304 



The most competent engineering firms in the Nation were employed 

 in designing and constructing the project, and the design was checked 

 and approved by the U.S. Army Corps of Engineers. Still, the analy- 

 sis by the planners and engineers of the project yielded estimates of 

 benefits and costs which were substantially different from those which 

 actually occurred. Part- of the discrepancy was due to simple optimism 

 and even some bias on the part of the analysts. An equally large part 

 seemed to be due to the inability of man to see even 25 years into the 

 future. In the case of silting, the state-of-the-art was such in 1930 

 that no adverse effects were envisioned. As a result the dredging bill 

 jumped from $18,000 to $2,029,756 annually. 



Section" 3. Trends in Estuarine Ecology Associated With Man's 



Activities 



The future character of estuarine ecological systems in the United 

 States will be determined by present and future pressures affecting 

 the estuarine zone, public decisions, and by the actions resulting from 

 public policy. Thus, the future nature and operation of the total bio- 

 physical environment will be shaped primarily by the socioeconomic 

 and institutional environments discussed in this report. 



Existing estuarine ecological systems will continue to operate either 

 in long-established dynamic patterns of chemical cycling, water cir- 

 culation and species behavior, or these activities will be increasingly 

 dominated by man's activities. Man's activities generally result in 

 great stresses on established plant, animal, and chemical processes, if 

 not total system modification. These activities may be controlled by 

 decisions made in the socioeconomic and institutional environments to 

 minimize impacts on the existing estuarine systems, thus retaining 

 their structure and operation ; or, the energy sources and stresses asso- 

 ciated with man's activities may be allowed to dominate estuarine 

 processes and, in effect, create wholly or partially different systems. 



From a strictly empirical or descriptive viewpoint, the emerging 

 new systems associated with man's activities are neither good nor bad 

 per se; the determination of values relating to these modified systems 

 must be made within the existing or potential socioeconomic and insti- 

 tutional frameworks. Values will be set in the marketplace, which in- 

 clude all the mechanisms whereby society normally measures the worth 

 of goods, services and wages, which in turn largely determine the pres- 

 sures placed on estuarine systems. The non-market system also deter- 

 mines values through the expression of clioices expressing social costs 

 and benefits not measured in standard economic terms. These two 

 major componrits of value-setting must be balanced if modification 

 and ultimate destruction of existing estuarine ecosystems is to be 

 avoided. 



stress and estuarine ecology 



Estuarine ecological systems consist of populations of organisms, 

 flows of water, pathways of cycling chemical elements, and organizing 

 mechanisms which are all tightly interrelated. These systems con- 

 stantly adjust as the principal elements in their operation change in 

 character, cfuantity, and composition. Thus, estuarine ecological 55^8- 

 tems, as with all ecological communities, are subject to change, and 

 either successfully adapt, or are replaced by other systems. 



