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Development of a fish-based index to assess the ecological status of oceanic-temperate streams in the Northern Iberian Peninsula
Abstract
Multimetric indices based on fish assemblages assessing the ecological status of rivers have been widely developed. Nevertheless, the heterogeneity of environmental conditions, biological assemblages, and human pressures require the development of suitable indices for different regions. In the Iberian Peninsula, where there is a lack of an accurate tool for monitoring systems under temperate oceanic conditions, indices are developed under a Mediterranean climate. Therefore, our goal was to develop and validate a multimetric index based on fish assemblages to evaluate the ecological status of streams and rivers from the Northern Iberian Peninsula under a temperate oceanic climate. For this, 147 streams (41 reference and 96 disturbed streams) were monitored from 2010 to 2014. At each site, we calculated the stress level based on human alterations. For the index development, the rivers were grouped into two large classes: salmonids and cyprinids. Ninety-one metrics were tested for their capability to discern stress level. The index was calculated as the mean of five metrics for salmonid rivers: the percentage of density of benthic species, the percentage of richness of species intolerant to contamination, the percentage of richness of species intolerant to low oxygen concentrations, the percentage of insectivore density, and the percentage of Salmo trutta density. As the mean of two metrics for cyprinid rivers, we considered the percentage of density of water column species and the percentage of density of species intolerant to low oxygen levels. In salmonid rivers, the longitudinal connectivity was evaluated by measuring the presence of Anguila anguila. The index was split into five ecological status classes, ranging from 0 (bad ecological status) to 1 (high ecological status). This index was compared with four other biological indices and its performance was validated for 793 study cases, thus demonstrating its suitability for employment in biomonitoring works to assess the ecological status of stream and river ecosystems from the Northern Iberian Peninsula under temperate oceanic conditions.
... The presence of alien species in degraded conditions and consequently their impacts on native fish assemblages have also been shown to yield useful information (Brown, 2000;Ferreira et al., 2012). Thus, the use of indices based on fish assemblages may provide a more complete and integrated view of ecosystem condition than assemblages of more local distribution and shorter life spans, such as biofilm and macroinvertebrates (De Bikuna et al., 2017). Fish are also of interest to the public because of cultural, recreational, and economic interests (Barbour, Gerritsen, Snyder, & Stribling, 1999;Flotemersch, Stribling, & Paul, 2006;Linke et al., 1999;McCormick et al., 2001). ...
... The suite of metrics selected supports assessment of the system from the perspectives of species richness and composition, migratory status, functional feeding groups, and habitat preferences. This combination is suitable to reflect the heterogeneity of environmental conditions, biological assemblages, and human pressures (De Bikuna et al., 2017;Karr, 1981;Marzin et al., 2012;Mostafavi et al., 2015;Pont et al., 2006). Performances of individual metrics do not reliably predict the joint performance of their summed index (Blocksom, 2003;Van Sickle, 2010) but can show disturbances differently, as described below for some important metrics of the KFMMI. ...
Large river systems are one of the most important water resources for human societies. However, the ecological integrity of large rivers has been altered greatly by human activities. To monitor and manage these ecosystems, multimetric indices (MMI) are considered as efficient tools. This study aimed to develop and validate a fish-based multimetric index for the Karun River basin, Iran (Karun fish-based multi-metric index [KFMMI]). Eighteen rivers and 54 sites in the basin were sampled in July-August 2019, and physico-chemical and habitat characteristics were used to identify reference sites based on principal components analysis (PCA). Of the 54 sites, 14, 26, and 14 sites were classified as least, moderate, and most disturbed sites, respectively. Fifty-four candidate metrics were evaluated for range, responsiveness, and redundancy with other metrics. This resulted in the identification of eight metrics (relative abundance of native and endemic taxa, relative richness of migratory taxa, relative richness of Leuciscidae taxa, relative richness of herbivorous taxa, relative abundance of cyprinid taxa, relative richness of vegetative inhabitant taxa, relative abundance of slow water flow, and relative richness of edge inhabitant taxa) that informed on species richness and composition, migratory status, functional feeding groups, and habitat preferences. The KFMMI showed excellent performance in separating least, moderate, and most disturbed sites in our study area. Regarding water quality, the KFMMI was classified 16, 5, and 29 sites as good, moderate, and bad, respectively. The discrimination efficiency of KFMMI was 81.6%, which makes it an effective management tool for directing restoration actions at most disturbed sites and intensifying protection of least disturbed sites. K E Y W O R D S biological indicator, fish metrics, multimetric index, reference site, water quality
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.
Multimetric indices based on biological communities for the assessment of the ecological status of streams and rivers have recently been developed for many regions. However, local differences in reference conditions, human impacts and biological communities make developing suitable indices for different regions of the world necessary. Thus, our goal was to develop and validate a multimetric index based on macroinvertebrates to evaluate the ecological status of streams from the Basque Country (north Spain). For this, 22 lowland calcareous streams (7 reference and 15 disturbed) were monitored from 1993 to 2005. At each study site, a stress level was calculated based on human impacts. Fifty-three macroinvertebrate metrics were tested for their capability to discern stress level. Our multimetric index was calculated as the mean of six metrics – genus richness, IBMWP, abundance of Sel_EPTD, abundance of Sel_ETD’, family richness of Sel_ETD and family richness of EPT. The index was split into five ecological status classes, ranging from 0 (bad ecological status) to 1 (high ecological status). This index was validated in 231 study sites in 108 streams of six different typologies, demonstrating suitability for application in biomonitoring and assessment studies in Basque streams.
The present work describes a field survey aiming at assessing the impact of a sewage treatment plant (STP) effluent on fish health by means of biomarkers. Indigenous fish were absent downstream of the STP. To elucidate the reason behind this, brown trout (Salmo trutta f. fario) were exposed in floating steel cages up- and downstream of a STP located at the Neckar River near Tübingen (Southern Germany), for 10 and 30 days. A combination of biomarker methods (histopathological investigations, analysis of the stress protein Hsp70, micronucleus test, B-esterase assays) offered the possibility to investigate endocrine, geno-, proteo- and neurotoxic effects in fish organs. Biological results were complemented with chemical analyses on 20 accumulative substances in fish tissue. Even after short-term exposure, biomarkers revealed clear evidence of water contamination at both Neckar River sites; however, physiological responses of caged brown trout were more severe downstream of the STP. According to this, similar bioaccumulation levels (low μg/kg range) of DDE and 12 polycyclic aromatic hydrocarbons (PAHs) were detected at both sampling sites, while up to fourfold higher concentrations of four PAHs, methyl-triclosan and two synthetic musks occurred in the tissues of downstream-exposed fish. The results obtained in this study suggest a constitutive background pollution at both sites investigated at the Neckar River and provided evidence for the additional negative impact of the STP Tübingen on water quality and the health condition of fish.
Adjustment of the Index of Biotic integrity (IBICAT) based on the use of fish as indicators of the environmental quality of the rivers of Catalonia
The objective of this study was to develop a rapid multimetric index using benthic macrofauna as bioindicators of ecological conditions for the upper reaches of the Piabanha-Paquequer-Preto Basin located in the state of Rio de Janeiro, Brazil. A total of 33698 macroinvertebrates were collected in 27 sites. Benthic macroinvertebrates were sampled using the multi-habitat method that consists in sampling 20 m2 of substrate collected in approximate proportion to the representation of all major habitat types in the reach. A subsampling procedure was used. The main steps followed to develop and test the index were: exclusion of unsuitable metrics using box-whisker plots, considering the degree of overlapping among interquartile limits (1º-3º) and confirmed by Mann-Whitney U test (p < 0.05) using six reference rivers and six impaired rivers. From all the candidate potential metrics, 36 were considered suitable. After identifying redundant metrics, through Spearman correlation analysis, and considering practical application criteria, six core metrics were selected to compose the Piabanha-Paquequer-Preto Multimetric Index (PPPMI) using the continuous method: Family richness, Shannon-Wiener family diversity, EPT family richness, %Diptera, %MOLD (Mollusca + Diptera) and %Collectors. The sensitivity of the index was tested in 15 rivers using a Principal Components Analysis (PCA) of the six environmental variables. The first axis of the PCA was highly correlated to the PPPMI scores (r = 0.703, p < 0.001). The PPPMI responded to a set of environmental variables associated to a gradient of human disturbance affecting the ecological condition of the waterbodies. This indicates that the PPPMI is an effective tool for biological monitoring and decision making in the hydrographic region of the Piabanha-Paquequer-Preto rivers.
1. Natural and anthropogenic disturbances are key forces governing the structure and functioning of aquatic communities. Understanding how these factors shape organism performance can help to identify the most vulnerable species and develop effective management strategies. This is particularly important for ichthyofaunas with high endemicity and low diversity, such as those of the Iberian peninsula.
2. We explored the suitability of a novel and simple condition index, the scaled mass index (SMI), based on mass-length relationships, for analysis of the effects that abiotic and biotic pressures have on the body condition of four fish taxa widely distributed in Mediterranean rivers in north-eastern Spain: Brown trout (Salmo trutta), Iberian redfin barbel (Barbus haasi), Ebro barbel (Luciobarbus graellsii) and minnows (Phoxinus spp.). The SMI performed better in explaining spatial variation in body condition than the Fulton Index, a traditional method for fish studies.
4. For all taxa, anthropogenic stressors influencing water quality and physical habitat explained more variance in SMI than other factors. Variation partitioning and GLM approaches consistently showed that SMI increased with elevation, reduced concentrations of toxic nitrogenous compounds, and well preserved riparian canopy and natural channel morphology, despite the fact that three of the study taxa are in expansion and generally considered “tolerant”. In addition, the application of SMI to an independent fish data-set showed that SMI provides a novel indicator of ecosystem health which performs better than the current index of biotic integrity developed in this region.
5. We discuss the likely mechanisms behind the strong effects of habitat quality on SMI, and the implications for our understanding of tolerance. Incorporating SMI into studies of fish monitoring is likely to improve the value of fish studies as indicators of river quality and ecological change. Further studies should compare the response of SMI to specific fish health indicators such as parasite load, haematological assays and pollutant bioaccumulation to improve our understanding of the value of SMI as a non-lethal diagnostic procedure.
Keywords: Mediterranean rivers, disturbance, endemic fish, body condition, non-lethal procedures, hierarchical partitioning, tolerance range, conservation status
The state–of–the–art in habitat modelling in the context of minimum flow requirements in Spanish rivers is presented. During the last decade Spanish Water Authorities, by law, had to include evaluations of ‘ecological flows’ (considered as minimum instream flows) in their water planning. Most of the ‘ecological flows’ determinations have been based on historical flow records (10% mean annual flow or flow frequency distribution) with no serious limnological considerations. However, as environmental awareness increased, Spanish Water Authorities and natural conservation institutions have promoted studies on instream flows based on different ethodologies. Palau and Alcazar (1996) proposed a method based on the application of the simple moving average forecasting model as a tool to obtain the information of minimum flows from historical daily flow records. In the Basque country, Docampo and de Bikuña (1995) developed a peculiar method based on the hypothesis that macro–invertebrate communities change along the river continuum. For each watershed, they have elaborated empirical relationships between the number of benthic species, the channel wetted perimeter and the instream flow, and it is assumed that the minimum acceptable flow is the one that is able to maintain at least 15 different species. Our laboratory has been working on flow requirements in streams and rivers based on habitat modelling through Instream Flow Incremental Methodology (IFIM). More than 100 stream reaches in Spain have been studied, analysing bed topography, hydraulic, substrate and refuge conditions, natural flow regime and aquatic communities composition, phenology and habitat requirements. Relationships between instream flows and potential useful habitat were established using 1 and 2–D hydraulic models, together with the habitat requirements of key indigenous fish species and macrobenthic diversity.
Minimum flows were determined by selecting those flows that produced the greatest rate of habitat change. The evaluation of the potential habitat produced by natural flow regimes was used to understand the life strategy of autochthonous fishes and their flow requirements. Variability of the natural flow regime was found to be the main factor structuring stream types. In torrential Mediterranean streams, basic flows were ecologically nonsense because the stream channel is too large relative to the wetted channel produced by modal flows. Here, fisheries life strategy is migration and, therefore, minimum flows must be calculated at a scale larger than that of stream reach. Minimum flows, natural flow regime and the habitat requirement of native fish species at different scale, are the components used to the proposal of an ‘ecological flow regime’ for each river reach.
Eleven physicochemical variables (pH, temperature, oxygen, percentage of oxygen saturation, orthophosphate, nitrite, nitrate, ammonium, orthosilicate, organic matter and organic matter in sediment) have been analysed in 175 sampling sites during four seasons in 1985. A principal component analysis has been applied after standardization of the density function of the variables, according to skewness and kurtosis. Four main groups of sites have been differentiated. These groups represent different degrees in the redox process of organic matter. (A) Very oxygenated sites with high pH values indicating that the mineralization process prevails. Organic matter appears in low concentrations and a reduced state. (B) Sites nutrient enrichment where elements with high oxidation number prevail (nitrite, nitrate, and orthophosphate). (C) Sites supporting high organic pollution. (D) Sites subjected to heavy urban and/or industrial dumping.
Assignment of values for natural ecological benefits and anthropocentric ecosystem services in riverine landscapes has been problematic, because a firm scientific basis linking these to the river's physical structure has been absent. We highlight some inherent problems in this process and suggest possible solutions on the basis of the hydrogeomorphic classification of rivers.We suggest this link can be useful in fair asset trading (mitigationand offsets), selection of sites for rehabilitation, cost-benefit decisions on incremental steps in restoring ecological functions, and general protection of rivers.
/Users/richardjohnson/Desktop/REFCOND Policy Summary.pdf
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.
Abstract A spatially based, river type-specific approach was used to develop an ecological assessment method for European rivers based on existing sampling data. The methodology comprised two main steps: (1) description of a river and fish assemblage typology based on minimally or slightly impacted sites and (2) analyses of impacted conditions for each type. Hierarchical cluster analysis of fish species assemblages identified 15 homogeneous groups in 11 European ecoregions. Discriminant analyses, based on abiotic characteristics, were used to predict fish types at impacted sites. The latter encompassed both regional (geographic position in Europe) and local factors (longitudinal zonation) influencing the distribution of riverine fishes. To assess ecological status, the responses of more than 400 metrics (species composition, abundance and age–length structure) to human pressures were tested for each river type separately. A maximum of 10 metrics per river type was selected using discriminant analysis. The density of intolerant species and feeding guilds had the highest capacity to predict the intensity of perturbation.
1.An index of riparian quality useful for the management of streams and rivers is presented. The purpose of the index is to provide managers with a simple method to evaluate riparian habitat quality. The index is easy to calculate and can be used together with any other index of water quality to assess the ecological status of streams and rivers. It may also be a useful tool for defining ‘high ecological status’ under the EC Water Framework Directive.2.The index, named QBR, is based on four components of riparian habitat: total riparian vegetation cover, cover structure, cover quality and channel alterations. It also takes into account differences in the geomorphology of the river from its headwaters to the lower reaches. These differences are measured in a simple, quantitative way. The index score varies between 0 and 100 points.3.The QBR index is calculated in the field through a two-sided A4 page form that may be completed in 10 min.4.The development of the QBR index included trials in four Mediterranean stream catchments in Catalonia (NE Spain). Seventy-two sampling sites were assessed and results were used to test the index.5.No taxonomic expertise is needed to apply the index, although some knowledge of local flora is required to differentiate between native and non-native tree species.6.These results show that the QBR index may be used despite regional differences in plant communities. The quality ranges obtained when the index is applied are not heavily influenced by observers at the same site.7.At present, the index is being used by different research teams and tested in a comparative study of 12 watersheds along the Mediterranean Spanish coast.8.It is expected that the QBR index may be adapted for use in other geographical areas in temperate and semi-arid zones without changes in the index rationale. Copyright © 2002 John Wiley & Sons, Ltd.
A multimetric Index of Biotic Integrity (IBI) based on fish data was developed to assess the ecological status of Iberian streams, in the context of the European Water Framework Directive.Fish assemblages were determined by electrofishing at 114 sites from 10 basins of the Júcar River Basin District. The sampled streams were typical Mediterranean streams with strong variation in flow, a species-poor and tolerant fish fauna, and low ecological specialization of the fish species. These features make it difficult to employ metrics based on species richness, trophic specialization, and reproductive strategy, which are typical of IBIs and similar indices.The proposed IBI (IBI-Jucar) is composed of five metrics related to fish health, age-structure, and abundance and richness of native and alien species. IBI-Jucar was validated by demonstrating high correlation with various measures of environmental degradation and with several biotic and habitat indices. It was also highly correlated with the European Fish Index (EFI+), despite different methods used for development and contrasting metrics obtained.The results underline the complementarity of different biotic indices and show that indices based on fish can be a valuable tool for determining environmental quality, even in species-poor Mediterranean streams.Copyright © 2011 John Wiley & Sons, Ltd.
Implementation of the Water Framework Directive requires tools for measuring and monitoring the ecological status of aquatic
ecosystems. Several indices are in use in the Iberian Peninsula, although there has been little comparison among them. We
sampled the fish assemblage and limnological features of the Tordera stream (NE Spain) quarterly from September 2001 to May
2003 to evaluate the usefulness of several fish metrics and to compare habitat quality and biotic indices currently in use.
Data for eight biotic and abiotic indices for this and three other Catalan river basins were also compiled in order to analyse
the relationships among indices. In the Tordera stream, fish abundance and richness increased with stream order except in
the last sampling site that had the lowest fish abundance owing to the effects of drought and water abstraction. Although
most indices were positively correlated, some displayed low or null correlations particularly for the Tordera basin which
is more affected by water abstraction and less by pollution; a commonly used physico-chemical index (ISQA) was the least correlated.
In a regional fish index (IBICAT) under development, the brown trout (Salmo trutta) has been previously considered as introduced in the Tordera basin. Here, we report an old published record that demonstrates
that trout was present before 1845 and we argue that its status should be considered as uncertain given the current information
available. Whether brown trout is treated as native or introduced to this river basin has profound effects on the results
of fish metrics because of its dominance in the upper reaches. We briefly discuss the role of introduced species, particularly
in headwater streams, in the development of fish indices. Our study exemplifies the need for careful, basin-specific assessment
of native/introduced status in the development of fish metrics.
Multivariate predictive models are widely used tools for assessment of aquatic ecosystem health and models have been successfully
developed for the prediction and assessment of aquatic macroinvertebrates, diatoms, local stream habitat features and fish.
We evaluated the ability of a modelling method based on the River InVertebrate Prediction and Classification System (RIVPACS)
to accurately predict freshwater fish assemblage composition and assess aquatic ecosystem health in rivers and streams of
south-eastern Queensland, Australia. The predictive model was developed, validated and tested in a region of comparatively
high environmental variability due to the unpredictable nature of rainfall and river discharge. The model was concluded to
provide sufficiently accurate and precise predictions of species composition and was sensitive enough to distinguish test
sites impacted by several common types of human disturbance (particularly impacts associated with catchment land use and associated
local riparian, in-stream habitat and water quality degradation). The total number of fish species available for prediction
was low in comparison to similar applications of multivariate predictive models based on other indicator groups, yet the accuracy
and precision of our model was comparable to outcomes from such studies. In addition, our model developed for sites sampled
on one occasion and in one season only (winter), was able to accurately predict fish assemblage composition at sites sampled
during other seasons and years, provided that they were not subject to unusually extreme environmental conditions (e.g. extended
periods of low flow that restricted fish movement or resulted in habitat desiccation and local fish extinctions).
The Index of Biotic Integrity (IBI) is a measure of fish assemblage health that has been used to assess catchment and stream quality throughout North America. It reflects human perturbations on natural environmental structures and processes. While preserving the ecological foundation of the original North American metrics, we have modified and adapted the IBI to the mainstem Seine River and its major tributaries in France. This successful modification of the IBI to a considerably different fish fauna on a different continent further supports its wider use outside the midwestern United States. Using data collected in 1967, 1981, and 1988–1989 from a total of 46 sites, we show spatial and temporal variation in the Seine as indicated by IBI scores. Statistically significant relationships were found between IBI and catchment area but insignificant relationships existed between IBI and an independent Water Quality Index (WQI) based on water chemistry. Comparisons between the IBI and the WQI indicate that the former is a more sensitive and robust measure of water body quality. Our results demonstrate that the IBI, combined with a statistically designed national monitoring program, would offer a reliable means of assessing spatial patterns and temporal trends in water body improvement or degradation in France. The more primitive fish families in the Basin were affected first by perturbations. These families include all the diadromous species found in the Seine and suggest serious disruption of their life histories.
The assessment of the ecological status of freshwater ecosystems is a key issue for many international laws such as the Water Framework Directive (WFD) in light of the actual impoverished status of these ecosystems. Different multimetric approaches have been successfully developed in different freshwater environments. However, multimetric indices are difficult to apply to Mediterranean rivers basins, characterized by freshwater fish communities very low in species richness and support a high number of endemics with generalist and opportunistic life strategies. Here we follow a site-specific approach to develop an adaptation of the multimetric procedure usually used in Indices of Biotic Integrity (IBI), resulting in the Index of Community Integrity (ICI). We modeled the presence–absence of 10 native freshwater fish species from the Guadiana River basin using the Assessment of Nearest Neighbor Analyses (ANNA) model, to assess the deviation of the observed and expected community composition at reference condition. ANNA, which is a multi-species model, allowed incorporating in the index some rare species, though not all of them present in the basin. Deviations were transformed into probabilities of belonging to a reference site and species by species measures were then integrated in a final score. The use of presence–absence only data reduces potential errors associated with estimations of species’ abundance and its seasonal changes, which is especially important in Mediterranean environments. The ICI was sensitive to both habitat degradation and the degree of dominance of non-native species within the freshwater fish community (or biotic perturbation), which have been traditionally overlooked in IBIs, but was unresponsive to natural sources of variation. Given the site-specific nature and the simplicity of the index that we propose here, we expect it to be applicable to other Mediterranean basins for which predictive models can be produced.
Biotic indices for algae, macroinvertebrates, and fish assemblages can be effective for monitoring stream enrichment, but little is known regarding the value of the three assemblages for detecting perturbance as a consequence of low-level nutrient enrichment. In the summer of 2006, we collected nutrient and biotic samples from 30 wadeable Ozark streams that spanned a nutrient-concentration gradient from reference to moderately enriched conditions. Seventy-three algal metrics, 62 macroinvertebrate metrics, and 60 fish metrics were evaluated for each of the three biotic indices. After a group of candidate metrics had been identified with multivariate analysis, correlation procedures and scatter plots were used to identify the four metrics having strongest relations to a nutrient index calculated from log transformed and normalized total nitrogen and total phosphorus concentrations. The four metrics selected for each of the three biotic indices were: algae—the relative abundance of most tolerant diatoms, the combined relative abundance of three species of Cymbella, mesosaprobic algae percent taxa richness, and the relative abundance of diatoms that are obligate nitrogen heterotrophs; macroinvertebrate—the relative abundance of intolerant organisms, Baetidae relative abundance, moderately tolerant taxa richness, and insect biomass; fish—herbivore and detritivore taxa richness, pool species relative abundance, fish catch per unit effort, and black bass (Micropterus spp.) relative abundance.
We analyzed the relation of the amount and spatial pattern of land cover with stream fish communities, in-stream habitat, and baseflow in 47 small southeastern Wisconsin, USA, watersheds encompassing a gradient of predominantly agricultural to predominantly urban land uses. The amount of connected impervious surface in the watershed was the best measure of urbanization for predicting fish density, species richness, diversity, and index of biotic integrity (IBI) score; bank erosion; and base flow. However, connected imperviousness was not significantly correlated with overall habitat quality for fish. Nonlinear models were developed using quantile regression to predict the maximum possible number of fish species, IBI score, and base flow for a given level of imperviousness. At watershed connected imperviousness levels less than about 8%, all three variables could have high values, whereas at connected imperviousness levels greater than 12% their values were inevitably low. Connected imperviousness levels between 8 and 12% represented a threshold region where minor changes in urbanization could result in major changes in stream condition. In a spatial analysis, connected imperviousness within a 50-m buffer along the stream or within a 1.6-km radius upstream of the sampling site had more influence on stream fish and base flow than did comparable amounts of imperviousness further away. Our results suggest that urban development that minimizes amount of connected impervious surface and establishes undeveloped buffer areas along streams should have less impact than conventional types of development.
Facilitation between species is thought to be a key mechanism by which biodiversity affects the rates of resource use that govern the efficiency and productivity of ecosystems; however, there is no direct empirical evidence to support this hypothesis. Here we show that increasing the species diversity of a functional group of aquatic organisms induces facilitative interactions, leading to non-additive changes in resource consumption. We increased the richness and evenness of suspension-feeding caddisfly larvae (Insecta, Trichoptera) in stream mesocosms and found that the increased topographical complexity of the benthic habitat alters patterns of near-bed flow such that the feeding success of individuals is enhanced. Species diversity reduces 'current shading' (that is, the deceleration of flow from upstream to downstream neighbours), allowing diverse assemblages to capture a greater fraction of suspended resources than is caught by any species monoculture. The fundamental nature of this form of hydrodynamic facilitation suggests that it is broadly applicable to freshwater and marine habitats; in addition, it has several analogues in terrestrial ecosystems where fluxes of energy and matter can be influenced by biophysical complexity. Thus, changes in species diversity may alter the probability of positive species interactions, resulting in disproportionately large changes in the functioning of ecosystems.
Continental aquatic systems from rivers to the coastal zone are considered within two perspectives: (i) as a major link between the atmosphere, pedosphere, biosphere and oceans within the Earth system with its Holocene dynamics, and (ii) as water and aquatic biota resources progressively used and transformed by humans. Human pressures have now reached a state where the continental aquatic systems can no longer be considered as being controlled by only Earth system processes, thus defining a new era, the Anthropocene. Riverine changes, now observed at the global scale, are described through a first set of syndromes (flood regulation, fragmentation, sediment imbalance, neo-arheism, salinization, chemical contamination, acidification, eutrophication and microbial contamination) with their related causes and symptoms. These syndromes have direct influences on water uses, either positive or negative. They also modify some Earth system key functions such as sediment, water, nutrient and carbon balances, greenhouse gas emissions and aquatic biodiversity. Evolution of river syndromes over the past 2000 years is complex: it depends upon the stages of regional human development and on natural conditions, as illustrated here for the chemical contamination syndrome. River damming, eutrophication and generalized decrease of river flow due to irrigation are some of the other global features of river changes. Future management of river systems should also consider these long-term impacts on the Earth system.
Mature plantation forests provide broadly similar stream habitat conditions to native forest and streams in these land uses typically have quite similar invertebrate and fish faunas. However, logging and replanting create regular disturbances to streams in plantations that can impact adversely on aquatic habitat and biota. Streamside riparian areas occupy the interface between the land and water and recent New Zealand studies have shown that maintaining forest vegetation in the riparian area during logging, together with sound land management practices elsewhere in the catchment, can protect streams from much of the disturbance that otherwise occurs during and after logging.
Hydroelectricity is increasingly used worldwide as a source of renewable energy, and many mountain ranges have dozens or hundreds of hydropower plants, with many more being under construction or planned. Although the ecological impacts of large dams are relatively well known, the effects of small hydropower plants and their weirs have been much less investigated. We studied the effects of water diversion of small hydropower plants on fish assemblages in the upper Ter river basin (Catalonia, NE Spain), which has headwater reaches with good water quality and no large dams but many of such plants. We studied fish populations and habitat features on control and impacted reaches for water diversion of 16 hydropower plants. In the impacted reaches, there was a significantly lower presence of refuges for fish, poorer habitat quality, more pools and less riffles and macrophytes, and shallower water levels. We also observed higher fish abundance, larger mean fish size and better fish condition in the control than in impacted reaches, although the results were species-specific. Accordingly, species composition was also affected, with lower relative abundance of brown trout (Salmo trutta) and Pyrenean minnow (Phoxinus bigerri) in the impacted reaches and higher presence of stone loach (Barbatula quignardi) and Mediterranean barbel (Barbus meridionalis). Our study highlights the effects of water diversion of small hydropower plants from the individual to the population and community levels but probably underestimates them, urging for further assessment and mitigation of these ecological impacts.
This study quantified the unique variation in stream fish and habitat and a land use disturbance index (LDI) at a variety of spatial scales: catchment, eight riparian polygons that varied in width and length (e.g. 50 m to all upstream reaches), upstream polygons of 1.6 and 3.2 km and the residual upland area of each site watershed not accounted for by each polygon. The analyses confirmed a hockey stick-shaped relationship between the fish community and the LDI, with sensitive species only present below an LDI of 11. The largest variation for most metrics was explained by the largest polygons, suggesting that local riparian conditions were not as important predictors of stream condition. LDI in upland areas, where zero-order streams occur, was also an important predictor of fish biomass and taxa richness. Contrary to expected, additive models with both catchment and riparian corridors provided minimal increases in predictive power, and no improvement in model performance occurred when data sets were stratified into sites below the LDI threshold. Finally, there was considerable covariation in the template and stressor predictor variables that made it difficult to quantify the unique variation in biological and physical responses accounted for by land use. That the 1600-m proximal polygon provided the best predictor of the fish community and temperature is supportive of there being some proximal effects of land use. Overall, our findings suggest that stream management must consider processes that occur in the entire upstream catchment and the entire riparian corridor, including the headwaters for success. Copyright © 2012 John Wiley & Sons, Ltd.
1. A multimetric index of fish assemblage integrity was developed and similarity analyses were conducted on fish species in two central Indian rivers and the effects of distance from municipal and industrial effluents on those indices then evaluated.
2. Five metrics from Karr et al. (1986 , Illinois Natural History Survey Special Publication 5, Urbana, IL) were adopted: intolerant species richness, % omnivorous individuals, % top carnivore individuals, total number of individuals and % individuals with anomalies. Seven new metrics (native species richness, native family richness, benthic species richness, water column species richness, % non-native individuals, % tolerant individuals and % herbivorous individuals) were added.
3. Non-native individuals represented 1–55% of the assemblages at sampled sites which held fish.
4. Fish were present at eleven sites and not collected at two sites, despite heavy metal concentrations exceeding U.S. Environmental Protection Agency acute criteria at all sites.
5. Two types of metric scoring were examined. The traditional 5–3–1 method showed the same pattern as continuous scoring from 0 to 10, but produced a higher integrity class at one site.
6. Scores on our modified index of fish assemblage integrity increased with distance downstream from a major effluent source in each river. Jaccard similarity scores between the least disturbed downstream site and all other sites decreased with increasing distance and disturbance.
7. It was concluded that Karr’s original index and its theoretical foundations are easily adaptable, even to an ichthyofauna containing no species, and only two families (Cyprinidae, Poeciliidae), in common with the midwestern United States.
1. Reliable lotic ecological monitoring requires knowledge of river typology, environmental factors, the effect of stressors known here as ‘pressures’ and appropriate indicators of anthropogenically induced change. We sampled benthic macroinvertebrate, fish, bird and macrophyte communities along an intermittent Mediterranean river and analysed community structure (relative abundance) and function (metrics) relative to environmental and pressure gradients in order to identify suitable indicator group(s) for future monitoring and mitigation programmes.
Abstract Biological indicators for Mediterranean rivers are poorly developed. This study evaluates the effectiveness of the Index of Biotic Integrity approach (IBI) with fish assemblages in the Guadiana catchment, a typical Mediterranean watershed in Southern Portugal. Reference sites were selected from a set of 95 sites, using a multivariate approach. Fifty-five candidate metrics were screened for range, responsiveness, precision and redundancy. Final metrics included: proportion of native fish, number of intolerant and intermediate species, number of invertivore native fish, number of phyto-lithophilic and polyphilic species, and catches of exotics. The IBI scores correlated with composite gradients of human impact and differed significantly between reference and non-reference sites. Application of the IBI to an independent validation set with 123 sites produced results congruent with the development set and repeatable assessments at 22 sites showed concordance in IBI scoring. This application highlights the effectiveness of the IBI approach even with fish assemblages of limited diversity and ecological specialisation as in Mediterranean streams.
Abstract A fish-based index applicable at the pan-European scale should encompass the relative importance of regional and local factors influencing the distribution of riverine fish. An effective way of using information available from fish assemblages to establish such a multimetric index is through the use of the reference condition approach that involves testing a fish assemblage exposed to a potential stressor against a reference condition. In this study, a variety of metrics based on count and abundance data and reflecting different aspects of the fish assemblage structure and function were selected from the literature for their potential to indicate degradation. Logistic and multiple linear regression procedures were applied, using an initial data set of 1000 reference sites fairly evenly distributed across European rivers (11 countries) and defined by some easily measured regional and local characteristics, to elaborate the simplest possible response model that adequately explains the observed patterns of each metric for a given site. A final list of 10 metrics was retained and the European Fish Index was tested using new independent datasets. The advantage of the resulting index to serve as a practical technical reference for cost-effective biological assessments of lotic systems in Europe is related to its ability to encompass basins and river size, and its sensitivity to physical and chemical alteration of the river ecosystem.
Abstract – The accuracy of bioassessment programmes is highly limited by the precision of the systems used to derive sensitivity–tolerance values for the organisms used as indicators. We provide quantitative support to the objective evaluation of freshwater fish species sensitivity to different sources of disturbance, accounting for co-variation issues not only between perturbations and natural gradients (especially river size), but also between different perturbations. With this aim, we performed two different principal component analyses: (i) on a general environmental matrix to obtain a perturbation gradient independent of river size effects and (ii) on human impairment-related variables to extract independent synthetic perturbation gradients. Then, we checked each species responses to those gradients to assess their sensitivity–tolerance through an available-used chi-squared analysis in the first approach and through a t-test/ancova analysis in the second one. In this way, we obtained sensitivity–tolerance which could be included in future bioassessment tools, enabling effective evaluations.
1. Periphytic diatoms, macrophytes, benthic macroinvertebrates and fish were sampled with standard methods in 185 streams in nine European countries to compare their response to degradation. Streams were classified into two main stream type groups (i.e. lowland, mountain streams); in addition, the lowland streams were grouped into four more specific stream types.
2. Principal components analysis with altogether 43 environmental parameters was used to construct complex stressor gradients for physical–chemical, hydromorphological and land use data. About 30 metrics were calculated for each sample and organism group. Metric responses to different stress types were analysed by Spearman Rank Correlation.
3. All four organism groups showed significant response to eutrophication/organic pollution gradients. Generally, diatom metrics were most strongly correlated to eutrophication gradients (85% and 89% of the diatom metrics tested correlated significantly in mountain and lowland streams, respectively), followed by invertebrate metrics (91% and 59%).
4. Responses of the four organism groups to other gradients were less strong; all organism groups responded to varying degrees to land use changes, hydromorphological degradation on the microhabitat scale and general degradation gradients, while the response to hydromorphological gradients on the reach scale was mainly limited to benthic macroinvertebrates (50% and 44% of the metrics tested correlated significantly in mountain and lowland streams, respectively) and fish (29% and 47%).
5. Fish and macrophyte metrics generally showed a poor response to degradation gradients in mountain streams and a strong response in lowland streams.
6. General recommendations on European bioassessment of streams were derived from the results.
The biogeographical distribution of brown trout mitochondrial DNA haplotypes throughout the Iberian Peninsula was established by polymerase chain reaction-restriction fragment polymorphism analysis. The study of 507 specimens from 58 localities representing eight widely separated Atlantic-slope (north and west Iberian coasts) and six Mediterranean drainage systems served to identify five main groups of mitochondrial haplotypes: (i) haplotypes corresponding to non-native, hatchery-reared brown trout that were widely distributed but also found in wild populations of northern Spain (Cantabrian slope); (ii) a widespread Atlantic haplotype group; (iii) a haplotype restricted to the Duero Basin; (iv) a haplotype shown by southern Iberian populations; and (v) a Mediterranean haplotype. The Iberian distribution of these haplotypes reflects both the current fishery management policy of introducing non-native brown trout, and Messinian palaeobiogeography. Our findings complement and extend previous allozyme studies on Iberian brown trout and improve present knowledge of glacial refugia and postglacial movement of brown trout lineages.
Phylogeographic, nested clade, and mismatch analyses of mitochondrial DNA (mtDNA) variation were used to infer the temporal dynamics of distributional and demographic history of brown trout (Salmo trutta). Both new and previously published data were analyzed for 1,794 trout from 174 populations. This combined analysis improved our knowledge of the complex evolutionary history of brown trout throughout its native Eurasian and North African range of distribution in many ways. It confirmed the existence of five major evolutionary lineages that evolved in geographic isolation during the Pleistocene and have remained largely allopatric since then. These should be recognized as the basic evolutionarily significant units within brown trout. Finer phylogeographic structuring was also resolved within major lineages. Contrasting temporal juxtaposition of different evolutionary factors and timing of major demographic expansions were observed among lineages. These unique evolutionary histories have been shaped both by the differential latitudinal impact of glaciations on habitat loss and potential for dispersal, as well as climatic impacts and landscape heterogeneity that translated in a longitudinal pattern of genetic diversity and population structuring at more southern latitudes. This study also provided evidence for the role of biological factors in addition to that of physical isolation in limiting introgressive hybridization among major trout lineages.
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