Microbial Communities of Bilge Water, Boat Surfaces and Port Water: A Global Comparison

Laura G. Schaerer, Ryan B. Ghannam, Timothy M. Butler, Stephen M. TechtmannDepartment of Biological Sciences Michigan Technological University

Introduction and Objectives

ApproachTwenty-one locations on three continents were sampled

Results Continued

Fig 1: (A) A diverse microbial community is present in all sample types, port water is most diverse. (B) PCoA plot shows samples grouped into three clusters. The boat samples are spread throughout the water samples indicating a certain level of similarity.

Different ASVs are enriched in theport water relative to the boat

How Source Tracker Works

Conclusions

Acknowledgements

Fig 2: Differential abundance analysis showed enrichment of specific ASVs in the port water relative to the boat. Red numbers indicate the number of enriched ASVs in each comparison. The enriched phyla were: Proteobacteria, Bacteroidetes, Cyanobacteria and Actinobacteria.

Fig 5: Source Tracker takes “sources” and “sinks” and outputs the proportion of each source present in each of the sinks in addition to an “unknown” source which accounts for variables not measured.

Water microbial signatures are present on the boat

• Port water seeds a variable portion of the microbial community on a boat, both theboat surface and bilge water.

• Ships may spread pathogens and other harmful microorganisms in bilge water andvia hull fouling, in addition to in ballast water.

This work was sponsored by DARPA Young Faculty Award D16AP00146. We would like to thank the Captain and Crews of the research vessels used in sampling. In particular we would like to thank Jamey Anderson and Christopher Pinnow for help in sample collection from ports in the Great Lakes.

Laura Schaerer – lgschaer@mtu.edu

Results

• The swabs taken from the hull of the boat and bilge samples will reflect the microbial community in the open water

• The microbial community on the boat is seeded by the microbial community in the water

Hypotheses

• Boats carry ballast water all over the world which can act as a conduit for dispersal of invasive species and pathogens.

• Microbes are ubiquitous in nearly every environment on earth.

• Shipping regulations aim to prevent further introduction of invasive species.

• Microbes also colonize ships’ surfaces and bilge compartment.

• Bilge water is disposed of into the environment; very little work has been done on bilge water microbial communities.

Fig 6: Microbial Community• 0.12% to 96.8% sourced from

water.• 0.00% to 93.9% sourced from

correct home port • Correctly identified:

-17/37 bilge samples-62/121 swab samples

• 40% of the bilge samples sourced from water on average

• 52% of the swab samples sourced from water

C

BA

Results Continued

Fig 4: Water-borne pathogens are becoming a concern world wide. (A) The relative abundances of genera often related to pathogens in our samples. (B) Shows variability in abundances of pathogens in our samples.

Diversity varies with sample type and location

A B

Cyanobacteria are present in the bilge

Fig 3: Because bilge compartment is dark, it is unlikely for Cyanobacteria to live there unless port water is entering the bilge. Abundance of cyanobacteria (A) is highly variable, but makes up a significant portion of each sample type. (B) A diverse community of Cyanobacteria is present in all sample types.

A B

Pathogens are present at relatively high abundances

A B

Future Directions• Further quantify the “unknown” portion of the output from Source Tracker to look

for additional sources to the boat microbiome such as air, soil, etc.• Look for persistent microbial signatures in bilge water to determine if there is a

microbial fingerprint from one location which persists as the boat travels toadditional locations.

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