Brook trout Salvelinus fontinalis populations inhabiting groundwater-fed, headwater streams are sensitive to biotic and abiotic changes caused by anthropogenic actions in their native range but can be very resilient in their introduced range. Brook trout have maintained a self-sustaining population in the Little Plover River, Wisconsin, despite fish kills during extreme low flows between 2005 and 2009

Predation on anadromous salmon can have important consequences for both predators and prey. Salmon provide large seasonal pulses of energy and nutrients via carcasses, eggs and juveniles to many freshwater consumers, and conversely, predation can represent a significant source of mortality for juvenile salmon. Recent declines of Chinook salmon (Oncorhynchus tshawytscha) populations in Alaska have raised

A myriad of factors affect stream fish assemblages, and most of them are intimately regulated by surrounding land uses. One of the most pernicious impacts on streams is the release of urban effluents. Accordingly, understanding the fish assemblage patterns as well as the environmental drivers that modulate them in the context of urban streams which also are exposed to other land uses is mandatory.

The common carp, Cyprinus carpio, is a large, long-lived, fecund and mobile cyprinid, which evolved in complex inter-braided Ponto-Caspian rivers that experience both springtime flooding and freezing winters. Studies suggest adults often move to productive, shallow lakes and floodplains to spawn because they often lack egg predators and then return to deeper normoxic waters to overwinter. Whether these

Introductions and invasions of non-native species alter nutrient cycling and trophic dynamics resulting in significant ecological disturbance. Stable isotope data were used to test for evidence of invader-induced trophic niche differences in a north Norwegian lake system differentially dominated by native European whitefish (Coregonus lavaretus) morphotypes and invasive vendace (Coregonus albula).

The reproductive activity of the fish assemblage in a large Neotropical reservoir was evaluated by surveying the occurrence of ichthyoplankton in response to spatial and temporal variation in environmental factors. Fish reproduction was investigated by capturing larvae along representative spatial gradients in the main body (longitudinal) and arms (lateral) of the reservoir. After identification, the

The diversity of predatory species plays a key role in ecosystem functioning but our understanding of the mechanisms underlying their coexistence is limited, particularly in freshwater ecosystems. Northern pike Esox lucius, European perch Perca fluviatilis and pikeperch Sander lucioperca are three widespread predatory species in European lakes, where they often coexist. As potential competitors, we

Understanding trade-offs associated with occupying various aquatic habitats provides a mechanistic understanding of habitat needs that can be used to evaluate the consequences of habitat loss or alteration. We used instream enclosures and field observations to identify how velocity affects the growth rates of four native species in the upper Gila River basin: longfin dace (Agosia chrysogaster) and

Variation in seasonal survival rates, densities and growth rates of coastal cutthroat trout (Oncorhynchus clarkii clarkii) were assessed across a size gradient of small, forested streams in the Pacific Northwest. We used a robust, mark-recapture study, stratified seasonally to estimate monthly survival rates of trout in coastal British Columbia (not including young-of-the-year). Survival estimates

Understanding the mechanisms that structure communities have been a major challenge in ecological theory. Functional trait-based approaches are increasingly used for studying the processes underlying community assembly. However, species-poor systems of Andean streams these processes are largely unknown. Tropical Andean streams are highly variable in space-time and characterised by the harsh or stable

The survival and establishment of alien fishes in novel environments can result in resource partitioning with native fishes. This can cause ecological impact and suppression of native populations. However, quantifying the impact of novel interactions between alien and native species remains highly challenging in the wild. Consequently, to determine the ecological risk of Lepomis gibbosus in case of

Floodplain lakes are ecosystems characterised by annual flood and dry cycles. Fish ecology is influenced by the flood pulse due to the large influx of allochthonous food resources and diversification of habitats during the flood cycle, while during the dry cycle, fishes tend to be confined in reduced habitat. The aim of this study was to evaluate the seasonal variation in trophic niche width and overlap

Muskellunge (Esox masquinongy Mitchill), northern pike (Esox lucius L.) and walleye (Sander vitreus Mitchill) often coexist in lake communities, yet uncertainty exists about the potential for interspecific competition among these top predators. Stable isotope data were used to assess niche overlap and diets of these predators in Elk Lake (Minnesota, U.S.A). δ13C indicated primary production sources

Increases in temperatures over the last century, more intensively after the eighties, were recorded in several databases for the south‐eastern Brazil. These increases are likely to change fish communities in aquatic systems by decreasing abundances, biomass and sizes of some species more sensitive to climate change. Reservoirs may be particularly susceptible to the effects of climate change, as they

Understanding the ecological dimensions of drought is critical for predicting how humans and nature will be affected by the expected increased prevalence of drought in the future. We tested life‐history‐based predictions for fish assemblage responses to drought using retrospective analysis of long‐term (1986–2003) fish surveys from two streams in the Appalachian Mountains of North America. We hypothesised

Ongoing climate change is leading to browning of many lakes and coastal areas, which can impair fish body growth and biomass production. However, whether and how effects of light limitation caused by browning on fish body growth vary over early ontogeny is unknown. In this study, we set up a mesocosm experiment to test whether roach (Rutilus rutilus) body growth responses to browning depend on body

Temporary water bodies are temporally variable ecosystems supported primarily by rainwater. The biota supported by such water bodies present a range of capacities to remain in this environment for all or part of their life cycles. During floods, temporary pools can connect with permanent streams, promoting changes in trophic networks in the aquatic food webs. The aim of this research was to analyse

Lateral hydrological connectivity (LHC) maintains the high biodiversity and ecosystem functions in the river–floodplain system. We investigated the changes in the taxonomic and functional composition of fish assemblages in the lateral connection channel between the Yangtze River and Poyang Lake, China, during the dry and wet seasons and which factors drive the changes. The results indicated more lake‐residence

Seasonal migrations of fish populations can have large effects on lake nutrient budgets and food web dynamics, but the addition of a migrating non‐native species may alter these dynamics. The Round Goby (Neogobius melanostomus) arrived in Lake Ontario (USA/Canada) about 20 years ago with a documented history of annual offshore–inshore migrations in its native range. Here we combined nearshore, fixed‐plot

Life‐history and other vital rate information is important for effective species conservation by informing demographic trends and aspects of population viability. However, species‐specific information is lacking for many small‐bodied freshwater fishes, which can make it difficult to relate demographic trends to threats or recovery actions. Silver Shiner (Notropis photogenis), a small‐bodied species

Water warming induced by human activities can impact fish larvae survival, notably because it influences larval development and prey abundances. Amphidromous gobies of the subfamily Sicydiinae are particularly sensitive to this threat as the newly hatched free embryos are poorly developed and the first feeding opportunity only occurs after they reach the ocean. Here, we studied how water temperature

The construction of dams creates a series of reservoirs, causing severe environmental changes and a biodiversity crisis. We aimed to investigate the relative roles of the construction of upstream cascade dams and the longitudinal gradient in environmental conditions in the spatial and temporal variations in fish assemblages in a downstream reservoir. Fish assemblage and abiotic data from four longitudinally

Adult salmonid migration to natal habitats and spawning are affected both by physiological factors and environmental conditions. While research has focused on physiological thresholds that influence the initiation of migration, few studies have investigated the relationship between both hydrological and thermal conditions and salmon spawning throughout the course of the reproductive period. We examined

To better understand the ecology of coldwater fishes in urban‐dominated landscapes, factors influencing seasonal brook trout (Salvelinus fontinalis) habitat use were assessed using backpack electrofishing surveys in three urban groundwater‐fed streams in central Ontario. Generalised additive models revealed that yearling brook trout (<100 mm TL) were primarily influenced by water quality (stream temperature

Ecomorphology and trophic ecology are considered important features in comprehending the feeding structure of fish communities. This study assesses the ecomorphological relationships among 45 fish species inhabiting the Eastern Himalayan torrential rivers, Murti and Jaldhaka by identifying morphological and trophic associations highlighted by prey acquisition strategies and the potential phylogenetic

Stable isotope ratios are powerful indicators that facilitate the understanding of the diet shifts and between‐habitat migration of aquatic animals. However, isotopic change rate can be variable even between the life stages of a single species, which affects field data interpretation. We conducted diet‐switch experiments to compare the δ13C and δ15N changes in multiple tissues between the growing and

Terrestrial invertebrates provide important prey subsidies to many stream fishes. Non‐native invertebrates are widespread in many ecosystems, yet they have received little attention in studies of subsidies to stream food webs. We sampled coastal basins in Big Sur, California, to determine the importance of non‐native isopods and other terrestrial invertebrates in the summer diet of steelhead/rainbow

Natal homing and straying are behavioural tactics of migratory animals that return to nursery habitats to breed as adults. Straying has evolutionary and ecological importance for species flexibility, interpopulation connectivity and success of invasive species in new environments. This study aimed to estimate the relative importance of straying and homing in introduced brown trout Salmo trutta spawning

We tested for effects of two dams on fish assemblages in the St. Joseph River, Indiana. Fishes were collected by boat electrofisher twice annually, at 23 sites from 1998 to 2018. Fish collection data were aggregated into CPUE counts of species per 500 m, and CPUE were pooled across sites above and below the dams. We used multivariate analyses to test for spatial and temporal variation for assemblages

Efforts to restore river ecosystem connectivity focus predominantly on diadromous, economically important fish species, and less attention is given to nonmigratory, small-bodied, benthic fish species. Data on benthic fish swimming performance and behaviour in comparison with ecologically similar native species are especially relevant for the study of one of the most successful invaders in the last

The Cichlidae are among the most diversified families of fish in the Neotropics and represent an important component of aquatic biodiversity. Understanding cichlid nest‐site selection is important for assemblages facing uncertain futures due to species invasions and environmental change. This information could be used to predict how inter‐ and intraspecific competition for reproductive space may affect

The introduction of exotic species has the potential to cause resource competition with native species and may lead to competitive exclusion when resources are limiting. On the other hand, information is lacking to predict under what alternate trophic conditions coexistence may occur. Comparing diets of native yellow perch Perca flavescens and nonindigenous white perch Morone americana, we examined

Offspring growth is greatly influenced by both the maternal and paternal genotypes. However, although the effects of maternal genotype on offspring growth are recognised widely, ecological studies of the paternal genotype have not focused on the links with physiological traits, especially at the embryo stage. In this study, we conducted three experiments to determine the effects of two contrasting

Understanding spatial variation in non-native fish species population ecology is imperative, where environmental, biotic and invasion-related mechanisms contribute to spatial heterogeneity. Established populations of invasive silver carp Hypophthalmichthys molitrix are currently found throughout a large portion of the upper Mississippi River (UMR) basin. Despite their recent invasion and broad environmental

Documenting responses of biotic assemblages to coal-mining impacts is crucial to informing regulatory and reclamation actions. However, attributing biotic patterns to specific stressors is difficult given the dearth of preimpact studies and prevalence of confounding factors. Analysing species distributions and abundances, especially stratified by species traits, provides insights into how assemblage

Swimming performance is a determinant characteristic for the survival of fish species and is related to their response to environmental disturbance. In this study, we evaluated how seasonal environmental variability of Mediterranean intermittent rivers influences swimming performance of a resident Iberian fish, the ruivaco, Achondrostoma oligolepis. Approximately forty fish of A. oligolepis were captured

Clearing land for the establishment of pasture is the principal cause of deforestation in the Amazon basin. We investigated how stream habitats and the taxonomic and functional structure of the fish fauna respond to the effects of the conversion of forest to pasture in the eastern Brazilian Amazon. We sampled 13 streams located in areas of forest and 13 streams within a pasture matrix. The structure

Recent large influxes of non‐native Pacific pink salmon (Oncorhynchus gorbuscha) to North European rivers have raised concern over their potential negative impacts on native salmonids and recipient ecosystems. The eggs and carcasses of semelparous pink salmon may provide a significant nutrient and energy subsidy to native biota, but this phenomenon has not been widely documented outside the species'

Bartram's Bass Micropterus sp. cf. cataractae is a rare black bass endemic to the Savannah River of the south-eastern United States and is threatened by habitat degradation and hybridisation with nonnative Alabama Bass Micropterus henshalli. While Bartram's Bass has been functionally extirpated from reservoirs, some populations persist in tributaries. Understanding the mechanisms affecting hybridisation

Through their multiple functions, refuges may be important for stream‐living fishes, particularly during stressful events such as seasonal low flow or drought. Coastal Cutthroat Trout Oncorhynchus clarkii clarkii is an ideal study organism to understand the importance of refuge. During seasonal low flow, lower water levels limit access to refuge and emigration, survival of fish is low, and predation

Trophic partitioning, defining how individuals or populations differ in their resource use, is expected to promote coexistence of sympatric species by reducing resource overlap. We used stable isotope measurements (δ13C and δ15N) to address niche characteristics (δ13C and δ15N ranges, isotope convex hull and standard ellipse areas, mean nearest neighbour distances and trophic positions) and trophic

The objectives of this study were to investigate the food resources consumed by two species of detritivorous fishes along the Apodi‐Mossoró River reservoir cascade system, located in the tropical semi‐arid region of Brazil. The hypotheses tested were as follows: (a) the diet, niche breadth and niche overlap of the species in the reservoirs downstream of the cascade are different due to the blockage

Resource use by organisms is mainly influenced by factors such as the morphology of individuals and the diversity and abundance of resources. For omnivores, the influence of these factors is more complex, as they have a morphology adapted to access different trophic levels, and any change in the environment can affect the quality or availability of resources. The aim of this study was to evaluate the

We investigated how the taxonomic and functional structures of fish assemblages in the lower Amazon River floodplain responded to seasonal hydrological variations. Fishes were sampled in 440 aquatic habitats across a floodplain area of 17,673 km2 during periods of high, receding, low and rising water. In addition, we recorded local environmental and landscape variables known to affect fish assemblages

Ecological studies have traditionally treated fish species or populations as homogenous groups; however, numerous studies have shown that intrapopulation variation in resource use is widespread. Within‐species diet differences are evident in small and large freshwater systems and may influence trophic and population dynamics. In a previous study of young yellow perch, spatial intrapopulation diet variation

Riparian forest may represent a key subsidy to aquatic food webs. While most research has been done in running waters, the origin of resources subsidising biomass and the role of riparian coverage in food webs remains largely unstudied in reservoirs. This research evaluated the role of forest riparian zones as food web subsidies in a recently formed reservoir of Ijuí River, Brazil. The diet of fish

Facultative migration occurs when, in response to prevailing conditions, individuals in a population may (or may not) undertake a migration. The brown trout (Salmo trutta) is a species that exhibits facultative migration, where some individuals within populations may move to mainstem rivers (fluvial–adfluvial migration), lakes (lacustrine–adfluvial migration), estuaries (partial anadromy) or sea (anadromy)

Populations of generalist fish can be composed of individuals specialised to a small subset of food resources, a process known as individual specialisation. In this study, we hypothesised that variation in the diet and morphology of individuals is related to habitat complexity and that greater levels of individual specialisation are found at intermediate levels of macrophyte biomass. Fish and aquatic

Variation in life history traits within and across species is known to reflect adaptations to different environmental drivers through a diversity of mechanisms. Trait variation can also help buffer species and populations against extinction in fluctuating environments and against anthropogenic disturbances. Here, we examine the distribution and drivers of Ocean‐type Chinook salmon (Oncorhynchus tschawytscha)

The Baltic Sea is a unique ecosystem and the largest body of brackish water in the world. It is inhabited by several originally freshwater fish species, one of them being pike (Esox lucius), which is adapted to the mesohaline conditions of the southern Baltic Sea and colonises its south‐western bays and lagoons. Using twelve microsatellite markers, we analysed the genetic structure of 407 Baltic Sea

A major goal in conservation is to preserve diversity across scales of biological organisation, from genetics to meta-communities. High genetic diversity promotes species resiliency through adaptive capacity (Healey, 2009), while ecological resiliency benefits from the direct relationship between species and functional diversity (Peterson, Allen, & Holling, 1998). Life-history trait expression represents

The recruitment of anadromous brown trout smolt from a small Baltic stream, frequently exposed to summer drought, was quantified for 9 years, and the effect from drought on smolt number and age composition analysed. Drought was quantified by, (a) a newly developed index quantifying the severity of summer drought (Drought Severity Index—DSI—based on amount of precipitation, monthly mean temperature

The Atlantic salmon (Salmo salar) population of the River Minho represents the southern natural distribution edge of the species. In line with the general trend for Atlantic salmon, this population has been declining over the years and is now at a critically low level. With river connectivity compromised by a large dam just 80 km upstream the River Minho's outlet, and an expected deterioration of climatic

In high-latitude lakes, air temperature is an important driver of ice cover thickness and duration, which in turn influence water temperature and primary production supporting lake consumers and predators. In lieu of multidecadal observational records necessary to assess the response of lakes to long-term warming, we used otolith-based growth records from a long-lived resident lake fish, lake trout

Migrating fish species are worldwide in decline due to several global changes and threats. Among these causes are man‐made structures blocking their freshwater migration routes. Shipping canals with navigation locks play a dual role in this. These canals can serve as an important migration route, offering a short cut between freshwater and the sea. In contrast, the navigation locks may act as barriers

The classical debate about the roles of endogenous factors and external drivers in regulating populations continues to be a very active area of scientific research, and these roles are even more complex in populations located in geographically marginal areas. We tested three hypotheses on two separate brown trout populations inhabiting the southernmost basins of the Iberian Peninsula, with the aims

The above article from the Ecology of Freshwater Fish, published online on 20 December 2019 in Wiley Online Library (https://onlinelibrary.wiley.com/doi/abs/10.1111/eff.12527), has been retracted by agreement between the journal Editor‐in‐Chief; the symposium editor, Phaedra Budy; and the author, Troy Zorn. The retraction has been made due to a mistake in the classification (accessible vs. landlocked)

The Chishui River is the last free‐flowing tributary of the upper Yangtze River, China, which has an important role in fish conservation. This study aimed to explore the spatial organisation of fish assemblages in this river. Field sampling was conducted biannually between 2015 and 2017 at 41 sites from its headwater and downstream. One hundred and twenty‐two fish species were captured, including 34

Migrations of juvenile salmon smolts are generally high‐risk, with predation often implicated in reduced survival. In theory, smolts can maximise survival via depensation, or synchronising movements to swamp predators. Depensation, however, is difficult to assess in the wild. Accounting for depensation could also generate more realistic telemetry‐based survival estimates for management. Here, we assess