Microbial community composition, extracellular enzymatic activities, and structure-function relationships in the central Arctic Ocean, a high-latitude fjord, and the North Atlantic Ocean
Public Deposited- Last Modified
- March 22, 2019
- Creator
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Balmonte, John Paul
- Affiliation: College of Arts and Sciences, Department of Marine Sciences
- Abstract
- Due to their abundance, diversity, and capabilities to transform and metabolize diverse compounds, microbial communities regulate biogeochemical cycles on micro-, regional, and global scales. The activities of microbial communities affect the flow of matter, energy sources of other organisms, and human health, as well as other aspects of life. Yet, the composition, diversity, and ecological roles of microbes in parts of the global oceans—from the high latitudes to the deep water column—remain underexplored. Drawing from microbiological, oceanographic, and ecological concepts, this dissertation explores several fundamental topics: 1) the manner in which hydrographic conditions influence microbial community composition; 2) the ability of these microbial communities across environmental and depth gradients to hydrolyze organic compounds; and 3) microbial structure-function relationships in different habitats and under altered environmental conditions. In the central Arctic Ocean, the composition and enzymatic function of pelagic, particle associated, and benthic bacterial communities varied with depth and region, in parallel with specific hydrographic features. The microbial structure-function relationship in the pelagic realm indicated functional redundancy, suggesting that bacterial compositional shifts—in response to the changing Arctic—may have complex and less predictable functional consequences than previously anticipated. In Tyrolerfjord-Young Sound, northeast Greenland, microbial enzymatic activity patterns were investigated in rivers and within the fjord. Activity patterns correlated with the composition of bacterial communities and dissolved organic matter in the same waters, suggesting that factors extrinsic (organic matter supply) and intrinsic (composition) to microbial communities may, in concert, influence their heterotrophic activities. Finally, functional consequences of differences in community composition were further explored in the North Atlantic. Enriched with high molecular weight organic matter, compositionally-distinct microbial communities exhibited convergent and divergent successional patterns. While convergent features were driven by several initially rare taxa, overarching successional differences in microbial community composition and enzymatic profiles provide evidence for the functional significance of community structure. The integration of community compositional analyses and enzymatic activity measurements has provided valuable information on the identity, ecological roles, and environmental sensitivity of microbial communities in previously underexplored oceanic regions and depths. These insights can be used to evaluate the potential for environmental changes to alter marine microbial community structure and function.
- Date of publication
- May 2018
- Keyword
- DOI
- Resource type
- Advisor
- Bane, John
- MacGregor, Barbara
- Glud, Ronnie
- Arnosti, Carol
- Teske, Andreas
- Degree
- Doctor of Philosophy
- Degree granting institution
- University of North Carolina at Chapel Hill
- Graduation year
- 2018
- Language
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This work has no parents.
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