Cold-water coral growth in the Alboran Sea related to high productivity during the Late Pleistocene and Holocene

Cold-water corals are common along the Moroccan continental margin off Melilla in the Alboran Sea (western Mediterranean Sea), where they colonise and largely cover mound and ridge structures. Radiocarbon ages of the reef-forming coral species Lophelia pertusa and Madrepora oculata sampled from those structures, reveal that they were prolific in this area during the last glacial–interglacial transition with pronounced growth periods covering the Bølling–Allerød interstadial (13.5–12.8 ka BP) and the Early Holocene (11.3–9.8 ka BP). Their proliferation during these periods is expressed in vertical accumulation rates for an individual coral ridge of 266–419 cm ka− 1 that consists of coral fragments embedded in a hemipelagic sediment matrix. Following a period of coral absence, as noted in the records, cold-water corals re-colonised the area during the Mid-Holocene (5.4 ka BP) and underwater photographs indicate that corals currently thrive there. It appears that periods of sustained cold-water coral growth in the Melilla Coral Province were closely linked to phases of high marine productivity. The increased productivity was related to the deglacial formation of the most recent organic rich layer in the western Mediterranean Sea and to the development of modern circulation patterns in the Alboran Sea.