How Historic Shipwrecks Influence Dispersal of Deep-Sea Microbiomes

This thesis investigates how historic shipwrecks potentially shape dispersal of deep-sea microbiomes. Processes impacting dispersal of microbiomes around artificial structures in the ocean and how they connect to other deep-sea habitats is unknown. Dispersal processes are explained for some macroorganisms by theories in ecology, specifically the Theory of Island Biogeography and the Wooden Stepping Stone hypothesis. These have not been investigated for microorganisms, and thus this work will probe if they are applicable to microbial biogeography in this habitat. Experiments were conducted to establish new “island-like” features in near proximity (25-125 m) to wooden-hulled historic shipwrecks in the northern Gulf of Mexico (GoM). The experiments were to determine if microbiomes exhibit dispersal patterns like those seen for macroorganisms. Biofilms formed on experiments, along with sediment and water samples collected near the shipwrecks were analyzed for microbiome richness, diversity, phylogenetic composition and determination of the source of taxa to biofilms. Investigation into the source of biofilms revealed the majority source was unknown for bacteria and archaea; however, archaea at one site located at approximately 1800 m water depth had high source proportion estimates for sediment. Richness and diversity decreased with decreasing proximity to both shipwrecks revealing historic shipwrecks may function as island-like habitats. The phylogenetic composition analysis shows strong selection by wood type for bacteria, and highlights differences in bacteria, archaea, and fungi dispersal patterns. The results of this thesis show that built structures, like shipwrecks, impact microbial biogeography in the deep sea