Population structure and conservation status of the red gorgonian Paramuricea clavata (Risso, 1826) in the Eastern Adriatic Sea

12 páginas, 5 figuras, 3 tablas.
Gorgonians are important structuring species of the Mediterranean hard-bottom communities that are threatened by disturbances such as increasing seawater temperature, mucilaginous events and destructive fishing, among others. In this study we assessed for the first time the population structure and conservation status of one of the most common gorgonians in the Eastern Adriatic Sea, the red gorgonian Paramuricea clavata. During late spring 2009, nine populations dwelling between 30 and 50 m depth were examined by SCUBA diving along 200 km of the Croatian coastline. The density ranged between 7 and 20 coloniesm 2 . The mean and maximum colony heights were 31.2 22.7 cm ( SD) and 138 cm, respectively. Two main patterns of P. clavata size frequency distributions were observed: the first one with a higher proportion of juveniles (~30%) observed mostly in the northernmost populations, and the second one with a higher proportion of larger colonies (>25% of colonies >40 cm in height). Regarding the disturbance impact level, the proportion of healthy colonies (with 60%) and the mean extent of injury (i.e. denuded axis or epibiosis) was 9.7 4% ( SD), indicating low impacts. Contrasting population size structures with high recruitment in mature populations provides new insights into the demographic structure of the Mediterranean gorgonian forests dwelling in their upper bathymetric range (
Part of the funding was provided by the Croatian Ministry of Culture through the grant allocated to Marine Explorers Society –“20,000 leagues” in 2009 and by the Croatian Ministry of Science and Education (project 119- 0362975-1226).