Plankton-fish interactions: an understudied link in Baltic Sea food webs and fisheries management

Small-sized pelagic fish have a central role in marine food webs as they control production of predatory fish and at the same time feed on zooplankton and thereby indirectly control algal blooms.

Understanding variation in plankton-fish feeding interactions are key for developing management strategies that promote fish stocks and enhance control on algal blooms. This, however requires detailed knowledge about feeding interactions from primary producers to upper trophic levels.

A current limitation is the lack of data on diet of small pelagic fish, taking the entire prey spectrum into account, hampering predictions of management strategies.

Here we will investigate prey preference of small pelagic fish including the entire prey spectrum using novel molecular tools that amplify and sequence low levels of DNA combined with network models to project trophic coupling under changing climate, nutrient and fisheries scenarios.

A refined understanding of trophic interactions between plankton and fish will provide important information on top-down and bottom-up drivers of commercially important fish (sprat, herring, cod) useful for fisheries management and reveal the ecological role of sticklebacks, a species that increased significantly in recent years.

These results will be of relevance to better understand temporal and spatial dynamics of fish feeding, growth and recruitment, which is important to advice ecosystem management for sustainable fisheries and prevention of algal blooms.