EESECTS OF WASTEWATERS ON MARINE BIOTA

Abstract

The ocean provides enormous capacity for dispersion and assimilation of human and natural wastes. Indeed marine ecosystems depend on such terrestrial sources for their nutrient supplies. It is incumbent cm man to cause minimal disruption and, if possible, beneficial effects from dispersing his wastes in the sea. The Southern California Bight receives the most intense exposure to discharged sewage of any exposed region along the Pacific coast of North America. Evidences of significantly altered chemical and biological conditions in southern California hare been demonstrated. Elevated concentrations of certain metals occur in sediments near some large sewage outfalls. Pesticide residues were extremely high in sand crabs from southern California. Beds of giant kelp decreased near some, but not all,sewage outfalls. Correctional measures are disoussed. Ecological surveys are currently used to provide early warning of potential biological problems near some southern California outfalls. A survey near an outfall removed from service indicated most changes in fish and macroinvertebrate populations occurred within a few months after the discharge ceased.