Diverse dietary strategy of lake anchovy Coilia ectenes taihuensis in lakes with different trophic status

Abstract

Omnivores always show flexible foraging habits and actively shift their diets responding to the varying local conditions as well as different ontogenetic trajectories. Littoral fish commonly exhibiting omnivorous diets across pelagic and benthic food webs has the potential effect on trophic dynamics and food web stability. Here, we studied dietary strategy of lake anchovy, a non-migratory omnivorous fish, in two freshwater lakes with distinctly different trophic states to reveal its trophic niche shifts and population-and individual- level feeding habits plasticity using stable isotope analysis. We found lake anchovy exhibited diverse dietary strategies at both population and individual levels according to habitat changes. In eutrophic Chaohu Lake, lake anchovy showed generalized niche but greater individual diet variation and fed primarily on zooplankton. Conversely, lake anchovy exhibited relatively specialized niche and lower individual variation, foraging mainly on shrimps and fishes in mesotrophic Dongting Lake. Hence, habitat trophic status can affect the diet composition of lake anchovy indirectly through complex prey responding, which constrains food web coupling and influence energy flux and trophic dynamics.