Abstract
Egg-burying reptiles need relatively stable temperature and humidity in the substrate surrounding their eggs for successful development and hatchling emergence. Here we show that egg and hatchling mortality of leatherback turtles (Dermochelys coriacea) in northwest Costa Rica were affected by climatic variability (precipitation and air temperature) driven by the El Niño Southern Oscillation (ENSO). Drier and warmer conditions associated with El Niño increased egg and hatchling mortality. The fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC) projects a warming and drying in Central America and other regions of the World, under the SRES A2 development scenario. Using projections from an ensemble of global climate models contributed to the IPCC report, we project that egg and hatchling survival will rapidly decline in the region over the next 100 years by ∼50–60%, due to warming and drying in northwestern Costa Rica, threatening the survival of leatherback turtles. Warming and drying trends may also threaten the survival of sea turtles in other areas affected by similar climate changes.
Highlights
Reproductive success of egg-burying species such as sea turtles depends upon the stability of the nest environment [1,2]
Mean monthly hatching success was influenced by precipitation accumulated in the two months before eggs were laid, precipitation in October, and average ambient temperature during the two months of incubation, The relationship was defined by a stepwise multiple regression equation: Figure 2
We found that Multivariate ENSO Index (MEI) was significantly correlated with hatching success and emergence rate, with positive values of MEI (El Nino) corresponding to years of low hatching success and emergence rates and negative values of MEI (La Nina) corresponding to years of high hatching success and emergence rates (Fig. 3A,B)
Summary
Reproductive success of egg-burying species such as sea turtles depends upon the stability of the nest environment [1,2]. It is suggested that crocodilians and turtles survived the mass extinction at the end of the Cretaceous Period in part because they laid eggs in substrates that provided relatively stable temperature and humidity throughout incubation [3,4]. Water exchange and incubation temperature influence hatching success of eggs and fitness of hatchlings. High temperature and dry substrates are unfavorable for egg development and hatchling quality [2,5,6,7,8] and can cause the loss of an entire reproductive season [9]. Changes in local climate can have important effects on reproductive success of reptiles
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