interface between the water and bottom where high biological activity 

 is concentrated. Bottom living animals and grassbeds are removed in 

 one area and are covered over in a different place. The heat gener- 

 ated from power plants is dispersed by mixing with the main body of 

 water in several estuaries; but this practice has produced some un- 

 expected vertical stratification problems involving salinity and tem- 

 perature as described by Cronin (1967). 



Estuaries are essential for the completion of the life histories 

 of a vast majority of shallow-water marine animals including those of 

 most commercial fisheries on the Gulf coast. Commenting upon the im- 

 portance of estuaries, Pearse and Gunter (1957) stated that "the 

 young of many animals usually thought of as marine, require areas of 

 low salinity for nursery grounds." They added further that "the dis- 

 tribution and abundance of the blue crab and of the commercial shrimp 

 of South Atlantic and Gulf coasts are dependent on the presence of 

 estuarine areas. The early stages of penaeid shrimp apparently re- 

 quire oceanic water, but the older larvae must reach bay waters or 

 perish." 



In addition to the migratory species, estuaries also host their 

 own indigenous populations of copepods, planktonic forms, several 

 species of mollusks, fishes, and palaemonid shrimp of the grass beds. 



In view of the biological and commercial importance of estuaries, 

 a team of consultants for the Corps of Engineers, Drs. Eugene Cronin, 

 Gordon Gunter, and Sewell Hopkins, analyzed the problem and made rec- 

 ommendations to the Corps to sponsor some research program on the 

 salinity problems of some coastal water species. 



Among the more important recommendations were: 



1. To determine the distribution, abundance, rates of growth, 

 and total production of some animal and plant species in 



22 



