Exposure to oil from the Deepwater Horizon spill may have lasting impacts on preservation of historic shipwrecks in the Gulf of Mexico. Submerged steel structures, including shipwrecks, serve as artificial reefs and become hotspots of biodiversity in the deep sea. Marine biofilms on submerged structures support settlement of microand macro-biota and may enhance and protect against corrosion. Disruptions in the local environment, including oil spills, may impact the role that biofilms play in reef preservation. To determine how the Deepwater Horizon spill potentially impacted shipwreck biofilms and the functional roles of the biofilm microbiome, experiments containing carbon steels disks (CSDs) were placed at five historic shipwreck sites located within, and external to the benthic footprint of the Deepwater Horizon spill. The CSDs were incubated for 16 weeks to enable colonization by biofilm-forming microorganisms and to provide time for in situ corrosion to occur. Biofilms from the CSDs, as well as sediment and water microbiomes, were collected and analyzed by 16S rRNA amplicon gene sequencing to describe community composition and determine the source of taxa colonizing biofilms. Biofilm metagenomes were sequenced to compare differential gene abundances at spill-impacted and reference sites. Biofilms were dominated by Zeta-, Alpha-, Epsilon-, and Gamma-proteobacteria. Sequences affiliated with the Mariprofundus and Sulfurimonas genera were prolific, and Roseobacter, and Colwellia genera were also abundant. Analysis of 16S rRNA sequences from sediment, water, and biofilms revealed sediment to be the main known source of taxa to biofilms at impacted sites. Differential gene abundance analysis revealed the two-component response regulator CreC, a gene involved in environmental stress response, to be elevated at reference sites compared to impacted sites within the spill plume fallout area on the seafloor. Genes for chemotaxis, motility, and alcohol dehydrogenases were differentially abundant at reference vs. impacted sites. Metal loss on CSDs was elevated at sites within the spill fallout plume. Time series images reveal that metal loss at a heavily impacted site, the German Submarine U-166, has accelerated since the spill in 2010. This study provides evidence that spill residues on the seafloor may impact biofilm communities and the preservation of historic steel shipwrecks.

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Domestication and breeding for human-desired morphological traits can reduce population genetic diversity via founder events and artificial selection, resulting in inbreeding depression and genetic disorders. The ferret (Mustela putorius furo) was domesticated from European polecats (M. putorius), transported to multiple continents, and has been artificially selected for several traits. The ferret is now a common pet, a laboratory model organism, and feral ferrets can impact native biodiversity. We hypothesized global ferret trade resulted in distinct international genetic clusters and that ferrets transported to other continents would have lower genetic diversity than ferrets from Europe because of extreme founder events and no hybridization with wild polecats or genetically diverse ferrets. To assess these hypotheses, we genotyped 765 ferrets at 31 microsatellites from 11 countries among the continents of North America, Europe, and Australia and estimated population structure and genetic diversity. Fifteen M. putorius were genotyped for comparison. Our study indicated ferrets exhibit geographically distinct clusters and highlights the low genetic variation in certain countries. Australian and North American clusters have the lowest genetic diversities and highest inbreeding metrics whereas the United Kingdom (UK) cluster exhibited intermediate genetic diversity. Non-UK European ferrets had high genetic diversity, possibly a result of introgression with wild polecats. Notably, Hungarian ferrets had the highest genetic diversity and Hungary is the only country sampled with two wild polecat species. Our research has broad social, economic, and biomedical importance.Ferret owners and veterinarians should be made aware of potential inbreeding depression. Breeders in North America and Australia would benefit by incorporating genetically diverse ferrets from mainland Europe. Laboratories using ferrets as biomedical organisms should consider diversifying their genetic stock and incorporating genetic information into bioassays. These results also have forensic applications for conserving the genetics of wild polecat species and for identifying and managing sources of feral ferrets causing ecosystem damage.

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