PART VIII — AQUATIC ECOSYSTEMS 



The Great Lakes Basin Commis- 

 sion, established in 1967, could pro- 

 vide a mechanism for initiating re- 

 gional planning and management. 

 But although the mechanisms, the 

 technical and scientific knowledge, 

 and the manpower and economic 

 need exist for unified efforts in 

 pollution abatement, water-resources 

 management, and regional planning 

 of the Great Lakes drainage basin, 

 these efforts are lacking. This fact is 

 of deep concern, because decisions 

 are being made and priorities estab- 

 lished in the absence of a unified or 

 regional plan or an understanding of 

 the Great Lakes as a total system. 



Status of Great Lakes 

 Eutrophication 



Although eutrophication of the 

 Great Lakes is a pressing national 

 problem, it has received little atten- 

 tion until recently. Our understand- 

 ing of the processes accounting for 

 the lakes' aging and eutrophication 

 (chemical enrichment) is based pri- 

 marily on studies of small lakes, and 

 much of this information is not di- 

 rectly transferable to the Great Lakes 

 because of scale difference. 



In general, aging processes begin 

 at the time of lake origin and go on 

 until the lake becomes extinct through 

 filling, ecological succession, and 

 eventual transformation into a ter- 

 restrial habitat. Nature or direction 

 of aging is controlled by such natural 

 forces as erosion and deposition, 

 hydrological and meteorological proc- 

 esses, chemical enrichment, biological 

 productivity, and ecological succes- 

 sion. The time-span of lake existence 

 may vary from a few decades to 

 many centuries depending on the 

 rates of these controlling forces or 

 processes. 



These natural forces, operating in 

 the absence of man, will produce a 

 predictable direction and rate of 

 change for a given ecosystem. But 

 man, through his activities (cultural 

 forces), modifies the natural trends 



and rates. Therefore, man's major 

 role in lake aging is that of deter- 

 mining the rates of change, especially 

 through chemical enrichment, com- 

 monly referred to as eutrophication. 



The activities of man that con- 

 tribute significantly to the process of 

 lake eutrophication are: 



1. Discharge of domestic and in- 

 dustrial wastes into waterways. 



2. Land-use practices that result 

 in runoff carrying silt loads, 

 fertilizers, farm-animal wastes, 

 and pesticides. 



3. Discharge of waste heat from 

 nuclear and fossil-fuel power 

 plants and industrial processes. 



4. Discharge of pollutants into the 

 air, which eventually enter wa- 

 terways by precipitation and 

 fallout. 



Our limited knowledge of Great 

 Lakes eutrophication has been de- 

 rived from a large number of isolated 

 studies over several decades. There 

 has been no attempt at a unified, 

 multidisciplinary study of one lake 

 or of the total Great Lakes as a sys- 

 tem. The general trends have been 

 identified but the mechanisms and 

 rates are known only qualitatively. 



The general status of Great Lakes 

 eutrophication may be summarized 

 as follows: Each of the five Great 

 Lakes has undergone measurable en- 

 vironmental changes in the past fifty 

 years. The lakes are now character- 

 ized by: 



1. An increase in chemical con- 

 tent of water and sediments 

 (phosphorus, nitrogen, calcium, 

 sulphate, potassium, and chlo- 

 rine); 



2. An increase in biological pro- 

 ductivity; 



3. A change in species composi- 

 tion of biota; 



4. A decrease in concentration of 

 dissolved oxygen; 



5. A decrease in transparency; 



6. Highly polluted conditions in 

 inshore areas, harbors, and 

 bays. 



Lake Erie is the most advanced 

 eutrophically because of its shallow- 

 ness, its southernmost geographic lo- 

 cation, and its large pollution input 

 from urban, industrial, and agricul- 

 tural sources. Lake Ontario ranks 

 second as a result of its position 

 furthest downstream in the intercon- 

 nected system of five lakes and its 

 large volume of deep water. It, too, 

 has received heavy pollution inputs 

 from cities, industries, and agricul- 

 tural activities. Lake Michigan ranks 

 third, with conditions in its southern 

 one-third being similar to those of 

 Lake Erie; the northern portion is of 

 high quality, resembling conditions 

 in Lakes Huron and Superior. The 

 latter two lakes and the northern 

 part of Lake Michigan comprise about 

 90 percent of the total volume of 

 the Great Lakes; they represent the 

 last large volume of good-quality 

 water in the United States. 



The data base for the Great Lakes 

 is poor. It lacks uniformity of qual- 

 ity, and is sparse or lacking in certain 

 areas. Much of the usable data have 

 been collected at irregular times over 

 a period of fifty years. There are 

 serious data deficiencies in the follow- 

 ing areas: 



1. Lake circulation, both open- 

 lake and inshore; 



2. Characteristics of thermal bars 

 that form inshore and isolate 

 the nutrient-rich river effluents 

 for periods of several weeks; 



3. Quantity, concentration, and 

 form of chemical inputs from 

 domestic, industrial, and land 

 drainage sources; 



4. Atmospheric input; 



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