Living reefs and CWC mounds in the Alboran Sea (Western Mediterranean). Holocene evolution and present-day conditions

• Main Authors: Lo Iacono, Claudio, Gràcia, Eulàlia, García-Ladona, Emilio, Gili, Josep Maria, Emelianov, Mikhail, Grinyó, Jordi, Perea, Héctor, Van Rooij, D.
• Format: Conference Object
• Language: unknown
• Published: 2016
• Subjects: Lophelia pertusa
• Online Access: http://hdl.handle.net/10261/172033

Lo Iacono, Claudio . et al.-- 6th International Symposium on Deep-Sea Corals (ISDSC), 11-16 September 2016, Boston We present recent insights on early Holocene to present spatio-temporal evolution of Cold-Water Coral (CWC) Mounds in the Moroccan Alboran Sea (Western Mediterranean). Despite most Alboran CWC mounds nowadays being inactive, new findings revealed the existence of living extensive reefs of Lophelia pertusa and Madrepora oculata. The West Melilla region consists of two clusters of elliptical mounds, ~45 m high, at 400-460m depth. Cabliers is a 25 km long, 140m tall CWC ridge, at 250-710m depth. Stratigraphic analysis, species composition, X-Ray CT scans and radiocarbon dating of gravity cores reveal intense coral growth 13.9-9.8ky BP. The demise of suitable conditions for CWCs in the Alboran Sea roughly coincides with the end of the Organic Rich Layer 1, ~9.2ky BP, as also confirmed by preliminary geochemical analyses. Nevertheless, the northern Cabliers Mound displays constantly high accretion rates until the present, corroborated by ROV footage revealing exceptional dense and thriving reefs distributed over at least 2 km along the top of Cabliers. The mixed Mediterranean-Atlantic ecological signature of the reefs is evident in the co-existence of large Madrepora and Lophelia colonies and their associated fauna. The advection of chlorophyll-rich Atlantic Waters (AW ) in the Mediterranean controls the particularly suitable conditions along the reefs, as confirmed by 35 surface CODE drifters (Medess-Gib experiment) transported to Cabliers following the Eastern Alboran Gyre, suggesting enriched food delivery. This work challenges the traditional notions of environmental factors controlling CWC proliferation, specifically in the Mediterranean, with relevant implications for the conservation of deep-sea natural resources Peer Reviewed