The effects of urbanization on small high salinity estuaries of the southeastern United States

Abstract

Future development in coastal areas of the southeastern United States (US) will likely result from urbanization (housing and tourist/service related activities) rather than industrialization. In an effort to identify potential impacts associated with urbanization, field studies were conducted in two small, high salinity estuaries of coastal South Carolina. The sites selected for study were Murrells Inlet, an estuary with a history of significant urbanization and North Inlet, a relatively pristine, undisturbed estuary. During field studies conducted in the fall of 1990, a series of 96-h in situ bioassays were undertaken at each of the sites. The species used were the grass shrimp, Palaemonetes pugio, and the mummichog, Fundulus heteroclitus. Water samples were collected at the site during these bioassays and analyzed for polyaromatic hydrocarbons (PAH) residues. Adult oysters, Crassostrea virginica, were also deployed at each of the sites during the in situ bioassays and analyzed for tissue PAH residues. Physicochemical water quality and rainfall were also monitored. Mean waterborne PAH levels were significantly higher at the urbanized Murrells Inlet site than at the more pristine North Inlet. Additionally, oysters deployed at the Murrells Inlet site showed increased PAH levels in comparison to baseline values while those deployed at the North Inlet had PAH levels well below baseline concentrations. No siterelated mortality was observed in the two species used in the bioassays. Fluctuations in salinity, dissolved oxygen, and pH were much less extreme at the urbanized Murrells Inlet site than at North Inlet. The less dynamic physicochemical environment at the Murrells Inlet site may be due in part to urban influences (i.e., jetty construction and bulkheading). Additional work is needed to better define the significance of these observations.