Beach Erosion and Inundation 



virtually all nesting beaches undergo regular cycles of sand 

 erosion and sand replacement (accretion) , the magnitude of which 

 varies from one area to another. Along the coast between Guyana 

 and French Guiana, where large numbers of turtles nest, beaches 

 completely disappear and new ones form at frequent, but 

 unpredictable intervals. Barrier islands, such as those along 

 the east coast of the U.S.A., are continuously eroding and 

 accreting, yet provide critical nesting habitat for loggerhead 

 turtles. 



Erosion and inundation are popularly perceived as important 

 causes of clutch mortality, but in fact, few studies have been 

 done to test this assumption. Certainly, heavy mortality does 

 occur during storms and hurricanes (Ross and Barwani 1982) . A 

 particularly severe storm may remove vast quantities of sand from 

 a beach, sometimes requiring years for the beach to recover. 



Investigators in Surinam have estimated that 20-30% of all 

 egg clutches laid each year are probably doomed because they are 

 deposited below the spring high tide line (Schulz 1975; Button 

 and Whitmore 1983) . On the other hand, studies done at 

 Tortuguero and in Florida, indicate that, barring major storms, 

 mortality caused by erosion can affect less than 6% of the total 

 egg clutches (Fowler 1979; Witherington 1986). 



In the past, intolerance of turtle eggs to any inundation by 

 sea water was widely believed. Mounting evidence indicates, 

 however, that moderate wave wash has a relatively innocuous 

 effect on egg survival (McGehee 1979; Mortimer 1981). 

 Witherington (1986) speculated that the primary cause of 

 mortality in clutches affected by surf conditions was not 

 drowning, but the partial exposure or total loss of a clutch to 

 erosion. The tolerance of an egg clutch to inundation seems to 

 vary depending on how long the eggs are immersed in water, and 

 during what stage in their development inundation occurs (C. 

 Limpus, pers. comm.). Also evidence indicates that cold shock, 

 which usually accompanies inundation, may alter the sex ratio 

 within a clutch (Mrosovsky et al. 1984). More research is needed 

 to determine exactly how salt water or fresh water inundation 

 affects the eggs within a clutch when it occurs for varying 

 lengths of time and at various stages during embryonic 

 development. 



Translocation of Doomed Egg Clutches as a Management Technicrue 



Ideally, an egg clutch that has been deposited too close to 

 the sea should be translocated to higher ground. If proper 



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