Acidic Precipitation and Its Consequences for Aquatic Ecosystems: A Review

Precipitation in Europe and eastern North America has become acidic, a result of increases in sulfuric and nitric acid aerosols produced by fossil‐fuel combustion, metal smelting, and industrial processes. The increased use of tall smoke stacks and particle removers has increased long‐range transport of acidic gases. Some metals and organic compounds also are transported atmospherically and deposited in acidic precipitation. In regions where acid‐neutralizing capacity of soils and water is low, the pH of lakes and streams has decreased and concentrations of metals have increased. Aquatic organisms have been affected in all trophic levels (decomposers, primary producers, primary and secondary consumers); abundance, production, and growth have been reduced and sensitive species have been lost. Fish have suffered acute mortality, reduced growth, skeletal deformities, and especially reproductive failure. Valuable commercial and recreational fisheries have been lost in certain areas and such losses will become more widespread if acidic precipitation continues. Remedial or mitigative actions directed toward the problem include hatchery production of acid‐tolerant fish and chemical neutralization of selected lakes and streams. The ultimate solution is reduction of the sources of atmospheric acid.