Pandit, S.*, Poesch, M. S., Kolasa, J., Pandit, L. K., Ruppert, J. L. W., and E. Enders (In Press). Long-term evaluation of the impact of urbanization on native and non-native fish assemblages. Aquatic Invasions.

Urbanization can homogenize species composition across aquatic ecosystems by introducing disturbance that can destroy the habitat of unique endemic or native species and/or create an alternative habitat for the few species able to adapt to these conditions. Here, we use a long-term decadal dataset (1971 to 2010) on the fish species presence in 16 subwatersheds within three watersheds in the Greater Toronto Area, Canada; and assessed whether fish communities have changed over time for three categories of species assemblages: (1) native species community only, (2) nonnative species community only, and (3) a combination of all species (all species). We considered three significant variables for which data exist: catchment area, distance to a species pool source, and percentage of urban cover (i.e., percent of the impervious area within a catchment) to determine whether these variables alter species richness. We used the nestedness metric to evaluate the degree of interdependence among site assemblages and site compositional degradation over time to contrast trends in native and non-native sets of species. Overall, nestedness temperatures (NTs, which is ‘heat of disorder’) for native fish is lower [T=11.01] than nonnative fish assemblages [24.47], indicating that native fish are more nested than non-native fish species assemblages. Among the four decadal scales, the native species community showed high nestedness during the 1970s, which declined later (the 2010s), and an opposite trend occurred for the non-native species community. Although total species richness increased over time, native richness decreased with urbanization, with non-native species richness increasing and overcompensating native losses. The study further suggests that the non-native fish communities become patchier (less predictable and less nested). This implies that further changes in fish communities are likely, and the patchiness may isolate communities making them more prone to perturbations.

Citation: Pandit, S., Poesch, M. S., Kolasa, J., Pandit, L. K., Ruppert, J. L. W., and E. Enders (In Press). Long-term evaluation of the impact of urbanization on native and non-native fish assemblages. Aquatic Invasions.

Also Read:

Theis S.*, Cartwright L., Chreston A., Coey B., Graham B., Little D., Poesch M.S., Portiss R., Wallace A. and J. L. W. Ruppert (In Press). A multi-metric index for assessing two decades of community responses to broad scale shoreline enhancement and restoration along the Toronto waterfront. Aquatic Conservation: Marine and Freshwater Ecosystems.

*Lab members: Shubha Pandit and Mark Poesch. Check out opportunities in the lab!

Pandit, S.N., Koriala, L., Maitland, B.M, Poesch, M.S., and E. Enders. (2017) Climate change risks, extinction debt, and conservation implications for an endangered freshwater fish Carmine Shiner (Notropis percobromus). Science of the Total Environment 598: 1-11.

Abstract:

Climate change is affecting many freshwater species, particularly fishes. Predictions of future climate change suggest large and deleterious effects on species with narrow dispersal abilities due to limited hydrological connectivity. In turn, this creates the potential for population isolation in thermally unsuitable habitats, leading to physiological stress, species declines or possible extirpation. The current extent of many freshwater fish species’ spatio-temporal distribution patterns and their sensitivity to thermal impacts from climate change − critical information for conservation planning − are often unknown. Carmine shiner (Notropis percobromus) is an ecologically important species listed as threatened or imperilled nationally (Canada) and regionally (South Dakota, United States) due to its restricted range and sensitivity to water quality and temperature. This research aimed to determine the current distribution and spatio-temporal variability in projected suitable habitat for Carmine shiner using niche-based modeling approaches (MaxEnt, BIOCLIM, and DOMAIN models). Statistically downscaled, bias-corrected Global Circulation Models (GCMs) data was used to model the distribution of Carmine shiner in central North America for the period of 2041–2060 (2050s). Maximum mean July temperature and temperature variability were the main factors in determining Carmine shiner distribution. Patterns of projected habitat change by the 2050s suggest the spatial extent of the current distribution of Carmine shiner would shift north, with > 50% of the current distribution changing with future projections based on two Representative Concentrations Pathways for CO2 emissions. Whereas the southern extent of the distribution would become unsuitable for Carmine shiner, suitable habitats are predicted to become available further north, if accessible. Importantly, the majority of habitat gains for Carmine shiner would be in areas currently inaccessible due to dispersal limitations, suggesting current populations may face an extinction debt within the next half century. These results provide evidence that Carmine shiner may be highly vulnerable to a warming climate and suggest that management actions – such as assisted migration – may be needed to mitigate impacts from climate change and ensure the long-term persistence of the species.

Citation: Pandit, S.N.*, Koriala, L., Maitland, B.M*, Poesch, M.S., and E. Enders. (2017) Climate change risks, extinction debt, and conservation implications for an endangered freshwater fish Carmine Shiner (Notropis percobromus). Science of the Total Environment 598: 1-11.

Predicted Change in Carmine Shiner Distribution given Climate Change Scenarios (RCP 2.6 top; RCP8.5 bottom) across various thresholds

Also Read:

Poesch, M.S., Chavarie, L., Chu, C., Pandit, S.N.*, and W. Tonn. (2016) Climate change impacts on freshwater fishes: A Canadian perspective. Fisheries 41(7): 385-391.

*Lab members: Shubha Pandit, Bryan Maitland, Mark Poesch. Check out opportunities in the lab!

Maitland, B.M., M.S. Poesch, Anderson, A.E., and S. Pandit. (2016) Industrial road crossings drive changes in community structure and instream habitat for freshwater fishes in the Boreal forest. Freshwater Biology. 61: 1-18.

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.

Citation: Maitland, B.M.*, M.S. Poesch, Anderson, A.E., and S. Pandit*. (2016) Industrial road crossings drive changes in community structure and instream habitat for freshwater fishes in the Boreal forest. Freshwater Biology. 61: 1-18.

Figure – Barplot of fish community metrics of (a) fish density (number per m2) and (b) species richness across stream types and upstream and downstream locations (mean +/- SE). Sample sizes for stream types were: culvert (Cul) N = 11, bridge (Bri) N = 11, reference (Ref) = 11. Significant differences across stream types are identified by upper case letters, while significant differences between upstream and downstream reaches are identified by lower case letters.

Also Read:

Fischer, S.M.*, Ramaza, P., Simmons, S., Poesch, M.S. and M.A. Lewis. (2023) Boosting propagule transport models with individual-specific data from mobile apps. Journal of Applied Ecology 60(5): 934-949.

*Lab members: Bryan Maitland, Shubha Pandit, Mark Poesch. Check out opportunities in the lab!

Poesch, M.S., Chavarie, L., Chu, C., Pandit, S.N.*, and W. Tonn. (2016) Climate change impacts on freshwater fishes: A Canadian perspective. Fisheries 41(7): 385-391.

Abstract:

Current and projected patterns of global climate change are a major concern to freshwater fisheries in Canada. The magnitude of the impacts of climate change vary among species and ecoregions. The latest climate change scenario projections for Canada suggest that by 2050 temperatures will increase between about 4.9°C ± 1.7°C (average mean ± standard deviation) and 6.6°C ± 2.3°C under the Representative Concentration Pathways (RCPs) 2.6 and 8.5 emission scenarios, respectively. These changes will have an important influence on the physiology, distribution, and survival of freshwater fishes, as well as other ecological processes in direct, indirect, and complex ways. Here we provide a perspective from the Canadian Aquatic Resources Section on the impacts of climate change to freshwater fishes. Given the geographic size and diversity of landscapes within Canada, we have divided our perspective into three regions: eastern, western, and northern Canada. We outline the impacts of climate change to these regions and outline challenges for fisheries managers. Because climate change does not operate in isolation of other environmental threats, nor does it impact species in isolation, we suggest improved inter jurisdictional integration and the use of an adaptive and ecosystem-based approach to management of these threats.

Citation: Poesch, M.S., Chavarie, L., Chu, C., Pandit, S.N.*, and W. Tonn. (2016) Climate change impacts on freshwater fishes: A Canadian perspective. Fisheries 41(7): 385-391.

List of species that have potential to extend their range and/or abundance northward into the Arctic, with some biological characteristics related to expansion of their existing ranges.

Also Read:

Theis, S.* Castellanos D.A., Hamann A. and M.S. Poesch. (2022) Exploring the potential role of habitat banks in preserving freshwater biodiversity and imperiled species in the United States. Biological Conservation 273: 109700.

*Lab members: Shubha Pandit, Mark Poesch. Check out opportunities in the lab!