In a comparative study, two existing bacteriological samplers and a newly designed device were tested for obtaining uncontaminated seawater samples. Serratia marinorubra was used as a tracer organism. It was possible to eliminate contamination to a large extent.
Jannasch, H. W., and W. S. Maddux. 1967. "A note on bacteriological sampling in seawater." Journal of Marine Research 25, (2). https://elischolar.library.yale.edu/journal_of_marine_research/1096