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ECOLOGY OF CLADOCORA CAESPITOSA (LINNAEUS, 1767), THE MEDITERRANEAN STONY CORAL, IN THE NORTHERN ADRIATIC SEA (GULF OF TRIESTE)

Cladocora caespitosa is an endemic coral of the Mediterranean Sea and an important carbonate bioconstructor that adds 3D complexity to the habitat, thus increasing marine biodiversity. Despite its important role in the ecosystem, the real status of the population along the majority of the Mediterranean coastline is still poorly investigated while very little is known about the resilience of the species. Using non-destructive visual surveys, colonies of C. caespitosa were investigated by SCUBA- diving in 2013 at 7 sites along the southern part of the Gulf of Trieste. Besides, one site was also sampled in July 2015. Data about colony size, index of sphericity and corallite diameter along each transect were collected. Almost all biometrical parameters significantly differed among sampling sites showing low occurrence of the larger size classes, which were relatively rare, compared to the abundance of small-sized colonies. This pattern of distribution is typical of long lived organisms. The positively skewed colony size distribution could be attributed both to a high mortality rate of small colonies unable to reach larger size class and to high fragmentation rate of colonies due to high hyrodynamism force. The historical comparison of our data of Bernardin site with the Schiller (1993) studies (1984-1989) has shown a change in the colonies size distribution, with a decrement of the small class and an increase of the medium class. In view of these findings we think that further assessment is required in order to evaluate the trend of the northernmost C. caespitosa population of the Mediterranean Sea.

CLADOCORA CAESPITOSA, MEDITERRANEAN, STONY CORAL, NORTHERN ADRIATIC SEA, GULF OF TRIESTE

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