Population structure of the deep coral Desmophyllum dianthus associated with a lost fishing gear/ line

The habitats created by cold-water corals (CWC) are among the most complex in the deep ocean and they are considered biodiversity hotspots with incalculable biological richness. However, distribution of these coral populations on Mediterranean platforms remains relatively unknown and only six provinces with certain density of CWC are recognised to date. During an INTEMARES survey carried off the southeast Iberian Peninsula in 2020, a lost longline was recovered in one of the hauls using a hard bottom dredge. The abandoned gear revealed populations of CWC, mainly Desmophyllum pertusum (Linnaeus, 1758) and Desmophyllum dianthus (Esper, 1794). The present study aims to contribute providing information on the coral D. dianthus in the Mediterranean and extending the distribution range of CWC in the south-eastern Iberian Peninsula by means of a population analysis of the individuals found on the recovered gear. Abundance and density of D. dianthus observed on the gear were higher than reported in other CWC populations in the Mediterranean Sea. Furthermore, in light of the results, there is potential for more unidentified populations of D. dianthus and other CWC species to be established in the area. Results also confirm the role of unwanted anthropogenic debris as a substrate for sessile organisms. • Fill knowledge gaps based on the distribution of CWCs in the Mediterranean. • Undesirable anthropogenic residue as opportunity for sessile species as CWCs. • High abundance and density of D. dianthus on the Seco de Palos seamount. • Possibility of new high-density CWC “province” in the Mediterranean.