Examples of positive effects of pollution, from sunken cars as reefs attracting fish and kelp, to oil sludge used as food for protein-producing microorganisms. Cooperation between powerplants and mariculture-producers has resulted in successful fish-growing in artificially heated waters: oysters at Northport; lobster at Maine; shrimp at Miami; catfish at Nashville, Lake Colorado (Texas), and Washington, D.C. Sportfishing on a salt-water beach near atomic power plants might be possible if discharges were controlled. Portions of the plant excavation could be used to restore and broaden beaches. Added circulation from fossil-fuel plants near Long Beach and Redondo Beach contributes to the daily flushing of their marinas. Toxic effects of quicklime on sea urchins helped restore giant-kelp beds off San Diego, Calif. Perhaps even oil spills can be converted to advantage. Beneficial effects from organic wastes on fish population are shown by milkfish production in the Philippines, Taiwan, and Indonesia. 31 pp. Ref.