Population niche breadth and individual trophic specialisation of fish along a climate-productivity gradient

Abstract A mechanistic understanding of how environmental change affects trophic ecology fish at the individual and population level remains elusive. To address this, we conducted a space-for-time approach incorporating gradients (temperature, precipitation nutrients), lake morphometry (visibility, depth area), communities (richness, competition predation), prey availability (richness density) feeding (population niche breadth specialisation) for 15 native taxa belonging to different thermal guilds from 35 subarctic lakes along marked climate-productivity gradient corresponding future climate predictions. We revealed significant contrasting responses two generalist species that are abundant widely distributed in region. The cold-water adapted European whitefish ( Coregonus lavaretus ) reduced specialisation warmer more productive lakes. Conversely, cool-water Eurasian perch Perca fluviatilis showed increased levels specialism gradient. Although differed way they consumed gradient, both switched consumption zooplankton cooler, less lakes, macrozoobenthos warmer, Species with specialist benthic or pelagic did not show changes conclude consumers, such as perch, have clear advantages over colder clear-water specialised morphs through their capacity undergo reciprocal benthic–pelagic switches associated change. flexibility is likely key trait dominance high latitudes under