Marine lake populations of jellyfish, mussels and sponges host compositionally distinct prokaryotic communities

Abstract

Marine lakes represent a unique aquatic environment. Here, we tested if prokaryotic communities of water, sediment, jellyfish, mussel and sponge biotopes differed in composition, higher taxon abundance and diversity. All of these proved to differ significantly among biotopes. In addition to this, we also observed significant differences in composition and diversity in mussel populations from different marine lakes. Diversity was particularly low in jellyfish populations, which were dominated by a single OTU, assigned to the genus Endozoicomonas, although individual samples also contained relatively abundant OTUs assigned to other phyla (e.g., Tenericutes). In contrast to jellyfish, Brachidontes mussels from different lakes housed highly distinct prokaryotic communities in terms of diversity and composition. An OTU assigned to the genus Endozoicomonas dominated mussels from a lake with limited connection to the open sea. Prokaryotic communities in mussels from a more connected marine lake were, in contrast, much more diverse. Sponges housed prokaryotic communities that were similar, but still distinct, to those found in water. Our results show that benthic and pelagic communities of marine lake organisms house distinct prokaryotic communities. Future research should focus on the functional implications of these differences and how they contribute to maintaining a healthy lake environment.