given lamprey control and point source clean-up, introduced salmonids would 

 flourish in the Great Lakes. '^^•''*' This prediction proved accurate in the short term, but 

 failed to recognize potential overexploitation of food fishes by salmonids, or 

 problems associated with bioaccumulation of dilute toxins in fish tissues.'' 



Bayou Texar (Pensacola, Florida) studies of community diversity and nutrient 

 cycling by algae and bacteria led to recommendations which included run-off control 

 and changes in basin morphometry. Implementation improved water quality, 

 including the alleviation of fish kills. 'o^ 



Diversity indices have been used frequently to describe the status of environmental 

 quality""<"'^''°^ and have provided a basis for requiring clean-up of ecological 

 systems. 'o* Simplification of community structure under stress has been sufficiently 

 documented'"- that such biological alterations in association with, for example, 

 effluents are commonly taken as evidence for reduced environmental quality.'"'* 



Another case study representing accomplishments in environmental assessment 

 and prediction during the 1970s is the ban of DDT from the U.S. market. This 

 resulted from extensive data on the biological effects of the pesticide, such as reduced 

 avian fecundity '"^-'o* and differential mortality of predators.'"'' 



Guidelines for reducing effects of large scale environmental change on ecosystems 

 might be derived from some studies. For example, in integrated resource management 

 of a watershed which is being logged, road-building, cutting, removal, and regrowth 

 could be adjusted to reduce the severity of effects predicted from changes in assessed 

 conditions.'"* 



Relevance to Present and Future Considerations 



Awareness that an ecosystem perspective is required to achieve effective manage- 

 ment of a particular resource — e.g., for commercial harvest, recreation, aesthetics, or 

 contaminant buffers — is believed to have resulted in enhanced ability to assess and 

 predict accelerated or aberrant environmental change. Technological and method- 

 ological improvements in the tools of environmental assessment during the 1970s 

 may have helped to increase the accuracy of prediction. As illustrated by problems in 

 toxicity testing associated with defining suitable methods to alleviate the deficiencies 

 of single species tests,-" tools of assessment may not be adequate to the task at hand. 



Environmental problems are proliferating and probably will continue to do so for 

 the foreseeable future. They remain unpredictable — and persistent (e.g., how to store 

 nuclear wastes?). New or aggravated problem areas of the 1970s include: effects of 

 acid rain,'"''"" changes in atmospheric COj from, for example, the burning of fossil 

 fuels,'" dredge spoils and landfills,"-'"^''"* toxic substances, 20'"5,ii6 thermal 

 alterations from industrial"'' and power plant"* cooling water and from nuclear 

 production reactors,"' entrainment and impingement, '2" pump-storage reservoirs 

 and low-head hydroelectric power development, ^^^ '2' and oil spills in coastal 

 waters. '22 Adequate environmental management requires some semblance of 

 understanding of natural environments, understanding which can only come from 

 knowledge, training, concern, and experience. Improved methods and data, 

 particularly of a long-term nature, are needed, but not without qualification. 

 Although enormous quantities of data may be generated, environmental issues are 

 frequently undecided, pending accumulation of more relevant data. Decisions must 

 often be made before appropriate information can be collected. In addition, in some 

 cases refined methods and analyses may not provide suitable objective information 

 for evaluation. Uncertainty and qualitative judgments have become more prominent 

 in environmental decisions, introducing delays which lead to increased regulatory 

 costs and stresses between business and environmental concerns." 



Eipper'23 at the beginning of the decade stated ". . .because we are being forced to 

 make increasingly critical decisions about ecosystems for which reliable predictive 

 data are often lacking, we must, collectively, develop a framework of genuinely useful 

 principles to guide our dealing with natural environments." One of these principles 



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