Mountain protected areas are highly vulnerable to land use changes and tourism pressures, which can present as degraded water quality from urban stormwater contamination. Using a standardized framework, we conducted a screening-level ecological risk assessment (SLERA) of stormwater quality in the main townsite of Banff National Park, Alberta, Canada. The town of Banff is home to approximately 8,300 residents but experiences large-scale anthropogenic pressure from more than four million annual visitors. End-of-pipe grab samples were collected from four outfalls and two upstream sites representing background conditions, during 21 rainfall and snowmelt events. Samples were assessed using a water quality index (WQI), which rated stormwater effluent from three outfalls as 'poor' and one outfall as 'marginal', while background sites rated 'good' and 'excellent'. The outfalls exhibited similar contaminant profiles, with frequent WQI exceedances for cadmium, copper, lead, zinc, total phosphorous, total suspended solids and turbidity. Chloride exceedances were observed exclusively in snowmelt and approached concentrations typical of large municipalities. Embedding a WQI within a SLERA framework provides a novel and transferable approach for preliminary risk identification where data and monitoring capacity are limited, particularly in small, cold climate municipalities.

Risk assessment is a cornerstone of aquatic invasive species (AIS) management, helping prioritise limited resources for prevention and control. However, national or regional-scale AIS risk assessments often lack the spatial resolution to reflect localised conditions, such as those in national parks. We conducted climate matching and semi-quantitative screening-level risk assessments (SLRAs) to evaluate the potential for introduction and impact of 159 aquatic non-native species in the montane and lower subalpine ecoregions of Banff National Park (BNP), a 6,641 km2 protected area receiving over 4 million visitors annually. To assess vector importance, we tallied the number of top-scoring species linked to each AIS introduction pathway present in BNP. Climate matching identified 110 fish and aquatic invertebrates with potential climate compatibility in the park. Of 55 species assessed via SLRA, 13 were classified as moderate risk and none were high risk, largely due to regulatory protections such as bans on bait use, restricted watercraft access, and absence of fish stocking or trade. Additional biophysical barriers-including cold stream temperatures and steep gradients-further reduce establishment likelihood. Nevertheless, cumulative risk from multiple moderate-risk species remains a concern. Montane lakes, which are warmer and more heavily used for recreation, exhibit only moderate compliance with boating regulations. Four moderate-risk species are desiccation-tolerant, highlighting watercraft as a key vector, while nine are linked to illegal deliberate release, including two present in downstream connected waters without upstream dispersal barriers. These findings emphasise the value of sitespecific AIS risk assessments in informing targeted prevention efforts and support the need for a suite of risk management activities to protect BNP and other mountain protected areas globally.

It can be challenging for practitioners to determine reasonable response actions following an environmental spill because there are risks associated with the recovery process, acute constraints on time, and few case studies available from antecedent events. Here, we evaluate environmental risk using a screening level assessment (SLA) and describe risk management actions during the response phase of a train derailment that released 600 tonnes of fly ash into a headwater creek in Banff National Park, Canada. Trace metal concentrations and physico-chemical parameters from downstream of the derailment site were compared to Canadian environmental quality guidelines and upstream reference values. There was a 1–2.2-fold exceedance of sediment quality guidelines (As, Cd, and Se) as well as a 3.6–17.5-fold exceedance of water quality guidelines (Al, Cd, Fe, and turbidity) downstream of the train derailment. Despite uncertainty about site-specific toxicity when using a SLA, we did require the removal of the settled fly ash from the creek based on the multiple exceedances of guidelines, regulatory context, wilderness setting, and potential contribution to cumulative effects downstream. Case studies that evaluate risk and describe risk management actions help practitioners make consistent and efficient decisions during the response phase of a spill.

Statistical stream temperature models predicting the fine-scale spatial distribution of water temperatures (i.e., “thermalscape”) can guide aquatic species recovery and habitat restoration efforts. However, stream temperature modelling is complicated by spatial autocorrelation arising from non-independence of sampling sites within dendritic networks. We used August mean temperature data from miniature sensors deployed in Canadian Rocky Mountain streams to demonstrate two statistical stream temperature modelling techniques that account for spatial autocorrelation. The first was a spatial steam network (SSN) model specifically developed to account for spatial autocorrelation in dendritic stream networks. The second was an integrated nested Laplace approximation (INLA) model that accounts for spatial autocorrelation but was not designed to address anisotropic stream network data. We evaluated the best-fitting SSN and INLA models using leave-one-out cross-validation. Relative to INLA, SSN models had lower RMSE (1.23 vs. 1.45 C) and higher r2 (0.71 vs. 0.61); however, the SSN models required more preprocessing steps before incorporating spatially correlated random errors. We provide practical advice, an open-access r-script, and data to help non-experts develop statistical stream temperature models.

Determining cryptic species and diversity in at-risk species is necessary for the understanding and conservation of biodiversity. The endangered Banff Springs Snail, Physella johnsoni , inhabits seven highly specialized thermal springs in Banff National Park, Alberta, Canada. However, it has been difficult to reconcile its species status to the much more common Physella gyrina using ecology, morphology and genetics. Here we used pooled whole-genome sequencing to characterize genomic variation and structure among five populations of P. johnsoni and three geographical proximate P. gyrina populations. By comparing over two million single nucleotide polymorphisms, we detected substantial genetic distance (pairwise F ST of 0.27 to 0.44) between P. johnsoni and P. gyrina , indicative of unique gene pools. Genetic clusters among populations were found for both species, with up to 10% for P. johnsoni and 30% for P. gyrina of genetic variation being explained by population structure. P. johnsoni was found to have lower genetic diversity compared to P. gyrina , however, no patterns of were observed between genetic diversity and population minimums. Our results confirm that designation of P. johnsoni as an endangered species is warranted and that both P. johnsoni and P. gyrina exhibit microgeographic population genomic structure suggestive of rapid local adaptation and/or genetic drift within environments. This study showcases the utility of genomics to resolve patterns of cryptic species and diversity for effective conservation management. Future studies on the functional genomic diversity of P. johnsoni populations are needed to test for the possible role of selection within this thermal spring environment.

Maintaining natural thermal regimes in montane stream networks is critical for many species, but as climate warms, thermal regimes will undoubtedly change. Mitigating impacts of changing thermal regimes on freshwater biodiversity requires knowledge of which elements of the thermal regime are limiting factors for aquatic biota. We used full-year stream temperature records sampled across a broad latitudinal gradient to describe the diversity of the thermal landscapes that bull trout ( Salvelinus confluentus ) occupy and identify potential divergences from thermal regimes where this species has been studied previously. Populations of bull trout occupied stenothermic, cold thermal niches in streams that exhibited low to moderate thermal sensitivity throughout the species’ range. However, winter thermal regimes in the central and northernmost streams were colder and more stable than in the southernmost streams, reflecting differences in sensitivity to air temperature variation and contributions of perennial groundwater to baseflow. In the southernmost streams, bull trout distributions appeared to be regulated by warm summer temperatures, whereas in northern streams, unsuitably cold temperatures may be more limiting. Our results also suggest that local differences in the extent of complete freezing during winter among northern streams may further limit the distributions of suitable habitats. Contrasts in limiting factors at bull trout range extents would suggest differential responses to climate warming wherein northern populations extend their range while southern populations contract, and an overall change in species status that is less dire than previously anticipated.

"Natural" disasters (also known as geophysical disasters) involve physical processes that have a direct or indirect impact on humans. These events occur rapidly and may have severe consequences for resident flora and fauna as their habitat undergoes dramatic and sudden change. Although most studies have focused on the impact of natural disasters on humans and terrestrial systems, geophysical disasters can also impact aquatic ecosystems. Here, we provide a synthesis on the effects of the most common and destructive geophysical disasters on aquatic systems (life and habitat). Our approach spanned realms (i.e., freshwater, estuarine, and marine) and taxa (i.e., plants, vertebrates, invertebrates, and microbes) and included floods, droughts, wildfires, hurricanes/cyclones/typhoons, tornadoes, dust storms, ice storms, avalanches (snow), landslides, volcanic eruptions, earthquakes (including limnic eruptions), tsunamis, and cosmic events. Many geophysical disasters have dramatic effects on aquatic systems. The evidence base is somewhat limited for some natural disasters because transient events (e.g., tornadoes and floods) are difficult to study. Most natural disaster studies focus on geology/geomorphology and hazard assessment for humans and infrastructure. However, the destruction of aquatic systems can impact humans indirectly through loss of food security, cultural services, or livelihoods. Many geophysical disasters interact in complex ways (e.g., wildfires often lead to landslides and flooding) and can be magnified or otherwise mediated by human activities. Our synthesis reveals that geophysical events influence aquatic ecosystems, often in negative ways, yet systems can be resilient provided that effects are not compounded by anthropogenic stressors. It is difficult to predict or prevent geophysical disasters but understanding how aquatic ecosystems are influenced by geophysical events is important given the inherent connection between peoples and aquatic ecosystems.

A fundamental consideration in aquatic invasive species risk management is the distribution of invasive taxa relative to the risk assessment area. However, sampling the distribution of aquatic invasive species (AIS) is costly and time consuming, especially when they are rare or clustered. While random sampling removes bias in most estimates, it could lead to many zeroes in the response variable if the target species is not evenly distributed. We surveyed the distribution of Tubifex tubifex , the obligate secondary host of Myxobolus cerebralis , an invasive parasite that causes whirling disease in salmonids. We used intensive grid and random sampling in a lake and two river systems but collected many samples with zero T. tubifex . Zero-altered models identified a single source of zero T. tubifex counts in each dataset and improved model validation compared to Poisson or negative binomial models. While T. tubifex counts were not predictable using the covariates we measured, the binomial processes identified zero odds of a T. tubifex occurrence at lake sites with water depths > 2 m and stream sites with channel slopes > 3%. These covariates could be used to stratify the landscape for future sampling, which would save survey time and resources and likely reduce uncertainty in parameter estimates. Model-based sample stratification could address some of the challenges with AIS surveys when species are at low abundance or are clustered.

Freshwater biodiversity is in a state of crisis. The recent development of a global emergency recovery plan to "bend the curve" for freshwater biodiversity lacks the necessary details for implementation in a regional context. Using Canada as an example, we describe a toolbox intended to equip decision-makers and practitioners with evidence-based tools for addressing threats to freshwater biodiversity. The toolbox includes two rubric-based scoring tools to inform users about the level of the reliability (e.g., transparent methods, critical appraisal) and relevancy to Canadian freshwater systems (e.g., habitat, species) of an evidence synthesis. Those scoring tools were applied to 259 evidence syntheses, also included in the toolbox, across fifty freshwater management actions. Habitat Creation, Invasive Species Removal, and Revegetation were found to have reliable evidence syntheses but there remain several actions for which the syntheses are not robust and where the evidence base is unreliable. We suggest the need for more rigorously conducted empirical tests of freshwater management actions, further evidence synthesis, and clearer conveyance of implications for decision-makers and practitioners. Decision-makers and practitioners should use the two scoring tools on syntheses outside this project and tailor them to their regions. Given the global interest in addressing the freshwater biodiversity crisis and the necessity to engage and empower decision-makers and practitioners on a regional basis, we anticipate this toolbox will serve as a model for regions beyond Canada. Future studies to understand if and how the toolbox is used will be needed to make refinements and ensure it benefits freshwater biodiversity.

Abstract The intentional introduction of native cold‐water trout into high‐elevation fishless lakes has been considered a tool to build resilience to climate change (i.e., assisted colonization); however, ecological impacts on recipient communities are understudied. The purpose of this study was to inform native cold‐water trout recovery managers by assessing potential consequences of translocating a regionally native trout (westslope cutthroat trout; Oncorhynchus clarkii lewisi) into fishless mountain lakes. This study compared littoral benthic invertebrate richness, diversity, community structure and abundance between three groups of lakes (fishless, native trout, nonnative trout) in the Canadian Rocky Mountains. While richness and diversity were preserved across all lake groups, other lines of evidence suggested that the introduction of native westslope cutthroat trout into fishless lakes can alter littoral benthic invertebrate communities in similar ways as nonnative brook trout (Salvelinus fontinalis). The community structure of cutthroat trout lakes resembled brook trout lakes compared to that of fishless lakes. For example, both trout‐lake groups contained a lower density of free‐swimming ameletid mayflies and a higher density of certain burrowing taxa. Risk assessments for trout‐recovery actions should consider the potential for collateral damage to recipient invertebrate communities. Future research should identify possible cascading trophic effects on species subsidized by invertebrate prey.

Little is known about the current state of freshwater biodiversity in Canada, one of the countries with the greatest amount of surface waters in the world. To address this knowledge gap, we compiled a list of all available assessments of conservation status for freshwater species (over 3,000 taxa) and further evaluated the overall status of six distinct taxonomic groups, focusing on organisms reliant on freshwaters [i.e., aquatic plants, invertebrates (with a focus on freshwater mussels), fishes, herpetofauna (reptiles and amphibians), birds, and mammals]. Overall, 11.7% of all freshwater species of plants and animals assessed were found to be ‘at risk’ (i.e., listed as ‘Threatened’, ‘Endangered’, or ‘Extirpated’) and 17.9% identified as ‘Special Concern’. We found that 37.9% of species lacked sufficient data to enable their status to be assessed. Data gaps in Canada’s assessment of its freshwater species were most prevalent in invertebrates (excluding freshwater mussels). Given the alarming state of freshwater biodiversity in Canada, we conclude by providing recommendations that focus on evaluating temporal trends and informing conservation actions.

Effective management of freshwater fish habitat is essential to supporting healthy aquatic ecosystems and sustainable fisheries. In Canada, recent changes to the Fisheries Act enhanced the protection of fish habitat, but application of those provisions relies on sound scientific evidence. We employed collaborative research prioritization methods to identify scientific research questions that, if addressed, would significantly advance the management of freshwater fish habitat in Canada. This list was generated by a diverse group of freshwater fish experts, including substantial contributions from practitioners who administer provisions of the Fisheries Act. The research questions generated in this study identify priority topics for future research, while highlighting issues that could be addressed with different funding models. As a result, this study should support evidence-based management of Canada’s aquatic resources by identifying scientific knowledge gaps faced by practitioners, and suggesting mechanisms to address them. Given the important contribution of Canadian freshwater systems to global ecosystem values, and the similar scientific challenges facing fish habitat managers in other jurisdictions, this study is likely to have broad applicability.

Abstract Freshwater biodiversity loss is one of the greatest environmental threats in our changing world. Although declines have been reported extensively in the literature, much less attention has been devoted to solving the freshwater biodiversity crisis relative to other ecosystems. The recently proposed Emergency Recovery Plan for Freshwater Biodiversity (Tickner et al., 2020, BioScience, 70(4), 330–342) outlines an ambitious but necessary set of overarching actions that can help “bend the curve” for freshwater biodiversity declines. This plan is timely given the present opportunity to adjust freshwater biodiversity targets in international biodiversity agreements and to encourage meeting targets of relevant Sustainable Development Goals. Yet, relying solely on a trickle down from such agreements to national and local scales will likely take too long, given the immediate urgency of the situation. Here, we advocate for a broader, concerted effort from all actors to ensure the Emergency Recovery Plan meaningfully influences the actions of practitioners at a local scale. We outline the roles and responsibilities of actors involved with policy, research, professional bodies and societies, advocacy, and industry, as well as practitioners themselves, in achieving this goal. It is our hope that this overview facilitates the real‐world actions needed to execute the Emergency Recovery Plan so that we can indeed “bend the curve” for freshwater biodiversity.

Understanding the historical distributions of species is vital to the conservation and restoration of native species, yet such information is often qualitative. We show that the paleolimnological history of threatened freshwater fishes can be reconstructed using species-diagnostic markers amplified from environmental DNA deposited in lake sediments (lake sedDNA). This method was validated through the detection of lake sedDNA from non-native trout (Yellowstone cutthroat trout, Oncorhynchus clarkii bouvieri), which corroborated historical records of human-mediated introductions. We also discovered native trout (westslope cutthroat trout, Oncorhynchus clarkii lewisi) lake sedDNA that predated human-mediated introductions of freshwater fishes in a watershed with high topographical relief. This unexpected result revealed that the westslope population was of native origin and requires immediate conservation protection. Our findings demonstrate that lake sedDNA can be used to determine the colonization history of freshwater fishes and the structure of ecosystems, aiding in the identification of native ranges, novel native diversity, and introductions of non-native species.

Understanding the historical distributions of species is vital to the conservation and restoration of native species, yet such information is often qualitative. We show that the paleolimnological history of threatened freshwater fishes can be reconstructed using species-diagnostic markers amplified from environmental DNA deposited in lake sediments (lake sedDNA). This method was validated through the detection of lake sedDNA from non-native trout (Yellowstone cutthroat trout, Oncorhynchus clarkii bouvieri), which corroborated historical records of human-mediated introductions. We also discovered native trout (westslope cutthroat trout, Oncorhynchus clarkii lewisi) lake sedDNA that predated human-mediated introductions of freshwater fishes in a watershed with high topographical relief. This unexpected result revealed that the westslope population was of native origin and requires immediate conservation protection. Our findings demonstrate that lake sedDNA can be used to determine the colonization history of freshwater fishes and the structure of ecosystems, aiding in the identification of native ranges, novel native diversity, and introductions of non-native species.

Manual tracking has been used since the 1970s as an effective radio telemetry approach for evaluating habitat use of fish in fluvial systems. Radio tags are often located by continually reducing the gain when approaching the tag along a watercourse to estimate its location, termed here as the ‘Gain Reduction Method’. However, to our knowledge the accuracy of this method has not been empirically evaluated and reported in the literature. Here, the longitudinal and lateral positional errors of radio tags are assessed when applying the Gain Reduction Method in a small stream environment. Longitudinal and lateral positional errors (i.e. the difference between the estimated and actual radio tag location) were evaluated based on the distance from the actual tag position, the gain recorded when estimating the tag position and a number of environmental parameters (i.e. stream depth, velocity, stream width and specific conductivity).

Dams represent one of the major forms of river alteration. As these structures reach the end of their lifespan, they often require extensive refurbishments or removal. A small‐scale water supply dam in Banff National Park (Alberta, Canada) was partially removed, creating a breach that allowed water to scour a new passage resembling a nature‐like fishway. We investigated the permeability of the partially removed dam as a means of validating the conservation benefits of the partial dam removal. We quantified the proportion of bull trout (Salvelinus confluentus), a threatened species in Canada, that approached and passed the fishway using radio telemetry receiver stations. The proportion of bull trout that approached the fishway was low (37.0%; N = 27 of 73), but was consistent with upstream reference sites (33%; N = 20 of 60). For those that did approach, the proportion of bull trout that passed yielded a high passage efficiency (77.8%; N = 21 of 27 that approached). The probability that a fish passed the fishway was related to water depth and time of day. Bull trout were more likely to pass when water depths were high (>0.40 m), and at night. Passage duration ranged from 5‐mins to 13‐days, suggesting that this resident species used the fishway for a variety of purposes (e.g., station holding and foraging) and not just transiting. Some individuals underwent large‐scale movements 2‐km upstream (15.1%; N = 11 of 73), or 2‐km downstream (2.7%; N = 2 of 73) following a successful passage event. This study provides new insight on how, in some instances, a breach in a dam can function as a nature‐like fishway, accommodating year‐round stream flows and providing hydraulic conditions suitable for fish passage without costly engineering or construction.

Nonnative salmonids have been intentionally introduced in North America for over a century and are now implicated in the decline of native aquatic species. Current management objectives for some national parks are to remove invasive species, where feasible. We evaluated the use of mechanical methods (gill nets and electrofishing) to eliminate a naturalized population of nonnative Brook Trout Salvelinus fontinalis in a subalpine headwater basin. We required a total of 1,383 continuous net nights/ha (net nights = number of nets x number of nights) over 5 years to completely eradicate 1,527 Brook Trout from both Lower (9.7 ha; 6 m maximum depth) and Middle (23.1 ha; 25 m maximum depth) Devon Lakes, Alberta, Canada. Electrofishing along the shoreline of both lakes resulted in the capture of 301 Brook Trout over 4 years. We required a total of 52.1 h/km of electrofishing over 5 years to completely remove 3,288 Brook Trout from the upper 4.5 km of the Clearwater River. We verified the absence of fish in the lakes with 1,558 net nights/ha of sampling over 4 years and in the river with 13.6 h/km over 2 years. This project confirms that mechanical methods are a viable option for removing introduced fish, even in relatively large (up to 20 ha) and deep (up to 25 m) mountain lakes. We surmised that our success (relative to that of projects described in the literature) was due to (1) the relatively simple alpine habitat, in which river and lake margins were clear of macrophytes, suspended sediment, and overhanging riparian vegetation, and (2) the sheer magnitude of our effort.

We used biotelemetry and human dimensions surveys to explore potential solutions to migration mortality of an endangered population of coho salmon caught as bycatch in an aboriginal beach seine fishery. From 2009 to 2011, 182 wild coho salmon caught as bycatch in the lower Fraser River (Canada) were radio-tagged and tracked as they attempted to complete their migrations to natal spawning areas over 300 km upstream. Failure to survive to reach terminal radio receiving stations averaged 39% over three years. This mortality estimate is low compared to those obtained from telemetry studies on other salmon fisheries in the Fraser River. However, this value is markedly higher than the mortality estimate currently used to manage the fishery's impact. It is also in contrast to the perceptions of the majority of aboriginal fishers, who did not think survival of coho salmon is affected by capture and release from their fishery. Increased probability of survival was associated with lower reflex impairment, which is consistent with previous findings. Reflex impairment was positively correlated with entanglement time, suggesting that greater efforts by the fishers to release bycatch from their nets quickly would minimize post-release mortality. Survey responses by aboriginal fishers also suggested that they are receptive to employing new bycatch handling methods if they are shown to increase post-release survival. However, attempts to facilitate revival of a subset of captured fish using cylindrical in-river recovery bags did not improve migration success. Fisheries managers could use the new information from this study to better quantify impacts and evaluate different harvest options. Since aboriginal fishers were receptive to using alternate handling methods, efforts to improve knowledge on minimizing reflex impairment through reductions in handling time could help increase bycatch survival. Such a direct integration of social science and applied ecology is a novel approach to understanding conservation issues that can better inform meaningful actions to promote species recovery.

Movement estimates derived from sub-daily tracking of radio-tagged bull trout Salvelinus confluentus on the Columbia River, British Columbia, Canada, were used to test whether interindividual variation in behaviour was repeatable among contexts, both short- and long-term. Interindividual variation in S. confluentus behaviour was consistent across contexts. These findings emphasize the potential for telemetry as a tool in animal personality and temperament research.