Environmental monitoring Aquatic ecology Geographic information systems Fish communities Freshwater fishes Mississippi River Water quality Aerial photography Aerial photography in botany Standards Aquatic habitats Conservation of natural resources Planning Fish populations Fishes Geographical distribution Fishes Monitoring Freshwater invertebrates Information storage and retrieval systems Geography Photographic interpretation Standards Remote sensing Stream conservation Computer programs Stream conservation Planning Stream measurements Suspended sediments Water levels Wildlife habitat improvement Computer programs Aerial photographs Standards Aerial photography in forestry Aquatic habitats Data processing Aquatic plants Computer simulation Aquatic plants Environmental aspects Aquatic plants Monitoring