Abstract
Sea turtle eggs are heavily influenced by the environment in which they incubate, including effects on hatching success and hatchling viability (hatchling production). It is crucial to understand how the hatchling production of sea turtles is influenced by local climate and how potential changes in climate may impact future hatchling production. Generalized Additive Models were used to determine the relationship of six climatic variables at different temporal scales on loggerhead turtle (Caretta caretta) hatchling production at seventeen nesting beaches in Bahia, Espirito Santo, and Rio de Janeiro, Brazil. Using extreme and conservative climate change scenarios throughout the 21st century, potential impacts on future hatching success (the number of hatched eggs in a nest) were predicted using the climatic variable(s) that best described hatchling production at each nesting beach. Air temperature and precipitation were found to be the main drivers of hatchling production throughout Brazil. CMIP5 climate projections are for a warming of air temperature at all sites throughout the 21st century, while projections for precipitation vary regionally. The more tropical nesting beaches in Brazil, such as those in Bahia, are projected to experience declines in hatchling production, while the more temperate nesting beaches, such as those in Rio de Janeiro, are projected to experience increases in hatchling production by the end of the 21st century.
Highlights
Oviparous reptiles, such as sea turtles, are heavily influenced by environmental temperature, since it can influence their life history, physiology, and behavioral traits, during egg incubation[1,2,3]
Accumulated precipitation alone or in combination with air temperature during incubation were the main climatic drivers of loggerhead hatchling production at Brazilian nesting beaches, with the effects of each climatic variable varying among states and nesting beaches
At beaches where precipitation was a significant driver of hatching success, there was a negative effect of precipitation, which could be a result of soil saturation or a rise of the water table level displacing air in between sand particles suffocating embryos resulting in clutch failure[16,33,34]
Summary
Oviparous reptiles, such as sea turtles, are heavily influenced by environmental temperature, since it can influence their life history, physiology, and behavioral traits, during egg incubation[1,2,3]. Considering the influence of the environment on sea turtles and projected increases in temperatures, there is concern over potential impacts on their populations, such as feminization of populations and reduced population stability[8,9,10] This concern has prompted an increase in the number of studies exploring climate change impacts on sea turtles (for reviews see2,11,12), with most focusing on how predicted changes in temperature will affect the sex ratio of hatchlings[13,14,15]. Nest temperatures may exceed 35 °C by several degrees in some populations (usually just prior to hatchling emergence) and eggs still successfully hatch[20] Despite these varying degrees of tolerance to environmental temperatures, hatchlings incubating in higher temperature nests may exhibit lower hatching www.nature.com/scientificreports/. We identified nesting sites in a large population that are most susceptible to climate change and projected potential effects on hatchling success under extreme (CMIP5 RCP 8.5, higher concentrations of greenhouse gas emissions causing higher increases in global temperatures) and conservative (CMIP5 RCP 4.5, lower concentrations in emission causing more mild increases in global temperatures) scenarios of climate change
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