EPSS Colloquium spring-2018

There are ~2,000 historic shipwrecks in the Gulf of Mexico spanning 500 years of history. Shipwrecks become artificial reefs and islands of biological diversity. Residues from the Deepwater Horizon Spill were deposited on the seafloor in areas where historic shipwrecks are present. The spill creates potential for contact of oil with shipwreck remains and the biological communities on and around them. These interactions may impact the preservation of historic shipwrecks. Accordingly, this study examined the spill’s lasting effects on microbiomes surrounding 7 historic shipwrecks. The study included steel-hulled World War II-era and wooden-hulled 19th century shipwrecks. Through comparative analysis of 16S rRNA sequence libraries from wrecks located within and external to the spill’s seafloor footprint, this study documented that the German U-boat U-166 and the sailing vessel known as Mardi Gras were exposed to deposited oil. The work also provided opportunity to examine the effect that shipwrecks have on microbiome diversity. A shipwreck may be an oasis for diversity, and assist transport of microorganisms across the seafloor. Sediment cores were collected along 200 m transects at 2, and 25 m intervals away from the wrecks, using Jason-style push corers or an instrumented MC800 deep-sea multicorer. Shannon diversity and species richness were highest near the shipwrecks, and declined as a function of distance. Bray-Curtis similarity revealed that community composition was distinct in samples near the wrecks vs. away from them. Communities were organized by distance, and secondarily by depth. This study indicates that deep-sea microbiomes are shaped by shipwreck ‘island habitats’.