Towards a local mass mortality of the Mediterranean orange coral Astroides calycularis (Pallas, 1766) in the Pelagie Islands Marine Protected Area (Italy)

In late summer 2020, a widespread mortality event severely affected colonies of the Mediterranean endemic orange coral Astroides calycularis in the Pelagie Islands (Strait of Sicily, southern Mediterranean Sea). The degree of the mortality impact at seven study sites of the archipelago (five within the Pelagie Islands Marine Protected Area) was quantified by estimating the proportion of affected colonies in populations of A. calycularis. Five of the seven surveyed sites revealed a low degree of impact, but Punta Ruperta and Cala Creta (both on the island of Lampedusa) showed a medium impact with values of 32.3% and 30.5% of affected colonies respectively. The 2020 mortality event coincided with a longer lasting and warmer anomalous summer period, with sea surface water reaching the highest temperatures recorded in the last decade across the archipelago. Given the alarming climatic predictions for the near future, new mortality events could occur, causing potentially new local extinctions in the Mediterranean Sea. In this context, the role of marine protected area management becomes crucial to detect mortality events of vulnerable species.