Investigating invasion patterns of Callinectes sapidus and the relation with research effort and climate change in the Mediterranean Sea.

The ecological stability of Mediterranean marine ecosystems is increasingly threatened by invasive alien species (IAS). This study examines the invasion dynamics of Callinectes sapidus, a high-risk and readily identifiable IAS across the Adriatic, Ionian, and Central Mediterranean subregions. A comprehensive dataset of published scientific and local ecological knowledge (LEK) records was compiled to analyze spatial and temporal patterns of diffusion. An increase in reported occurrences was found across the entire study area, spreading from south to north. Heterogeneous sampling methods hinder direct comparisons across regions, underscoring the need for standardized reporting protocols. LEK supported the clarification of overall patterns of C. sapidus diffusion and enhanced the resolution of temporal and spatial distribution data. The temporal progression of the invasion aligns with phases of arrival, establishment, and expansion. A close association was observed with both research effort and rising sea surface temperatures (SST). This study highlights the importance of integrating climate data and community-based knowledge in IAS monitoring and demonstrates a methodology for assessing climate-linked biological invasions in marine environments.