Effects of the 2015 heat wave on benthic invertebrates in the Tabarca Marine Protected Area (southeast Spain)

In the late summer of 2015, extensive mortality of scleratinian corals, gorgonians, and sponges was observed in the Marine Protected Area of Tabarca (southeast Spain). Quantitative data indicated that at 25 m depth the sea fan Eunicella singularis was the most affected species (50% of colonies affected by partial mortality); while in shallow waters more than 40% of the endemic scleractinian coral Cladocora caespitosa population showed tissue lesions that affected more than 10% of their surfaces. Other affected species were the scleractinian corals Oculina patagonica and Phyllangia mouchezii, the sea fan Leptogorgia sarmentosa and the sponge Sarcotragus fasciculatus. This mortality event coincided with an abnormal rise in seawater temperature in this region. Microbiological analysis showed a higher abundance of culturable Vibrio species in invertebrates exhibiting tissue lesions, which indicated that these opportunistic pathogens could be a key factor in the process.