Thermal constraints shape metabolic scaling and distribution of the tufted ghost crab (Ocypode cursor) in the Mediterranean Sea

Abstract

The Mediterranean Sea is undergoing significant environmental changes due to climate change and the introduction of non-native species, impacting biodiversity and ecosystem dynamics. Ocypode cursor (tufted ghost crab) has expanded its range, likely in response to changing thermal conditions.This study investigates the metabolic scaling of O. cursor across three active months (July, August, and September) under air- and water-breathing conditions during both daytime and nighttime. The results revealed seasonal variation in metabolic scaling, with significant differences in intercept values and scaling slopes among months. During daytime air-breathing conditions, metabolic rates increased in August and September regardless of body size, while at night in August, larger crabs exhibited higher metabolic rates. Under water-breathing conditions, smaller crabs showed greater metabolic responses in August during the day, whereas nighttime activity remained stable across months. These results indicate that temperature, diel cycle, and respiratory mode shape metabolic scaling as a comparative indicator of thermal performance rather than a direct proxy for fitness. Understanding these responses provides insight into O. cursors ecological flexibility and contributes to assessing ectotherm responses to ongoing Mediterranean warming.