Thermal resilience at the sand-air interface: linking metabolism, habitat suitability, and activity patterns in Ocypode cursor under natural temperature fluctuations

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Understanding how semi-terrestrial ectotherms respond to thermal variability is essential for predicting their resilience to climate warming. We investigated the thermal tolerance and metabolic performance of the Mediterranean tufted ghost crab Ocypode cursor , a protected species expanding its range northward in the Mediterranean Sea. Using in situ respirometry across a wide temperature gradient (12-36°C), we established the first thermal performance curve (TPC) for the species and coupled it with high-frequency sand temperature records to derive a thermal habitat suitability (THS) index. The results revealed a relatively restricted thermal performance range, with an optimal metabolic temperature (T opt ) of 24.3°C and model-derived performance thresholds between 21.8 and 33.5°C, defining a limited thermal performance margin (≈ 9°C). Daily and seasonal THS dynamics closely matched observed activity rhythms, showing that crabs were active during early-morning or nocturnal periods when surface temperatures fell within the range of maximal aerobic performance, and inactive during cooler or excessively warm phases. This study’s coupling of physiology, microhabitat temperature, and behavior underscores the role of burrows as key thermal refuges enabling persistence under fluctuating conditions. By integrating physiological and environmental data, this study provides a predictive framework for assessing the vulnerability and adaptive capacity of O. cursor populations. These insights offer valuable guidance for the conservation and management of Mediterranean sandy beaches, where increasing heat stress and anthropogenic disturbance threaten this emblematic species and its habitat.

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