Protist grazing and viral lysis as prokaryotic mortality factors at Baltic Sea oxic-anoxic interfaces

Interface zones between oxic and anoxic water masses (pelagic redoxclines) host highly active prokaryotic communities, mediating important biogeochemical transformations. However, for marine pelagic redoxclines almost no knowledge exists on the magnitude of the loss processes affecting these prokaryotic communities. We assessed the importance of protist grazing and viral lysis as prokaryotic mortality factors for 2 central Baltic Sea redoxclines using a combination of microscopy and experimental community manipulation techniques. Our results demonstrate that protist grazing dominated prokaryotic mortality at suboxic (