Variations in leatherback turtle nest environments: consequences for hatching success

Abstract

Physical and biological conditions of nests in which sea turtle embryos develop can vary among and within nesting beaches. Monitoring these conditions and their effects on embryonic development should be considered when assessing conservation efforts to increase sea turtle hatch- ling production. Sandy Point National Wildlife Refuge (SPNWR), St. Croix, US Virgin Islands, hosts a leatherback turtle Dermochelys coriacea nesting colony that has increased exponentially in the past 2 decades, due in part to an ongoing egg relocation program. We characterized the influence of nest environment conditions (e.g. partial pressures of oxygen, pO2, and carbon dioxide, pCO2, and tem- perature) on hatching success of relocated eggs at 3 different sites at SPNWR to evaluate potential intra-beach variation in nest environment conditions and hatching success. Although nest conditions varied significantly among sites, hatching success did not vary significantly among relocation sites. Among all clutches and sites, hatching success varied significantly with minimum pO2, maximum pCO2, and maximum temperatures measured in leatherback nests. Thus, leatherback embryos col- lectively affected their nest environment (i.e. decreased pO2, increased pCO2, and temperature), and appeared to show developmental sensitivity to low pO2 and high levels of pCO2 and temperature in nests. Our study shows the importance of considering sea turtle nest environment conditions when designing and executing beach-based conservation strategies such as egg relocation programs.