turtles. The possible effect of the low frequency noise it 

 produces also warrants further investigation (Frazier 1980) . 

 Probably the worst impact would be felt in those areas where only 

 limited nesting beach is available. Whenever possible, boat 

 traffic should be restricted in the vicinity of nesting beaches 

 during the nesting season. Shrimp trawlers which usually operate 

 close to shore may catch large numbers of turtles in their 

 internesting habitat (Coston-Clements and Hoss 1983) . 



Chemical Pollution 



The most obvious form of chemical pollutant in the nesting 

 habitat is oil. Tar balls can be found on even the most remote 

 beaches of the world (such as at Ascension Island, located mid- 

 way between Brazil and West Africa) . Oil pollution is a problem 

 increasing in magnitude, but few studies have been done to 

 quantify how oil affects incubating eggs and hatchlings. Fritts 

 and McGehee (1982) found that fresh crude oil will cause 

 significant mortality and morphological change in the incubating 

 embryos, but that weathered oil may not. In a preliminary study 

 based thus far on few data in the Persian Gulf — where the level 

 of oil pollution is probably the worst in the world — J. Miller 

 (pers. comm.) found no obvious indication that oil mixed into the 

 sand lowers hatching success. Nevertheless, more research is 

 needed to document sublethal or delayed lethal effects of oil 

 pollution. Eggs, embryos, and hatchlings are more vulnerable 

 than adults since volatile and water soluble contaminants can be 

 absorbed into the egg (see review by Coston-Clements and Hoss 

 1983) . Both oil spills and the resulting clean up operations 

 could have harmful effects at the nesting beach (Coston-Clements 

 and Hoss 1983) . 



Pollution Caused by Physical Debris 



Beaches throughout the world are becoming more and more 

 polluted by man-made debris that washes ashore. This debris 

 includes light bulbs, styrofoam, plastics, aerosol cans, tar, 

 wood, glass, cloth, fiberglass, fishing line and other gear, and 

 organic garbage (Hirth 1987) . Studies are needed to quantify the 

 extent of this problem and to determine whether the debris 

 interferes with the activities or movements of either the adults 

 or the hatchlings. In 1986, vast quantities of plastic beads 

 carpeted parts of the beach at Tortuguero (A. Meylan, pers. 

 comm.). Small objects like these, if abundant enough, could 

 become incorporated into the beach sand, and ultimately alter its 

 thermal properties or the patterns of gas diffusion within it. 



Although debris does float in from far away, in some areas 

 much of it is dumped locally. Large cruise ships and military 

 vessels have frequently been implicated in illegal offshore 



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