fish consumption. Continued limnological research will provide a more complete understanding of the behavior of toxic substances in aquatic environments.
Assessment of damage from acid rain and other airborne pollutants : Nations around the world have signed treaties to control acid rain. Limnological research is increasing the understanding of long-term effects of acid rain on aquatic communities, leading to improved predictive models and mitigation and restoration techniques.
Control of exotic species: Numerous exotic species (both plants and animals) have disrupted aquatic ecosystems in North America, sometimes with high costs. For example, the zebra mussel, accidentally discharged into the Great Lakes with the ballast water of an oceangoing ship in 1986, will cause an estimated $4 billion in damages before the turn of the century, primarily because of clogging of water intake pipes and loss of native mussels and clams. Research by limnologists is a key component of plans to control the undesired proliferation of exotic plant and animal species.
Prevention of species extinction: According to some estimates, at least 30 percent of all North American fish species are rare, at risk of extinction, or extinct. Limnological research can help determine more accurately the distribution of native species, the factors that influence their success in certain habitats, the effects of species loss on aquatic communities, and how best to protect critical species.
In the past, water management decisions have often been made in isolation, without adequately considering the synergistic relationships among a variety of isolated actions. For example, the Clean Water Act focused primarily on reducing water pollution from sewage and industrial facilities and paid much less attention to the range of other human impacts on water bodies. Future water management will demand professionals who are broadly trained to view water bodies as systems that are integrated with the surrounding landscape and in which biological, physical, and chemical processes are interrelated. Education in limnology provides the type of broad perspective needed to understand how water bodies behave in environments without significant human influence and how they are affected by human activities. This broad perspective is essential for any strategy that aims to control environmental problems by considering the full range of risks and benefits.
Because most of the early limnologists were trained in biology, professors of limnology historically have been housed in departments of biological science (including zoology and botany). However, during the second