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Thermal conditions in the nest affect the development of sea turtle clutches, with high temperatures potentially reducing reproductive success and the quality of hatchlings. In a warming climate, increasing temperatures could become a threat to sea turtles in many locations. This has prompted the implementation or recommendation of climate mitigation strategies in nests that incubate in hatchery conditions. Here, olive ridley turtle (Lepidochelys olivacea) clutches relocated to a beach hatchery in Playa Grande, Costa Rica (10° 20 N, 85° 51 W) were used to study the effect of temperature on hatching success and hatchling size. Data from 5 nesting seasons (2017/18 to 2022/23, excluding 2020/21) were tested to determine the effect of mean incubation temperature by thirds of development, as well as over the whole incubation period. Hatching success was lower at low and high temperatures and higher at intermediate ones during the second and last thirds of development. Optimal mean temperature ranges were 29–32 °C and 32–35 °C across the second and last thirds of development respectively, and 30–32.5 °C during the whole incubation period. There was no statistically significant effect of temperature on hatching success during the first third of development. High temperature resulted in shorter carapace width but did not statistically affect mass or carapace length. The temperature effect on carapace width occurred in all thirds of development. Studying temperature effects on target species nests at the local level, throughout incubation, and over multiple years is important for applying climate mitigation strategies properly. [ABSTRACT FROM AUTHOR]

To maximise reproductive fitness, species make trade-offs among reproductive traits, e.g., offspring quantity vs. offspring size, within energetic, anatomical, and physiological constraints. Sea turtles are a model taxon to study reproductive trade-offs, because they lack parental care and because there are strong selective pressures on hatchlings due to high predation rates. Natural selection therefore typically favours optimising offspring size over offspring quantity. Nevertheless, the balance between these traits varies between both sea turtle populations and species. Here, we quantified individual variation in reproductive traits of olive ridley turtles (Lepidochelys olivacea) in northwest Costa Rica. Olive ridley females displayed considerable inter-female variation in reproductive traits with larger females producing larger clutches. These larger females also produced longer and heavier hatchlings than smaller females despite producing similar sized eggs. Females did not exhibit a trade-off between clutch size and egg mass, although variation in clutch size (coefficient of variation = 16.8%) was greater than that of egg mass (10.1%). Producing more eggs per clutch had 1.8 times the effect of producing heavier eggs at increasing clutch mass. The effect of clutch frequency was 2.5 times that of clutch size on seasonal egg production and 2.4 times that of clutch size on seasonal hatchling production. In conclusion, olive ridley turtles exhibit considerable variation in reproductive traits, but their small body size constrains clutch size and has implications for their overall reproductive output., Author(s): Christopher R. Gatto [sup.1] , Nathan J. Robinson [sup.2] , James R. Spotila [sup.3] [sup.4] , Frank V. Paladino [sup.3] [sup.5] , Pilar Santidrián Tomillo [sup.3] Author Affiliations: (1) [...]

Sea turtles bury their eggs in nests at depths ranging from 25 to 100 cm. After hatching, turtles crawl up to the surface and emerge over several days. Some hatchlings fail to emerge and die in the sand column. In this study, we investigated the effect of the depth of the drying front (the region separating saturated and partially dry sand), number of hatchlings emerging, depth of nest and temperature on the emergence of hatchling leatherback turtles (Dermochelys coriacea) over the course of three nesting seasons (2008-2009, 2011-2012 and 2012-2013) at Playa Grande, Costa Rica. The depth of the drying front affected the number of hatchlings that failed to emerge in all years and high temperature reduced emergence rate in 2008-2009 and 2012-2013, but not in 2011-2012. Most of the variability in emergence rate was explained by the number of hatchlings emerging and the depth of the drying front. The number of dead hatchlings was mainly explained by the depth of the drying front and temperature. Depth zones within the sand column that included the drying front and the egg chamber registered the greatest number of dead hatchlings. The depth of the drying front, temperature and number of hatchlings remaining in the sand column increased and the emergence rate decreased as the season progressed. Leatherback turtles are critically endangered in the eastern Pacific Ocean. Conservation strategies towards improving the conditions in the nest environment (i.e. nest irrigation and shading to decrease the depth of the drying front and temperature) could boost hatchling production and contribute to revert declining population trends., Author(s): Jennifer Swiggs [sup.1] , Frank V. Paladino [sup.1] [sup.2] , James R. Spotila [sup.2] [sup.3] , Pilar Santidrián Tomillo [sup.2] [sup.4] Author Affiliations: (Aff1) 0000 0001 2285 0696, grid.257412.7, [...]

Oceanographic sampling is often limited to local and temporally concise assessments of complex, transient, and widespread phenomena. However, long-lived, migratory pelagic vertebrates such as leatherback turtles (Dermochelys coriacea, Vandelli 1761) can provide important integrated information about broad-scale oceanographic processes. Therefore, the present study analyzed stable carbon and nitrogen isotope ratios ([delta][.sup.13.C] and [delta][.sup.15.N]) of egg yolk and red blood cells from nesting leatherback populations from Costa Rica in the eastern Pacific in 2003-2004 and 2004-2005 and from St. Croix in the North Atlantic in 2004 and 2005 to establish differences between nutrient sourcing and its influence on higher trophic level consumers in both ocean basins. Whereas [delta][.sup.13.C] signatures were similar between Costa Rica (-19.1 [+ or -] 0.7[per thousand]) and St. Croix (-19.4 [+ or -] 1.0[per thousand]) leatherbacks, reflecting the pelagic foraging strategy of the species, Costa Rica leatherback [delta][.sup.15.N] signatures (15.4 [+ or -] 1.8[per thousand]) were significantly enriched relative to St. Croix leatherback [delta][.sup.15.N] signatures (9.8 [+ or -] 1.5[per thousand]). This [delta][.sup.15.N] difference likely reflects inter-basin differences in nitrogen cycling regimes and their influence on primary productivity being transferred through several trophic levels. Thus, high-order marine consumer movements, habitat preferences, and stable isotope signatures can be combined with ocean sampling to elucidate interactions between oceanographic processes and marine megafauna., Introduction Oceanographic sampling often has been confined to local 'snapshots' of processes that are actually widespread and transient, and models derived from such information are unable to fully characterize complexities [...]