Climate change implications for the nest site selection process and subsequent hatching success of a green turtle population

Abstract

Sandy beach habitat where sea turtles nest will be affected by multiple climate change impacts. Before these impacts occur, knowledge of how nest site selection and hatching success vary with beach microhabitats is needed to inform managers on how to protect suitable habitats and prepare for scientifically valid mitigation measures at beaches around the world. At a highly successful green turtle (Chelonia mydas) rookery at Akumal, Quintana Roo, Mexico, we measured microhabitat characteristics along the beach crawl (rejected sites) and related nest site conditions (selected sites) to subsequent hatching success rates for 64 nesting events. To our knowledge, this is the first study to report environmental data along the nesting crawl for a green turtle population and the first to use natural breaks in the data to describe their preferred habitat ranges. Our results indicate that turtles were likely using a combination of cues to find nest sites, mainly higher elevations and lower sand surface temperatures (Kruskal-Wallis test, H=19.84, p<0.001; H=10.78, p<0.001). Hatching success was significantly and negatively correlated to sand temperature at cloaca depth (Spearman's Mitig Adapt Strateg Glob Change ρ=−0.27, p=0.04). Indeed, the preferred range for cloaca sand temperatures at the nest site (26.3-27.5°C) had significantly higher hatching success rates compared to the highest temperature range (Tukey HSD=0.47, p=0.05). Sand temperatures at various depths were intercorrelated, and surface and cloaca depth sand temperatures were correlated to air temperature (ρ=0.70, p=0.00; ρ=0.26, p=0.04). Therefore, rising air temperatures could alter sand temperature cues for suitable nest sites, preferred nest site ranges, and produce uneven sex ratios or lethal incubating temperatures. Elevation cues and preferred ranges (1.4-2.5 m) may also be affected by sea level rise, risking inundation of nests.

Massive Influx of Pelagic Sargassum spp. on the Coasts of the Mexican Caribbean 2014–2020: Challenges and Opportunities

“…The most severe negative impacts for the turtles and their habitats are Four species of sea turtle nest along this coast; the green turtle (Chelonia mydas), loggerhead (Caretta caretta), hawksbill turtle (Eretmochelys imbricate), and leatherback (Dermochelys coriacea), in descending order of abundance, [65][66][67]. The females lay their eggs mostly in dune zones [68], and they have been seen crossing the beached masses of sargasso to nest on the upper part of the beach; thus to date, there is no evidence that nesting behavior in the region has been significantly impacted by sargasso. However, during the incubation period of the eggs, decomposing sargasso can induce temperatures that are lethal for the embryos.…”

Using Lidar Data to Assess the Relationship Between Beach Geomorphology and Kemp’s Ridley (Lepidochelys kempii) Nest Site Selection Along Padre Island, TX, United States

“…The results of this study can also be expanded upon to calculate the extent of nesting habitat that may be at risk to sealevel rise and identify beaches where nesting may shift. Sea-level rise has the potential to cause an increase in nest inundation events and to change beach geomorphology characteristics key to sea turtle nesting, such as beach slope and elevation (Pendleton et al, 2004;Stutz and Pilkey, 2011;Williams, 2013;Santos et al, 2015). Annual and seasonal measurements of beach geomorphology characteristics could be used to calculate how the morphology of nesting beaches is changing and to predict the extent and location of optimal nesting habitat as the beaches continue to shift (Katselidis et al, 2013).…”

Phylogeography, genetic stocks, and conservation implications for an Australian endemic marine turtle

“…Observed genetic discontinuities between adjacent flatback populations imply strong natal fidelity to breeding locations for some populations, which may limit spatial shifts as habitat becomes unsuitable, whether from climate change or other factors. Such behavioural limits may be in evidence in females that continue to nest on beaches that produce substantial periods of lethal temperatures for embryos (Santos, Livesey, Fish, & Lorences, ) or that nest on beaches where streetlights disorient hatchlings away from the ocean (Kamrowski, Limpus, Pendoley, & Hamann, ). Alternatively, patterns in the distribution of haplotypes that are found across thousands of kilometres are indicative of long‐distance dispersal through time and the ability of turtles to colonize new areas.…”