Once species or their habitat have declined, restoration and reclamation is needed. One important component of restoration and reclamation is developing habitat offsets. Many countries have adopted habitat offsetting policies (e.g., Canada, United States, Europe, Australia, New Zealand, and United Kingdom), where the ideal goal is ecological equivalency, such that offsets are done in a manner which replaces habitats “like-for-like” in areas in close proximity to where those habitats were displaced. When ecological equivalency cannot be achieved with habitat offsets, such as when the extent, duration and intensity of the impacts are sufficiently broad in spatio-temporal scale (e.g. surface mining, Sun et al. 2017), offsetting currencies and flexibility may be needed. Research topics, includes: assessing the efficacy of fish stocking for restoration, developing methods to for offsetting fisheries productivity, advancing expertise and methodologies in hydroacoustics.
A recent review article on compliance and ecosystem function (Theis et al. 2019) in freshwater offsets was highlighted on CBC News and CBC radio in Edmonton and Calgary
Press Play to hear the interview on Edmonton AM or click this link to get redirected to CBC Edmonton AM Radio’s webpage.
Press Play to hear the interview on Calgary’s EyeOpener or click this link to get redirected to CBC EyeOpener Radio’s webpage.
Thesis Title: Paleolimnological Reconstruction of Westslope Cutthroat Trout (Oncorhynchus clarki lewisi) in Alpine Lakes using a Next-Generation Sequencing Platform (link; co-supervisors: R. Vinebrooke, M. Taylor)
Author: Hedin Nelson-Chorney
Abstract
Understanding historical species distributions is vital to the conservation and restoration of native species, yet such information is often qualitative. Here, 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 sediment DNA). This method was validated through the detection of lake sediment DNA from non-native trout (Yellowstone cutthroat trout; Oncorhynchus clarkii bouvieri), which corroborated historical records of human-mediated introductions. Moreover, we discovered native trout (westslope cutthroat trout; Oncorhynchus clarkii lewisi) lake sediment DNA that predated human-mediated introductions of freshwater fishes in a watershed with high topographical relief. This unexpected result revealed that the population was of native origin and requires immediate conservation protection. Our findings demonstrate that lake sediment DNA 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.
Thesis Title: Impacts of a novel predator on aquatic invertebrates in fishless lakes: Implications for conservation translocation
Author: Allison L.K. Banting
Abstract
Fishless mountain lakes hold important ecological and conservation value. As such, managers are establishing conservation goals (e.g., non-native fish removal) to restore the naturalness to many of these lakes. Simultaneously, managers who are recovering native (coldwater) fish populations threatened by climate change (e.g., Westslope Cutthroat Trout, Oncorhynchus clarki lewisi and Bull Trout, Salvelinus confluentus) are exploring conservation strategies involving the intentional translocation of native fish species to more suitable areas. These areas include unoccupied, or naturally fishless, stream and lake habitat within their native range or favorable habitats outside their native range. This action presents a potential threat for fishless mountain lakes as conservation managers view these as recovery habitat for imperiled native fish species. The purpose of my study was to inform native fish recovery efforts by assessing the potential consequences of translocating native fishes to naturally fishless lakes, thus outside their historic distribution. Forty alpine and sub-alpine lakes in Banff National Park, Alberta and Kootenay National Park, British Columbia were sampled and divided into three lake types, including 13 naturally fishless lakes, 13 native fish-bearing or native fish-stocked lakes, and 14 non-native fish-stocked lakes historically unoccupied by fish. Littoral invertebrate community composition, density and diversity were examined among lake types to 1) quantify the impacts of introducing non-native fishes into historically fishless lakes, and 2) quantify the differences between native fish lakes and naturally fishless lakes. These comparisons provided context for the scale of impact between two predators of different geographic origins (native vs. non-native) introduced to fishless lakes. The variation in environmental gradients amoung lake types was controlled for, suggesting fish presence strongly influenced changes to invertebrate community density and composition. Native and non-native fishes have the capacity to similarly alter littoral invertebrate community composition of fishless lakes, yet non-native fishes appear to have the greatest impact on littoral invertebrate density. Although impacts vary between native and non-native predators, the introduction of any novel fish predator to a fishless lake will result in a negative impact to key littoral macroinvertebrates, such as Gammaridae, Ephemoptera and Plecoptera, and a positive impact to burrowing taxa, such as Oligochaeta, Nemata and Chironomidae. While the introduction of non-native fishes has been repeatedly shown to affect invertebrate communities, the translocation of native fishes similarly has the potential to alter the ecology of a naturally fishless lake. With considerations for possible aquatic-terrestrial cross boundary effects, this study suggests that conservation ecologists consider the entire ecosystem when building resilience for climate change.
Thesis Title: Establishment, spread and impact of Prussian Carp (Carassius gibelio), a new invasive species in Western North America.
Author: Cassandra Docherty
Abstract
Freshwater ecosystems are some of the most imperilled on the planet. Invasive species pose the second largest threat to freshwater organisms after habitat degradation. Aquatic introductions have led to extinctions, competition for resources, hybridization, the introduction of foreign pathogens and the alteration of ecosystem structure and function. One of the most recent invaders in western North America is Prussian Carp (Carassius gibelio). The first record of this species in North America was in 2000, in Alberta, Canada, yet little is known about its invasion, current distribution or effects on stream communities. In Eurasia, Prussian Carp have been assessed as one of the most harmful invasive fish species because of its ability to reproduce asexually, high environmental tolerances and preference for human modified habitats. The arrival of Prussian Carp in western North America poses concerns for many native freshwater species. Therefore, the objectives of this study were to assess the severity of Prussian Carp’s invasion in western North America by 1) mapping Prussian Carp distribution and rate of spread since its initial arrival; 2) analysing the impact of Prussian Carp on native fish species; and 3) identifying environmental parameters that predict Prussian Carp presence. Using kernel density functions, we found that the range of Prussian Carp increased in Alberta, Canada from approximately 500 km² since its arrival (estimated as 2000) to over 20,000 km² in 2014. The rate of spread is increasing at an exponential rate over five year increments (e.g. 1.6, 2.1, and 2.3 times), suggesting rapid expansion since first detection. Our results did not indicate that Prussian Carp have a negative effect on native fish species, which is likely due to its recent expansion into these areas and an already depauperate species community. The most important habitat variables that best predicted the presence of Prussian Carp were: dense aquatic vegetation, high conductivity, pH, high dissolved oxygen and low flow rates indicating preference for relatively slow, eutrophic streams. Successful management of this species in western North America will require the integration of all levels of government between neighbouring provincial and national borders, as well as the public. Prussian Carp are a highly mobile species and given the connection to other watersheds in Canada and proximity to the Missouri/Mississippi drainages in the United States, agencies throughout North America should be aware of this invasive species and the potential impacts on native biota
Citation: Thayer, D.*, Ruppert, J.L.W., Watkinson, D., Clayton, T. and M.S. Poesch. (2017) Identifying temporal bottlenecks for the conservation of large-bodied fishes: Lake Sturgeon (Acipenser fluvescens) show highly restricted movement and habitat-use overwinter. Global Ecology and Conservation 10: 194-205.
Abstract
The relationship between species’ size and home range size has been well studied. In practice, home range may provide a good surrogate of broad spatial coverage needed for species conservation, however, many species can show restricted movement during critical life stages, such as breeding and over-wintering. This suggests the existence of either a behavioral or habitat mediated ‘temporal bottleneck,’ where restricted or sedentary movement can make populations more susceptible to harm during specific life stages. Here, we study over-winter movement and habitat use of Lake Sturgeon (Acipenser fulvescens), the largest freshwater fish in North America. We monitored over-winter movement of 86 fish using a hydro-acoustic receiver array in the South Saskatchewan River, Canada. Overall, 20 fish remained within our study system throughout the winter. Lake Sturgeon showed strong aggregation and sedentary movement over-winter, demonstrating a temporal bottleneck. Movement was highly restricted during ice-on periods (ranging from 0.9 km/day in November and April to 0.2 km/day in mid-November to mid-March), with Lake Sturgeon seeking deeper, slower pools. We also show that Lake Sturgeon have strong aggregation behavior, where distance to conspecifics decreased (from 575 to 313 m) in preparation for and during ice-on periods. Although the Lake Sturgeon we studied had access to 1100 kilometers of unfragmented riverine habitat, we show that during the over-winter period Lake Sturgeon utilized a single, deep pool (<0.1% of available habitat). The temporal discrepancy between mobile and sedentary behaviors in Lake Sturgeon suggest adaptive management is needed with more localized focus during periods of temporal bottlenecks, even for large-bodied species.
*Lab members: Donnette Thayer, Jonathan Ruppert, Mark Poesch. Check out opportunities in the lab!
Monthly core (C) and range (R) extent kernel density maps for: A) November, B) December, C) January, D) February, E) March, and F) April. Black lines are core range (50% percentile), broken lines range (90th percentile) extent.
Citation: Maitland, B.M.*, Anderson, A. and Poesch, M.S. (2016) Prioritising culvert removals to restore habitat for at-risk salmonids in the Boreal forest. Fisheries Management and Ecology 23: 489-502.
Abstract
Stream crossing structures are an increasingly prevalent anthropogenic feature on North American riverscapes, particularly in watersheds affected by industrial resource development in sensitive boreal environments. If improperly managed, stream crossings have the potential to alter fish habitat and impede fish movement. This study assessed instream habitat characteristics and fish communities from 33 culverted, bridged and reference streams in an industrialising region of the boreal forest in west-central Alberta. Mixed-effects modelling and multivariate analysis were used to determine impacts of stream crossings at three scales: whole-stream scale, within-stream scale and the interaction of scales. Instream habitat characteristics such as mean depth, water velocity, percent fines, turbidity, water temperature and dissolved oxygen showed significant between-stream as well as within-stream differences among stream crossings. The majority of fish species exhibited significantly lower densities (n m−2) in upstream habitats as compared to downstream habitats, including a significant reduction in Slimy Sculpin densities in culverted streams. Multivariate tests corroborated these results, showing that fish assemblages differ as a function of stream type. This study suggests industrial stream crossings influence abiotic habitat characteristics in freshwater ecosystems, restrict biotic connectivity and impact fish community structure at the whole-stream and within-stream scales. Alterations to stream ecosystems associated with stream crossings may be driving large-scale changes in stream fish communities in the boreal forest. With expanded development expected in much of North America’s boreal region, mitigation measures which limit impacts from stream crossings are needed to ensure proper ecosystem function in freshwater systems.
*Lab members: Bryan Maitland, Mark Poesch. Check out opportunities in the lab!
Site Locations of Assessed Stream Crossings, including (a) Simoneete, (b) Latronell and (c) Deep Valley watersheds in Alberta Canada.
Prioritization given: net habitat gain (a,d), number of barriers removed (c,f) and the mean cost per barrier (c,f) across Deep Valley and Latronell subwatersheds.
The Alberta Conservation Association provided a grant to help research the impact of stocking of non-native trout on alpine ecosystems. This project is being led by MSc student Allison Banting with the help of Dr. Mark Taylor and Rolf Vinebrooke. Thanks ACA for your continued support of the PoeschLab.
Thesis Title: Stream Crossings in the Western Boreal Forest: Assessing Impacts and Prioritizing Restoration for Native Freshwater Fishes
Author: Bryan M. Maitland
Abstract
Growing anthropogenic development in response to rising demands for natural resources is a major concern for freshwater fish, particularly in resource rich regions such as Canada’s boreal forest. Expanding networks of industrial resource roads has led to the installation of hundreds of thousands of stream-crossing structures that are becoming increasingly common anthropogenic features on North American riverscapes. These structures can reduce available fish habitat, deteriorate instream habitat, and disrupt ecological connectivity by acting as barriers to fish and aquatic organism movement. My objectives were (i) to determine the extent to which commonly installed stream crossings affect stream fish communities in a boreal forest watershed, and (ii) to assess the application of operational research tools that utilize an optimization framework for mitigating the effects of fragmentation on native freshwater fish and informing restoration planning in the boreal forest. I used mixed-effects modeling and multivariate analyses to determine the effects of stream crossings from 33 culverted, bridged, and reference streams in an industrializing region of the boreal forest in west-central Alberta. Instream habitat characteristics such as mean depth, percent fines, and turbidity showed significant between- as well as within-stream differences among stream crossings. I found that the majority of fish species exhibited significantly lower densities (n·m -2) in upstream habitats as compared to downstream habitats, including a significant reduction in Slimy Sculpin densities in streams with culverts compared to reference streams. Multivariate tests showed that fish assemblages differ as a function of stream type and location. The prioritization method utilized in this study suggests that large gains in potential connectivity could be realized with a moderate investment (~$200K to $500K). I found that the operational research tool can be used to develop cost-benefit curves from the study watersheds, which can be used to minimize overall restoration costs to achieve particular management objectives in watersheds of interest, as well as provide defendable evidence for budget planning to regulators and decision-makers. Additionally, varying model parameters that account for species-specific differences in habitat use (e.g. dispersal distance) affected prioritization solutions, and should be considered in future prioritization analyses. In addition to effecting fish passage and stream connectivity, my results suggest that culverts may also be altering fish habitat, further contributing to large-scale changes in stream fish communities in the boreal forest. Further, my research highlights the efficacy of a novel, easy to use optimization-based barrier prioritization toolset that has minimal data requirements, is applicable to both stream-resident and long-range migratory species, and significantly reduces the mathematical and technical expertise needed to perform relatively complex optimization analyses.
Citation: Poesch, M.S., Walker, S.C., and Jackson, D.A. 2009. Functional diversity indices can be driven by methodological choices and species richness. Ecology 90(2): 341-346.
Abstract
Functional diversity is an important concept in community ecology because it captures information on functional traits absent in measures of species diversity. One popular method of measuring functional diversity is the dendrogram-based method, FD. To calculate FD, a variety of methodological choices are required, and it has been debated about whether biological conclusions are sensitive to such choices. We studied the probability that conclusions regarding FD were sensitive, and that patterns in sensitivity were related to alpha and beta components of species richness. We developed a randomization procedure that iteratively calculated FD by assigning species into two assemblages and calculating the probability that the community with higher FD varied across methods. We found evidence of sensitivity in all five communities we examined, ranging from a probability of sensitivity of 0 (no sensitivity) to 0.976 (almost completely sensitive). Variations in these probabilities were driven by differences in alpha diversity between assemblages and not by beta diversity. Importantly, FD was most sensitive when it was most useful (i.e., when differences in alpha diversity were low). We demonstrate that trends in functional-diversity analyses can be largely driven by methodological choices or species richness, rather than functional trait information alone.
Citation: Poesch, M.S., Mandrak, N.E., and McLaughlin, R.L. 2008. A practical framework for selecting among single species, multi-species and ecosystem-based recovery plans. Canadian Journal for Fisheries & Aquatic Science 65: 2656-2666.
Abstract
Science-based approaches for selecting among single-species, community-, and ecosystem-based recovery plans are needed to conserve imperilled species. Selection of recovery plans has often been based on past success rates with other taxa and systems or on economic cost, but less on the ecology of the system in question. We developed a framework for selecting a recovery plan based on the distributions and ecology of imperilled and nonimperilled species across available habitat types and applied it to fishes in the Sydenham River, Ontario, Canada. We first tested whether distributions of fishes were adequately predicted by habitat features hypothesized to limit the distributions of imperilled fishes versus a broader set of habitat features known to predict fish distributions. We then tested whether imperilled species occurred in similar or disparate habitat types. For the Sydenham River, an ecosystem-based recovery plan was deemed most appropriate because imperilled species occur in disparate habitat types. We lastly provide decision criteria to facilitate applications of our framework to the selection of recovery plans for other species and systems.
