Drivers of freshwater fish colonisations and extirpations under climate change

Abstract

Climate change is expected to bring about profound rearrangement of ecological communities by affecting individual species distributions. The resulting communities arise from the idiosyncratic responses of species to future changes, which ultimately relate to both shrinking and expanding species ranges. While spatial patterns of colonisation and extirpation events have received great attention, the identification of specific drivers remains poorly explored. This study aims to investigate the relative contribution of species gain and loss to the turnover of fish assemblages in French rivers under future climate change, and to identify their principal drivers. Future projections of potential habitat suitability in 2080 derived from species distribution models for 40 fish species showed that colonisations and extirpations could play counterbalancing roles in the reshuffling of communities. Simultaneously, these two processes exhibited patchy spatial patterns, segregated along the longitudinal and altitudinal gradients, resulting in dramatic species turnover of ∼ 60% of the current composition of species assemblages. Beyond the effect of topographic location, colonisations were found to be driven by temperature seasonality while extirpations were affected by modifications in both thermal and precipitation regimes. These results generate the possibility of developing ecosystem‐based management tools focused on the early identification of areas where particular species may be sensitive to climate changes. Disentangling the drivers of colonisation and extirpation processes provides ready‐to‐use information that may be easily integrated into conservation planning. This information could be used to identify potential hotspots of species gain and loss and to then compare these hotspots with newly favourable areas so as to consider their actual accessibility in order to facilitate future range shifts.

Evolutionary processes driving spatial patterns of intraspecific genetic diversity in river ecosystems

“…due to climate change; Conti et al . ), or that a downstream‐directed colonization occurs after a mass extinction, an introduction or a glacial event (Cyr & Angers ). In these cases, the processes can generate positive relationships between distance from the river mouth and allelic richness, as was confirmed by supplementary simulations (see Appendix S2, Supporting information).…”

“…during a range shift due to climate change; Conti et al . ). Ultimately, this may generate the observed DIGD.…”

On the use of climate covariates in aquatic species distribution models: are we at risk of throwing out the baby with the bath water?

“…Lacking direct estimates of water temperature and hydrology, some studies of aquatic organisms have used air temperature and/or precipitation as surrogates for 'instream' conditions (Wenger et al 2011, Logez et al 2012, Conti et al 2015. However, others have argued that the use of air temperature and precipitation as instream surrogates may be unjustified (Elith and Leathwick 2009, Al-Chokhachy et al 2013, Huang and Frimpong 2016.…”

Climate change and European rivers: An eco‐hydromorphological perspective

“…In less resilient systems, significant increases in mean/maximum temperature regime are likely to result in a taxonomic shift towards more tolerant species and, in particular, may facilitate susceptibility to invasion by alien species that typically exhibit broad ecological plasticity (Rahel & Olden, 2008;Britton, Cucherousset, Davies, Godard, & Copp, 2010;Conti, Comte, Hugueny, & Grenouillet, 2015). O'Briain, Shephard, Coghlan, and Kelly (2019) report that increased temperatures created a shift in fish community from a brown trout-dominated (S. trutta L.) fish assemblage to predominance of more thermally tolerant fish species.…”