Plankton are crucial components of the pelagic food web by contributing to key biogeochemical processes. This diverse group is affected by biotic and abiotic factors and due to their low trophic levels, they are responsible for shaping the pelagic food web, thus understanding their interactions is important to develop management strategies. However, assessing their biotic interactions in situ is challenging and little is known about the impact of environmental conditions on this interactome. In this project, we investigate mesozooplankton prey preference at high taxonomy resolution using DNA metabarcoding on the 16S and 18S rRNA gene along a salinity gradient in the Baltic Sea. This project submission contains 16S and 18S rRNA sequences libraries from the gut content of Temora longicornis, Acartia spp., Centropages hamatus and Evadne nordmanni collected along the Baltic Sea salinity gradient in June 2019 and September 2020.