Date of Award

8-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Environmental Toxicology

Advisor

Klaine, Stephen J

Committee Member

Bain , Lisa J

Committee Member

Carraway , Elizabeth R

Committee Member

Scott , Mark

Abstract

In 2011 the State of South Carolina population was over 4.6 million people and has increased at a rate of around 15% (1.5% per year) throughout the last decade. While the population density per square mile is relatively low compared to other US states, it seems certain the population will further increase in years to come. Increasing population density leads to urbanization resulting in an increase in impervious surfaces such as roadways, parking lots, and building roofs. This changing land use can have dramatic effects on smaller streams and creeks which form the upper reaches of watersheds. Although water systems can become fragmented, watersheds encompass the entire drainage area of a region. A changing landscape upstream can have dramatic effects many miles downstream from the initial source of disturbance.
Freshwater species worldwide face accelerated extinction rates relative to most other wildlife taxa. The southeastern U.S. in particular is of high concern due to long term declines in native fish and aquatic species. Consequences of poor land management practices (i.e. siltation, excessive nutrients, flow disruption) can negatively impact flora and fauna that depend on these water sources for survival, reproduction, and/or development. Due to the interconnected nature of water systems, water flow will end up in larger rivers, reservoirs, and coastal areas. Because of the importance and uniqueness of these habitats, local flora and fauna could be at high risk if the wadeable streams in the upper reaches are developed. Currently there is not enough information on how the surrounding landscape influences the quality of water and aquatic ecosystems to make informed decisions regarding aquatic conservation and restoration. Because the human population is ever increasing, a better understanding of anthropogenic influences would allow us to make better, more informed land management decisions.
The goal of this dissertation was to study effects of a changing land use on fish health and fish assemblage by measuring a set of biochemical biomarkers in an abundant fish species, Lepomis sp. (sunfish), commonly found in wadeable streams in South Carolina. The data set incorporates information on land use, fish species assemblage, abiotic habitat characteristics, and biomarker responses from over a hundred random wadeable stream sites throughout the state. Biomarker responses, which are changes at the biochemical and cellular level, were correlated with changes throughout multiple levels of organization (i.e. tissue, individual, population, and community).
Results of this work indicate Lepomis sp. are a widely distributed fish type that can be used as a model to represent all fish species in an assemblage at a sampling location, the magnitude of chemical contamination detected in Lepomis sp. via biomarker response can be used to determine changes in overall fish assemblage structure, and 10% urban surface and greater is a threat pathway leading to deleterious effects on aquatic ecosystems (both in disruption of fish assemblage integrity and increasing biomarker response). Within a watershed, fish health at the organism, population, and community scales declines concomitantly in response to increasing urban surfaces.
As the human population continues to increase, there will be an increased burden of aquatic contaminants resulting in a decline in the diversity of fish and other aquatic life. Sensitive species will be the first to disappear. Eventually, a watershed may become so badly deteriorated that only a few tolerant or specialized species will remain. Results of this research revealed threat pathways to fish health and aquatic resources, identify the magnitude of the anthropogenic impact on watersheds at a statewide level, and provide a scientific basis for sustainability from the scientific community to stakeholders, land developers, and policy creators.

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