Little is known about the origin of predation resistant bacteria (PRB) and how they interact with their environment and community members. We performed a study in the coastal northern Baltic Sea, to elucidate the sources and factors governing occurrence of PRB. We looked for PRB with an intracellular and extracellular lifestyle. We searched for their co-occurrence and interaction with potential microeukaryotic hosts. Water samples were collected in four bays, as well as in inflowing freshwater and offshore water during the productive season. The findings of this study are of interest to fundamental science as well as for water management operations to mitigate pollution sources.