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importance to man, such as shrimp, menhadden, flounders, and red 

 drum (fig. IV. 1.38). 



Estuarine wildlife can be classified into four categories: (1) fur 

 bearing animals, (2) game waterfowl, (3) ornamental shore birds, and 

 (4) the common wildlife that can tolerate human presence. 



The primary fur bearers are the fur seal in Alaska, nutria in the 

 South Atlantic and Gulf States, the common eastern muskrat in New 

 Jersey, the Virginia muskrat in the Central Atlantic States, and the 

 Louisiana muskrat in Alabama, Mississippi, Louisiana, and Texas. 

 Secondary in importance are the racoon, mink, and otter. 



The dependence of waterfowl on the estuarine zone is both complex 

 and incompletely understood. The primary sport species, such as mal- 

 lards and canvasbacks, have been successfully adapted to manmade 

 changes in their environment, particularly those changes not affecting 

 the nesting sites. 



The ornamental shore and sea birds are a particularly esthetic at- 

 traction among the national famia. Tliese birds are generally more 

 dependent upon estuarine conditions than the more mobile waterfowl 

 and, in addition, have demonstrated a considerably greater sensitivity 

 to the overall encroachment of man. These birds include whooping 

 cranes, pelicans, bald eagles, egrets, ibis, and many others. 



GOVERNING SUBDIVISIONS OF THE BIOPHYSICAL ENVIR0N3IENT 



Solar energy and gravitational energy are the basis for everything 

 that happens naturally in the estaurine zone. This discussion of the 

 biophysical environment has been concerned primarily with the en- 

 vironmental conditions surrounding the transformation of these ener- 

 fies into forms useful in living processes and exploitable by man. Three 

 ifferent sets of subdivisions of the biophysical environment were used 

 in this discussion. 



Differences in the external environment divided the estuarine zone 

 of the United States naturally into 10 geographic regions, each subject 

 to a particular governing combination of the external influences of 

 tide, ocean currents, wave action, sedimentation, and climate. This 

 subdivision into estuarine biophysical regions gave broad ranges of 

 conditions in each region, but the importance of local coital condi- 

 tions in governing energy flows via water movement paved the way for 

 a subdivision of the estuarine zone according to 10 morphological 

 groups having similarities in water movement, circulation, and the 

 ability to rid themselves of wastes. 



A subdivision according to ecological communities was also based 

 primarily on geographical location, but again coastial conditions made 

 it necessary to identify small ecosystems governed by specific local 

 conditions witliin each of the major groupings. 



The Socioeconomic Environment 



The socioeconomic environment of the estuarine zone is the direct 

 result of its value as a means of sustenance, a place to live, a source 

 of enjoyment, and a route of transportation. The laws regulating 

 man's activities in this zone are historically intended to protect and 

 serve individual and group interest in dealing with each other. Only 

 recently has it become apparent that the laws protecting man from 



