Exposure of Marine Birds to 

 Environmental Pollutants 1 



by 

 Harry M. Ohlendorf 



U.S. Fish and Wildlife Service 



Patuxent Wildlife Research Center 



Laurel, Maryland 20811 



Robert W. Risebrough and Kees Vermeer 



Canadian Wildlife Service 

 Department of the Environment 



Ottawa, Ontario (RWR) 

 Delta, British Columbia (KV) 



Abstract 



It is unlikely that any marine birds remain uncontaminated by the synthetic 

 organochlorine compounds that have become ubiquitous pollutants. Marine 

 birds also are increasingly exposed to petroleum compounds as a result of the 

 exploitation of undersea petroleum deposits, increased tanker traffic, and ex- 

 pansion of coastal petrochemical industries. 



Lethal and reproductive effects of organochlorines on marine birds have 

 been most pronounced in coastal areas receiving effluents discharged by 

 manufacturing plants. For example, particularly severe DDT contamination in 

 southern California and elevated levels of dieldrin and related chemicals in the 

 Netherlands have killed local marine birds or inhibited their reproduction. 

 Eggshell thinning, apparently resulting from exposure to DDE, is widespread 

 among estuarine species, and eggshells of peregrine falcons (Falco peregrinus) 

 have become thinner in all areas of the species' range thus far studied. In 

 more contaminated coastal areas, reproductive success of the peregrine falcon 

 is low. Adverse effects of organochlorines on the reproduction of other species 

 also have been found. 



The oiling of feathers and the associated mortality of marine birds are not 

 the only adverse effects of oil pollution; ingestion of oil may cause death by 

 dehydration by interfering with ion transport and water balance in the gut. 

 Surfactants used to disperse oil spills also have serious consequences for ma- 

 rine birds. Dissolved oil fractions may kill or poison the biota the birds feed 

 on. The physiological effects of the incorporation of more persistent com- 

 pounds into marine food webs are unknown. 



Contamination of marine birds by most metals and certain trace elements 

 has not been documented, although elevated mercury levels have been ob- 

 served in birds of certain estuarine and local marine environments. The signifi- 

 cance of elevated mercury levels and small plastic particles found in the 

 stomachs and pellets of marine birds is not yet known. 



1 A summary of this paper was presented at the 13-15 May 1975 international symposium on "Conser- 

 vation of Marine Birds of Northern North America," in Seattle, Washington. The paper was written 

 in 1975-76, and certain portions have been amended or updated as references were published. Proceed- 

 ings of the symposium are being prepared for publication, but this paper on environmental pollutants 

 is being published separately because of its great length and the delay in publication of the entire 

 Proceedings. 



