Abstract

Posidonia oceanica (L.) Delile, endemic species of the Mediterranean sea, forms extensive meadows in the infralittoral coastal seawaters of the basin. Actually, Posidonia beds are suffering a fast regression caused by marine pollution and by an increasing human pressure. However, in these last decades the warming trend of Mediterranean coastal waters have caused an increase of Posidonia flowering events, as a consequence of a sexual reproduction of the species, especially along the Western Mediterranean coasts of Italy. This study shows all the flowering events occurred along Italian coasts in last decades, reporting a lot of records in the Western Mediterranean basin. The research highlights a clear link between the increasing trend of flowering events and the gradual rise of Sea Surface Temperature occurring in the Western Mediterranean seawaters. A case study reporting a massive flowering event in the Calabria Tyrrhenian coast, occurred in the year 2025, confirms this increasing trend and the shift of reproductive modes of the species towards sexual reproduction. So, Posidonia oceanica could represent an early signal of a climate change scenario.

Keywords:Posidonia flowerings; Sea olives; Seedlings; Sea surface temperatures; Italian coasts