Term of Award

Summer 2025

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Biology

Committee Chair

John Carroll

Committee Member 1

Tyler Cyronak

Committee Member 2

Tiehang Wu

Abstract

Coastal ecosystems provide critical carbon sequestration services, yet the microbial mechanisms underlying carbon storage remain poorly understood, particularly in non-vegetated habitats. This study investigated whether restored oyster reefs (Crassostrea virginica) enhance sediment carbon storage potential by stabilizing microbial communities and promoting efficient organic matter processing. I hypothesized that reef-mediated sediment stabilization and organic deposition would create conditions favoring microbial degradation of complex carbon compounds into stable soil organic matter, ultimately supporting anaerobic carbon storage. To test this, I compared sediment biogeochemistry, enzyme activity, and microbial community structure between three restored oyster reef sites and two unstructured control sites in coastal Georgia across two seasons (May and October 2024). Reef sites demonstrated significant sediment stabilization, with lower bulk density (0.39 vs. 0.73 g cm⁻³) and higher water content (70% vs. 53%) than controls by October. Nutrient accumulation was dramatic at reef sites, including 5,888 % increases in ammonium and 95% increases in organic carbon. Despite these environmental changes, reef-associated microbial communities maintained remarkable taxonomic stability, with only 23 amplicon sequence variants (ASVs, 0.1%) showing seasonal abundance changes compared to 1,264 ASVs (5.2%) at control sites. This 55-fold reduction in seasonal responsiveness was accompanied by consistent Shannon diversity at reef sites, while control sites only had comparable diversity levels in Fall samples. Functional analysis revealed that reef communities established amino acid metabolism capabilities early in the season, particularly l-asparagine utilization, suggesting enhanced processing of nitrogen-rich organic inputs. Predicted metabolic pathways indicated that control sites harbored communities with diverse degradation capabilities (143 enriched pathways), while reef sites showed minimal enrichment (2 pathways), suggesting more conservative metabolic strategies conducive to carbon preservation. These findings demonstrate that oyster reef restoration promotes microbial stability and efficient organic matter processing, supporting their potential role as blue carbon sinks through microbial-mediated carbon sequestration.

OCLC Number

1531379615

Research Data and Supplementary Material

No

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