Deep-Sea Biofilms, Historic Shipwreck Preservation and the Deepwater Horizon Spill

Abstract

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.

Geomicrobiology of a seawater-influenced active sulfuric acid cave

“…Members of these genera are typically associated with marine and halophilic water habitats, featured by chemolithotrophic activities related to sulfur and sulfidic compounds oxidation, and nitrogen metabolism in anoxia and absence of light [57–60]. In association with chemolithotrophs, FC filaments host marine oligotrophic Gammaproteobacteria Cellvibrionales and Alteromonadales members, the latter being considered dominant colonizers of marine biofilms able to metabolize various hydrocarbon compounds [61], which are also possibly involved in nitrogen and sulfur metabolism in shallow-water hydrothermal vent ecosystems [62].…”

Effects of pollution on marine organisms

“…Accelerated metal loss occurred in the aftermath of the DWH oil spill from the submarine wreck, U‐166, located within 20 km of the Macondo well head in an area heavily impacted by oil flocculant residue. Biofilm community composition was significantly different between oil impacted and reference sites with a greater presence of oil‐degrading genes in the impacted areas (Mugge et al, 2019).…”

A Shallow Water Ferrous-Hulled Shipwreck Reveals a Distinct Microbial Community

“…These systems consist of microbial interactions, chemical reactions, and intermingled transport processes; each of these characteristics can influence the functional role of the biofilm on any attached surface ( Videla and Herrera, 2005 , 2009 ; Zuo, 2007 ; Little et al, 2008 ). By attaching to metal structures, they eliminate access to the metal surface, but the role of the biofilm is strongly dependent on the surrounding environment ( Mugge et al, 2019 ). These biogeochemical interactions are important to investigate and characterize because they impact the surrounding ecosystem composition and overall functions, such as nutrient and metal cycling, adding to the novelty of a shipwreck ecosystem ( Mallefet et al, 2008 ; Yin et al, 2015 ; Hamdan et al, 2018 ; Mugge et al, 2019 ).…”

“…By attaching to metal structures, they eliminate access to the metal surface, but the role of the biofilm is strongly dependent on the surrounding environment ( Mugge et al, 2019 ). These biogeochemical interactions are important to investigate and characterize because they impact the surrounding ecosystem composition and overall functions, such as nutrient and metal cycling, adding to the novelty of a shipwreck ecosystem ( Mallefet et al, 2008 ; Yin et al, 2015 ; Hamdan et al, 2018 ; Mugge et al, 2019 ).…”