How shipwrecks shape microbial biodiversity and biogeography across deep-sea sediments

Leila J Hamdan1, Justyna J Hampel2, Rachel Moseley3, Rachel L Mugge4, Anirban Ray4, Taylor Runyan Lee5 and Warren T Wood6, (1)University of Southern Mississippi, School of Ocean Science and Engineering, Ocean Springs, MS, United States, (2)University of Southern Mississippi, Ocean Springs, United States, (3)University of Southern Mississippi, United States, (4)University of Southern Mississippi, Ocean Springs, MS, United States, (5)US Naval Research Laboratory, Ocean Sciences Division, Washington, DC, United States, (6)US Naval Research Laboratory, Ocean Sciences Division, Stennis Space Center, MS, United States
The Gulf of Mexico has more than 2,000 known historic shipwrecks. These built structures may shape microbial life on the seafloor as microorganisms move from and are transported between them. Since historic shipwrecks are often isolated features on the seabed, each shipwreck could be considered as an “island-like” system. This study tests the hypothesis that shipwrecks exhibit island biogeography patterns. Specifically, the work addressed if shipwrecks have a signature (core) microbiome, and if microbial diversity increases as a function of proximity to the shipwrecks. The island effect on sediment microbiomes was investigated at the historic shipwreck Anona, a luxury steam yacht that sank in 1944 at ~1200 m water depth in the northern Gulf of Mexico. Sediment cores were collected along four radial transects extending from the bow, stern and mid-ship on both the port and starboard sides of the shipwreck. Samples were collected on these transects by remotely operated vehicle (ROV) using Jason-style push corers at distances of 2 – 100m away from the shipwreck. Sediment cores were also collected at distances of 150 – 1000m away from the shipwreck using an instrumented MC800 deep-sea multicorer. The cores were sampled at 2-cm intervals, and genomic DNA was extracted using the FastDNA® SPIN kit. 16S rRNA gene amplification was carried out with the B969F/BA1406R primer set to target the V6-V8 region of bacteria, and sequencing was performed on the Illumina MiSeq platform. Shannon diversity and species richness for sediment bacteria were positively correlated with proximity to the shipwreck. Community composition was distinct in samples near the wreck vs. away, and the sediment core microbiome in samples collected near the shipwreck (2 – 25m) was distinct from sediment microbiomes at greater distances. This study is the first to show that deep-sea microbiomes are shaped by the presence of built structures, and that structures impact biodiversity across a lateral extent on the seabed.