Impact of marine heatwaves for sea turtle nest temperatures

Abstract

There are major concerns about the ecological impact of extreme weather events. In the oceans, marine heatwaves (MHWs) are an increasing threat causing, for example, recent devastation to coral reefs around the world. We show that these impacts extend to adjacent terrestrial systems and could negatively affect the breeding of endangered species. We demonstrate that during an MHW that resulted in major coral bleaching and mortality in a large, remote marine protected area, anomalously warm temperatures also occurred on sea turtle nesting beaches. Granger causality testing showed that variations in sea surface temperature strongly influenced sand temperatures on beaches. We estimate that the warm conditions on both coral reefs and sandy beaches during the MHW were unprecedented in the last 70 years. Model predictions suggest that the most extreme female-biased hatchling sex ratio and the lowest hatchling survival in nests in the last 70 years both occurred during the heatwave. Our work shows that predicted increases in the frequency and intensity of MHWs will likely have growing impacts on sea turtle nesting beaches as well as other terrestrial coastal environments.

Reconstructing past thermal conditions in beach microclimates

“…Additionally, we show that predictions of sand temperature using large‐scale records agree with those using local air temperature records at one of our study sites, that is, large‐scale proxies give a good indication of local conditions. This result agrees with the recent finding that broad‐scale environmental measurements can reflect local measurements (Hays et al, 2021). However, one important point to note is that the more local records – such as the air temperature records obtained from the airport used in our study – may not extend as far back in time as other large‐scale records, and so reconstruction of past sand temperatures will be limited.…”

“…How to cite this article: Laloë, J.-O., Chivers, W. J., Esteban, N., & Hays, G. C. (2021). Reconstructing past thermal conditions in beach microclimates.…”

“…For sea turtles, the correlative approach using either air temperature (AT) and/or sea surface temperature (SST) has been widely used to reconstruct sand temperatures at nesting sites (Bentley et al, 2020; Chatting et al, 2021; Fuentes et al, 2009; Hays et al, 2003; Jensen et al, 2018). However, there has been debate about whether AT or SST provides the best proxy for these sand temperature reconstructions (Bentley, Kearney, et al, 2020; Fuentes et al, 2009; Hays et al, 2021). Here we set out to resolve this debate using sand temperature data at nest depths for sea turtle nesting sites across the world.…”

Can a present-day thermal niche be preserved in a warming climate by a shift in phenology? A case study with sea turtles

“…the environment in which sea turtle eggs incubate. Previous work has shown that SST and air temperature (AT) measured over large scales near nesting sites are tightly correlated with sand temperature at nest depths [ 48 – 51 ]. More recently it was shown that the gradients of these relationships are consistent across sites, and that for every 1°C increase in AT, sand temperature at nest depth increases by an average 0.86°C (standard deviation = 0.26°C, n = 36; [ 52 ]).…”

The ecological importance of the accuracy of environmental temperature measurements

“…Ecologists can then use these open-source data to create models to address environmental questions about their focal taxon (e.g. [ 23 , 24 ]). Data from such sources can be accompanied by the deployment of in situ temperature loggers (electronic supplementary material, table S1).…”