The Impact of Energy Availability and Substrate Complexity on Anaerobic Microbial Communities in Marine Sediment

Author: Lim, Sujung

Year: 2024

Degree: Dissertation (Ph.D.)

Advisor: Orphan, Victoria J.

Committee Members: Sessions, Alex L.; Leadbetter, Jared R.; Fischer, Woodward W.; Orphan, Victoria J.

Option: Geobiology

DOI: 10.7907/67j6-4885

Abstract

This thesis probes the interplay of organic matter complexity (Chapters 1 and 2) and local redox gradients (Chapter 3) with the community structure and function of the anaerobic marine sediment microbiome. Deep marine sediments, despite being generally organic-poor, harbor a vast diversity of microorganisms that are critical to the global nutrient cycle. Transient nutrient inputs such as whale falls result in hotspots of microbial community activity in an environment that normally processes heavily degraded organic material from the upper ocean. These organic loading events result in transitions down redox gradients and dynamic shifts in the local energy availability of the microbial communities. Through in situ seafloor and laboratory microcosm experiments, we provide insights into the impact of energy availability and carbon complexity on maintaining hierarchical and complex community interactions, community activity, and systematic and functional diversity.

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