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At least 217 records · Page 12Linked to original sources

USGS2006

Variation in thermal tolerance and routine metabolism among spring- and stream dwelling freshwater sculpins (Teleostei: Cottidae) of the southeastern United States

Evolutionary theory predicts that some aquatic organisms may adapt by directional selection to limiting physical environmental conditions, yet empirical data are conflicting. We sought to test the assumption that sculpins (family Cottidae) inhabiting thermally stable springs of the southeastern United States differ in temperature tolerance and metabolism from populations inhabiting more thermally labile stream habitats. Spring populations of pygmy sculpins ( Cottus pygmaeus ) and Ozark sculpins ( C. hypselurus ) differed interspecifically in thermal tolerance from populations of stream-dwelling mottled ( C. bairdi ) and Tallapoosa sculpins ( C. tallapoosae ), and both stream and spring populations of banded sculpins ( C. carolinae ). No intra- or interspecific differences in thermal tolerance were found among populations of C. bairdi, C. talla poosae , or C. carolinae . Cottus pygmaeus acclimated to 15°C differed intraspecifically in routine metabolism from fish acclimated to 20° and 25°C. Cottus pygmaeus and stream-dwelling C. bairdi and C. carolinae acclimated to temperatures of 20° and 25°C showed no interspecific differences in routine metabolism. Our results suggest that some spring-adapted populations or species may be more stenothermal than stream-dwelling congeners, but a greater understanding of the interactions of other physical and biological factors is required to better explain micro- and macro habitat distributions of eastern North American sculpins.

Ecology of Freshwater Fish↗

USGS2014

Role of large- and fine-scale variables in predicting catch rates of larval Pacific lamprey in the Willamette Basin, Oregon

Pacific lamprey Entosphenus tridentatus is an anadromous fish native to the Pacific Northwest of the USA. That has declined substantially over the last 40 years. Effective conservation of this species will require an understanding of the habitat requirements for each life history stage. Because its life cycle contains extended freshwater rearing (3–8 years), the larval stage may be a critical factor limiting abundance of Pacific lamprey. The objective of our study was to estimate the influence of barriers and habitat characteristics on the catch-per-unit-effort (CPUE) of larval Pacific lamprey in the Willamette River Basin, Oregon, USA. We sampled lampreys at multiple locations in wadeable streams throughout the basin in 2011–13 and used an information theoretic approach to examine the relative influence of fine- and large-scale predictors of CPUE. Pacific lamprey was observed across the basin, but its relative abundance appeared to be limited by the presence of natural and artificial barriers in some sub-basins. Lower velocity habitats such as off-channel areas and pools contained higher densities of larval lamprey; mean Pacific lamprey CPUE in off-channel habitats was 4 and 32 times greater than in pools and riffles respectively. Restoration and conservation strategies that improve fish passage, enhance natural hydrologic and depositional processes and increase habitat heterogeneity will likely benefit larval Pacific lamprey.

Oregon↗

USGS2021

Piscine predation on juvenile salmon in sub-arctic Alaskan rivers: Associations with season, habitat, predator size and streamflow

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 concern that predation might inhibit their recovery. Here, we quantify patterns of predation by freshwater fishes on juvenile salmon across seasons, habitats, predator sizes and streamflow levels in the Arctic-Yukon-Kuskokwim region of Alaska. We analysed piscivore stomach contents and identified prey using DNA sequence “barcoding.” In coastal rivers, juvenile pink ( O . gorbuscha ) and chum ( O . keta ) salmon contributed heavily to Arctic grayling ( Thymallus arcticus ) and Dolly Varden char ( Salvelinus malma ) diets, coho salmon ( O . kisutch ) prey were rare, and Chinook salmon were not detected. In interior rivers, Arctic grayling, burbot ( Lota lota ) and northern pike ( Esox lucius ) consumed small numbers of Chinook salmon. Predation on Chinook salmon was documented disproportionately in sloughs during a summer of exceptionally high streamflow. Dietary and distributional patterns suggested northern pike and burbot may exclude salmon from sloughs in low-gradient river reaches that would otherwise provide suitable rearing habitat. The data also provided tentative support for the hypothesis that high streamflow induces juvenile Chinook salmon to move from mainstem habitats into sloughs, where they face an increased risk of mortality. Incorporating predation risk into climate adaptation, fisheries management and habitat restoration decisions may help to facilitate Chinook salmon recovery.

Alaska↗

USGS2024

Life-history connections to long-term fish population trends in a species-rich temperate river

Fishes exhibit a diverse range of traits encompassing life-history strategies, feeding behaviours and spawning behaviours. These traits mediate fish population responses to changing environmental conditions such as those caused by anthropogenic stressors. The Conasauga River, located in northwestern Georgia and southeastern Tennessee, USA, hosts a diverse assemblage of over 75 species of freshwater fish, some of which are locally or regionally endemic, and many of which are imperilled. Annual monitoring data have shown population declines in multiple fish species of conservation concern in the Conasauga River since at least the 1990s, raising the possibility that other taxa could be declining as well. We quantified temporal changes in fish communities at six shoal sites sampled annually in most years from 1996 to 2022, and asked whether species traits hypothesized to underlie population vulnerability to environmental alteration were correlated with species-specific trends for 32 taxa. We estimated that total counts of fish in annual samples declined by ~2% per year, although declines were uneven among species and generally greater for less abundant taxa. Tests for species traits corresponding to temporal population trends provided evidence that crevice-spawning minnows and smaller-bodied taxa had steeper declines compared with broadcast spawners and larger, longer-lived, more fecund taxa. Lower abundance, reliance on a particular habitat feature, and life-history traits that may limit population resilience to disturbance may all prove useful for identifying riverine fishes at particular risk of future population decline.

Georgia↗

USGS2020

Resource partitioning across a trophic gradient between a freshwater fish and an intraguild exotic

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 variation in resource partitioning and body condition across a prominent longitudinal nutrient gradient in Lake Erie (north‐eastern United States, Canada). As measured with Analysis of Similarity and Schoener's index, diet similarity declined monotonically from west to east tracking declines in nutrients, productivity and relative abundance of both species. Additionally, diet similarity increased from spring through fall, following seasonal development of stratification and hypolimnetic hypoxia—phenomena which tend to increase spatial overlap between these species. Finally, relative weights of both species peaked in the Central Basin (relative weights > 0.85), which, on average, had intermediate values of prey diversity, ecosystem trophic status and water clarity. Our results highlight that native yellow perch coexist with invasive white perch under a wide range of trophic conditions. Of importance to fishery managers, mesotrophy in the Central Basin correlated with the highest body conditions and intermediate prey resource partitioning, although the effect size was small and variable. While competitive exclusion appears unlikely, the goal of reducing nutrient inputs in Lake Erie could affect not only the distributions of both species but also stakeholder decisions about where to fish.

Lake Erie↗

USGS2013

Population-level effects of egg predation on a native planktivore in a large freshwater lake

Using a 37-year recruitment time series, we uncovered a field pattern revealing a strong, inverse relationship between bloater Coregonus hoyi recruitment success and slimy sculpin Cottus cognatus biomass in Lake Michigan (United States), one of the largest freshwater lakes of the world. Given that slimy sculpins (and deepwater sculpin Myoxocephalus thompsonii) are known egg predators that spatiotemporally overlap with incubating bloater eggs, we used recently published data on sculpin diets and daily ration to model annual bloater egg consumption by sculpins for the 1973–2010 year-classes. Although several strong year-classes were produced in the late 1980s when the proportion of eggs consumed by slimy sculpins was extremely low (i.e., <0.001) and several weak year-classes were produced when the proportion of bloater eggs consumed was at its highest (i.e., >0.10–1.0), egg predation failed to explain why recruitment was weak for the 1995–2005 year-classes when the proportion consumed was also low (i.e., <0.02). We concluded that egg predation by slimy and deepwater sculpins could have limited bloater recruitment in some years, but that some undetermined factor was more important in many other years. Given that slimy sculpin densities are influenced by piscivorous lake trout Salvelinus namaycush, the restoration of which in Lake Michigan has lagged behind those in lakes Superior and Huron, our study highlights the importance of an ecosystem perspective when considering population dynamics of fishes.

Lake Michigan↗

USGS2018

Scale‐dependent effects of isolation on seasonal patch colonisation by two Neotropical freshwater fishes

The metapopulation paradigm has been central to improve the conservation and management of natural populations. However, despite the large number of studies on metapopulation dynamics, the overall support for the relationships on which the paradigm is based has not been strong. Here, we studied the occupancy dynamics of two Neotropical fishes (i.e., Pimelodella gracilis and Leporinus friderici ) to investigate two fundamental premises of the metapopulation paradigm, that is, that isolation and area/habitat quality affect colonisation and extinction probabilities in predictable ways. In order to do this, we used a modification of occupancy models that allows modelling the probability of a site's occupancy as a function of the occupancy of its neighbourhood. We found a weak positive effect of neighbourhood occupancy on P . gracilis colonisation, which is consistent with the propagule rain metapopulation, that is, colonists arriving from outside the studied system. However, we found a strong negative neighbourhood effect on extinction probability, suggesting that declining populations from stream sections are rescued from extinction by neighbouring patches. In contrast, the effect of neighbourhood occupancy on the metapopulation dynamics of L. friderici was in the opposite direction, affecting positively colonisation but not affecting extinction rates, which is consistent with the classical metapopulation model. In addition, the occupancy dynamics of both species were affected by water velocity. To our knowledge, this is the first study to link directly dispersal to local population dynamics in Neotropical fishes, and one of the few studies doing inferences on spatial population dynamics based on direct estimates of neighbourhood occupancy.

Ecology of Freshwater Fish↗

USGS2017

From salmon to shad: Shifting sources of marine-derived nutrients in the Columbia River Basin

Like Pacific salmon ( Oncorhynchus spp.), nonnative American shad ( Alosa sapidissima ) have the potential to convey large quantities of nutrients between the Pacific Ocean and freshwater spawning areas in the Columbia River Basin (CRB). American shad are now the most numerous anadromous fish in the CRB, yet the magnitude of the resulting nutrient flux owing to the shift from salmon to shad is unknown. Nutrient flux models revealed that American shad conveyed over 15,000 kg of nitrogen (N) and 3,000 kg of phosphorus (P) annually to John Day Reservoir, the largest mainstem reservoir in the lower Columbia River. Shad were net importers of N, with juveniles and postspawners exporting just 31% of the N imported by adults. Shad were usually net importers of P, with juveniles and postspawners exporting 46% of the P imported by adults on average. American shad contributed <0.2% of the total annual P load into John Day Reservoir, but during June when most adult shad are migrating into John Day Reservoir, they contributed as much as 2.0% of the P load. Nutrient inputs by American shad were similar to current but far less than historical inputs of Pacific salmon owing to their smaller size. Given the relatively high background P levels and low retention times in lower Columbia River reservoirs, it is unlikely that shad marine-derived nutrients affect nutrient balances or food web productivity through autotrophic pathways. However, a better understanding of shad spawning aggregations in the CRB is needed.

Columbia River, John Day Reservoir↗

USGS2021

Rapid colonisation post-displacement contributes to native fish resilience

Native freshwater fish are experiencing global declines. Determining what drives native fish resilience to disturbance is crucial to understanding their persistence in the face of multiple stressors. Fish colonisation ability may be one factor affecting population resilience after disturbance. We conducted displacement experiments in headwater streams in Wyoming, USA, to evaluate mottled sculpin ( Cottus bairdii ) and mountain sucker ( Catostomus platyrhynchus ) colonisation ability. Specifically, we (1) determined whether fish could colonise sites rapidly after displacement, (2) evaluated site-level factors affecting colonisation, and (3) compared species-level differences in movement and colonisation capabilities. Mountain sucker recovered to pre-displacement abundances within 6–11 weeks, but mottled sculpin were still at slightly reduced abundances. For both species, the majority of colonists were unmarked new individuals and size–structure was similar to pre-displacement size–structure. Fish colonisation was best predicted by pre-displacement abundance and an interaction between per cent riparian cover and species identity. The slower colonisation rate of mottled sculpin may relate to movement ability as average daily movement rate and movement extent were significantly greater for mountain sucker. Our results demonstrate that colonisation is one mechanism allowing fish populations to be resilient in the face of disturbance and that species' traits provide insight into fish colonisation capabilities. Experimental approaches provide mechanistic insight into colonisation dynamics, enhancing our understanding of native fish resilience in degraded stream ecosystems and their response to restoration actions.

Wyoming↗

USGS2014

Body size and condition influence migration timing of juvenile Arctic grayling

Freshwater fishes utilising seasonally available habitats within annual migratory circuits time movements out of such habitats with changing hydrology, although individual attributes of fish may also mediate the behavioural response to environmental conditions. We tagged juvenile Arctic grayling in a seasonally flowing stream on the Arctic Coastal Plain in Alaska and recorded migration timing towards overwintering habitat. We examined the relationship between individual migration date, and fork length (FL) and body condition index (BCI) for fish tagged in June, July and August in three separate models. Larger fish migrated earlier; however, only the August model suggested a significant relationship with BCI. In this model, 42% of variability in migration timing was explained by FL and BCI, and fish in better condition were predicted to migrate earlier than those in poor condition. Here, the majority (33%) of variability was captured by FL with an additional 9% attributable to BCI. We also noted strong seasonal trends in BCI reflecting overwinter mass loss and subsequent growth within the study area. These results are interpreted in the context of size and energetic state-specific risks of overwinter starvation and mortality (which can be very high in the Arctic), which may influence individuals at greater risk to extend summer foraging in a risky, yet prey rich, habitat. Our research provides further evidence that heterogeneity among individuals within a population can influence migratory behaviour and identifies potential risks to late season migrants in Arctic beaded stream habitats influenced by climate change and petroleum development.

Alaska↗

USGS2015

Sex-biased survivorship and differences in migration of wild steelhead (Oncorhynchus mykiss) smolts from two coastal Oregon rivers

In salmonids with partial migration, females are more likely than males to undergo smoltification and migrate to the ocean (vs. maturing in freshwater). However, it is not known whether sex affects survivorship during smolt migration (from fresh water to entry into the ocean). We captured wild steelhead ( Oncorhynchus mykiss) smolts in two coastal Oregon rivers (USA) and collected fin tissue samples for genetic sex determination (2009; N = 70 in the Alsea and N = 69 in the Nehalem, 2010; N = 25 in the Alsea). We implanted acoustic tags and monitored downstream migration and survival until entry in to the Pacific Ocean. Survival was defined as detection at an estuary/ocean transition array. We found no effect of sex on smolt survivorship in the Nehalem River in 2009, or in the Alsea River in 2010. However, males exhibited significantly lower survival than females in the Alsea River during 2009. Residency did not influence this result as an equal proportion of males and females did not reach the estuary entrance (11% of males, 9% of females). The sexes did not differ in timing or duration of migration, so those variables seem unlikely to explain sex-biased survivorship. Larger males had higher odds of survival than smaller males in 2009, but the body size of females did not affect survivorship. The difference in survivorship between years in the Alsea River could be due to flow conditions, which were higher in 2010 than in 2009. Our findings suggest that sex may affect steelhead smolt survival during migration, but that the difference in survivorship may be weak and not a strong factor influencing adult sex ratios.

Oregon↗

USGS2022

Landscape geomorphology and local-riverine features influence Broad Whitefish (Coregonus nasus) spawning habitat suitability in Arctic Alaska

Landscape-level geomorphic processes influence the spatial and temporal arrangement of fish habitats in freshwater ecosystems and fishes move across riverscapes, selecting a suite of habitats to maximise fitness. Here, we explore the influence of geomorphology on stream channel attributes and assess Broad Whitefish ( Coregonus nasus ) spawning habitat potential in the Colville River in Arctic Alaska. Using high-resolution digital surface models (5 m 2 ), we quantified the stream network extent and summarised channel habitat attributes continuously across the drainage network. Next, we developed an intrinsic potential (IP) model for Broad Whitefish by using geomorphic channel parameters previously understood to be associated with spawning habitats (channel width, median substrate size and channel braiding) to estimate the potential of streams across the Colville River watershed to provide spawning habitat. Our model results show the majority of habitat with high IP (≥0.6) was located within the braided sections of the main channel, which encompass >1548 km, but only 2% of the total channel network. The IP model was tested by tracking radio-tagged Broad Whitefish using aerial surveys. Prespawn fish moved into the watershed starting mid-July and mostly used habitat with moderate to very high IP in the middle and lower watershed. Several individuals were relocated in smaller multichannels with vegetated bars that contained very low IP (≤0.2), suggesting that other factors, such as hyporheic flow, may also influence spawning habitat selection. Our study demonstrates that IP modelling offers a useful method to quantify spawning habitat potential in data-poor riverscapes, providing useful information for managers to assess potential anthropogenic impacts and develop conservation plans to protect essential Broad Whitefish habitat.

Alaska↗

USGS2024

Sensitivity of Alabama freshwater gastropod species to nickel exposure

Snails are effective bioindicators due to their prolific distribution, high level of endemism, and capacity to accumulate contaminants. Freshwater snails have unique ecological niches which are imperiled by land‐use change and the introduction of hazardous chemicals. To assess how environmental alterations affect gastropods, lab‐based studies are needed to characterize the toxicity of specific stressors. This can help guide policy decisions and remediation efforts. The aim of this research was to characterize acute toxicity of nickel (Ni) on endemic snails ( Somatogyrus georgianus [Walker, 1904], Elimia cahawbensis [Lea, 1861], and Elimia spp.) and measure the accumulation of Ni and mineral elements including calcium (Ca), magnesium, potassium, and sodium (Na). Snails were exposed to six concentrations (25–800 µg/L) of Ni for 96 h. Among the studied snail species, E. cahawbensis was the most sensitive to Ni, with the lowest lethal concentration where 50% of the organisms died (LC50) at 88.88 µg/L Ni after 96 h. The LC50 at 96 h for S. georgianus was 167.78 µg/L Ni, and 393.13 μg/L Ni for Elimia spp. Except for Elimia spp., mortality of the other two snail species corresponded to the whole‐body uptake of Ni. Nickel exposure also influenced Ca and Na uptake for Elimia spp. All three endemic species are potential candidate species for evaluating localized effects of human activities, and the present study provides a first step in characterizing how snails would be affected by environmental alterations. More research could further characterize potential effects of other human stressors on these endemic snail species. Future research into subindividual responses and routes of exposure can further elucidate variations in species sensitivity.

Alabama↗

USGS2019

A brief introduction to integrated pest management for aquatic systems

Aquatic invasive plants and animals are increasingly becoming a problem, causing severe economic and ecological damage to critical freshwater systems. The best strategy for controlling an invasive pest employs an integrated pest management (IPM) approach using a combination of biological, physical, chemical, and social/cultural control methods. Here, we examine the history and development of IPM and provide a discussion of the components of an IPM program involving development, evaluation, and management. Control approaches will be reviewed and the application of this technique to aquatic systems will be discussed. A discussion of the Great Lakes Fishery Commission's (GLFC) Integrated Management of Sea Lamprey Petromyzon marinus Control Program will be provided to illustrate the application of IPM to an aquatic system.

North American Journal of Fisheries Management↗

USGS2009

Ecology of stream fish: Insights gained from an individual-based approach to juvenile Atlantic salmon

Using data from an ongoing study of juvenile Atlantic salmon growth and survival in tributaries of the Connecticut River, USA, we compare standard population-level approaches to those focusing on individuals. We highlight the potential benefits of resampling individually tagged stream fish as compared to standard approaches. Specifically we focus on growth, survival, movements and population estimation. The advantages of estimating sizes and growth rates from individual size trajectories include obtaining growth histories and the ability to perform retrospective analysis of the consequences of different life-history strategies. An example might be the patterns of growth leading to either early maturity or migration. Resampling known individuals is the only way we know to chart both short-term and long-term movements and to assign growth and mortality consequences to such movements. Finally, individual-level data permit robust estimation of survival and density/abundance using methods such as Cormack/Jolly-Seber. The results indicate that population estimates were about 10% lower using individual data than using population data, that survival from sample to sample was typically >90%, that the majority of recaptured fish did not move during the summer, that growth was rapid during spring and most fish lost mass during the summer and that growth trajectories for maturing and non-maturing fish showed substantially different patterns. An individual-based approach to stream fish ecology provides the opportunity to explore the mechanisms responsible for population-level patterns but comes at the cost of significant field effort. Tradeoffs between increased data resolution and the effort required to obtain the data must be considered before undertaking individual-based field studies of stream fishes.

Massachusetts↗

USGS2002

Diet dynamics of the adult piscivorous fish community in Spirit Lake, Iowa, USA 1995-1997

Diets of adults of six important piscivorous fish species, black crappie Pomoxis nigromaculatus, largemouth bass Micropterus salmoides, northern pike Esox lucius, smallmouth bass Micropterus dolomieui, walleye Stizostedion vitreum, and yellow perch Perca flavescens were quantified in Spirit Lake, Iowa, USA from May to October in 1995-1997. Forty-one prey taxa were found in the diets of these species, including 19 species of fish. The most important prey taxa overall were yellow perch, amphipods and dipterans. Diets of northern pike and walleye were dominated by yellow perch. Largemouth bass diets included large percentages of both yellow perch and black bullhead Ameiurus melas. Smallmouth bass diets included large percentages of both yellow perch and crayfish. Black crappie and yellow perch diets were dominated by invertebrates, primarily amphipods and dipterans. There were pronounced differences in diets among species, among size classes within species and over time. Most of the dominant prey taxa we documented in the diets of piscivorous species were in accordance with previous studies, but a few deviated significantly from expectations. Many of the temporal diet changes were asynchronous among piscivorous species and size classes, suggesting different responses to common prey resources over time.

Ecology of Freshwater Fish↗

USGS2017

Groundwater declines are linked to changes in Great Plains stream fish assemblages

Groundwater pumping for agriculture is a major driver causing declines of global freshwater ecosystems, yet the ecological consequences for stream fish assemblages are rarely quantified. We combined retrospective (1950–2010) and prospective (2011–2060) modeling approaches within a multiscale framework to predict change in Great Plains stream fish assemblages associated with groundwater pumping from the United States High Plains Aquifer. We modeled the relationship between the length of stream receiving water from the High Plains Aquifer and the occurrence of fishes characteristic of small and large streams in the western Great Plains at a regional scale and for six subwatersheds nested within the region. Water development at the regional scale was associated with construction of 154 barriers that fragment stream habitats, increased depth to groundwater and loss of 558 km of stream, and transformation of fish assemblage structure from dominance by large-stream to small-stream fishes. Scaling down to subwatersheds revealed consistent transformations in fish assemblage structure among western subwatersheds with increasing depths to groundwater. Although transformations occurred in the absence of barriers, barriers along mainstem rivers isolate depauperate western fish assemblages from relatively intact eastern fish assemblages. Projections to 2060 indicate loss of an additional 286 km of stream across the region, as well as continued replacement of large-stream fishes by small-stream fishes where groundwater pumping has increased depth to groundwater. Our work illustrates the shrinking of streams and homogenization of Great Plains stream fish assemblages related to groundwater pumping, and we predict similar transformations worldwide where local and regional aquifer depletions occur.

Colorado, Kansas, Nebraska↗

USGS2012

Environmental factors regulating the recruitment of walleye Sander vitreus and white bass Morone chrysops in irrigation reservoirs

Understanding the environmental factors that regulate fish recruitment is essential for effective management of fisheries. Generally, first-year survival, and therefore recruitment, is inherently less consistent in systems with high intra- and interannual variability. Irrigation reservoirs display sporadic patterns of annual drawdown, which can pose a substantial challenge to recruitment of fishes. We developed species-specific models using an 18-year data set compiled from state and federal agencies to investigate variables that regulate the recruitment of walleye Sander vitreus and white bass Morone chrysops in irrigation reservoirs in south-west Nebraska, USA. The candidate model set for walleye included only abiotic variables (water-level elevation, minimum daily air temperature during winter prior to hatching, annual precipitation, spring warming rate and May reservoir discharge), and the candidate model set for white bass included primarily biotic variables (catch per unit effort (CPUE) of black crappie Pomoxis nigromaculatus , CPUE of age-0 walleye, CPUE of bluegill Lepomis macrochirus and CPUE of age-3 and older white bass), each of which had a greater relative importance than the single abiotic variable (minimum daily air temperature during winter after hatching). Our findings improve the understanding of the recruitment of fishes in irrigation reservoirs and the relative roles of abiotic and biotic factors.

Nebraska↗