Term of Award

Summer 2017

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

Checo Colón-Gaud

Committee Member 1

Stephen Vives

Committee Member 2

James Roberts

Abstract

The Ogeechee is a fifth order river that originates in the Georgia Piedmont region and flows through the Coastal Plain region in the Southeastern portion of the state. The Ogeechee is one of the last unregulated rivers in Georgia; allowing for studies to occur under a natural flow regime. To my knowledge, studies that incorporate fish into ecological networks (e.g., food webs) are yet to be developed for the Ogeechee River, thus, one of the main objectives of this research was to address this knowledge gap. Five fish species were collected from June 2016 to October 2016 in order to construct a connectance food web in the Ogeechee to understand the role (i.e., trophic interactions) of major fish feeding guilds in relation to each other and to other consumer groups (i.e., macroinvertebrates) present in the river. In addition to the connectance food web, Redbreast Sunfish were collected seasonally from June 2016 to March 2017 to examine the potential for seasonal shifts in the diets of this popular sport fish. Diets of all fish were analyzed using gut content analysis and used to create a connectance food web using Cheddar, a package in RStudio. Diets were compared to composite taxa lists generated from an ongoing, two year study (2014-2016) of the Ogeechee River for four study species (Bannerfin Shiner, Redbreast, Snail Bullhead and Spotted Sucker) through electivity analyses. Permutational Multivariate Analysis of Variance (PERMANOVA) and Non-metric Multidimensional Scaling (NMDS) techniques were used to compare diets across seasons for Redbreast, and across age classes for Redbreast and Snail Bullhead. Connectance of the food web was found to be 0.285 and link density was 31.87, while the number of nodes present in the food web was 112. The Ogeechee River food web appears to be above average in terms of connectance and link density and further illustrates the dynamic nature of coastal plain, blackwater river systems. Analysis of Redbreast data shows that stomach content composition differs significantly by season when prey items were grouped by habit or order. These findings suggest that Redbreast Sunfish utilize what is available during the different seasons, thus exhibiting an opportunistic feeding strategy. This study is one of the first to construct a food web including multiple fish feeding guilds in a coastal plain, blackwater river. With these data, it is hoped that some of the knowledge gaps in food web studies in coastal plain rivers will be filled and that the information generated will facilitate future studies of trophic interactions of major consumer groups in river systems of the region.

Research Data and Supplementary Material

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