New contribution on distribution and ecology of Dendrophyllia ramea (Linnaeus, 1758): abundance hotspots off the Northeastern Sicilian waters

Description

1. Dendrophyllia ramea is a poorly known arborescent scleractinian coral, whose worldwide distribution is limited to the southern part of the Mediterranean basin, and to the Atlantic Ocean between Macaronesia and Gulf of Cadiz. The geographical distribution and abundance of D. ramea were herein updated, considering a total of 19 records, seven of which have never previously been reported in scientific papers. 2. Between 2010 and 2017, five Remotely Operative Vehicle surveys carried out along the Sicilian coast recorded 89 colonies. No exhaustive data on density and ecology of this species have been published to date. Data for two areas off the north-eastern Sicilian waters (Aeolian Island and Gulf of Patti) are reported, including the species' bathymetric distribution, abundance, population density, colony morphometry, population size structure and surrounding habitat description. 3. Size structure and density of D. ramea populations were compared with lost fishing gear density. Around the Aeolian Islands, where little lost fishing gear was observed, the D. ramea population was denser compared with the populations at two sites within the Gulf of Patti, where a greater amount of lost fishing gear was observed. The analysis of D. ramea size classes (single corallite, 2–5 polyps, >5 polyps) at different sites showed that impact varied with fishing gear typology: while lines damage the branches of larger colonies, nets can completely remove them. 4. The limited distribution of D. ramea in some areas also makes this species very vulnerable to impacts such as changes in the chemical–physical characteristics and circulation of sea water. Dendrophyllia ramea is classified as 'Vulnerable' according to the Mediterranean IUCN Red List, and it is listed in the Barcelona Convention (Annex B). Data on the distribution of D. ramea allows us to review the species' classification and propose that its status be changed to 'Endangered'.

Additional details