Temperature Conditions in Artificial Sea Turtle Nests: Toward Optimized Hatchery Management

Climate change poses a significant threat to species with temperature-dependent sex determination, such as sea turtles. Their conservation often involves relocating nests to hatcheries, which is also crucial on the Pacific coast of Guatemala, where virtually no hatchlings emerge from natural nests. Populations there rely heavily on hatcheries, yet nest temperature monitoring in relation to environmental and management factors is rarely conducted. Research is needed to improve artificial nest management and hatchery design. This study investigated how distance to the hatchery wall, number of eggs, position in the nest, development period, season, and weather conditions influenced temperature variation in Olive Ridley Turtle (Lepidochelys olivacea) nests. We generally found nest temperatures within viable ranges and near the pivotal temperature for Olive Ridleys. The pivotal temperature of Olive Ridley was exceeded 6%-21% of the time during the thermosensitive period of all nests (starting days 9-15 and ending days 33-37 of incubation), and the upper thermal tolerance limit was rarely reached. However, nests closer to concrete walls were up to 1°C warmer than those farther away, and 30-40 more eggs per nest raised average temperatures by 0.7°C. These findings suggest that distance to hatchery walls and egg numbers per nest can be tools to manipulate nest temperatures and sex ratios. The sex ratios in this study were slightly female-biased. However, optimal sex ratios remain poorly understood, and reliance on ex situ incubation may reduce population adaptability to environmental changes. Ex situ nest conditions in our study displayed lower temperatures than potential in situ conditions, which exceeded the lethal threshold in 86% (z-test, p < 0.001) of the measurements. Our study emphasizes the need for careful hatchery management to safeguard sea turtles against the effects of climate change but also to avoid the consequences of overcompensation due to mismanagement.