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 wi...

Acidic Precipitation and Its Consequences for Aquatic Ecosystems: A Review

In light of the current rising mean temperatures and fluctuations in temperature extremes involved in global climate change, a cause-and-effect understanding of the temperature- dependent impacts of additional environmental stressors on marine life is crucial for the elaboration of how marine ecosystems will shape in the future. The thermal environment plays a direct role in the distribution and survival of marine ectotherms through the temperature-dependent effects on their physiology, as well as indirectly by affecting the organism's susceptibility to other biotic and abiotic stressors. We review studies that have investigated the effects of temperature and anthropogenic pol- lution by trace metals, with a focus on metabolic regulation as a major mechanism that underlies the interactive effects of temperature and metals on the physiology and survival of ectotherms. These studies suggest that impairment of energy metabolism plays a key role in the synergistic effects of these stressors, and we elaborate a mechanistic framework for understanding these interactions. Fur- thermore, the present study seeks to provide an impetus for future investigations in order to define more precisely the physiological mechanisms and functional properties of temperature-pollution interactions.

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Interactive effects of metal pollution and temperature on metabolism in aquatic ectotherms: implications of global climate change

Fatigue and exercise tests with fish

Effects of chronic sublethal exposure to waterborne Cu, Cd or Zn in rainbow trout. 1: Iono-regulatory disturbance and metabolic costs.

Swimming behavior of fish is impaired by exposure to a diversity of contaminants. Gross aberrations in swimming can be qualitatively assessed while subtle changes in swimming behavior arising from sublethal exposures can be detected through a more detailed analysis of this response. Compared to other swimming behavior variables, the physical capacity to swim against water flow tends to be affected at relatively high toxicant concentrations and often presages mortality. Orientation to water flow, however, is altered at sublethal concentrations. Frequency of activity is a more sensitive measure in detecting contamination than measurements of survival alone. Alterations in swimming behavior have been detected during exposures to various contaminants at concentrations as low as 0.7 to 5% of their LC50 values and at concentrations that subsequently inhibited growth after longer periods of exposure. Analysis of swimming patterns provides even higher resolution for analysis of swimming behavior, and increased availability of the instrumentation necessary for such measurements should facilitate use of this approach. Fish swimming activity can easily be incorporated in test protocols to expand the sensitivity of standard toxicity tests.

F.W.H. Beamish

Papers

Effects of copper, pH and hardness on the critical swimming performance of rainbow trout (Salmo gairdneri Richardson)

Lethal toxicity of permethrin (NRDC-143) to rainbow trout, salmo gairdneri, in relation to body weight and water temperature