Habitat Partitioning in a Freshwater Fish Community

Distribution spatiale et activité des poissons en milieu lacustre : impacts des facteurs environnementaux à partir d’une approche multi-échelle. Application à la retenue des Bariousses

Thesis

Full-text available

Jul 2014

Romain Roy

Aquatic ecosystem functioning in human-impacted environments is highly dependent of its uses; in consequence, the environment of biological communities is generally fluctuating. Studying the link between environment and organism in fluctuating environments is generally more complex compared to steady environments. The main objective of this work was to better understand how fish populations respond to environmental modifications in a reservoir affected with water level fluctuations (WLF), the Bariousses’s reservoir located on the Vézère River. A multiscale approach was used with different biological (community and individual) and temporal (annual and daily cycles) scales. A special attention was given to the littoral zone as it plays a key role for lake fish communities and since it is strongly affected by WLF. This work is divided in 4 parts. The first part presents the characteristics of the study site and the second part describes the impact of WLF on the studied habitats using a mapping of the littoral zone. The consequences of hydrological stress through the changes in habitat conditions were also analyzed as well as the effects of water temperature and photoperiod. The third part shows the effect of the temporal variability of environmental conditions induced by WLF on the composition of the littoral fish community (sampled by electrofishing). The fourth part presents an innovative positioning system acoustic telemetry (Vemco Positioning System) that was used to study the impact of WLF at the individual scale by analyzing the behavior of 90 individuals from three different fish species (pikeperch, pike and perch) with a satisfactory accuracy (average error of 3.3 m after filtration). The results of this work showed that WLF induced a temporal variability of the littoral zone surface and volume. In addition, a gradual decrease of the structural complexity of littoral habitats was associated with lower water level inducing a trend to homogenization (dominance of thinner substrates without vegetation). Despite these changes in habitats conditions induced by WLF, littoral fish community did not show any clear change in composition. High inter-individual variability of behavioral responses was observed in response to environmental fluctuations, but the temperature and photoperiod were the two major structural parameters controlling fish activity and spatial distribution. Water level affected a part of the fish population since more individuals attended the littoral zone and were less mobile when available habitats were more complex (with a high water level). These results allowed us to suggest some ideas for the management of water levels in the studied reservoir focused on the fish population. Keywords: reservoir, fish, littoral zone, water level fluctuations, temperature, photoperiod, individuals.

Resilience of littoral food webs to oligotrophication and neozoa invasion

Thesis

Jan 2020

Maike Sabel

Shared Histories of Co-evolution May Affect Trophic Interactions in a Freshwater Community Dominated by Alien Species

Article

Full-text available

Sep 2019

Interactions occurring between species in multiple invaded freshwater ecosystems are often difficult to observe and study. Studies on invasive alien species typically focus on single species, and, when the species community is exclusively composed of alien species, their interactions, eventual facilitation and hindering processes are very scarcely assessed. To investigate such a community, the species community in the Arno River (Tuscany, Italy) was examined as a model system using the combined approach of stable isotopes and dietary analyses. Established alien species have formed a pyramid shaped community with the European catfish Silurus glanis and the North American channel catfish Ictalurus punctatus in the apex position, followed by opportunistic predatory (Lepomis gibbosus) and omnivore (Alburnus alburnus, Cyprinus carpio, Barbus barbus, Pseudorasbora parva, Padogobius sp., Tinca tinca) species. These species were observed to feed on a variety of primary producers (Myriophyllum sp., Potamogeton sp., Phragmites australis) and consumers (aquatic insects, molluscs, Dikerogammarus villosus, Procambarus clarkii, Palaemon antennarius, tadpoles). Remarkably, the channel catfish Ictalurus punctatus showed an ontogenetic niche shift, with juveniles occupying a slightly higher trophic position than mature individuals. Pseudorasbora parva and A. alburnus showed a strong niche overlap, with the former having a wider niche. Such wide niches were also found for the invasive crustaceans D. villosus and P. clarkii. Outgoing from our findings, we suggest that life-history and geographic origin play a role in determining competition and interaction type among alien species, with species from the same geographic area showing a lower potential to compete than species from different areas, hence affecting their potential impact on native species.

Using Hierarchical Bayesian Multispecies Mixture Models to Estimate Tandem Hoop-net-Based Habitat Associations and Detection Probabilities of Fishes in Reservoirs

Article

Full-text available

May 2016
T AM FISH SOC

Species distribution models are useful tools to evaluate habitat relationships of fishes. We used hierarchical Bayesian multispecies mixture models to evaluate the relationships of both detection and abundance with habitat of reservoir fishes caught using tandem hoop nets. A total of 7,212 fish from 12 species were captured, and the majority of the catch was composed of Channel Catfish Ictalurus punctatus (46%), Bluegill Lepomis macrochirus (25%), and White Crappie Pomoxis annularis (14%). Detection estimates ranged from 8% to 69%, and modeling results suggested that fishes were primarily influenced by reservoir size and context, water clarity and temperature, and land‐use types. Species were differentially abundant within and among habitat types, and some fishes were found to be more abundant in turbid, less impacted (e.g., by urbanization and agriculture) reservoirs with longer shoreline lengths; whereas, other species were found more often in clear, nutrient‐rich impoundments that had generally shorter shoreline length and were surrounded by a higher percentage of agricultural land. Our results demonstrated that habitat and reservoir characteristics may differentially benefit species and assemblage structure. This study provides a useful framework for evaluating capture efficiency for not only hoop nets but other gear types used to sample fishes in reservoirs. Received October 14, 2014; accepted December 23, 2015 Published online April 11, 2016

Strukturierende Faktoren der litoralen Fischartengemeinschaft angelfischereilich bewirtschafteter Baggerseen in Niedersachsen

Article

Jan 2012

Die Rolle biotischer und abiotischer Faktoren für die Zusammensetzung von Fischartengemeinschaften in Stillgewässern wurde bereits vielfach untersucht. Bisherige vergleichbare Analysen fokussierten jedoch zumeist auf große (> 50 ha) natürliche Gewässersysteme oder auf ausgewählte Habitate. Kleine, künstlich geschaffene Standgewässer, vor allem Abgrabungsgewässer, waren hingegen selten Gegenstand fischfaunistischer wissenschaftlicher Untersuchungen. In vorliegender Studie wurden die litoralen Fischbestände von 19 angelfischereilich bewirtschafteten, kleinen (0,69 bis 11,93 ha) und flachen (maximale Tiefe 1,1 bis 12,8 m) Baggerseen in Niedersachsen untersucht. Fischfaunistische Kennwerte wurden in den Jahren 2011 und 2012 mithilfe von Stellnetzen und Elektrofischerei quantifiziert. Die ermittelten Fischgemeinschaftskennzahlen wurden sodann auf lineare Zusammenhänge mit morphologischen und produktionsbiologischen Umweltvariablen und Charakteristika der Habitatstruktur getestet, um die strukturierenden Faktoren der Fischartengemeinschaft zu ermitteln. Die 19 Untersuchungsgewässer waren insgesamt artenreich (bis zu 19 Fischarten pro Gewässer, im Mittel 12 ± 3 Arten). Hecht (Esox lucius) und Karpfen (Cyprinus carpio) waren in allen Gewässern vertreten, Aal (Anguilla anguilla), Barsch (Perca fluviatilis), Plötze (Rutilus rutilus), Rotfeder (Scardinius erythrophthalmus) und Schleie (Tinca tinca) in 95% der Baggerseen. Standortuntypische, rheophile Arten wurden höchst selten angetroffen, ebenso nichtheimische Arten, was auf eine naturschutzfachlich nachhaltige Bewirtschaftung durch die Angelvereine hinweist. Biomasse und Abundanz der Fische im Litoral, vor allem der Barsche und Plötzen, korrelierten überwiegend positiv mit Anzeigern des Trophiestatus und der Gewässerproduktivität (Chlorophyll a, Gesamtphosphor und Sichttiefe), während Raubfischabundanzanteile zurückgingen. Zudem nahm den Erwartungen entsprechend mit steigendem Trophiegrad die mittlere Totallänge des Durchschnittsfisches in der Gemeinschaft ab. Auch die mittlere Gewässertiefe stellte sich als relevanter Strukturfaktor der Fischartengemeinschaft heraus: Mit zunehmender mittleren Tiefe verringerten sich Abundanz und Biomasse von Fischen im Litoral sowie die Artenzahl der Gemeinschaft. Der Effekt der von Makrophyten geprägten Habitatstruktur wurde durch die produktionsbiologischen und morphologischen Faktoren überlagert. Die vorgelegte Studie belegt, dass vor allem der Nährstoffgehalt und die Gewässermorphologie die Fischgemeinschaft von Baggerseen bestimmen, ähnlich wie zuvor für natürliche Standgewässer in Norddeutschland beschrieben. Geringe Wassertiefen und hohe Nährstoffgehalte in Form von Phosphor, indiziert durch vergleichsweise trübes Wasser, erhöhen der Studie zufolge die Tragekapazität der Gewässer für Fischbiomasse. Die Anlegung von Flachwasserbereichen in tiefen Baggerseen ist eine empfehlenswerte Managementmaßnahme, um die Fischbestände zu steigern.

Diet Partitioning in a Diverse Centrarchid Assemblage in the Atchafalaya River Basin, Louisiana

Article

Full-text available

Jul 2015

We examined trophic and habitat resource partitioning among seven centrarchid species inhabiting four macrohabitat types in the Atchafalaya River basin (ARB), a 900-km2 bottomland hardwood swamp in south-central Louisiana. Fish (n = 2,036) were collected at 24 sites by boat electrofishing, and trophic position was determined from stomach contents and tissue analysis of 15N and 13C stable isotope signatures (n = 140). Stomach content analysis (index of relative importance), Morisita's index of dietary overlap, and canonical correspondence analysis revealed little effect of ARB macrohabitat type on centrarchid trophic relationships despite significant habitat alterations in dredged canals. Analyses revealed substantial diet overlap among three predominately insectivorous species (Bluegill Lepomis macrochirus, Redspotted Sunfish L. miniatus, and Longear Sunfish L. megalotis), whereas much more distinctive trophic positions were occupied by Largemouth Bass Micropterus salmoides (dominant prey = fish), Black Crappies Pomoxis nigromaculatus (palaemonid shrimp), Redear Sunfish L. microlophus (mollusks), and Warmouths L. gulosus (crayfish). Stable isotope signatures reflected dietary differences among species and complemented stomach content analyses in assessing the feeding ecology of these centrarchids, although isotopic similarities were sometimes higher than actual similarities in diet composition. Results suggest that centrarchid functional morphology and prey selection, combined with the diversity and productivity of ARB littoral habitats, effectively reduce the potential for competition among the seven cohabiting centrarchids.Received October 28, 2014; accepted March 31, 2015

Habitat occupancy patterns of juvenile fishes in a large lowland river: Interactions with macrophytes

Article

Full-text available

Sep 2000
Arch Hydrobiol

Juvenile fish were sampled by electric fishing using the point abundance sampling method in September 1998 in the Lower Saone River, during a very low discharge period when current velocity was not the structuring factor. Patterns exhibited by the four most abundant species were investigated at different spatial scales of habitat heterogeneity using logistic regression analysis. At the higher scale (distinction between side-arms and channel), significant responses were always characterized by higher probabilities of presence in side-arms. Three of the four species showed patterns at the mesohabitat scale (the different macrophytes beds), At the microhabitat scale (the sampling point), the role of aquatic macrophytes was investigated by distinguishing the main species. In order to investigate the relationship between juvenile fish abundance and food habitat characteristics, phyto- and zooplankton were sampled in each mesohabitat, in both channel and side-arms. The type of vegetation appeared to be crucial in the determination of plankton abundance, but plankton abundance was not sufficient to explain patterns of habitat use in the fishes. Morphological characteristics of the different macrophytes studied were contrasted. Then we hypothesized that such differences resulted in different habitat quality (i.e. protection against predators) and may have affected the habitat use of juvenile fishes.

Characterization of fish assemblages in eleven multi-use reservoirs from North Carolina, USA

Article

Full-text available

Aug 2023

Managing impounded river systems is a recurring challenge for aquatic resource professionals because reservoirs serve multiple functions with different ecological and socioeconomic outcomes. However, research on fishes in reservoirs has disproportionally focused on recreationally and economically important species, with less attention directed toward fish assemblages despite the potential for management at the assemblage level. As such, evaluation of relationships between reservoir fish assemblages and biotic and abiotic factors and testing whether assemblage structure is affected by changing environmental conditions may deepen ecological understanding and provide insights for reservoir fisheries management. Our overall objective was to assess these relationships in 11 reservoirs from North Carolina, USA. We sampled fish assemblages in the reservoirs, which spanned five river basins representing a range of habitat conditions, using experimental gillnets and pulsed DC nighttime electrofishing. Multivariate statistical analyses indicated that taxonomic differences in fish assemblage composition among river basins followed a gradient of productivity. The top contributing species to reservoir dissimilarity were bluegill (Lepomis macrochirus), gizzard shad (Dorosoma cepedianum), black crappie (Pomoxis nigromaculatus), and white perch (Morone americana). These four species were positively associated with factors that reflect increasing eutrophic conditions in the 11 reservoirs and could, therefore, serve as indicators of reservoir productivity, anthropogenic influence, and fish assemblage structure, in addition to their key role in reservoir fisheries management. Whereas fisheries research has historically focused on assessing fish populations, our results illustrate the ecological and management insights derived from simultaneously collecting assemblage- and population-level data. Research on reservoir fish assemblages in relation to biotic and abiotic conditions may help advance fish ecology and management alike.

Using historical catch data to evaluate predicted changes in fish relative abundance in response to a warming climate

Article

Full-text available

Jun 2023
ECOGRAPHY

Using models to predict future changes in species distributions in response to projected climate change is a common tool to aid management and species conservation. However, the assumption underlying this approach, that ecological processes remain stationary through time, can be unreliable, and more empirical tests are needed to validate predictions of biotic outcomes of global change. The scarcity of reliable historical and long‐term datasets can make these tests difficult. Moreover, incorporating abundance and multiple sampling methods can improve model predictions and usability for management. Our study 1) provides insight into how well models can predict environmental change under a warming climate, 2) incorporates multiple sampling gears and abundance data in modeling to better capture changes in populations and 3) shows the value of historical datasets for improving predictive models of population change. We used contemporary (2003–2019) and historical (1936–1964) abundance datasets of the North American fish largemouth bass Micropterus salmoides in lakes across the state of Michigan, USA. We developed Bayesian hierarchical models that leverage the use of multiple gears in contemporary lake surveys to estimate the relative catchabilities of largemouth bass for each gear and hindcast the models to predict historical abundance. Our estimates of relative density change over time were correlated with temperature change over time; increasing surface water temperature led to increasing largemouth bass density. Hindcasting models to historical lake temperatures performed similarly in predicting historical density to models predicting contemporary density. Our results suggest that models built using spatial environmental gradients can reliably predict population changes through time. Understanding the sampling methods and the environmental context of observational datasets can help researchers test for potential sampling biases and identify confounding factors that will improve predictions of future impacts of environmental change.

Resource use of crucian carp along a lake productivity gradient is related to body size, predation risk, and resource competition

Article

Full-text available

Jun 2022
ECOL FRESHW FISH

Generalist fish species can feed on a wide resource spectrum and across trophic levels depending on resource availability and trophic interactions. Crucian carp (Carassius carassius) represents a good candidate species to investigate variation in the trophic ecology of generalist fish as it can be found in highly variable fish communities and its resource use is well documented. In this study, we explored the trophic ecology of crucian carp at the individual and population levels using stable isotope and gut content analysis. We tested if trophic resource use varied according to lake productivity, predation risk, intra- and interspecific competition, or individual fish size. We found that crucian carp resource preference was highly variable among and within lakes. In predator-free lakes, small crucian carp occurred in high densities, showed increased interindividual specialisation, and relied mainly on pelagic zooplankton. In presence of predators, large crucian carp occurred in low densities and included greater proportions of benthic macroinvertebrates in their diet. This shift in resource use was further favoured in productive, shallow lakes where littoral prey were probably abundant. Resource partitioning was an important factor determining crucian carp niche use, as fish had higher trophic position in absence of other cyprinids. Crucian carp showed highly dynamic resource use and food preferences in response to variable environmental conditions. Overlooking complex diet preferences of generalist fish may lead to an oversimplification of freshwater community dynamics.

Single target acuity in the common sunfish (Lepomis gibbosus)

Article

Sep 2021

Vision is considered to contribute to foraging, territorial, and reproductive behavior in sunfish. In these contexts, sunfish need to perceive single targets, such as prey items or body markings from either conspecifics or individuals of other sunfish species, from some distances. We determined the single target acuity of six common sunfish in a behavioral experiment to assess whether the visual abilities of sunfish correspond with behavioral observations or reactive distance measures and thus to assess the limits of vision regarding the mentioned behaviors. Single target acuity for full-contrast single targets amounted to 0.17 (0.13 - 0.32) deg. When contrast was reduced to Weber contrasts of 0.67 and 0.41, single target acuity dropped to 0.34 (0.31 - 0.37) deg, and finally to 0.42 (0.34 - 0.54) deg. Single target acuity would thus allow common sunfish to perceive biologically relevant stimuli at reasonable distances even when contrast is reduced.

Abiotic factors influence species co‐occurrence patterns of lake fishes

Article

Sep 2021

Abiotic factors are recognized for their strong influence on community structure. Habitat diversity is related to resource availability that influences species richness and abundance. In lakes, surface area and depth have been used as measures of the size and diversity of habitat, and have strong effects on the structure of entire communities. We tested whether abiotic variables, related to habitat size, influence co‐occurrence patterns of species pairs of fishes by analysing groups of lakes within a specific area and depth categories in two regions in Ontario, Canada. We used null models to obtain co‐occurrence patterns and standard effect sizes for each species pair within each area and depth category. We estimated standard effect sizes relative to lake area or depth and determined whether species co‐occurrence patterns change systematically as these measures of habitat increase. We evaluated groups of species where factors such as predation and habitat filtering have been shown to structure those assemblages, and we tested whether area and depth alter the species associations and our interpretation of these relationships. We found significant differences between the observed and expected distributions of regression slopes relating co‐occurrences to area and depth in both regions across all species, which indicated the strong influence of both variables on the overall co‐occurrence patterns. We observed a significant negative trend of the co‐occurrence patterns across lake area categories for the predator–prey species, indicating that the effect of predation was stronger in smaller lakes, but it was reduced in larger lakes, possibly due to increased habitat and resource availability. We show that pooling results as done in standard community null models can lead to Type II errors due to the ‘cancellation’ of opposing ecological signals. Our results demonstrate the effect of environmental variables on species co‐occurrence patterns, but the divergent results obtained between geographical regions suggest that such patterns are context‐dependent. This study emphasizes the importance of considering abiotic factors in null models of species co‐occurrence to obtain reliable and detailed information about the association patterns between species.

Vertical oscillations of the thermocline caused by internal waves modify coldwater pelagic fish distribution: Results from a large stratified lake

Article

Jun 2021
J GREAT LAKES RES

Fishes typically occupy a species-specific temperature range, with their occupied depth being related to the lake’s temperature profile. When a fish’s preferred temperature range coincides with the thermocline, the location of their preferred thermal habitat is influenced by the rise and fall of internal waves, leading to possible changes in fish depth. These internal waves are common in large, stratified lakes, yet we do not know how they affect the spatial distribution and behavior of freshwater fishes. We conducted nighttime hydroacoustic surveys in a large, deep embayment of a large thermally stratified lake to observe whether pelagic fish respond to vertical oscillations of the thermocline caused by internal waves. The coldwater pelagic fish in our study (primarily cisco, Coregonus artedi) typically occupied a narrow vertical band approximately 5–8 m thick and temperatures between 10.8 ± 0.8–13.6 ± 1.6 °C (fishes sized 106–500 mm), just below the thermocline (centered around 15–17 °C). Importantly, the upper bound of fish depth varied in response to vertical thermocline movements associated with internal waves, suggesting fish respond to changes in their physical environment on timescales commensurate with basin-scale internal wave periods (hours to days), to remain within their preferred thermal habitat. Dissolved-oxygen levels were typically above avoidance thresholds of these fish, thus not likely exerting a strong influence on fish location. Our findings emphasize the need to account for internal waves when designing hydroacoustic and netting surveys, as thermocline movements can influence where fish are located.

Plasticity versus Evolutionary Divergence: What Causes Habitat Partitioning in Urban-Adapted Birds?

Article

Sep 2020

Habitat partitioning can facilitate the coexistence of closely related species and often results from competitive interference inducing plastic shifts of subordinate species in response to aggressive, dominant species (plasticity) or the evolution of ecological differences in subordinate species that reduce their ability to occupy habitats where the dominant species occurs (evolutionary divergence). Evidence consistent with both plasticity and evolutionary divergence exist, but the relative contributions of each to habitat partitioning have been difficult to discern. Here we use a global data set on the breeding occurrence of birds in cities to test predictions of these alternative hypotheses to explain previously described habitat partitioning associated with competitive interference. Consistent with plasticity, the presence of behaviorally dominant congeners in a city was associated with a 65% reduction in the occurrence of subordinate species, but only when the dominant was a widespread breeder in urban habitats. Consistent with evolutionary divergence, increased range-wide overlap with dominant congeners was associated with a 56% reduction in the occurrence of subordinates in cities, even when the dominant was absent from the city. Overall, our results suggest that both plasticity and evolutionary divergence play important, concurrent roles in habitat partitioning among closely related species in urban environments.

Habitat and community structure modulate fish interactions in a neotropical clearwater river

Article

Full-text available

Apr 2020
NEOTROP ICHTHYOL

Species interactions can modulate the diversity and enhance the stability of biological communities in aquatic ecosystems. Despite previous efforts to describe fish interactions in tropical rivers, the role of habitat characteristics, community structure, and trophic traits over these interactions is still poorly understood. To investigate among-habitat variation in substratum feeding pressure and agonistic interactions between fishes, we used remote underwater videos in three habitats of a clearwater river in the Central Western, Brazil. We also performed visual surveys to estimate the abundance and biomass of fishes and proposed a trophic classification to understand how these variables can affect fish interactions. Community structure was the main factor affecting the variation in the interactions among the habitats. Biomass was the main variable determining which habitat a fish will feed on, while species abundance determined with how many other species it will interact in the agonistic interaction networks for each habitat. Specific habitats are not only occupied, but also used in distinct ways by the fish community. Overall, our results demonstrate the importance of the heterogeneity of habitats in tropical rivers for the interactions performed by the fishes and how the intensity of these interactions is affected by community structure.

Long-term changes in littoral fish community structure and resilience of total catch to re-oligotrophication in a large, peri-alpine European lake

Article

Full-text available

Aug 2020
FRESHWATER BIOL

1. The littoral zone of lakes is used as spawning, shelter, or feeding habitat for many fish species and hence is of key importance for overall lake functioning. Despite this, hardly any studies exist examining the long-term dynamics and response of the littoral fish community, composed mostly of juvenile fish, to environmental change. Here, we study the response of total catch per unit effort (CPUE) and individual species CPUE of such a community to 17 years of oligotrophication and examine whether the species responses can be characterised as synchronous or asynchronous. 2. We analyse a data set of beach seine catches carried out during morning and twilight , late spring and late summer at three sites in large and deep Lake Constance from 1997 to 2014. Generalised additive mixed models were used to explore changes in CPUE of the overall community and of the most frequently occurring species, and Kendall's W test was applied to examine whether the dynamics of fish species were synchronous or asynchronous. 3. Species-specific and total CPUE strongly differed between morning and twilight and between spring and summer indicating an important role of behavioural and life cycle adaptations of species for CPUE. In addition, also the CPUE of some species seeking shelter behind larger stones was lower at sites without these. 4. Total CPUE did not decline suggesting the overall abundance of littoral fish was resilient to declining nutrients. In contrast, fish community composition changed strongly during the study period due to increases in some species (dace, loach, perch) and decreases in others (bream, burbot, chub, ruffe), indicating response diversity of fish to oligotrophication. The type of community dynamics was scale-dependent, whereby significantly synchronous dynamics according to Kendall's W were observed when taking seasonal variability into account. In contrast, significantly asynchronous species dynamics were observed when only

Evidence of fish spillover from freshwater protected areas in lakes of eastern Ontario

Article

Full-text available

Jul 2019

Research has identified numerous conservation benefits attributed to the use of marine protected areas (MPAs), yet comparatively less is known about the effectiveness of freshwater protected areas (FPAs). This study assessed multiple long‐standing (>70 years active) intra‐lake FPAs in three lakes in eastern Ontario, Canada, to evaluate their potential conservation benefits. These FPAs were intended initially to protect exploited populations of largemouth bass ( Micropterus salmoides (Lacépède, 1802)), but since their establishment no empirical data have been collected to evaluate the effectiveness of FPAs for protecting bass or the broader fish community. A comparative biological census of fish species abundance, biomass and species richness was conducted using snorkelling surveys within FPAs, along the bordering transition zones, and in more distant non‐protected areas of the lake that had similar habitats to the FPAs. In general, the FPAs yielded benefits that were most obvious (in terms of abundance and biomass) for the focal protected species (i.e. largemouth bass) as well as several shiner species. Largemouth bass and shiner abundance and biomass were highest in the FPA, lowest in the distant non‐protected areas, and intermediate in the transition zone. Species richness was also highest in the FPAs in two of the three lakes. Collectively, these results support the use of FPAs as a viable and effective conservation strategy that extends beyond simply limiting the exploitation of a target species. Beyond the benefits afforded to fish within the FPA, evidence of spillover in adjacent areas was also observed, which is promising. Additional research is needed on the effectiveness of FPAs in a variety of regions and water‐body types facing various threats in an effort to understand when, where and how to best use FPAs to benefit aquatic biodiversity.

A question of scale: Weak evidence for broad regional synchrony in fish year-class strength within or among species in inland lakes

Article

Feb 2019
FISH RES

Spatially-correlated abiotic and biotic conditions can potentially induce synchrony in the dynamics of disparate populations or species. However, such potential synchrony among species or populations may be tempered by dynamics operating at finer temporal and spatial scales, as well as species-specific responses to environmental conditions. We examined within-and among-species synchrony in year-class strength across 130 lakes in northern Indiana over 30 years to evaluate the relative scale of potential synchrony and its possible ecological mechanisms in five recreationally important fish species: black crappie (Pomoxis nigromaculatus), bluegill (Lepomis macrochirus), largemouth bass (Micropterus salmoides), redear sunfish (L. microlophus), and yellow perch (Perca flavescens). Bluegill and black crappie recruitment was significantly positively correlated when the species coexisted, and relative year-class strength of both species was positively related to mean annual wind speed. However, there were few other instances of recruitment synchrony between or within species, regardless of whether synchrony was assessed within or among lake systems. In addition, habitat similarity and regional weather patterns also played a limited and inconsistent role in shaping recruitment strength or synchrony in these small inland systems. These results suggest that fish recruitment dynamics in small, inland systems are most often a function of system-specific biotic interactions that mask limited input from broader climatological influences, and that understanding recruitment in small lakes will require examinations on appropriately fine spatial and temporal scales.

Littoral habitat loss caused by multiyear drought and the response of an endemic fish species in a deep desert lake

Article

Full-text available

Jan 2019

• Multiyear drought is projected to increase in frequency and duration in arid and semiarid regions across the world, threatening native species and ecosystem function. The effects of multiyear drought are often exacerbated by human water use for consumption, energy production, and agriculture, which, in lentic ecosystems, manifest in reduced lake elevation and altered habitat for aquatic species. • Here, we demonstrate that decreasing lake levels, associated with drought and water management, reduce the availability of littoral cobble habitat to fishes by creating an elevation‐explicit littoral habitat map. We combined long‐term fish catch data and a lake elevation time series with our elevation‐explicit littoral habitat map to test whether fish species population demographics are related to drought‐driven changes in littoral habitat. • We surveyed the littoral zone of Bear Lake, Utah and Idaho, U.S.A., from full pool to a depth of >12 m, totalling 94.86 km² surveyed. As lake elevation decreased >6 m from full pool to the lowest historical elevation, the area of littoral cobble decreased by >97%. Bear Lake sculpin (Cottus extensus, Cottidae), a cold‐water fish species which relies on cobble for reproduction, catch per unit effort decreased by >75% with littoral cobble, and year class strength declined by as much as 86%, but varied across age. • We predicted the response of age‐0 to age‐4 sculpin under high and low cobble availability. Our simulations predict a 60%–85% decline in juvenile sculpin CPUE (age‐2 and younger) when cobble availability decreases from the 95th to 5th percentile. • Our study provided a unique opportunity to identify quantitative linkages between climate‐driven littoral habitat loss and an ecologically important profundal fish species, expanding our understanding of potential future pathways through which climate change may affect lentic ecosystems and fishes.

Effects of Gizzard Shad Reduction on Relative Abundance, Growth, and Body Condition of Bluegills and Largemouth Bass in a Small Kansas Impoundment

Article

Full-text available

May 2018

Gizzard Shad Dorosoma cepedianum are commonly manipulated as a prey species in the United States but are widely viewed as undesirable in small impoundments because of direct and indirect effects on desirable sport fishes. Montgomery State Fishing Lake in southeastern Kansas became populated with Gizzard Shad during a flood event in 2007, and subsequent monitoring efforts indicated the Bluegill Lepomis macrochirus population was negatively affected. Remedial action involving reservoir dewatering and application of rotenone (target concentration of 7.5 μg/L) was conducted during the winter of 2013–2014, and responses of Bluegills and Largemouth Bass Micropterus salmoides were monitored for 3 years posttreatment. Gizzard Shad were not extirpated following treatment, but their relative abundance decreased 99.8%. Relative abundance of age-0 Bluegills and Largemouth Bass immediately increased following treatment in 2014 but decreased to pretreatment levels in 2015 and 2016. Conversely, growth of age-0 Bluegills decreased in 2014, but increased to pretreatment levels in 2015 and 2016. Growth of age-0 Largemouth Bass slightly decreased following treatment. Growth between the development of the second and third annulus did not differ among years for either species. Body condition of stock-length Bluegills and stock-length Largemouth Bass was greatest in 2012 but declined in subsequent years. These results suggest that, contrary to previously published studies, the reduction of Gizzard Shad had minimal effect on Bluegill and Largemouth Bass populations in Montgomery State Fishing Lake. However, intraspecific, density-dependent functions might have masked true responses of Bluegill and Largemouth Bass growth and body condition to Gizzard Shad reduction. Managers should understand that Gizzard Shad removal or reduction can have variable effects in aquatic systems and should be cognizant of potential outcomes and how those might affect fish populations and associated fisheries.

Fish community of a small karstic Neotropical drainage and its relationship with the physical habitat

Article

Full-text available

May 2018

In the present study we examined surface and subterranean sites in order to compare the fish fauna composition and characteristics of the physical habitat in a stream located in a Neotropical karst landscape at the São Francisco River basin, Minas Gerais State, Brazil. We investigated the effects of physical habitat characteristics related to river morphology, substrate composition, wood and canopy cover on the fish community and investigated whether subterranean habitats have additional effects responsible for shaping the fish community structure. During the sampling period (dry season; July 2012), 28 species distributed in 3 orders and 9 families were collected (773 individuals in total). Characiformes was the most diverse group in the studied area, with 16 registered species (57% of the sampled fauna). We did not find cave-adapted fish species during the study, although four non-troglomorphic species (two Characiformes and two Siluriformes) were sampled exclusively in the cave. The species composition was possibly affected by environmental differences, showing distinct patterns between the five sites studied. Canopy cover and the percentage of organic matter on the streambed accounted for most of the variation observed in the fish fauna composition (distance-based linear matrix: adjusted R² = 0.56; P = 0.02). In the system studied, Siluriformes have a greater chance of occupying subterranean habitats, with higher relative abundance and richness inside the cave sites. We believe that number, size and position of subterranean spaces within a karst watershed have additional effects on fish community composition through their selective pressure on species traits.

Reproductive state leads to intraspecific habitat partitioning and survival differences in greater sage-grouse: Implications for conservation

Article

Jan 2018

Context. Inter-and intraspecific habitat partitioning is widespread across taxa, yet limited information is available on differences in intraspecific habitat selection by same-sex individuals among differing reproductive states. Understanding habitat selection by conspecifics of different reproductive states may help optimise conservation efforts, particularly for gallinaceous bird species such as greater sage-grouse (Centrocercus urophasianus), which are long-lived but have only moderate reproductive rates. Aims. We predicted that habitat use differed between grouse under different reproductive states and that reproductive investment decreased survival of adults in summer. Methods. We compared habitat characteristics used by brood-rearing and broodless female sage-grouse and evaluated the influence of reproductive investment and habitat use on survival of adult females. Key results. We found that brood-rearing and broodless female sage-grouse partitioned habitat at micro-and macrohabitat scales. Broodless females were more likely to survive the summer. Conclusions. Our findings suggest reproductive state variability in habitat selection by female sage-grouse. Broodless females were roosting and foraging in concealed habitats with intermediate visual obstruction and annual vegetation productivity, but less food forb availability compared with early and late brood-rearing females. In contrast, brood-rearing females likely selected more herbaceous understoreys to predictably maximise foraging opportunities and promote growth of their chicks, which appeared to mitigate the influence of reproductive costs on summer survival, particularly during the late brood-rearing period. Implications. Survival of adult females is critical for population persistence of sage-grouse and other long-lived Galliformes, yet conservation efforts generally focus on habitats used during nesting and brood-rearing. Our results suggest that habitat partitioning is a potential risk-aversion strategy where individuals across different reproductive states likely select habitats to maximise their survival. Conservation efforts should focus on conserving habitats used by both brood-rearing and broodless sage-grouse to ensure population persistence.

Whole-lake addition of coarse woody habitat: Response of fish populations

Article

Full-text available

Apr 2012

Lakeshore residential development (LRD) reduces coarse woody habitat (CWH) in lakes resulting in negative effects on fishes. We tested whether the addition of CWH could reverse those effects. We added CWH to Camp Lake, a lake with CWH abundances similar to developed lakes, following 2 years of study of the fish populations in the reference and treatment basins. Both basins were monitored for 4 years following the manipulation. Specifically, we tested for changes in the population dynamics (densities, size-structure, growth), diet, and behavior (habitat use) of bluegill (Lepomis macrochirus) and largemouth bass (Micropterus salmoides). CWH addition had no discernible effect on fish population dynamics. Diet and behavioral responses were more pronounced in the treatment basin. Prey diversity and availability increased. Piscivory increased, with decreased reliance upon terrestrial prey, for largemouth bass. Habitat use was positively correlated with CWH branching complexity and abundance. Our study suggests that negative effects observed in fish populations through CWH reductions cannot be reversed in the short-term by adding CWH. We recommend that regulations governing the LRD process be protective of CWH.

Habitat Partitioning and Seasonal Movement of Red Drum and Spotted Seatrout

Article

Dec 2016

Acoustic telemetry was used to examine habitat use and movement of two sympatric gamefishes, red drum (Sciaenops ocellatus) and spotted seatrout (Cynoscion nebulosus), at two spatial scales (habitat and bay) within an estuarine complex. Habitat-scale tracking (~ 1 m–1 km) based on an acoustic positioning system revealed that seagrass was used extensively by both species. Red drum also commonly associated with oyster reef and boundaries between habitat types. Spatial overlap between the two species was limited and indicative of habitat partitioning; red drum were commonly observed in the shallow, inner lagoon and spotted seatrout in the deeper, open bay portion of the array. Conspicuous diel shifts were also observed for spotted seatrout; fish transitioned from seagrass to bare substrate and displayed greater rates of movement at night than day. Bay-scale (1–50+ km) tracking over a two-year period primarily showed limited movement within bays; however, directed bay-scale movements by both species were observed during winter and spring, when a small contingent of individuals moved up to 70 km from original tagging locations. Habitat use and movement were species specific and subject to temporal variation, both diel and seasonal. Habitat-scale connectivity was influenced by seascape structure and water depth, and bay-scale connectivity was generally limited, suggesting the sustainability of these fisheries is likely influenced by local conditions.

Effects of water-level fluctuations on the environmental characteristics and fish-environment relationships in the littoral zone of a reservoir

Article

Full-text available

Dec 2016
FUND APPL LIMNOL

Water-level fluctuations are a major function of reservoirs that influence the littoral zone of the lake, and prove to be of high importance for the whole biological communities of lakes. Working on a French hydropower reservoir, we studied the influence of water-level fluctuations on intra-annual variations of littoral habitat availability and their consequences for the structure of fish assemblages inhabiting the littoral zone. As the water level decreased significantly, habitat conditions tended to be much more homogeneous. The proportion of sites with a thin substrate and low slope increased, while submerged vegetation and riparian shade disappeared. The relationship between habitat complexity and fish assemblage changed along the water-level gradient. The habitat effect on assemblage structure was strongest when the water-level conditions were high and very high, and weaker for low and very low water-level conditions. A homogenization of fish assemblages was observed when the water-level condition reached a threshold. These results suggest an effect of water-level management in structuring fish assemblages of the littoral zone of a reservoir due to a decrease of habitat complexity.

Exotic species, Micropterus salmoides as a Key Bioindicator Influencing the Reservoir Health and Fish Community Structure

Article

Full-text available

Oct 2016

This study was carried out to analyze the difference of fish fauna, ecological indicator characteristics, biological status of other fish population and fish community structures between two groups of reservoir ecosystems along with the invasion of introduced Micropterus salmoides. Six reservoirs were selected and divided into two groups; reservoirs non-invaded and invaded by M. salmoides were RNIv and RIv respectively. Total 28 species 11,519 individuals were sampled in RNIv whereas 19 species 1,925 individuals were sampled in RIv. Korean endemic fish population dominates in RNIv, exotic fish species, especially M. salmoides population dominate in RIv. Sensitive species dominates in RNIv, while tolerant species and carnivore species dominate in RIv. The analysis of total length size distribution showed some difference, particularly in special size group between RNIv and RIv. Also, the analysis of total fish biomass showed a significant difference in accordance with M. salmoides inhabitation. According to the fish community analysis results, as M. salmoides proportion increased, species richness and diversity were decreased. Overall data suggests that the dominant distribution of M. salmoides may influence simplification of the fish fauna, species composition as well as community structure and affect the length distribution and biomass of other fish population negatively.

Grundlagen zur Ermittlung des fischereilichen und ökologischen Schadens durch wasserbauliche Anlagen im Land Brandenburg

Article

Full-text available

Apr 2011

Spatial partitioning in the use of structural woody habitat supports the cohabitation of two cod species in a large lowland river

Article

Full-text available

Oct 2015

Many freshwater fish worldwide have been shown to use Structural Woody Habitat (SWH) for a variety of reasons. The mid reaches of the Murray River, a large lowland river in southeastern Australia, was surveyed by boat electrofishing, to investigate the use of SWH type (hollows, rootmass and solids), SWH distance to bank (near bank, intermediate to bank and mid-channel) and the interaction between SWH type and distance to bank. The study found that Murray cod catch per unit effort (CPUE) increased in near-bank areas when hollows were a component of the SWH. The CPUE of trout cod was higher when hollows were present. However, the interactions between distance to bank and hollow SWH were complex and dependent on presence or absence of rootmass. The species-specific interactions between SWH microhabitat and distance to bank found within this study has important relevance for stream managers. The common practice of realigning SWH favours Murray cod over trout cod, which could have negative consequences for the endangered trout cod. More broadly, managers may need to consider a balance of SWH type and where it is placed in the river for the species they are targeting when rehabilitating rivers via the introduction of SWH.

Effect of meteorological conditions and water level fluctuations on the year-class strength of pikeperch (Sander lucioperca L.) and Perch (Perca fluviatilis L.) in a French reservoir

Article

Full-text available

Jan 2004

Christine Argillier

Locomotor activity patterns of muskellunge (Esox masquinongy) assessed using tri-axial acceleration acoustic transmitters

Article

May 2015
ENVIRON BIOL FISH

The trade-off between remaining stationary and being active has consequences for the survival and growth of fishes. Recent advancements in telemetry tools have enabled researchers to assess activity patterns of free-swimming fishes using tri-axial acceleration-sensing acoustic transmitters. This study describes the summer activity patterns of muskellunge (Esox masquinongy) in an 8 km reach of the Rideau River, Ontario between 1 June and 20 August 2010. Acceleration measurements indicated that muskellunge tended to remain inactive for much of the time. The effect of time of day (i.e., diel patterns), water temperature, and fish size were also examined. Activity was lowest at dawn, increased throughout the day, peaked at dusk, and declined at night. Activity also declined above temperatures of 25 °C and was lower for larger muskellunge. A comparison of fish captured with rod and reel versus boat electrofisher failed to reveal a significant difference in behaviour. The results of this study illustrate the utility of accelerometer transmitters for studying the behavioural ecology of free-swimming fishes. The results also confirm that muskellunge are generally sedentary during the summer period, but do exhibit reasonably pronounced diel activity patterns.

Nesting Season Food Habits of 4 Species of Herons and Egrets at Lake Okeechobee, Florida

Article

Full-text available

Jan 1997

Jeff P. Smith

Based on the composition of nestling regurgitations collected during 3 breeding seasons, fish were the most important prey group for Great Egrets (Ardea alba: N = 200 nest-day samples; aggregate percent biomass [APB] = 73.4%), Snowy Egrets (Egretta thula: N = 115; APB = 91.4%), and Tricolored Herons (E. tricolor: N = 68; APB = 97.3%). For Little Blue Herons (E. caerulea: N = 57), grass shrimp (Palaemonetes paludosus; APB = 39.7%) ranked higher in overall importance than all fishes combined (APB = 36.5%). Dietary overlap, as measured by Schoener's Similarity Index, was greatest between Snowy Egrets and Tricolored Herons (77%) and lowest between Tricolored Herons and Little Blue Herons (30%). Diet diversity, as measured by Shannon's Index, was highest for Great Egrets (2.04), intermediate for Snowy Egrets (1.71) and Tricolored Herons (1.68), and lowest for Little Blue Herons (1.60). Great Egrets ate a wider variety of fish species and sizes, especially larger fishes, and more crayfish than the other species. Little Blue Herons ate fewer fish and more grass shrimp and insects, and ate smaller forage fishes than Tricolored Herons but similar-sized fish as Snowy Egrets. The coarse-scale trophic composition of Snowy Egret and Tricolored Heron diets did not differ significantly, but Tricolored Herons ate larger forage fishes than Snowy Egrets. Pronounced interannual and intercolony variation in diet composition suggested that Great Egrets and Little Blue Herons switched prey types as hydrologic conditions and habitat availability changed. Conversely, lack of such variation suggested that Snowy Egrets and Tricolored Herons adjusted their foraging tactics to ensure continued encounters with preferred prey despite changing habitat conditions. These results are generally consistent with other published data, help confirm some generalizations about foraging strategies and patterns of niche differentiation among these ecologically similar species, and have implications for managing the Lake Okeechobee ecosystem.

Morphology predicting ecology: incorporating new methodological and analytical approaches

Article

Full-text available

Feb 2014

Associations between the morphology of animals and their ecology have contributed to our understanding of phenotypic diversity by helping to relate form and function. Most early studies on fishes used traditional measurements of linear distances on the body or fins to quantify morphological variation among taxa. More recently, geometric morphometric analyses have gained popularity for assessing phenotypic shape variation. Along with new methodologies for quantifying morphological variation, researchers have become increasingly aware of the influence of phylogeny on morphological and ecological traits. Our study, which spanned seven cyprinid genera, assessed the abilities of traditional and geometric morphometric approaches to characterize ecologically relevant morphological variation. Furthermore, we compared morphometric approaches employing two analyses (partial Mantel test and Phylogenetic Canonical Correlation Analysis (PCCA)) that test for correlations among data sets while explicitly accounting for phylogenetic relationships. Traditional morphology and body shape showed similar correlations with habitat use in all analyses. In contrast, only traditional morphology was correlated with diet; however, this was only revealed by the PCCA. Our findings indicated the taxonomic span of species under study and the statistical treatment of data are important factors to consider when choosing between traditional or geometric morphometric approaches. In addition, a better understanding of phylogenetic relationships will improve our ability to establish associations between morphology and ecology.

Community Structure of Indigenous Fishes Relative to Invasive Tilapia and Habitat Variation in Lakes of Quintana Roo, Mexico

Article

Jan 2022

Increased aquaculture production has resulted in the widespread establishment of African Oreochromis species in Mexico, impacting native ichthyofauna. In the state of Quintana Roo, part of the Caribbean versant of the Yucatan Peninsula, Oreochromis spp. are widely distributed. However, there are still limited quantitative data on their abundance relative to indigenous species or their influence on native fish diversity. Here we quantified the ichthyofauna of six lakes from this region, and recorded Oreochromis spp. from three of these lakes; they were relatively uncommon and represented less than 3% of the total captures. No evidence was found of tilapia influencing native fish biodiversity. On the other hand, we observed that greater dissolved oxygen and pH were associated with the highest biodiversity within and across lakes. Spatial comparisons highlighted the importance of other water chemistry variables, alongside substrate heterogeneity and lake area, as influential in determining native fish community structure. These results suggest that Oreochromis spp. may have strong limitations on their population size, due to the presence of predatory native fish species, or scarce suitable ecological resources (food, breeding habitat). Hence, conservation-focussed lake-wide management of native species and their core habitats may promote environmental resistance against negative effects of Oreochromis spp. regional expansions.

Seasonal habitat use of three predatory fishes in a freshwater ecosystem

Article

Full-text available

Sep 2022
HYDROBIOLOGIA

To understand the spatiotemporal overlap in the habitat use of sympatric predators, we studied longitudinal activity and reservoir section and depth use of pike (Esox lucius), pikeperch (Sander lucioperca) and catfish (Silurus glanis) in the Římov Reservoir, using an autonomous telemetry system for 11 months. We found significant differences among these species in studied parameters that varied considerably over tracked period. Pike consistently used the same sections of the reservoir, while pikeperch and catfish frequently visited a tributary during the warm season (late spring and early autumn), and moved closer to the dam during the cold season (late autumn to early spring). Pike longitudinal activity was highest in the cold season, pikeperch in the warm season, and catfish activity peaked in both seasons. Overlap in the depth use among species was higher in the warm season, when all species used the upper layer of the water column, and lower in the cold season, when pikeperch and catfish used deeper areas. These results demonstrated overlay and temporal variation of habitat use among these predators, as well as potential spatiotemporal space for their direct ecological interactions.

Environmental determinants of fish abundance in the littoral zone of gravel pit lakes

Article

Full-text available

Jun 2021
HYDROBIOLOGIA

The type and extent of habitats along the shoreline specify the distribution of fish in the littoral zone of lakes, but effects are likely species and size-specific and might be overwhelmed by lake-level environmental factors that drive fish abundance (e.g. trophic state). We applied a replicated transect-sampling design by electrofishing assessing fish abundance and distribution along the banks of 20 gravel pit lakes in Lower Saxony (Germany). Boosted regression trees were used to analyse the impact of different characteristic habitat types (e.g. vegetated, woody or open water zones), shoreline water depth and lake-level environmental variables on species-specific fish abundances. In contrast to earlier studies, lake-level environment and transect-level habitat type similarly influenced the abundances of differently sized fish species in the littoral zone of gravel pit lakes. The abundance of almost all fish species increased with lake productivity and extent of structured littoral habitats, mostly following non-linear relationships. Our work suggests that investments into the quality of littoral habitat, and not merely the control of nutrient inputs or other lake-level environmental factors, can promote abundance of most gravel pit lake fish species, in particular those who depend on the littoral zone for at least part of their life-cycle.

Biotechnology in Industrial Waste Treatment and Bioremediation

Book

Oct 2020

Species‐pair associations, null models, and tests of mechanisms structuring ecological communities

Article

Full-text available

Jul 2019

Biotic interactions and niche processes are fundamental determinants of community structure and species co‐occurrence. Most studies of species co‐occurrence have focused on negative association patterns (segregation presumed to arise from competition), often ignoring positive aggregations, although positive and negative associations may arise from multiple mechanisms. We used a pairwise approach to identify co‐occurrence patterns of 76 fish species across almost 9500 lakes, followed by a meta‐analytic approach to compare the co‐occurrence pattern of each species pair across watersheds and determine their cumulative species associations. Biological information relating to species’ phylogeny, habitat preferences, and diet was used to group species into relevant subsets in order to test community assembly processes of competition, predation, and habitat filtering. We found consistent non‐random patterns of co‐occurrence in nearly half the species pairs and more extremely aggregated than segregated species pairs. Observed co‐occurrence patterns indicated the importance of shared habitat requirements and predation, rather than competition, driving positively aggregated and negatively segregated species associations, respectively. Our meta‐analytic approach incorporating important biological attributes permitted the testing of specific mechanisms of community assembly, providing novel insights into the major determinants of fish community structure and their generality across a vast set of lakes.

Auswirkungen einer winterlichen Rohrwerbung auf Bestandsstruktur und Habitatfunktion von Phragmites-Röhrichten

Book

Full-text available

Aug 2017

Die ökologischen Effekte einer mosaikartigen winterlichen Rohrwerbung wurden untersucht. Dabei konnten der Bestand selber, die Vegetation, Fische, Amphibien und Vögel berücksichtigt werden. Phragmites-Halme wachsen nach eine Mahd in höheren Dichten, bleiben aber etwas kürzer. Durch die Methodik kam es an den seeseitigen Ausdehnungsfronten der Röhrichte zu mahbedingten Schäden am Schilf. Für die Fischbestände war kein Einfluss der Wintermahd erkennbar. Amphibien profitierten von der Mahd, und hielten sich auf den geschaffenen Flachwasserflächen auf. Bei den Vögeln zeigte sich eine erhöhte Artenvielfalt nach der Mahd, die freien Flachwasserflächen wurden als Habitat von vorher abwesenden Arten angenommen. Bei einer Schilfbrüter-Art zeigte sich eine Abnahme der vorher hohen Bestandsdichte.

First reported actinopterygian from the Navajo Sandstone (Lower Jurassic, Glen Canyon Group) of southern Utah, USA

Article

Apr 2017

We report the first occurrence of an actinopterygian fish from the Lower Jurassic Navajo Sandstone, discovered in the Grand Staircase-Escalante National Monument in southern Utah, U.S.A. The site contains multiple individuals, preserved within an interdune deposit, possessing the elongate modified dorsal scales usually characterizing semionotiform fishes. The presence of moderately sized fish provides further evidence that interdune oases were occasionally persistent environmental habitats within the greater Navajo dune system, and that the paleobiota is still woefully undersampled. Additionally, this site could help fill a gap in the actinopterygian fossil record between the patchy Lower Jurassic and better-known Middle Jurassic documentation of western North America.

Écologie des juvéniles 0+ et 1+ de chevalier cuivré (Moxostoma hubbsi),une espèce menacée, comparée à celle des quatre autres espèces de Moxostoma (M. anisurum, M.carinatum, M. macrolepidotum, M. valenciennesi) dans le système de la rivière richelieu

Thesis

Full-text available

Nov 1999

Nathalie Vachon

Le chevalier cuivré (Moxostoma hubbsi), seul vertébré endémique au Québec, est menacé d’extinction (officiellement désigné menacé en vertu de la Loi québécoise sur les espèces menacées ou vulnérables depuis le 8 avril 1999). La seule population encore décelable est dans la rivière Richelieu où elle vit en sympatrie avec quatre autres espèces du même genre (M. macrolepidotum, M. anisurum, M. valenciennesi et M. carinatum). Différentes études ont mis en évidence une diminution de son abondance et de son aire de répartition et un faible succès de reproduction. Les causes potentielles de son déclin seraient d’origine anthropique, principalement attribuables à la détérioration et à la contamination de l’habitat. À l’heure actuelle, les divers travaux ont porté principalement sur les adultes du chevalier cuivré mais les données concernant les juvéniles et les interactions entre les différentes espèces en milieu naturel sont encore très fragmentaires. L’acquisition de connaissances sur l’ensemble du cycle vital est primordiale pour la mise en place de mesures visant sa sauvegarde. En vue de compléter nos connaissances, cette étude vise à comparer la croissance et l’alimentation de même qu’à caractériser l’habitat des juvéniles 0+ et 1+ des différentes espèces de chevalier dans la rivière Richelieu. Deux hypothèses ont été mises de l’avant en rapport avec l’alimentation. La première prévoit que les espèces dont les périodes de fraye sont rapprochées présentent un recouvrement plus élevé de leur régime alimentaire et la seconde stipule que le degré de recouvrement du régime alimentaire des juvéniles 0+ des différentes espèces est plus élevé durant l’été et s’atténue à l’automne. Les spécimens ont été capturés à la seine de rivage de juin à novembre 1997 ainsi qu’au printemps et à l’automne 1998. L’abondance relative des juvéniles 0+ et 1+ de chevalier cuivré est très faible soit 0,4 % (16 spécimens ont été capturés). Au cours de la première année, les jeunes chevaliers fréquentent les rives caractérisées par de faibles profondeurs (profondeur moyenne ≤ 1,5 m et profondeur maximale ≤ 3 m), de faibles pentes (≤ 20°), pourvues de végétation et où le substrat est relativement fin (mélange d’argile-limon et sable). La taille moyenne des jeunes chevaliers cuivrés de l’année (40,4 mm) est nettement inférieure à celle des autres espèces qui est d’environ 60 mm pour les chevaliers rouge et blanc, 52 mm chez le jaune et de 48,7 mm chez le chevalier de rivière. Les mêmes tendances ont été trouvées chez les juvéniles 1+. Les juvéniles 0+ et 1+ de chevalier s’alimentent principalement de microcrustacés (cladocères de la famille des chydoridés et copépodes harpacticoïdes), des larves d’insectes (chironomides), de vers (nématodes) et d’algues (diatomées et desmidées). Les régimes alimentaires diffèrent généralement peu entre les espèces (recouvrement élevé) à l’exception du chevalier rouge qui se distingue nettement des autres par sa plus grande utilisation de larves d’insectes. De même, au fil de leur première saison de croissance, les régimes alimentaires des jeunes chevaliers des différentes espèces varient peu. Ces résultats infirment les deux hypothèses précédemment énoncées. Plusieurs données recueillies au cours de la présente étude mettent en évidence que les jeunes chevaliers cuivrés présentent davantage de caractères de vulnérabilité par rapport aux autres espèces et ce, dès leur première année de vie. Pour l’ensemble de l’échantillon de jeunes chevaliers, nous n’avons pu mettre en évidence de mortalité qui serait sélective quant à la taille au cours de leur premier hiver. Cependant, dans le cas particulier du chevalier cuivré, en raison du très faible nombre de captures, l’hypothèse ne peut être rejetée. Nos résultats ne viennent que confirmer que le chevalier cuivré est en danger de disparition. Des actions concrètes telles la protection des aires de reproduction et d’alevinage, l’élaboration d’un plan de reproduction de même que l’ensemencement de spécimens de plus grande taille que ceux déjà remis en milieu naturel doivent être mises de l’avant le plus tôt possible pour le sauvegarder. Enfin, un suivi périodique du recrutement des jeunes chevaliers de l’année pourrait être effectué en vue de mesurer l’impact des diverses actions entreprises et de suivre de près les populations de chevaliers jaune et de rivière qui pourraient également être en difficulté dans la rivière Richelieu. Mots clés : Moxostoma, hubbsi, menacé, juvénile, alimentation, croissance, habitat, identification.

Ontogenetic loops in habitat use highlight the importance of littoral habitats for early life-stages of oceanic fishes in temperate waters OPEN

Article

Full-text available

Mar 2017

General concepts of larval fish ecology in temperate oceans predominantly associate dispersal and survival to exogenous mechanisms such as passive drift along ocean currents. However, for tropical reef fish larvae and species in inland freshwater systems behavioural aspects of habitat selection are evidently important components of dispersal. This study is focused on larval Atlantic herring (Clupea harengus) distribution in a Baltic Sea retention area, free of lunar tides and directed current regimes, considered as a natural mesocosm. A Lorenz curve originally applied in socio-economics to describe demographic income distribution was adapted to a 20 year time-series of weekly larval herring distribution, revealing size-dependent spatial homogeneity. Additional quantitative sampling of distinct larval development stages across pelagic and littoral areas uncovered a loop in habitat use during larval ontogeny, revealing a key role of shallow littoral waters. With increasing rates of coastal change, our findings emphasize the importance of the littoral zone when considering reproduction of pelagic, ocean-going fish species; highlighting a need for more sensitive management of regional coastal zones.

ECOLOGY – Ecological effects of marine protected areas: conservation, restoration, and functioning

Article

Full-text available

Sep 2011

Human-induced environmental disturbance – through fishery activities, coastal development, tourism and pollution – is a major challenge to the restoration and conservation of marine biodiversity. Synthesizing the latest research into marine biodiversity conservation and fisheries management, this book provides regional and global perspectives on the role of Marine Protected Areas (MPAs) in confronting this challenge. The approach is multidisciplinary, covering all the fields involved in designating and assessing MPAs: ecology, fisheries science, statistics, economics, sociology and genetics. The book is structured around key topics, including threats to marine ecosystems and resources, the effects and effectiveness of MPAs and the scaling-up of MPA systems. Both theoretical and empirical approaches are considered. Recognizing the diversity of MPA sciences, the book also includes one part designed specifically as a practical guide to implementing scientific assessment studies of MPAs and monitoring programs.

A risk analysis of sunfishes (Centrarchidae) and pygmy sunfishes (Elassomatidae) in The Netherlands

Technical Report

Full-text available

Mar 2010

The family Centrarchidae includes about 34 species, which all have their native range in North America. In the Netherlands the most ill famous member is Lepomis gibbosus. This in the Netherlands invasive species is the only member of the family with established populations. These populations can be found all over the Netherlands and the species seems to be still expanding. Its negative image is caused by its presence in many isolated water bodies where it has a strong negative impact on the fauna, including rare amphibians such as the common spadefoot (Pelobates fuscus) and the European tree frog (Hyla arborea). Because of this impact a wholesaler has decided stop selling this species in 2010. In this study it is shown that another nine species of Centrarchidae should be considered to be potentially invasive. They are all at least available for export in North America and have a high probability of establishment based on their thermal biology: A. rupestris, P. annularis, P. nigromaculatus, L. cyanellus, L. macrochirus, L. megalotis s.l. (L. megalotis s.s. & L. peltastes), M. dolomieu & M. salmoides. When considering possible climate change in the period 1990-2050 L. auritus should be included in this list. These species are all flexible in their habitat preferences and are likely to find suitable habitats in most regions in the Netherlands. With these centrarchids known to be good dispersers, it is likely that they will spread relatively easily after establishing reasonable populations. The family Elassomatidae, which is also reviewed as they might be a potential substitute for centrarchids in trade, is considered to be of no risk as they are unlikely to survive Dutch winters. Like L.gibbosus also other Centrarchidae are likely to affect ecosystems mainly by predation (amphibians, smaller fish species, damselflies, etc.) and competition with other predatory fish. Especially ecosystems, lacking comparable native predatory fish species prior to the establishment of such an exotic centrarchid, are susceptible to significant ecological impact. Centrarchidae have not been reported to be vectors for parasites or diseases of special concern. The establishment of larger centrarchid species will have a small, positive social and economic impact to commercial fisheries, the angling society and related business. When established, centrarchid populations can in most instances only be eradicated with rigorous measures like dewatering or the use of piscicides. Obviously, the prevention of entries and further spread reduces the need for such actions. The major components of prevention are banning of potential invasive species from trade and educating the public about the impact of centrarchids.

Growth, Density, and Interspecific Influences on Pumpkinseed Sunfish Life Histories

Article

Jun 1994

Michael G. Fox

I collected data on 27 pumpkinseed (Lepomis gibbosus) populations in eastern and central Ontario and conducted a transplant experiment with one of these populations to test growth and competition-related predictions of several life history models. The predictions are that early maturity and high gonadal investment will occur: (1) in large and fast-growing juveniles; (2) in populations with low adult: juvenile growth ratios; (3) in populations with low density; and (4) in the absence of bluegill sunfish (Lepomis macrochirus), a competing congener. Predictions 1 and 4 were fully supported and Prediction 2 was partly supported, but Prediction 3 was not. The earliest maturing juveniles within populations were significantly larger than conspecifics of the same age that did not mature. Females from a lake population that were transplanted into a fishless pond exhibited both significantly faster growth and a significantly higher gonad to body mass ratio (gonado-stomatic index) that females living in the lake. At the population level, juvenile growth was significantly correlated with age at maturity (r = 0.52), but not with gonadostomatic index, whereas the Adult : Juvenile Growth Ratio showed a significant, negative correlation wih gonadosomatic index (r = 0.66), but not with mean age at maturity. Mean age at maturity showed a stronger correlation with the indicator of life-span and adult survival rate (r = 0.74), suggesting that mortality is more important than growth in the shaping of reproductive life histories of pumkinseed. High population density was associated with early maturity and high gonadal investment, the opposite of what was predicted. However, pumpkinseed populations that co-occurred with bluegills did mature significantly later and at a larger size and tended to have a lower gonadal investment than populations living in waterbodies without bluegills. This difference in reproductive patterns in the presence of bluegill is consistent with two-stage life history theory and may be the result of a direct effect of bluegills on pumpkinseed growth and survivorship, as well as differences in environmental conditions were the two species do or not co-occur.

Food, Predation Risk, and Microhabitat Selection in a Marsh Fish Assemblage

Article

Full-text available

Oct 1988

Fishes moving onto the surface of a tidal freshwater marsh from an adjacent stream were sampled with flume nets in spring through autumn for 2 yr. Significantly higher numbers were found at sites adjacent to shallow-sloped depositional banks than at sites adjacent to deeper, steeper sloped erosional banks of the stream. Marsh surface features appeared similar, so explanations for this apparent habitat selection were sought in the subtidal portion of the stream. To determine whether the relative abundance of benthic invertebrate prey differed in the two environments, litter bags were placed in the subtidal for 4 wk. Despite higher numbers of invertebrates in erosional zones, both the wet biomass per sample and the mean wet biomass per organism were significantly greater in depositional sites. To test the hypothesis that invertebrate food is more available to fishes in the depositional subtidal, banded killifish (Fundulus diaphanus) were placed in feeding enclosures in both depositional and erosional subtidal habitats in two streams. These fish obtained significantly more food in the shallow depositional subtidal. To test the hypothesis that predation pressure differs with subtidal geomorphology, mummichogs (Fundulus heteroclitus) were tethered on the first half of the rising tide in both depositional and erosional environments in three creeks. Significantly more mummichogs disappeared from tethers and were presumed taken on erosional banks. We conclude that two mechanisms operate in the stream subtidal to give rise to the greater fish abundance at marsh surface sites adjacent to depositional areas. At low tide, when small fishes are confined to creek channels, they select shallow depositional habitats where (1) the availability of benthic invertebrate prey is greatest and (2) predator pressure is less. As the tide rises and inundates the marsh surface, these small fishes seek shelter on the marsh surface adjacent to their preferred low-tide refuge.

Ontogenetic Niche Shifts in Largemouth Bass: Variability and Consequences for First-Year Growth

Article

Jan 1996

Mark H. Olson

The ontogeny of many size-structured organisms is marked by a series of niche shifts that divides a population into ecologically distinct stages. Consequently, overall population dynamics are affected both by processes operating within individual stages and by factors that influence transitions between stages. In largemouth bass (Micropterus salmoides), there is a diet shift from littoral invertebrates to fish that typically occurs sometime in their 1st yr. I examined factors that influenced this shift by tracking diet and growth trajectories of young-of-year (YOY) bass cohorts in several Michigan lakes over 2 yr. Cohorts differed in consumption rates of invertebrate prey, which led to an early divergence in bass growth among lakes. This variation in early growth had dramatic consequences for the timing of the shift to piscivory. In lakes with rapid growth in the invertebrate feeding stage, bass were able to gain a size advantage over YOY bluegill (Lepomis macrochirus), their primary fish prey, which facilitated a shift to piscivory as soon as these bluegill became available as food. In contrast, slow growth during the invertebrate feeding stage reduced the size advantage of bass over bluegill and delayed or even prevented the shift to piscivory in the 1st yr. Niche shifts in bass were also sensitive to environmental conditions early in the growing season. In 1992, low temperatures caused a reduction in growth rates that prevented the establishment of a size advantage over bluegill in all but one lake. Bass grew much faster after switching to piscivory; thus the shift from invertebrates to fish strongly influenced sizes attained by YOY bass by autumn. Because survivorship of YOY bass is strongly size dependent (particularly through the first winter), the timing of the shift to piscivory may be important in determining survival and recruitment rates. Therefore, processes that operate on bass in the invertebrate feeding stage can influence the shift to piscivory, and this can potentially have important effects on the dynamics of the population as a whole.

The Role of Foraging Profitability and Experience in Habitat Use by the Bluegill Sunfish

Article

Full-text available

Feb 1981

This study integrates laboratory and field results to interpret habitat use and switching by individual bluegill sunfish (Lepomis macrochirus). Prey handling and search times for the bluegill were determined from laboratory feeding experiments at different prey sizes and densities in open water and sediment habitats. Relationships were then constructed to predict the expected return per unit time foraging in these habitats. Experience (learning) was found to increase foraging efficiency up to fourfold over the course of six to eight foraging bouts. A population of 225 bluegills was then introduced into a pond consisting predominantly of open water and sediment habitats. This population exhibited several habitat switches as resources declined during the 3-mo experiment; in addition, the population split over a 5-wk period, with individuals specializing on one habitat or the other. These specialists were considerably more successful than habitat generalists as measured by average amount of food in the stomachs. Return rates estimated from the laboratory experiments indicated that the two habitats were nearly equal in foraging profitability. The individual specialization indicated that learning and mutually interfering foraging mechanisms were involved in the species' use of the two habitats. The results suggest that learning and sampling are important aspects of both habitat use and the specialization of individuals within a population.

Does Morphology Predict Ecology? Hypothesis Testing within a Freshwater Stream Fish Assemblage

Article

Full-text available

Nov 1992

Seventeen fish species (eight genera and five families) from the Roanoke River (Virginia) were evaluated on the following characters: 1) species-occurrence across 12 microhabitat measures; 2) percent occurrence of 13 food items in gut analyses; and 3) 34 head, fin, and body measurements. In analyses across families, two-way Mantel tests revealed that taxonomy and body shape were each significantly related to one another, and to the trophic matrix. Yet, three-way Mantel comparisons indicated that body shapes of constituent species were significantly correlated only with taxonomy, and not with diet. To circumvent the confounding effects of taxonomy, the largest family in the study (Cyprinidae, eight species represented) was evaluated separately. Morphology was significantly related to the microhabitat matrix, and to no others. Previous field studies have indicated that cyprinids segregate along habitat rather than trophic dimensions. Ecomorphological analyses thus appear to be a valid assay for structure within fish assemblages only when limited to within-family comparisons (where the effects of history appear less significant). When many different families are involved in the analysis, historical influences predominate. -from Authors

Depth Distributions of Armored Catfish: Predator-Induced Resource Avoidance?

Article

Apr 1984

Mary Power

Four species of armored catfish (Loricariidae) have size-specific depth distributions in a Panamanian stream, with larger fish in deeper water. Depth distributions do not change from the dry to the rainy season, despite a two- to three-fold increase in habitat area for larger loricariids. Throughout the year, standing crops of the loricariids' attached algal food are relatively high in shallow water, but decrease rapidly with depth. Over 2@1 yr, large Ancistrus spinosus, the most common pool-dwelling loricarriid, showed significant seasonal changes in somatic growth rates, with maximum rates in the early rainy season and minimum rates in the late dry season. Significant seasonal changes in mortality rates, estimated from rates of disappearance of marked individuals, were not detected. These data are consistent with the following hypothesis: small loricariids are limited, perhaps by predation, at densities below those necessary to deplete algae in shallow water. Larger loricariids avoid shallow water where they are vulnerable to fishing birds, even in the dry season when food is in short supply in deeper areas.

Predation and Resource Partitioning in Two Sunfishes (Centrarchidae)

Article

Full-text available

Apr 1984

Gary G Mittelbach

Large bluegills Lepomis macrochirus and pumpkinseeds L. gibbosus (>75 mm SL) exhibited distinct diet and habitat separation in 3 small Michigan lakes. Bluegills foraged primarily on open-water zooplankton (Daphnia), while pumpkinseeds specialized on vegetation-dwelling gastropods. These differences in resource use by large fish were directly related to differences in their functional morphology and foraging ability. In laboratory feeding experiments, pumpkinseeds had significantly lower prey handling times for gastropods than did bluegill. The bluegills, on the other hand, was the more efficient when feeding on zooplankton. The diets and habitat use of small bluegills and pumpkinseeds (= or <75 mm SL), however, were quite similar. Small fish of both species foraged predominantly in the vegetation, and 76-91% of their average seasonal diet was vegetation-dwelling prey (non-gastropods). This increase in shared resources among small fish was due to 1) piscivorous fish restrict small size-classes to the vegetation where they are less vulnerable, and 2) small pumpkinseeds are unable to feed effectively on snails, the adult resource in the vegetation. The 2 species are nearly equal competitors in the juvenile habitat, but were not in equal abundance across the study lakes; the ratio of bluegills to pumpkinseeds ranged from 25:1 to 1:1. The pattern in species abundance was directly related to the availability of 'adult' resources (snails and zooplankton), suggesting that the volume of the competitive refuge experienced by each species at larger sizes is the predominant factor controlling relative numbers.-from Author

Habitat Partitioning in a Freshwater Fish Community

Abstract

No full-text available

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