Term of Award

Fall 2023

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (restricted to Georgia Southern)

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

Risa A. Cohen

Committee Member 1

Michele Guidone

Committee Member 2

Stephen P. Vives

Committee Member 3

Beth Myers

Abstract

Surface waters receive megatons of plastic waste each year that ultimately accumulate in rivers, lakes, and oceans. Once in the environment, plastics degrade into microplastics in a variety of shapes with microplastic fibers (MFs) being the most common. Existing data suggest MFs decrease zooplankton feeding and survival, which may adversely affect zooplankton abundances, community composition, and potentially higher trophic levels that depend on planktonic food resources. Improving our understanding of MF toxicity will allow us to better predict the effects of plastic contamination and target remediation efforts. Chapter one evaluates the response of the zooplankton Daphnia magna to MFs of different lengths and found that while the proportion of zooplankton ingesting fibers was similar across treatments regardless of length, the accumulation of MFs within daphnids differed. Despite MF ingestion, there were no differences in mortality after 7 days across all treatments. Chapter two describes the use of pond mesocosms containing plankton communities to assesses whether plankton community composition changes in response to MFs over 28 days of exposure. The results suggest that zooplankton may exhibit a stress response to MFs, increasing in abundance and potentially inducing changes in community composition over longer time periods. Although the abundance of phytoplankton in the water column did not differ between treatments, periphyton chl a decreased in response to MFs while mass remained similar, suggesting a change in the algal component of the periphyton community. The final chapter compares the use of bulk water and plankton tow sampling methods to quantify microplastic contamination along the Ogeechee River, GA, USA. Bulk water sampling resulted in concentrations between 1.2 - 6.13 MFs L-1 while estimates from plankton tows were 4 - 5 magnitudes lower (4.6x10-5 - 3.7x10-4 MFs L-1). In general, this study suggests Ogeechee River MP contamination is on the low end of the range for US waterbodies (0.00042 – 103 MPs L-1) and encourages the use of bulk water sampling to estimate MP concentrations.

OCLC Number

1475307990

Research Data and Supplementary Material

No

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