Abstract
<jats:p>This study provides a biogeographical characterization of protozoan endoparasite Haplosporidium pinnae's distribution following the associated Mass Mortality Event of endangered bivalve Pinna nobilis in 2016. The epizootic has reached mortality rates between 80% - 100% and was first reported in the south-western Mediterranean Sea. It has since spread to north-western waters, followed by the Tyrrhenian and Ionian seas of the central Mediterranean, and has most recently (2023) reached the Aegean sea and the Çanakkale Strait in Turkey, most likely due to oceanic currents or intermediate host transmissions. In this study, we use presence-only Ecological Niche Modelling (ENM) techniques with the Maximum Entropy (MaxEnt) software, in order to accurately predict habitat suitability as a proxy of distribution range of H. pinnae in relation to biotic and abiotic conditions, such as definitive host presence, surface current velocity, water temperature and salinity by collecting occurrence data from published articles and websites like the Global Biodiversity Information Facility (GBIF), as well as gathering environmental information from the Bio-ORACLE database. By comparing ENM projections under present and future scenarios, taking anthropogenic interferences, such as climate change, exploitation and global warming into account, we can analyse the consequences of these variables upon H. pinnae and other Haplosporidian parasite populations, as these species are highly sensitive to environmental conditions and are often extremely host-specific.</jats:p>