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The integration of invasive species into native communities may result in the destabilization of food webs through predation of native prey and competition with native predators. These negative effects are likely to be exacerbated by climate change, increasing the frequency of heat waves, droughts, and high-flow events. Invasive Round Goby (Neogobius melanostomus) and native White Sucker (Catostomus commersonii) were collected from the wild and acclimated to a range of temperatures expected to capture increases in temperature under climate change. In the laboratory, we measured the effects of temperature (19, 22, 25, and 28°C) and velocity gradients (0, 0.15, 0.3, 0.6 m/s at 22 and 25°C) on the prey consumption and foraging behavior of each species. We found that the prey consumption and number of attacks (lunges at prey) of both species increased with temperature but were consistently higher in Round Goby. Velocity had an interactive effect with temperature for prey consumption and foraging behavior, where generally, velocity tolerance for both species was higher at 22°C than at 25°C. White Sucker tolerance to velocity was higher than Round Goby, suggesting that systems with higher velocities may provide a competitive advantage in high-flow environments. Our results stress the importance of interactive experiments when examining the impact of invasive species on native competitors under shifting climatic conditions. [ABSTRACT FROM AUTHOR]

Animal movement is increasingly affected by human alterations to habitat and climate change. In wetland systems, widespread hydrologic alterations from agriculture have changed the shape, function, and stability of shallow streams and wetland habitats. These changes in habitat quality and quantity may be especially consequential for freshwater fishes such as Grass Pickerel (Esox americanus vermiculatus), a small predatory fish found in disjunct populations across southern Ontario and listed as Special Concern under Canada's Species at Risk Act. To characterize Grass Pickerel movement response to stream-channel alterations, Fisheries and Oceans Canada implemented a tracking study to monitor the movements of a Grass Pickerel population in an agricultural drain on the Niagara Peninsula (Ontario, Canada). From 2009 to 2013, 2007 Grass Pickerel were tagged and tracked in the 37.3 km2 Beaver Creek watershed using a combination of mark-recapture surveys and eight fully automated passive integrated transponder tag antennas. Most individuals moved within 500 m (i.e., stationary fish) while 16% of the fish moved > 500 m (i.e., mobile fish), with a maximum median movement distance of 1.89 km and a maximum movement distance of 13.5 km (a long-tail distribution). Most movements occurred near the largest confluence where only a few were long-distance upstream or downstream movements. Mobile fish were larger than their stationary counterparts. Grass Pickerel in sites with higher abundance had more mobile fish, implying potential density dependence. Our results highlight that, while a long-distance dispersal ability exists in extant Grass Pickerel populations, the current conditions of riverscapes may prevent these dispersals from occurring. For declining Grass Pickerel populations, limitations to their movement ecology may substantially increase the likelihood of local extirpations. [ABSTRACT FROM AUTHOR]

This study identifies the current spatial and temporal patterns of threats to at-risk freshwater fishes within Canada. Data for 65 at-risk freshwater fishes were collated from the Committee on the Status of Endangered Wildlife in Canada Assessment and Status reports with threat calculators. Using these data, the overall threat impact level and the threat impact of the 11 categories in the threat calculator were compared for all species and separately by conservation status, which indicates their risk of extinction. These threats were also compared temporally to a study completed in 2006 and spatially between National Freshwater Biogeographic Zones. The threats of invasive species and pollution had the highest impacts, accounting for 18.9% and 16.8% of the weighted impact on at-risk freshwater fishes, respectively. Since 2006, all threats have been increasing, except for natural disasters. The Great Lakes–Upper St. Lawrence River Biogeographic Zone had significantly more at-risk freshwater fishes and overall weighted threat impact than other zones, with pollution, invasive species, and natural system modification contributing the most to the imperilment in this region. [ABSTRACT FROM AUTHOR]

Aim: We employed a climate‐matching method to evaluate potential source regions of freshwater invasive species to an introduced region and their potential secondary spread under historical and future climates. Location: Global source regions, with primary introductions to the Laurentian Great Lakes and secondary introductions throughout North America. Methods: We conducted a climate‐match analysis using the CLIMATE algorithm to estimate global source freshwater ecoregions under historical and future climates with an ensemble of global climate models for climate‐change scenario SSP5‐8.5. Given existing research, we use a climate match of ≥71.7% between ecoregions to indicate climatic conditions that will not inhibit the survival of introduced freshwater organisms. Further, we estimate the secondary spread of freshwater invaders to the ecoregions of North America under historical and future climates. Results: We identified 54 global freshwater ecoregions with a climate match ≥71.7% to the recipient Laurentian Great Lakes under historical climatic conditions, and 11 additional ecoregions were predicted to exceed the threshold under climate change. Three of the 11 ecoregions were located in South America, a continent where no matches existed under historical climates and eight were located in the southern United States, southern Europe, Japan and New Zealand. Further, we identify 34 North American ecoregions of potential secondary spread of freshwater invasions from the Great Lakes under historical climatic conditions, and five ecoregions were predicted to exceed the threshold under climate change. Main Conclusion: We provide a climate‐match method that can be employed to assess the sources and spread of freshwater invasions under historical and future climate scenarios. Our climate‐match method predicted increases in climate match between the recipient region and several potential source regions, and changes in areas of potential spread under climate change. The identified ecoregions are candidates for detailed biosecurity risk assessments and related management actions. [ABSTRACT FROM AUTHOR]

Aim: Biological communities are the result of a stepwise spatiotemporal filtering process, driven by large‐scale historical and local contemporary determinants. The biogeographical pattern and species richness of North American fishes are predominantly determined by historical processes of past glaciations and postglacial dispersal and by contemporary environmental and ecological processes. We evaluated the effects of postglacial dispersal through glacial Lake Agassiz and habitat heterogeneity, represented by lake surface area, on contemporary freshwater fish species richness patterns of northwestern Ontario lakes. Location: Northwestern Ontario, Canada. Taxon: Freshwater fishes. Methods: Applying the theory of island biogeography and species–area curves, we examined the effects of isolation from the past dispersal corridor of glacial Lake Agassiz and habitat heterogeneity on species richness across 264 contemporary lakes. While controlling for correlations among the predictor variables, generalized linear models were constructed between species richness, as the response variable and the explanatory variables of lake elevation and surface area, and connection to the dispersal corridor. Results: Differential cover by glacial Lake Agassiz led to variation in fish species richness across contemporary lakes and it is higher in lakes that were covered by Lake Agassiz relative to basins remaining outside of the boundaries of the glacial lake. Lake surface area is the strongest predictor of species richness, while lake elevation is the strongest factor predicting isolation. Main Conclusions: Habitat heterogeneity and postglacial colonization have led to differences in fish richness within the same geographical region, which increases with lake surface area and decreases with elevation. These are likely driven by greater niche diversity facilitating the assembly of more diverse communities and isostatic rebound and fluctuating levels of Lake Agassiz isolating lakes at high elevations from the dispersal route earlier during the colonization process, respectively. These patterns underscore the importance of incorporating historical and environmental community determinants in biodiversity studies. [ABSTRACT FROM AUTHOR]

Aim: Most studies focusing on terrestrial ecosystems have shown that non‐native species are more likely to invade phylogenetically clustered communities, that the introduction of non‐native species increases phylogenetic clustering in the recipient communities, and that the latter is more conspicuous for recipient communities at a larger spatial scale. However, whether these patterns hold for aquatic ecosystems is rarely tested. Here, we investigate the phylogenetic structure of native and non‐native freshwater fish assemblages at a continental spatial extent. Location: The continental United States and Canada. Time period: Current. Methods: We collated native and naturalized non‐native species lists of freshwater fishes for each watershed at local and regional spatial scales. Two phylogenetic metrics (MPDses and MNNDses) representing different evolutionary depths were used to quantify the phylogenetic dispersion of each watershed fish assemblage and were related to temperature and precipitation using correlation and regression analyses. Values of the metrics were compared between the two spatial scales. Results: Our study found that (1) phylogenetically more diverse fish communities tended to be invaded by fewer non‐native fish species, and that non‐native species more frequently invaded communities with lower phylogenetic dispersion (i.e. higher phylogenetic clustering), (2) introduction of non‐native fishes reduced phylogenetic clustering in some watershed but increased clustering in others, (3) introduction of non‐native species caused phylogenetic dispersion to increase in watersheds with low phylogenetic diversity and to decrease in watersheds with high phylogenetic diversity and (4) phylogenetic clustering for fish assemblages at the larger spatial scale was smaller than that at the smaller spatial scale. Main conclusions: Support for Darwin's naturalization and preadaptation hypotheses in freshwater fish assemblages depends on the phylogenetic diversity of assemblages within the invaded watersheds. Our results are contrary to previous studies that found that the introduction of non‐native species increases phylogenetic clustering in the recipient communities more strongly at a larger spatial scale. [ABSTRACT FROM AUTHOR]

Eighty nine (42%) of Canada's 215 freshwater fish species have been assessed as at risk by the Committee on the Status of Endangered Wildlife in Canada. This study examines genomic population structure of the at-risk Grass Pickerel (Esox americanus vermiculatus), a small (≤ 33 cm) predatory fish that in Canada has a range spanning approximately 114,000 km2 of southern Ontario. Within this range it occupies approximately ten sites that are mostly shallow, weedy, and slow-flowing. Its populations and habitat are declining. This study defines population clusters and quantifies genomic diversity within and between populations based on > 5500 loci and > 950 SNPs from genomes of 66 individuals representing the subspecies' entire Canadian range. Ordination and STRUCTURE analyses revealed four major geographic/genomic clusters centered in the Georgian Bay-Severn River, southeastern shore of Lake Huron, Niagara Peninsula, and upper St. Lawrence River. Major clusters were distinguished by relatively high Hudson Fst values (0.205–0.480), with Georgian Bay-Severn River being consistently most distinct. The Niagara Peninsula major cluster contained an additional three discernable sub-clusters differentiated by Fst values as great or greater than major clusters, despite spanning only ca. 200 km2. Genomically distinct Niagara sub-clusters occurred in Abino Drain, Big Forks Creek, and Tea Creek. Samples from sites between both major and minor clusters exhibited admixture from adjacent clusters. Despite current management of Grass Pickerel under a single designatable unit throughout its Canadian range, we map considerable geographic population structure that should help guide the designation of additional conservation units. [ABSTRACT FROM AUTHOR]

Aim: Here, we use an integrative, comprehensive risk assessment framework as a screening tool to evaluate how the invasion risk of previously failed introduced freshwater fish species, commonly found in the live‐trade pathway, will change under future climate‐change scenarios. Location: Laurentian Great Lakes, North America. Methods: The 34 species screened for invasion risk previously failed to establish populations, likely due to poor environmental suitability, low propagule pressure, and/or biotic resistance from the recipient community, and are most commonly found in the increasingly important live‐trade pathway. Using established trait‐based models, we quantified the probability of establishment success and probability of having high ecological impact in the decade of first introduction and present‐day communities (2020) based on known species extirpations, introductions and establishments between 1870 and 2020. We completed a climate match analysis under future climate‐change scenarios based on 16 bioclimatic variables. This approach identified a list of species that should be prioritized in surveillance management. Results: We identified seven species that have an increased climate match with the region and an increased probability of establishment success. Five of these species have an increased probability of high ecological impacts. Twenty‐four species have a current probability of establishment success greater than 50% and 33 species have a current probability of high ecological impacts greater than 50%. Climate match was dynamic under future climate‐change scenarios with 14 species experiencing a better match between their native geographical range and the Laurentian Great Lakes region. Main conclusions: Our models identify and predict the invasion risk of non‐native freshwater fish species present in pathways relevant to the Great Lakes region and provide a comprehensive framework for future management that prioritize efforts to species of highest risk. This framework could be applied to different taxa, pathways, and/or ecosystems to estimate current and predicted invasion risk under multiple scenarios. [ABSTRACT FROM AUTHOR]

Understanding the relative roles of the historical, environmental, and anthropogenic processes underlying spatial biodiversity patterns is crucial to predict the impacts of global environmental changes. We quantified the relative roles of these factors in influencing species richness of total, native, non-native, and at-risk freshwater fishes in 985 tertiary watersheds across Canada while accounting for correlations among descriptors and spatial autocorrelation. Our findings indicate differences in factors influencing richness patterns among species categories. Environmental factors related to energy availability and historical factors related to post-glacial recolonization both played roles in shaping spatial variation in native species richness. In contrast, variation in non-native species richness was largely related to human activities increasing propagule pressure and habitat disturbance, which were greater for foreign species (i.e., not native to Canada) than for translocated native species. Anthropogenic processes and environmental conditions were both important determinants of at-risk species richness. Our study emphasizes the importance of an integrated approach that simultaneously considers natural and anthropogenic processes to better predict the fish biodiversity change at the landscape scale. [ABSTRACT FROM AUTHOR]

Climate change has emerged as an increasingly important threat to freshwater systems. To cope with rapidly changing thermal regimes, freshwater fishes must either relocate or adjust through genetic adaptation and/or phenotypic plasticity. Short‐term responses to elevated water temperature have been well studied in freshwater fishes; however, far less is understood about change induced by long‐term exposure. Furthermore, few studies have investigated the effects of temperature on already imperilled species, which may be more sensitive to environmental change.This study investigated the effects of rearing temperature on critical thermal maximum (CTmax), agitation temperature (Tag, temperature at which fish show behavioural signs of thermal stress) and gill size in pugnose shiner, Notropis anogenus, a threatened species in Canada. Juvenile pugnose shiner were reared for 4 months across five different ecologically relevant temperatures. CTmax and Tag were measured under normoxia and acute exposure to hypoxia to test for oxygen sensitivity of the upper thermal limits in this species.CTmax increased with elevated water temperature. Tag also increased with rearing temperature and occurred, on average, 4.3°C above acclimation temperatures. The CTmax and Tag were lower when fish were exposed acutely to hypoxia. Interestingly, gill size (e.g. total gill filament length) increased with rearing temperature, which may increase oxygen uptake capacity and support increased metabolic demands of warmer waters.Overall, pugnose shiner show plasticity in several traits in response to long‐term exposure to elevated water temperature that may facilitate persistence in warmer waters. However, acute hypoxia exposure reduced thermal tolerance, stressing the importance of evaluating interactive effects of multiple stressors.Identifying source populations of pugnose shiner with greater thermal tolerance or implementing captive breeding under higher temperature regimes may improve the success of re‐introduction efforts in the face of climate change, but the consequences to fitness of increased thermal tolerance should be examined. [ABSTRACT FROM AUTHOR]

For freshwater fishes, elevated water temperatures associated with climate warming and hypoxia can co-occur and are likely to interact as both affect oxidative metabolism. We quantified the effects of acclimation to elevated temperature and hypoxia on the thermal tolerance of pugnose shiner (Notropis anogenus), a cyprinid fish threatened in its Canadian range. In one experiment, pugnose shiner underwent two-week sequential acclimations to six increasing temperatures. Fish acclimated to warmer waters increased their critical thermal maximum (CTmax), while the agitation temperature (Tag) was 3.4 °C lower than the CTmax. In another experiment, fish were acclimated to three dissolved oxygen treatments (>95%, ∼56%, or ∼40% air saturation) for two weeks and tested under >95% and 40% conditions. CTmax was lower when measured under 40% for normoxia-acclimated fish but not for hypoxia-acclimated fish. Hypoxia-acclimated fish had higher Tag and smaller agitation windows than normoxia-acclimated fish, suggesting that hypoxia acclimation improves aspects of thermal tolerance. We examine the plasticity of thermal tolerance of pugnose shiner, showing that they may be more vulnerable to high temperatures compared with other non-imperiled Notropis species. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Fisheries & Aquatic Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Fisheries & Aquatic Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Round goby (Neogobius melanostomus) is a benthic freshwater fish native to the Ponto-Caspian region in Europe that was first recorded in the Laurentian Great Lakes basin in 1990 in the St. Clair River in Sarnia, Ontario. It has since become one of the major invasive species of the Great Lakes. The mechanisms through which round goby has become a successful invader are poorly understood. It has been hypothesized that phenotypic plasticity of species may influence their establishment, spread, and impact. If a species is phenotypically plastic, it could more easily adapt to a variety of environments. We examine whether phenotypic variation is present in round goby in the Laurentian Great Lakes and whether morphological variation in dorsal and lateral shape is related to habitat type and time since invasion. Morphological variation in preserved round goby specimens was analyzed for dorsal and lateral shape differences between lake, large river, and river habitats, waterbody of origin (Erie, Huron, Michigan, Ontario, Simcoe) and time since initial invasion (i.e., early, mid, recent) using a Procrustes ANOVA and visualized using a principal component analysis. There is significant variation in body shape among lake and river populations, which may be due to differences in water flows between these habitats. Lake specimens have an overall deeper body shape, whereas river specimens have an overall shallow body shape and large river specimens are intermediate in shape. The results of this study help better understand what morphological mechanisms facilitate invasions and provide valuable information for management decisions related to spread of round goby in the Great Lakes basin. [ABSTRACT FROM AUTHOR]

Aim: A better understanding of native and non‐native species responses to environmental conditions, historical processes, and human pressures is crucial in the face of global environmental changes affecting biodiversity. Here, we evaluate the relative roles of environmental, historical and anthropogenic factors in influencing species richness of native and non‐native freshwater fishes in watersheds across North America. Location: North America (exclusive of Mexico). Time period: Recent. Major taxa studied: Freshwater fishes. Methods: We compiled an extensive dataset of native and non‐native fish richness in 2,993 watersheds across North America, together with corresponding data for environmental (climatic, geographic), historical and anthropogenic factors. We used variance partitioning and hierarchical partitioning to quantify the relative importance of environmental, historical and anthropogenic factors in explaining richness variation in native and non‐native [overall, and by geographic origin (foreign/translocated) and pathway (authorized/unauthorized)] fishes, while accounting for correlations among explanatory variables and spatial autocorrelation. Results: Overall importance of environmental and anthropogenic factors was greater than historical factors in explaining both native and non‐native richness. Precipitation‐related factors were more important in explaining native richness, whereas non‐native richness was largely associated with temperature‐related factors. However, richness related to authorized introductions was less constrained by temperature than unauthorized introductions. Dam density, road density and urbanization gradient were major anthropogenic factors related to non‐native richness, yet their relative importance varied among origin‐ and pathway‐based categories. Conclusions: Our findings indicate different environmental drivers influence native and non‐native fish richness patterns in North America. The accumulation of non‐native species in watersheds depends on the interaction between environmental conditions and anthropogenic‐based processes related to introduction history including geographic origin, introduction pathway, and propagule pressure, where the latter likely plays a major role. Warmer regions with high human population densities and more impoundments are more prone to fish invasions, mostly via unauthorized introductions. [ABSTRACT FROM AUTHOR]

Many of the watersheds in southern Ontario have been highly modified to facilitate the removal of surface water from agricultural fields. These modified streams are often classed as municipal drains and are subject to periodic drain maintenance under the Drainage Act. Municipal (agricultural) drain maintenance involves removal of built-up sediment and associated aquatic vegetation, and may also include channelization of the stream and removal of riparian vegetation. Despite the periodic disturbance due to drain maintenance, agricultural drains are home to many fish species in southern Ontario, including species at risk. Beaver Creek, a tributary of the Niagara River in southwestern Ontario, is classed as a municipal drain and is home to a population of Grass Pickerel (Esox americanus vermiculatus), a species at risk in Canada. In the fall of 2011 a section of Beaver Creek was subjected to drain maintenance. In an effort to mitigate potential harmful effects of the drainage activities on the Grass Pickerel population, reconstruction incorporating natural stream channel design features was also implemented. The fish community of Beaver Creek was sampled in the impacted reach where maintenance occurred, an adjacent control reach that was not subject to maintenance, and a downstream reach where the two converged, from 2009-2013 and again in 2015. A series of before-after-control-impact (BACI) analyses were conducted to determine the effect of maintenance and reconstruction activities on the Grass Pickerel population and the physical and chemical habitat in Beaver Creek. BACI analyses were also conducted on three time scales to determine the most effective monitoring time frame for future drainage projects. Results of this study indicate that reconstruction incorporating natural stream channel design features had a positive impact on the Grass Pickerel catch per unit effort in the newly created pools and mitigated the effects of channelization on habitat characteristics such as stream velocity. The diversity of the stream fish community was not affected by the maintenance and reconstruction activities. Changing the amount of time that monitoring is conducted can influence the ability to detect effects of drainage activities. In this study, monitoring for at least three years prior to the drainage works, along with post-project monitoring of at least four years following was required to determine the effects of drainage activities. [ABSTRACT FROM AUTHOR]

The addition of nonnative species and loss of native species has modified the composition of communities globally. Although changes in β‐diversity have been well documented, there is a need for studies incorporating multiple time periods, more than one dimension of biodiversity, and inclusion of nestedness and turnover components to understand the underlying mechanisms structuring community composition and assembly. Here, we examined temporal changes in functional dissimilarity of fish communities of the Laurentian Great Lakes and compared these changes to those of taxonomic dissimilarity by decade from 1870 to 2010. Jaccard‐derived functional dissimilarity index was used to quantify changes in functional β‐diversity within communities, between all possible pairs of communities, and using a multiple‐site index among all communities. β‐diversity was partitioned into components of nestedness and turnover, and changes were examined over time. Similar to patterns in taxonomic dissimilarity, each community functionally differentiated from the historical community of 1870, with Lake Superior changing the most (~24%) and Lake Ontario the least (~14%). Although communities have become taxonomically homogenized, functional β‐diversity among all communities has increased over time, indicating functional differentiation. This is likely due to functional similarity between the communities being historically high (i.e., ~88% similar in 1870). The higher taxonomic relative to functional turnover indicates that the species being replaced between communities are functionally redundant, which could occur given the harsh environmental conditions of the region and/or as a result of the recent glacial history of the region. High functional nestedness across communities reflects dispersal limitations, with smaller communities being functional subsets of large communities closer to source populations. The functional differentiation observed is likely due to nonnative species with functional traits unique to the region establishing or the loss of functionally redundant native species; however, it is important to note that patterns of homogenization were periodically observed through time. Our study demonstrates the possible factors regulating diversity in the Laurentian Great Lakes fish communities, that patterns of taxonomic and functional β‐diversity are dynamic over time and vary in the magnitude and direction of change, and that taxonomic diversity should not be used to predict changes in functional diversity. [ABSTRACT FROM AUTHOR]

Many conservation efforts for freshwater fishes have been undertaken; however, continuing the monitoring of both the distribution and the abundance of species to determine the effectiveness of these actions can be difficult. As species increase in rarity, they are more difficult to detect in the field, making inferences on occupancy less reliable.Conventional sampling methods, such as electrofishing and seining, require the physical handling of rare fishes, which may cause stress and mortality and, consequently, compromise conservation goals and limit monitoring programmes. Non‐invasive surveillance methods, including underwater video, are playing an increasingly important role.In this study, occupancy models were used to estimate the detection probability of underwater cameras as an alternative to the conventional sampling methods for rare stream fishes. Redside dace (Clinostomus elongatus), a small minnow listed as Endangered, was used as a model organism for rarity. A total of 69 historical redside dace sites were sampled using three sampling methods to determine the effect of gear type on detecting and identifying the habitat preferences of this rare minnow.On average, using multiple underwater cameras is as effective at detecting a rare minnow as conventional sampling methods (backpack electrofisher and seine) and causes no harm.The detection probability of both underwater cameras and backpack electrofishing were adversely affected by turbidity, whereas seining was positively affected by stream velocity. The probability of occupancy of redside dace is driven by open channels and sediment size, and this provides a strong basis for informing stream restoration projects.The use of multiple underwater cameras over conventional sampling methods is recommended when sampling for rare and endangered minnows in systems with low turbidity. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Reviews is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biodiversity loss is a serious issue for freshwater fishes in temperate climates and there is a need for more information in this area. A study was conducted to assess fish community changes in the littoral zone of 22 lakes over a 45 year period (compared years 1969-1979 and year 2014). To compare fish communities, historical seining records were compiled for 22 inland lakes and compared with contemporary data sampled using the same protocol. Fish abundance data analyzed using a multivariate approach identified a shift from cyprinid-dominated communities to centrarchid-dominated communities between time periods. There was no evidence to support a strong influence of invasive species on these communities, but there have been significant changes in temperature and land use around these lakes since the historical data sets were collected. This is an important contribution to our understanding of biodiversity change in North American freshwater fish communities and may influence fisheries management approaches in the future. [ABSTRACT FROM AUTHOR]

The native ranges of many species in North America reach their northern extent in southern Canada, which results in several aquatic species with core populations found farther south being assessed as at risk by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) and receiving protection under the Species at Risk Act (SARA)., To determine traits that predict at-risk status for freshwater fishes in Canada a classification and regression tree analysis was performed using a suite of ecological and life-history traits, and the species' distributions in Canada., Range-edge distribution in Canada was a significant predictor of a species assessed as at risk by COSEWIC and to be listed as at risk under SARA. Other predictive traits included Balon reproductive guild, reproductive age/maximum age ratio, and lifespan. Species with economic value were also not likely to be assessed as at risk by COSEWIC. Analyses showed greater inconsistency in listing status under SARA than COSEWIC assessment, and a bias toward not listing species, despite predicted at-risk status, was evident., The predictive models may prove useful in making future conservation decisions and highlight species that should have their status (re)assessed. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Zoology is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Determining the occurrence and site occupancy of rare and endangered species can be challenging, particularly without causing harm or stress to the species of concern., Environmental DNA (eDNA) detection was used to assess habitat occupancy by spotted gar ( Lepisosteus oculatus), which is federally listed as Threatened in Canada, with known occurrences limited to a small number of locations in southern Ontario., Quantitative polymerase chain reaction (qPCR) assays were developed to detect spotted gar eDNA, which was detected in all but one previously recorded location. The eDNA method was shown to be more effective than traditional netting for detecting spotted gar habitat use., The use of qPCR allowed for quantification of substantial variation in detection strength (copy number) among replicate eDNA samples, with implications for establishing sampling designs for detection and surveillance., The use of eDNA for detection and monitoring of aquatic species of conservation concern shows great potential as a non-invasive method for assessing species occurrences and habitat occupancy, as well as for informing targeted sampling by conventional capture methods., Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Aquatic invasive species have become one of the most serious threats to freshwater biodiversity due to the severe negative impacts they can have on native ecosystems. Examining the potential pathways that aquatic invasive species may use to invade and spread throughout the Great Lakes basin is a critical step in preventing their spread. This study focused on a major shipping canal, the Welland Canal, as a possible dispersal corridor for invasive species within the Great Lakes basin, specifically evaluating the ability of fishes to utilize canals and locks as a dispersal corridor between waterbodies. To determine the extent to which fishes were moving within the canal and through the eight locks, we captured, tagged, and released 179 fish of 10 species within the canal with acoustic tags and tracked their movement using 34 acoustic receivers placed in strategic locations within the system. Seven tagged fish (3.9%) moved from the canal into lakes Ontario or Erie. Within the canal, only one fish (0.6%) moved through the flight locks (locks 4, 5, and 6). These results indicate that fishes can move through the Welland Canal and out of it into lakes Ontario or Erie, but that the locks, particularly the flight locks, limit such dispersal. [ABSTRACT FROM AUTHOR]

Aim Impacts of non-native species have motivated development of risk assessment tools for identifying introduced species likely to become invasive. Here, we develop trait-based models for the establishment and impact stages of freshwater fish invasion, and use them to screen non-native species common in international trade. We also determine which species in the aquarium, biological supply, live bait, live food and water garden trades are likely to become invasive. Results are compared to historical patterns of non-native fish establishment to assess the relative importance over time of pathways in causing invasions. Location Laurentian Great Lakes region. Methods Trait-based classification trees for the establishment and impact stages of invasion were developed from data on freshwater fish species that established or failed to establish in the Great Lakes. Fishes in trade were determined from import data from Canadian and United States regulatory agencies, assigned to specific trades and screened through the developed models. Results Climate match between a species' native range and the Great Lakes region predicted establishment success with 75-81% accuracy. Trophic guild and fecundity predicted potential harmful impacts of established non-native fishes with 75-83% accuracy. Screening outcomes suggest the water garden trade poses the greatest risk of introducing new invasive species, followed by the live food and aquarium trades. Analysis of historical patterns of introduction pathways demonstrates the increasing importance of these trades relative to other pathways. Comparisons among trades reveal that model predictions parallel historical patterns; all fishes previously introduced from the water garden trade have established. The live bait, biological supply, aquarium and live food trades have also contributed established non-native fishes. Main conclusions Our models predict invasion risk of potential fish invaders to the Great Lakes region and could help managers prioritize efforts among species and pathways to minimize such risk. Similar approaches could be applied to other taxonomic groups and geographic regions. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Fisheries & Aquatic Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT [ABSTRACT FROM AUTHOR]

Background: DNA barcoding aims to provide an efficient method for species-level identifications using an array of species specific molecular tags derived from the 59 region of the mitochondrial cytochrome c oxidase I (COI) gene. The efficiency of the method hinges on the degree of sequence divergence among species and species-level identifications are relatively straightforward when the average genetic distance among individuals within a species does not exceed the average genetic distance between sister species. Fishes constitute a highly diverse group of vertebrates that exhibit deep phenotypic changes during development. In this context, the identification of fish species is challenging and DNA barcoding provide new perspectives in ecology and systematics of fishes. Here we examined the degree to which DNA barcoding discriminate freshwater fish species from the well-known Canadian fauna, which currently encompasses nearly 200 species, some which are of high economic value like salmons and sturgeons. Methodology/Principal Findings: We bi-directionally sequenced the standard 652 bp ''barcode'' region of COI for 1360 individuals belonging to 190 of the 203 Canadian freshwater fish species (95%). Most species were represented by multiple individuals (7.6 on average), the majority of which were retained as voucher specimens. The average genetic distance was 27 fold higher between species than within species, as K2P distance estimates averaged 8.3% among congeners and only 0.3% among concpecifics. However, shared polymorphism between sister-species was detected in 15 species (8% of the cases). The distribution of K2P distance between individuals and species overlapped and identifications were only possible to species group using DNA barcodes in these cases. Conversely, deep hidden genetic divergence was revealed within two species, suggesting the presence of cryptic species. Conclusions/Significance: The present study evidenced that freshwater fish species can be efficiently identified through the use of DNA barcoding, especially the species complex of small-sized species, and that the present COI library can be used for subsequent applications in ecology and systematics. [ABSTRACT FROM AUTHOR]

Presents a study which featured a broad analysis of freshwater fish species biodiversity in relation to environmental and stress metrics throughout Canada. Materials and methods used; Comparative regional assessment of biodiversity and environmental index; Combination of indices for regional assessment.

Effective conservation requires that species recovery measures are informed by rigorous scientific research. For imperilled freshwater fishes and mussels in Canada, numerous research gaps exist, in part owing to the need for specialized research methods. The Canadian Freshwater Species at Risk Research Network (SARNET) was formed and identified or implemented approaches to address current research gaps, including (1) captive experimental research populations, (2) nonlethal methods for estimating abundance and distribution, (3) nonlethal field methods to measure life-history parameters, (4) species distribution models informed by co-occurring species, (5) conservation physiology to inform habitat and threat science, (6) evidence syntheses to evaluate threats and recovery measures, (7) disease-transmission models to understand mussel–host relationships, (8) experimental mesocosms and manipulative experiments to evaluate key habitat stressors, (9) threat and hazard models for predictive applications, and (10) rigorous evaluation of surrogate species. Over a dozen threat- and recovery-focused SARNET research applications are summarized, demonstrating the value of a coordinated research program between academics and government to advance scientific research on, and to support the recovery of, imperilled freshwater species. [ABSTRACT FROM AUTHOR]

Declines in North American freshwater biodiversity can be largely attributed to anthropogenic disturbances that reduce habitat quantity, quality, and connectivity. In the Laurentian Great Lakes, wetlands have been significantly lost as a result of agricultural land-use practice, yet high species richness and several at-risk fishes persist. These patterns lead to the hypothesis that Great Lakes wetland fishes are in extinction debt, meaning there is a time lag between habitat loss and local extinction. To test this hypothesis, we sampled current species richness of wetland-specialist fishes in protected and unprotected wetlands in the Lake Erie basin. We predicted species richness in unprotected wetlands using parameter estimates (slope and intercept) from protected wetlands. Extinction debt was measured as a positive difference between predicted and observed species richness. We determined how much area would be required to support current species richness and compared this to minimum-area requirements for eight at-risk fishes. Species richness was significantly higher than predicted in unprotected wetlands, indicating that fishes in them are in extinction debt. This result indicates that there is time available to restore disturbed wetlands and prevent local extinction. We identified 17 wetlands of high priority for restoration (>10 species bound for extinction) and determined that the restoration of 178 km2 of wetland habitat would reduce the risk of future biodiversity loss. This is the first direct study of extinction debt in freshwater fishes. Additional extinction-debt assessments in aquatic systems are needed to extend the ecological theory and fundamental application of extinction debt beyond terrestrial systems. • Based on species-area relationships of wetland fishes, there is evidence of unpaid local extinctions in unprotected Great Lakes coastal wetlands. • We identified 17 wetlands of high priority for restoration (>10 species bound for extinction), containing eight at-risk fishes • The restoration of 178 km2 of habitat across 29 unprotected wetlands would reduce the risk of further biodiversity loss • Additional area is needed to support minimum-area requirements for lake chubsucker, grass pickerel, and spotted gar in unprotected wetlands [ABSTRACT FROM AUTHOR]