Performance assessment of retrofitted water control structures at Mattamuskeet National Wildlife Refuge, North Carolina / by Charlton Holloman Godwin.

Summary Located in Hyde County in northeastern North Carolina, Lake Mattamuskeet is a 16,000-hectare, oligohaline, coastal bay lake, which comprises the majority of Mattamuskeet National Wildlife Refuge. Rainfall and subsequent runoff are the only sources of freshwater input. Situated at the head of each of four drainage canals, concrete water control structures (WCSs) contain flapgates that act passively to allow surplus water to exit the Lake while preventing saltwater intrusion from Pamlico Sound. This connectivity between lake and sound allows several species of anadromous and/or estuarine fish and invertebrates to utilize lake habitats during various life cycle phases. Traditional sport fisheries included largemouth bass Micropterus salmoides and other Centrarchids, alewife Alosa pseudoharengus, white perch Morone americana, and blue crab Callinectes sapidus. A reconfiguration of the WCS flapgates in the late 1980s caused a severe decline in these lake fisheries. This three-year study (2001-2003) assesses the retrofitting of the WCS flapgates and their subsequent operational efficiency with regard to water level management, fish passage, and the recovery of certain fish stocks. The first study component evaluated performance of wooden versus aluminum flapgates in WCSs. Aluminum flapgates opened significantly wider than did wooden flapgates imder the same head pressure, and passed significantly more fish and invertebrates (3358 vs. 1641 respectively). The second study component assessed the effects of manually opening flapgates during extended drought periods; saltwater intrusion into lake freshwater habitats and fish passage through the WCS was monitored. Salinity in the Lake was not significantly increased while allowing natural restocking of organisms and emigration of estuarine dependant juveniles. The last study component documented subsequent recovery of alewife spawning runs into the Lake. Spawning run estimates for 2001 and 2003 (8836 and 38,731 respectively) were much lower than estimates made in 1970 and 1971 (199,600 and 167,300 respectively), but show a steady upward trend from the estimates made in 1997 and 1998 (178 and 454 respectively). Results document the importance of coastal bay lakes as critical habitat for freshwater and estuarine dependant species. Continued monitoring of WCSs and newly installed aluminum flapgates is needed to ensure the recovery of these important recreational fisheries.
General notePresented to the faculty of the Department of Biology.
General noteAdvisor: Roger A. Rulifson
Dissertation noteM.S. East Carolina University 2004
Bibliography noteIncludes bibliographical references (leaves 117-121).
Genre/formAcademic theses.
Genre/formAcademic theses.
Genre/formThèses et écrits académiques.

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