Nationally consistent methods for site selection and data collection used in NAWQA's monitoring and assessment studies allow for comparisons of landscape influences on biological communities in different environmental settings. Hydrology, latitude, altitude, physiography, and land use were used to identify these influences in the South Platte (SPLT) and Apalachicola-Chattahoochee-Flint (ACF) River basins. Both basins have similar anthropogenic influences; however sampling site selections reflect the contrasting settings of the semi-arid West and the temperate Southeast. Fish richness and diversity, and organochlorine contaminants in aquatic biota were compared in different settings in each basin. In both basins, distributions of organochlorine contaminants were related to land use, with chlordane detected in urban watersheds, and DDT detected primarily in agricultural watersheds. Altitude (SPLT) and latitude (ACF) interact with land use to influence fish communities; hydrologic alterations resulting from irrigation in the SPLT basin were a dominant influence on fish communities. In the ACF basin, fish communities are sensitive indicators for distinguishing water quality and associated land uses because fish richness is greater and hydrologic alterations are not as extensive. Benthic invertebrate or algal assessment are likely more sensitive indicators in the SPLT.
1 U.S. Geological Survey, 13039 Amwiler Rd., Atlanta, GA 30360
2 U.S. Geological Survey, Box 25046, MS 415, Denver Federal Center, Lakewood, CO 80225