Bacteria-zooplankton interactions: a key to understanding bacterial dynamics and biogeochemical processes in lakes?

• Applicant: Professor Dr. Hans-Peter Grossart
• Subject Area: Microbial Ecology and Applied Microbiology
• Term: from 2011 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 201319348

Worldwide, metazoan zooplankton represents an enormous surface and biomass in pelagic systems but their linkage with bacteria has been assumed to be rather indirect (via nutrient cycling and trophic cascades). However, a zooplankter’s body carries a high abundance of diverse bacteria, which can account for a substantial fraction and diversity of pelagic bacteria. Zooplankton bodies are organic-rich micro-environments that support fast bacterial growth. Their physical-chemical conditions differ from those in the surrounding water and hence select for different bacterial communities. Until now, information on bacteria- zooplankton interactions is still limited to only a few zooplankton groups and environments, in particular copepods in coastal and estuarine waters. Therefore, our proposal focuses on bacteria-zooplankton interactions in lakes. Since zooplankton taxa can have very different life history traits we will compare a large number of zooplankton taxa in a variety of lakes. In field and lab studies we will investigate these interactions with a high spatial and temporal resolution. We will address 4 topics: A) spatial and temporal variations in bacteria-zooplankton association, B) microbial dynamics in the zooplankton gut microhabitat, C) bacterial dispersal by migrating zooplankton and D) effects on microbial activities during the mid-summer zooplankton decline. We aim to fundamentally change the way we understand pelagic food webs and the ecological role of bacteria-metazoan interactions.

• DFG Programme: Research Grants