Projected compositional shifts and loss of ecosystem services in freshwater fish communities under climate change scenarios

What are the projected impacts of climate change on community composition and consequentially on the distribution of functional traits? Answers to these questions are somewhat unclear but critical for designing ecological management strategies. Here we forecast potential impacts of climate change on freshwater lake fish communities of Ontario, Canada, by contrasting species composition, species richness, functional diversity and functional composition for present versus projected communities under “best-case” and “business-as-usual” climate change scenarios. Results indicate that the composition of projected communities differs from present, and includes a shift from cold- and cool-water species to warm-water species. Species richness in projected communities is estimated to increase by 60–81%, but functional diversity is estimated to decline. These projected communities are estimated to have on average 22% shorter mean body length, 38% lighter body weight and 36% less fecundity than present. Also, the present configuration of sport and commercially important fishes are projected to decline in their distribution, potentially impacting ecosystem services associated with commercial and recreational fisheries. Together, climate change may initiate a compositional shift that may result in an important shift in community functional structure, which is likely to affect important aquatic ecosystem services.