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Trophic Changes in a Freshwater Tidal Food Web After Water Quality Improvements and Invasive Species (Ictalurus furcatus) Introduction

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dc.contributor.advisor de Mutsert, Kim Pehrson, Casey Margaret
dc.creator Pehrson, Casey Margaret 2020-05-05 2021-01-27T14:00:14Z 2021-01-27T14:00:14Z
dc.description.abstract Gunston Cove, a freshwater tidal tributary to the Potomac River in Virginia, USA, underwent a stable state shift in 2005 from a phytoplankton-dominated state to a macrophyte-dominated state. Blue Catfish were observed as an invasive in the tributary in 2001 and a local population has since been established. An ecosystem modeling approach is used to evaluate the impacts of water quality improvement and invasive species introduction on ecosystem structure and function in Gunston Cove. Two trophic models are constructed in Ecopath with Ecosim using long-term survey data, and used to compare aquatic communities before and after the ecosystem underwent a stable state shift in which the primary production shifted from phytoplankton-dominated to submerged aquatic vegetation-dominated. Additionally, invasive Blue Catfish were introduced to Gunston Cove in 2001. Trophic changes accompanying water quality improvement and the subsequent stable state shift are evaluated, in addition to the trophic impacts of invasive species introduction. The comparative approach allows evaluation of the effects of both events on trophic dynamics and ecosystem maturity and function. The comparison of Mixed Trophic Impact analyses shows that the invasive Blue Catfish is correlated with functional displacement of native catfishes in the Gunston Cove food web and reduced trophic impacts of the native catfishes on the greater food web. The comparison of system metrics showed evidence of a maturing system following water quality improvements. The food web model representing Gunston Cove in the current submerged aquatic vegetation stable state provides a foundation for future research and evaluation of management and policy decisions. en_US
dc.language.iso en en_US
dc.subject ecosystem model en_US
dc.subject trophic network en_US
dc.subject fisheries en_US
dc.subject ecology en_US
dc.subject food web model en_US
dc.subject Gunston Cove en_US
dc.title Trophic Changes in a Freshwater Tidal Food Web After Water Quality Improvements and Invasive Species (Ictalurus furcatus) Introduction en_US
dc.type Thesis en_US Master of Science in Environmental Science and Policy en_US Master's en_US Environmental Science and Policy en_US George Mason University en_US

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