Climate change impacts on structure and diversity of fish communities in rivers

Abstract

It is widely accepted that climate change constrains biota. Yet, because of the lack of consistent multisite and multitaxon surveys, few studies have addressed general rules about how climate change impacts on structure and diversity of animal communities. Especially, the relative influence of nonclimatic anthropogenic disturbances on this impact is fairly unknown. Here, we present for the first time a meta-analysis assessing the effect of global warming on stream organisms. Fish communities of large rivers in France undergoing various anthropogenic pressures showed significant increase in proportions of warm-water species and of specific richness during the last 15-25 years. Conversely, the equitability decreased, indicating a gradual decrease of the number of dominant species. Finally, the total abundance increased, coupled with rejuvenation and changes in size-structure of the communities. Interestingly, most of these effects were not depressed by the strength of nonclimatic anthropogenic disturbances. Conversely, geographical location of communities and especially closeness of natural barriers to migration could influence their response to climate change. Indeed, increase in the proportion of southern species seemed hindered at sites located close to the southern limit of the European species' geographical ranges. This work provides new evidence that climate change have deep impacts on communities which, by overtaking the effects of nonclimatic anthropogenic disturbances, could be more substantial than previously thought. Overall, our results stress the importance of considering climate change impacts in studies addressing community dynamics, even in disturbed sites.

Severity Multipliers as a Methodology to Explore Potential Effects of Climate Change on Stream Bioassessment Programs

“…For the EQR only small poor quality mountain streams showed increasingly negative ratios with increasing multipliers. The FRI indicating a more downstream influenced community is in line with other studies on climate change effects on fish [19,29,30]. The actual differences in FRI of the communities range from a negligible −0.03 in poor small lowland and good small mountain streams, up to 0.37 in small good lowland streams; they are thus on average lower than the zonal changes modelled by Pletterbauer et al [19] for three future emission scenarios (A1b, A2, and B1).…”

“…The actual differences in FRI of the communities range from a negligible −0.03 in poor small lowland and good small mountain streams, up to 0.37 in small good lowland streams; they are thus on average lower than the zonal changes modelled by Pletterbauer et al [19] for three future emission scenarios (A1b, A2, and B1). We did not further analyze EQR in fish assessment results due to missing key influential components for fish assessments, particularly size and age structure, which have been shown to change due to climate change [30].…”

Sensitivity of native and non-native mollusc species to changing river water temperature and salinity

“…Climate change may affect environmental conditions, and subsequently bioinvasions, by altering the pool of potential invaders and influencing the chance that non-native species will establish (Rahel and Olden 2008). Studies on the effects of climate change in lake and river systems have shown changes in freshwater species composition and diversity for fish (Buisson et al 2008;Daufresne and Boet 2007) and macroinvertebrates (Burgmer et al 2007;Chessman 2009;Daufresne et al 2004;Mouthon and Daufresne 2006). Abiotic changes in river systems typically include increases in water temperature, river dynamics and salinity (Gornitz 1991;Webb 1996).…”

Physico-chemical thresholds in the distribution of fish species among French lakes

“…Temperature has a direct effect on fish activity, growth, metabolism, reproduction and development but can also influence communities and populations via biotic interactions (Petchey et al, 1999;Voigt et al, 2003;O'Connor et al, 2009;Rall et al, 2010;Yvon-Durocher et al, 2010;Ohlberger et al, 2011;Vucic-Pestic et al, 2011;Reuman et al, 2014). From this viewpoint, 1-3°C increase in temperature due to global warming have been shown to have major impacts on fish community structure and diversity (Daufresne et al, 2004(Daufresne et al, , 2009Daufresne and Boet, 2007). Temperate species generally avoid water warmer than 30°C and the temperature preference is a commonly used criterion to classify fish into cold and warm water species (Holcik et al, 1989;Wehrly et al, 2003).…”