Drivers and functions of protist parasites in plankton food webs

Parasitic symbionts play a major role in the functioning and equilibrium of carbon flow in marine food webs.

But the extent and strength of zooplankton parasites are still poorly known, mainly because they are hard to detect, often hidden and consequently frequently overseen.

Yet, recent observations uncovered a large number of parasitic dinoflagellates in the global ocean that often dominate interactions with zooplankton.

Here, we propose to advance knowledge in a widespread parasitic interaction between crustacean zooplankton that perform key ecosystem functions, and parasitic dinoflagellates that structure marine pelagic food webs.

As a novel contribution, we propose studies based on metabarcoding and microscopy data from field collected samples across the Baltic Sea environmental gradient to detect drivers of zooplankton parasite interactions, uncover the underlying mechanisms and host range of interactions.

An infection laboratory experiments will provide crucial information about the fitness consequences for copepod hosts and how infections are facilitated by harmful algal blooms.

This knowledge will be integrated in network models to quantify the structuring role of parasites in pelagic food webs and used to predict zooplankton infections and dynamics, which is of relevance for sustainable fisheries and prevention of algal blooms.

These results are of great importance to predict how environmental change will affect disease outbreak and energy flow in marine systems.