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

Austin Francis

Committee Member 1

James Roberts

Committee Member 2

Steve Vives

Abstract

The presence of healthy fish populations is a cornerstone of many important ecological mechanisms. These populations are supported by the recruitment of ichthyoplankton, or the egg and larval stages of fishes, as the primary determinant of population growth. Increases in average global water temperatures can alter the composition of fish communities and thus the offspring found in planktonic stages. I compared a large data set of ichthyoplankton surveys completed from 2009-2011 to a replicated six-month sampling period from May – November of 2024. Collection was conducted weekly to biweekly during night flood tides using a fixed suspension ichthyoplankton net (1mm mesh) in the Moon River of Savannah, GA to compare environmental and fish community data. I hypothesized that environmental data would reflect global climate trends and if so, there would be a change in family level community composition, diversity, abundance, and/or spawning phenology. I also investigated any possible trends in environmental data that were significant predictors of abundance in multiple important fish families. I found that change in temperature over Julian date in 2024 was different compared to 2009-11 (p< 0.01), meaning there was a warmer fall season in addition to a decrease in salinity in 2024 (p< 0.01) likely due to four major hurricanes making landfall in Georgia. Fish abundance was higher in 2009 compared to all years (p< 0.01) due to a raised sea level anomaly during that summer. There was higher family level richness in 2024 compared to 2010 (p< 0.05), however, no difference was found between all years for both Shannon and Pielou’s Evenness indices (p>0.05). Additionally, the community composition of Moon River ichthyoplankton showed no variation in families which dominated contributions towards abundance. There was no change in spawning phenology for important fish families that could not be explained by inter-year variation. Significant predictors for increases in Gobiidae and Cynoglossidae abundance include East-to-West winds and North-to-South winds respectively (p< 0.05). These findings suggest that regardless of effects of climate change on the environment, they were not severe enough to cause any large-scale changes in family level assemblages within the Moon River at this time.

OCLC Number

1528836051

Research Data and Supplementary Material

No

Download

Share

COinS