Term of Award

Fall 2023

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

J. Checo Colon-Gaud

Committee Member 1

Stephen P. Vives

Committee Member 2

John Carroll

Abstract

Coastal wetlands are threatened by the compounding effects of sea level rise and historical land modification. Historically, much of Sapelo Island, Georgia was deforested and drained using a series of ditches and canals to create arable land fit for agriculture and to provide drainage to the inhabited parts of the island. Today, this network of artificial channels is believed to be facilitating the movement of saltwater from the nearby estuary into freshwater areas on the interior of the island. This study aimed to better understand the frequency and magnitude of salinity intrusion events along with their resulting impacts to the ecology of benthic macroinvertebrate communities on Sapelo Island. I utilized a water sensor network to monitor the hydrology of Oakdale Creek, one of Sapelo’s primary artificial channels. I coupled this with seasonal assessments of benthic macroinvertebrate community composition and function by using rapid bioassessment protocols (RBP) and leaf pack deployments. Results indicated that of the four sites, Dixie, was tidally influenced and had significantly higher decomposition rates than all other sites. Dixie also had a significantly different macroinvertebrate community composition when compared to non-tidal sites. All sites were regularly exposed to salinities >5 ppt, which can cause negative impacts to the survival and productivity of freshwater aquatic organisms. RBP scores were relatively low at all sites when compared to reference values indicating impairment. Findings highlight the ability of small artificial channels to transport saline water, especially during large weather events (i.e., hurricanes). Additionally, I showed that interior sites on Sapelo Island that are distant from the estuarine interface are being regularly exposed to saline water which prevented the development of a robust macroinvertebrate community. Results of this study will inform local land managers on the current state of artificial channels on the island especially as it relates to future management in the face of rising sea levels and continued land use change on the island.

OCLC Number

1417413844

Research Data and Supplementary Material

No

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