Consequences for aquatic trophic cascades

Researchers: Thomas Mehner, Kate Laskowski,
Associated researcher: Gregor Kalinkat 

Background: Species-specific differences in feeding strategies, habitat use and morphology between top fish predators are known to modify the strength of trophic cascades. For example, cruising pelagic predators such as pikeperch may suppress the density of pelagic planktivorous fishes, hence the filtering zooplankton is released from predation, and phytoplankton biomass will be reduced. In contrast, less strong pelagic trophic cascades are expected in lakes where the only dominant top predator is pike whose ambush predator strategies is confined to nearshore zones and daylight feeding. However, it has so far completely been neglected that pike populations can be composed of both littoral and inactive, and pelagic and active individuals.

The goal of this subproject is to investigate whether and to what extent differences in BT in predator populations affect community interactions in lakes. Our main hypothesis is that the relative frequencies of BT directly correlate with the strength of trophic cascades.