type of damage to wildlife populations is unknown. 



Dramatic losses of waterbirds (ducks, geese, 

 coot, swans, gannets, murres, and others) result 

 from contamination of the plumage by oil from the 

 surface of the water. Once the bird's plumage is 

 soaked with oil, the bird loses its natural insula- 

 tion to the cold and dies. Many hundreds of thou- 

 sands of birds have died from oil pollution in 

 some years in North American waters. 



Oil that settles to the bottom of aquatic habitats 

 can blanket large areas and destroy the plants and 

 animals of value to waterfowl. Reportedly, some 

 oil sludges on the bottoms of aquatic habitats tend 

 to concentrate pesticides, thus creating a double 

 hazard to waterfowl that would pick up these con- 

 taminants in their normal feeding process. 



Pesticides 



No pesticides should occur in water to the 

 degree that they affect the health, reproduction, 

 and natural growth of wildlife. Although tolerable 

 limits of pesticides for fish and aquatic inverte- 

 brates presently serves as the best guideline to 

 limits that might not cause excessive harm to wild- 

 life, we must call attention to the paucity of our 

 knowledge on the significance of biological mag- 

 nification. Keith (1966) and Hickey, Keith, and 

 Coon (1966) reported 14 ^g/1 of DDT and its 

 metabolites in lake bottom muds. About 50 times 

 that quantity was reported in amphipods (Ponto- 

 poreia affinis), 500 times as much in fish and old 

 squaw ducks, and 15,000 times as much in herring 

 gulls that ate the fish. Reproduction of the gulls 

 decreased. 



DDT residues in wildlife are cosmopolitan, oc- 

 curring even in penguins from the Antarctic. Con- 

 centration of insecticides in the flesh of edible wild 

 animals poses a potential hazard to man's well 

 being. Recently, the hunting season for pheasants 

 in California was closed for a while because of 

 concern about secondary poisoning to man. 



In our infinite ignorance of the dynamics of 

 biological magnification in wildlife habitats, toler- 

 able limits for pesticides in water cannot be real- 

 istically established. 



Seldom do we observe mass mortality of wildlife 

 from pesticide application, but occasionally iso- 

 lated examples occur. Sincock (personal com- 

 munication) observed an aerial spraying operation 

 of 2 pounds of toxaphene and 1 pound of DDT 

 per acre for armyworm control on soybeans in 

 Virginia in September 1960; 2 days later he was 

 called to determine the cause of death of several 

 geese and ducks penned in the area. Dead fish in 



adjacent canals also confirmed the presumptive 

 diagnosis of death from pesticidal poisoning. 



Nuisance and toxic growths 



Algae present several problems to wildlife and 

 their habitat. Excessive blooms can reduce light 

 penetration, as already mentioned; Nostoc spp. 

 and other colonial algae often attach to higher 

 aquatic plants and virtually weigh them to the 

 bottom, causing their destruction. Cladophora sp. 

 growths in Great South Bay, Long Island, have 

 become a major problem as a result of fertilization 

 by sewage effluents and wastes from duck farms. 

 Although problems with sewage disposal occur 

 throughout the Nation, some of the most severe 

 occur in small, coastal resort areas that must ac- 

 commodate a massive influx of tourists during the 

 warm, summer season, along with the skyrocketing 

 use of boats with toilet facilities. 



Sincock, Inglis, and Irby (unpublished data) 

 contacted most agencies concerned with pollution 

 and conservation problems along the Atlantic and 

 Gulf Coast in August 1966. Many examples of 

 sewage pollution were found. One large southern 

 city dumped 15 million gallons of untreated 

 sewage each day into its harbor. Another mid- 

 Atlantic city had major problems with odors 

 caused by the disintegration of sea lettuce {Viva 

 lactuca) that thrived upon sewage effluent in the 

 harbor. 



Several of our national wildlife refuges are, 

 unfortunately, downstream from the inflow of 

 treated and untreated sewage. The problems in- 

 clude offensive odors, sterility of the entire aquatic 

 biota, excessive algal blooms that exclude light, 

 and toxic algae. Some algae, e.g., sea lettuce, re- 

 portedly taint the flesh of brant and other water- 

 fowl that consume it. 



Several of the blue-green algae are toxic. Olson 

 (1964) states, "When a toxic strain becomes 

 predominant in a water bloom, hundreds of birds 

 may die in a few hours. Then any living creature 

 that drinks the water is a potential victim, and 

 shorelines may be strewn with bodies of mammals, 

 land birds, and waterfowl." Gorham (1964), 

 discussing livestock and wildlife poisoning from 

 his notable research on algae poisoning, states 

 "Five species have been most implicated in such 

 poisonings: Microcystis aeruginosa (including 

 Mic. toxica), Anabaena flos-aquae (including /In. 

 lemmermannii) , Aphanizomenon flos-aquae, 

 Gloetrichia echinulata, and Coelospaerium kutz- 

 ingeanum." In controlled tests, Olson (1964) 



97 



