Nest inundation from sea-level rise threatens sea turtle population viability

Abstract

Contemporary sea-level rise will inundate coastal habitats with seawater more frequently, disrupting the life cycles of terrestrial fauna well before permanent habitat loss occurs. Sea turtles are reliant on low-lying coastal habitats worldwide for nesting, where eggs buried in the sand remain vulnerable to inundation until hatching. We show that saltwater inundation directly lowers the viability of green turtle eggs (Chelonia mydas) collected from the world's largest green turtle nesting rookery at Raine Island, Australia, which is undergoing enigmatic decline. Inundation for 1 or 3 h reduced egg viability by less than 10%, whereas inundation for 6 h reduced viability by approximately 30%. All embryonic developmental stages were vulnerable to mortality from saltwater inundation. Although the hatchlings that emerged from inundated eggs displayed normal physical and behavioural traits, hypoxia during incubation could influence other aspects of the physiology or behaviour of developing embryos, such as learning or spatial orientation. Saltwater inundation can directly lower hatching success, but it does not completely explain the consistently low rates of hatchling production observed on Raine Island. More frequent nest inundation associated with sea-level rise will increase variability in sea turtle hatching success spatially and temporally, due to direct and indirect impacts of saltwater inundation on developing embryos.

Climate change resilience of a globally important sea turtle nesting population

“…Significant losses of 8%–65% of nesting habitat are predicted for several sea turtle rookeries, under climate change scenarios of median severity (Baker, Littnan, & Johnston, ; Fish et al., , ; Fuentes, Limpus, Hamann, & Dawson, ; Katselidis, Schofield, Stamou, Dimopoulos, & Pantis, ). Additionally, temporary inundation of beaches, associated with the increasing prevalence and intensity of storms, is expected to lower hatching success (Pike, Roznik, & Bell, ; Van Houtan & Bass, ). It is yet uncertain whether sea turtles will be able to adapt to the current rapid changes, but they have certainly endured climate change in the past (Poloczanska et al., ).…”

Climate Change Impacts on Florida’s Biodiversity and Ecology

“…Shifts may also occur at a more regional scale. There has been a northward shift in loggerhead sea turtle (Caretta caretta) nests along Melbourne Beach, Florida, the largest loggerhead turtle rookery in the Atlantic Ocean, likely due to warming temperatures (Reece et al 2013b (Fuentes et al 2010;Katselidis et al 2014;Pike et al 2015). For example, it is projected that Melbourne Beach will decrease in area by 43% from 1986 to a future with 0.5 m of sea level rise; this will restrict nesting to narrow beaches, increasing risk of erosion and crowding resulting in nests overlapping with each other (Reece et al 2013b (Pike 2013;.…”

Beachrock formation via microbial dissolution and re-precipitation of carbonate minerals

“…Microorganisms inhabit the beachrock in the form of epilithic mats on the surface ( Figure 2C), as euendolithic communities boring into sediment grains, and as cryptoendolithic communities in the interstices within the beachrock ( Figure 2D). Pike et al (2015) found that although the microbial community composition varied by location in the beachrock, it is typically dominated by non-heterocystous cyanobacteria. For the present study, samples were collected to include both the older re-cemented blocks and an associated younger beachrock that held the older blocks in place at the time of sampling ( Figure 2B).…”