native range. The complexity and ubiquity of these interactions are good arguments for considering parasitism when evaluating stressors of aquatic systems.
Low environmental temperatures are immunosuppressive for ectothermic vertebrates, such as teleosts. In particular the available data support the notion that, at least in channel catfish, virgin T cells, rather than memory T cells, B cells or accessory cells are particularly susceptible to the inhibitory influences of lower temperatures on adaptive immune responses. The probable mechanisms involved in such suppression in teleosts are reviewed, and considerations are offered regarding cause and effect relationships between such immunosuppression and the development of infectious diseases in fish.
Threats to imperiled freshwater fauna in the U.S. were assessed through an experts survey addressing anthropogenic stressors and their sources. Specifically, causes of historic declines and current limits to recovery were identified for 135 imperiled freshwater species of fishes, crayfishes, dragonflies and damselflies, mussels, and amphibians. The survey was designed to identify threats with sufficient specificity to inform resource managers and regulators faced with translating information about predominant biological threats into specific, responsive actions. The findings point to altered sediment loads and nutrient inputs from agricultural nonpoint pollution; interference from exotic species; and altered hydrologic regimes associated with impoundment operations as the three leading threats nationwide, accompanied by many lesser but still significant threats. Variations in threats among regions and among taxa were also evident. Eastern species are most commonly affected by altered sediment loads from agricultural activities, whereas exotic species, habitat removal/damage, and altered hydrologic regimes predominate in the West. Altered sediment loading from agricultural activities and exotic species are dominant problems for both eastern mussels and fishes. However, eastern fishes also appear to be suffering from municipal nonpoint pollution (nutrients and sediments), whereas eastern mussels appear to be more severely affected by altered nutrient impacts from hydroelectric impoundments and agricultural runoff. Our findings suggest that control of nonpoint source pollution associated with agriculture activities should be a very high priority for agricultural producers and governmental support programs. Additonally, the large number of hydropower dams in the U.S. subject to federal re-licensing in coming years suggests a significant opportunity to restore natural hydrologic regimes in the affected rivers.Se estimaron amenazas a la fauna dulceacuícola de los Estados Unidos en riesgo mediante un estudio de expertos enfocado en estresores antropogénicos y sus fuentes. Se identificaron específicamente las causas de disminuciones históricas y los límites actuales para la recuperación de 135 especies dulceacuícikolas de peces, langostinos, libélulas, mejillones y anfibios en riesgo. El estudio fué diseñado para identificar amenazas con suficiente especificidad como para informar a los manejadores de recursos y reguladores que encaran la traducción de información sobre amenazas biológicas predominantes en acciones específicas y sensibles. Los resultados apuntan hacia cargas de sedimentos y entrada de nutrientes alterados por fuentes agriculturales sin puntos de contaminación; interferencia de especies exóticas y regímenes hidrológicos alterados asociados a operaciones de retención, como las amenazas más importantes a nivel nacional, acompañadas por muchas otras menores pero aún significativas amenazas. Tambien fueron evidentes variaciones entre regiones y entre taxas. Las especies del este son mas comunmente afectadas por cargas de sedimentos de actividades agriculturales, mientras que las especies exóticas, la remoción/daño del hábitat y alteración de regimen hidrológico predominaron en el oeste. Cargas de sedimentos alteradas por actividades agriculturales y especies exóticas son problemas dominantes tanto en mejillones como en peces del este. Sin embargo, los peces del este aparentemente también sufren de descargas municipales sin puntos de contaminación (nutrientes y sedimentos), mientras que los mejillones parecen ser mas severamente afectados por la ateración de nutrientes debido a retenciones hydroeléctricas y descargas agriculturales. Nuestros resultados indican que el control de fuentes de contaminación sin puntos asociadas a actividades agriculturales deben ser de alta prioridad para los productores agrícolas y programas de soporte gubernamental. Adicionalmente, la gran cantidad de represas en los Estados Unidos sujetas a re-expedición de licencias federales en los próximos años, sugiere una oportunidad significativa para restablecer los regímenes hidrológicos en los ríos afectados.
Selected features of the responses by fish to helminth parasites are discussed and comparison is made where appropriate with mammals. These include: (i) Factors influencing host specificity and consideration of the mechanisms that underpin the restriction of some parasites in their host spectrum, (ii) How fish leucocytes kill helminth larvae, with emphasis on the role of released oxygen (ROS) and nitrogen (RNS) free radicals from macrophages, (iii) Immune evasion strategies used by fish helminths, including invasion of immunologically privileged sites, encystment, adsorption of host proteins on the parasite surface, and high surface membrane turnover, (iv) Potential immunogens for vaccination and use for immunodiagnosis of infection, and (v) Natural and induced protection against helminths, with emphasis on the potential for future vaccination strategies.
Threats to imperiled freshwater fauna in the U.S. were assessed through an experts survey addressing anthropogenic stressors and their sources. Specifically, causes of historic declines and current limits to recovery were identified for 135 imperiled freshwater species of fishes, crayfishes, dragonflies and damselflies, mussels, and amphibians. The survey was designed to identify threats with sufficient specificity to inform resource managers and regulators faced with translating information about predominant biological threats into specific, responsive actions. The findings point to altered sediment loads and nutrient inputs from agricultural nonpoint pollution; interference from exotic species; and altered hydrologic regimes associated with impoundment operations as the three leading threats nationwide, accompanied by many lesser but still significant threats. Variations in threats among regions and among taxa were also evident. Eastern species are most commonly affected by altered sediment loads from agricultural activities, whereas exotic species, habitat removal/damage, and altered hydrologic regimes predominate in the West. Altered sediment loading from agricultural activities and exotic species are dominant problems for both eastern mussels and fishes. However, eastern fishes also appear to be suffering from municipal nonpoint pollution (nutrients and sediments), whereas eastern mussels appear to be more severely affected by altered nutrient impacts from hydroelectric impoundments and agricultural runoff. Our findings suggest that control of nonpoint source pollution associated with agriculture activities should be a very high priority for agricultural producers and governmental support programs. Additonally, the large number of hydropower dams in the U.S. subject to federal re-licensing in coming years suggests a significant opportunity to restore natural hydrologic regimes in the affected rivers.
Tolerance values for families of arthropods are presented to enable calculation of a family-level biotic index (FBI) in the field. In six streams differing in substrates and degree of organic pollution, an average of 23 min, 35 s was needed to assess the condition of a stream in the field using the FBI; this period was at least an hour less than is normally required to evaluate a stream with the generic- and species-level biotic index (BI). Comparison of the FBI and BI of replicated samples from these six streams and from 120 random samples from other Wisconsin streams showed that some accuracy is lost by using the FBI, with the FBI usually indicating greater pollution than the BI in unpolluted or slightly polluted streams and less pollution in polluted streams. The purpose of the FBI is to provide a rapid, but less critical, evaluation of streams in the field by biologists who can recognize arthropod families by sight. It is not intended as a substitute for the BI.
Actinocleidus oculatus (Mueller, 1934), the type species of Actinocleidus Mueller, 1937, and A. recurvatus Mizelle and Donahue, 1944 (Monogenea: Ancyrocephalinae) from the gills of Lepomis gibbosus L. (pumpkinseed) in Ontario, Canada, are redescribed with details of their internal anatomy as well as the sclerotized components of the haptor and copulatory complex. A revised generic diagnosis incorporating features of the reproductive system is presented.
A review of literature suggested that yield of Eurasian perch, Perca fluviatilis, in Lake Constance was greatest with moderate eutrophication. During eutrophication (1950–76), changes also took place in food, growth, distribution, and diseases of perch. Differences in perch between Lake Constance and other German or Alpine lakes of various degrees of eutrophy were found with respect to growth, yield, the relation of growth to yield, food, and the relation of food to growth. Similarities were apparent for perch in these lakes in terms of their age composition, age at maturity, and mortality. Only limited data were available for pikeperch, Stizostedion lucioperca, mainly on stocking success, yield, and growth. The status of percids in Lake Constance indicates that eutrophication has led to conditions favoring percids. Key words: Percidae, Lake Constance limnology, eutrophication, yield, Perca fluviatilis, food, growth, distribution, disease, Stizostedion lucioperca
SUMMARY This paper deals largely with the dynamics and changes in the helminth parasite communities of fish along the trophic gradient of lakes. The use of parasitological community data as a bioindicator of environmental health underlines the need to study parasite communities at comparable localities with known pollution levels. The comparison of the conditions in different habitats might be helpful to differentiate between normal fluctuations in ambient conditions and pollution-mediated effects. Therefore, the present study was designed to examine the community structure of parasites in snow trout (Schizothorax niger Heckel) inhabiting 3 lakes of contrasting trophic status in Kashmir. The idea of selecting the lakes, namely Anchar (strongly hypereutrophic), Dal (eutrophic) and Manasbal (mesotrophic) for this study was intentional as they depict different trophic gradients and exhibit the desirable pattern which was a prerequisite for this study. The findings presented in this article suggest an apparent lake-wise gradient in community structure, as the increase in trematode and cestode infections in Anchar was markedly greater, to levels clearly distinguishable from those in the other two water bodies. We conclude that human-induced eutrophication of lakes modifies the parasite community at component level and community-level studies on parasites may provide information on health status of lakes.
Severe melanotic liver and visceral fibroses in bluegill associated with infections of plerocercoids of Proteocephalus sp. and metacercariae of the digenean Posthodiplostomum minimum, were studied by light and transmission electron microscopy. Fibrosis was most evident in bluegill carrying heavy worm burdens. Tubular and multilocular melanotic and non-melanotic cysts were formed of concentric layers of non-cellular eosinophilic connective tissue surrounding central spaces containing basophilic material. Moribund and deteriorating plerocercoids and metacercariae were surrounded by, and sometimes invested with, fibrous tissue. Living plerocercoids in the liver were surrounded by necrotic and compressed hepatocyte zones. Fibro-blasts, epithelioid cells and eosinophilic granulocytes were common in compressed cell zones. Intrahepatic fibrotic cysts were surrounded by granulomatous zones. Parenchyma in fibrotic livers showed increased numbers of macrophages, melano-macrophage centres and engorged blood vessels with thickened walls. Histochemical tests for lipofuscin and haemosiderin were strongly positive in melanotic liver tissue. Ultrastructural changes in hepatocytes adjacent to fibrotic cysts and epithelioid zones included intranuclear lipid and glycogen inclusions, chromatin alterations and mitochrondrial degeneration. Bile canaliculi, sinusoids and perisinusoidal spaces showed reduced micro villarsurfacesand a decrease in luminar diameter. Degenerating hepatocytes contained phagolysosomes and myelin bodies.
Seven biomarkers in 204 spottail shiners Notropis hudsonius were examined for effects of pollution and parasites on fish health at localities along the St Lawrence River, Canada. The number of pigmented macrophage centres and pigmented macrophages in the spleen was significantly higher at polluted localities receiving urban and industrial effluents than at reference localities, indicating that they were good indicators of exposure to pollution in spottail shiners. Seven of the nine species of parasites found in 1+ year fish showed significant correlations with biomarkers. More parasites (18 species) but fewer correlations with biomarkers were observed in 2+ year fish, indicating that parasite effects were more pronounced in young spottail shiners. A significant negative relationship was observed between condition factor and Neoechinorhynchus rutili in 1+ year fish, suggesting its potential pathological significance in young spottail shiners. High abundance of Plagioporus sinitsini was associated with higher spleen macrophage counts and lower indices of condition at polluted localities. Furthermore, infection by P. sinitsini in polluted conditions appeared to have a greater negative effect on fish health than either stressor alone, providing further evidence that parasites should be considered when examining effects of pollution on fish health.
A laboratory study was conducted to determine copper toxicity to the endoparasitict ematode Posthodiplostomum minimum (MacCallum) relative to snail first intermediate hosts and bluegills (Lepomis macrochirus Rafinesque) as second intermediate hosts. To determine copper effects on cercariae, the life-cycle stages of P. minimum were established in the laboratory. A 96-h median lethal concentration (LC50) test for bluegills was performed, and the calculated value of 0.892 mg/L total Cu was considered in selection of copper concentrations for all other experiments. Snail hosts (Physella gyrina (Say)) exposed to copper concentrations equal to 0, 8.9, 22.3, 44.6, and 89.2 μg/L Cu, exhibited a significant toxic response with ∼64% and ∼87% mortality occurring in the 44.6 and 89.2 μg/L concentrations, respectively. The 7-d LC50 for snails was 38.0 μg/L Cu. Free-swimming cercariae exposed to the same copper concentrations exhibited a similar toxic response with a 9-h LC50 of 32.0 μg/L Cu and a 12-h LC50 of 26.0 μg/L Cu.
We conducted a Before-After-Control-Impact (BACI) study using larval di-geneans infecting the California horn snail, Cerithidea californica, to evaluate the success of an ecological restoration project at Carpinteria Salt Marsh in California, USA. Digenean trematodes are parasites with complex life cycles requiring birds and other vertebrates as final hosts. We tested two hypotheses for prevalence and species richness of larval trem-atodes in C. californica: (1) prior to the restoration, sites to be restored would have lower trematode prevalence and species richness relative to unimpacted control sites, and (2) that these differences would diminish after restoration. The sites to be restored were initially degraded for trematode species. They had a mean trematode prevalence (12%) and species richness (4.5 species) that were lower than control sites (28% trematode prevalence and 7 species). Despite the differences in prevalence, the proportional representation of each trematode species in the total community was similar between sites to be restored and control sites. Over the six years following restoration, trematode prevalence nearly qua-drupled at restored sites (43%) while the prevalence at control sites (26%) remained un-changed. In addition, species richness at restored sites doubled (9 species), while species richness at the control sites (7.8 species) did not change. Immediately after restoration, the relative abundance of trematode species using fishes as second intermediate hosts declined while those using molluscs as second intermediate hosts increased. Trematode communities at restored and control sites gradually returned to being similar. We interpret the increase in trematode prevalence and species richness at restored sites to be a direct consequence of changes in bird use of the restored habitat. This study demonstrates a new comparative technique for assessing wetlands, and while it does not supplant biotic surveys, it informs such taxonomic lists. Most importantly, it provides a synthetic quantification of the linkages among species in wetland food webs.
Since 1900, 123 freshwater animal species have been recorded as extinct in North America. Hundreds of additional species of fishes, mollusks, crayfishes, and amphibians are considered imperiled. Using an exponential decay model, we derived recent and future extinction rates for North American freshwater fauna that are five times higher than those for terrestrial fauna. Assuming that imperiled freshwater species will not survive throughout the next century, our model projects a future extinction rate of 4% per decade, which suggests that North America's temperate freshwater ecosystems are being depleted of species as rapidly as tropical forests.
Resumen: Desde 1900, 123 especies animales de agua dulce han sido reportadas como extintas en Norteamérica. Cientos de especies adicionales de peces, moluscos, langostinos y anfibios están considerados como amenazados. Utilizando un modelo exponential de disminución, derivamos tasas de extinciones recientes y futuras para la fauna de agua dulce de Norteamérica, mismas que son cinco veces mayores que aquellas para la fauna terrestre. Asumiendo que las especies de agua dulce en peligro no sobrevivirán a lo largo del próximo siglo, nuestro modelo proyecta una tasa de extinción futura de 4% por décda, lo cual sugiere una disminución de especies en los ecosistemas templados de agua dulce de Norteamérica tan rápida como la que ocurre en bosques tropicales.
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Monogeneans are of great interest to the ecologists because of their simple life cycle and are considered as one of the important and sensitive parasites to any changes in water quality. The monogenean gill parasite, Diplozoon kashmirensis of the Carassius carassius was examined with the aim to evaluate the infection level and the factors influencing the infection. Our results showed that highest prevalence (34.22%) of D. kashmirensis was in the lake having high trophic status and least prevalence (10.90%) in the lake having least trophic status. Infection levels were significantly higher at the basins/sites having deteriorated water quality in comparison to the basins/sites having better water quality. The combined effect of pollutants and eutrophication showed decrease in intensity of D. kashmirensis in one of the polluted/hypertrophied site in the hypertrophic lake (Anchar Lake), while as synergistic effect (i.e. increase) on prevalence and intensity was observed in one of the polluted/hypertrophied site in the eutrophic lake (Dal Lake). Sex was not an important factor influencing the D. kashmirensis in three lakes. The study showed that condition factor was significantly higher in the hypertrophic lake and in an uninfected fish. In addition microhabitat influenced the Diplozoon infection. Most preferable site for the D. kashmirensis was middle sector of the gill. Furthermore, the gill parasite showed significantly positive correlation (rp=0.6, P<0.05) with water temperature in the hypertrophic lake, thus showing the impact of water temperature on this parasite. It was concluded that intra lake differences, season, condition factor, microhabitat and water temperature influenced the infection of D. kashmirensis. It seems from the data that eutrophic and hypertrophic habitats were favourable for the D. kashmirensis. The D. kashmirensis showed both antagonistic and synergistic response to the combined effect of pollution and eutrophication.
It is probable that very young Physa became infected with the cercariae of P. minimum centrarchi. Snails infected in nature produced 840 to 8,940 cercariae per 24 hours, and the maximum longevity of cercariae was 32 hours. Cercariae were found to be infective for at least 24 hours after emergence. Cercariae did not emerge at 15 °C, but did at 18 °C and higher; they were not infective at 15 °C, but were at 18 to 27 °C. Of 14 species of fish exposed to the cercariae of the centrarchid line only sunfish and bluegills became infected. Fathead minnows were experimentally infected with the minnow line of cercariae. Metacercariae taken from a species of one fish family and transplanted into a species of a different fish family did not survive as long as when transplanted into a fish of the same family.
The cumulative effects of multiple stressors are becoming a priority concern for ecotoxicologists, ecologists and conservation biologists working to understand threats to ecosystems and species. In that context, parasites and pathogens are increasingly a focus of attention. Parasites interact with natural and anthropogenic stressors to increase mortality and reduce animal health in myriad ways in a wide spectrum of host and parasite taxa. The combined effects of parasites and other stressors can reduce either resistance or tolerance to infection. Recommendations are provided to guide further research.