posal areas, by ever-increasing discharge of domes- 

 tic sewage and trade wastes, and by numerous 

 contaminants which reach natural waters as a 

 result of widespread and nonselective use of 

 insecticides and pesticides. Danger from the 

 discharge of radioactive materials from nuclear 

 plants and the disposal of low level radioactive 

 wastes in the sea not far from shore presents a 

 new and serious threat to the usefulness of the 

 renewable aquatic resources of coastal areas. 



Some of the changes produced by man such as 

 improvement of coastal waters for navigation, 

 construction of liunicane barriers, use of tidal 

 land for Iniikling of industrial plants are consist- 

 ent with rapid population gi'owth and industriali- 

 zation. Other changes, such as pollution, destruc- 

 tion of natural oyster beds by failure to return 

 shells and other materials needed for the attacli- 

 ment of young oysters, and overfisliing are 

 unnecessary and should be avoided. 



A balance between the needs associated with 

 industrial progi-ess and population pressure on 

 one side, and effective conservation of natural 

 aquatic resources on the other can and must be 

 found. 



POLLUTION 



The pollution problem is complex. It has 

 many facets that should be studied from social, 

 economic, and biological points of view. An in- 

 vestigation of the biological aspects of pollution, 

 discussed in this section, deals with the complex 

 ecological relationship between the life in tlie 

 tidal areas and the environment affected by the 

 addition of a number of organic and inorganic 

 contaminants. 



One of the major difficulties encountered in 

 studies of the biological effects of pollution is the 

 lack of a generally accepted definition of the 

 term. Pollution means different things to differ- 

 ent people: to a Public Health officer pollution 

 implies a potential health hazard caused by the 

 dischai'ge of domestic sewage and industrial waste; 

 an engineer of a manufacturing plant is primarily 

 concerned with the quality of water needed for 

 the industry; the conserxationist has in mind 

 danger to wildlife and means for its protection ; 

 sport and commercial fishermen fear that foreign 

 substances discharged into coastal waters will 

 affect tlie availability of fish; a marine ecologist 

 tries to find out how the animal and plant life is 

 affected by changes in the environment; and the 

 layman, considering that pollution is synonymous 



with filthy conditions on beaches and in coastal 

 waters, raises his voice in protest against unsani- 

 tary and esthetically objectionable situations. 



In court litigations involving damages allegedly 

 caused by pollution, a biologist appearing as an 

 expert for either side is handicapped in his testi- 

 mony either by lack of a legal definition of pollu- 

 tion or by the generalities used to describe it. 

 No definition of the term pollution is given in the 

 Oil Pollution Acts of 1924 and 1961. The Water 

 Pollution Control Acts of 1948 and 1961 (United 

 States Congress, 1948, 1961) make frequent refer- 

 ences to the "abatement of stream pollution" and 

 declare in the 1948 act that pollution is a public 

 nuisance "which endangers the health or welfare 

 of persons in a State other than that in which the 

 discharge originates." The inclusion of the word 

 "welfare" puts emphasis on the economic aspects 

 of pollution and, therefore, increases the scope of 

 the definition. 



After conducting a comprehensive study of all 

 available State, Federal, and international pollu- 

 tion laws, the U.S. Public Health Service (1950) 

 prepared the following broad definition of pollution: 



"Pollution" means such contamination, or other altera- 

 tion of the physical, chemical or biological properties, of 

 any waters of the State, or such discharge of any liquid, 

 gaseous or solid substance into any waters of the State as 

 will or is likely to create a nuisance or render such waters 

 harmful or detrimental or injurious to public health, safety 

 or welfare, or to domestic, commercial, industrial, agricul- 

 tural, recreational, or other legitimate beneficial uses, or 

 to livestock, wild animals, birds, fish or other aquatic life. 



Although this definition is broad and useful, it has 

 not been incorporated in existing Federal statutes 

 and, therefore, lacks legal weight. 



The amount of waste discharged into coastal 

 waters of the United States from municipalities 

 and industrial plants in the last decade has reached 

 astronomical proportions and is being augmented 

 by runoff water which carries the numerous or- 

 ganic phosphorus and hydrocarbon insecticides 

 used in both control and eradication of agricul- 

 tural crop-damaging pests. Under present condi- 

 tions it is probably impossible to find water along 

 our coast which has not been contaminated. 



Some pollutants contain highly toxic substances 

 and cause mortalities among marine populations. 

 Others are less toxic and have no lethal effect on 

 adult organisms but decrease the rate of survival 

 of their larvae; decrease the rate of growth of 

 juvenile forms and afl^ect the reproductive capa- 



FACTORS AFFECTING OYSTER POPULATIONS 



441 



