First observations of deep-sea coral reefs along the Angola margin

Type Article
Date 2009-11
Language English
Author(s) Le Guilloux E.1, Olu KarineORCID1, Bourillet Jean-FrancoisORCID2, Savoye Bruno2, Iglesias S. P.3, Sibuet Myriam1
Affiliation(s) 1 : IFREMER, Ctr Brest, Dept Etud Ecosyst Profonds, Lab Environm Profond, F-29280 Plouzane, France.
2 : IFREMER, Ctr Brest, Dept Geosci Marines, F-29280 Plouzane, France.
3 : Museum Natl Hist Nat, UMR 5178, Stn Biol Marine, Dept Milieux & Peuplements Aquat, F-29182 Concarneau, France.
Source Deep Sea Research Part II: Topical Studies in Oceanography (0967-0645) (Elsevier), 2009-11 , Vol. 56 , N. 23 , P. 2394-2403
DOI 10.1016/j.dsr2.2009.04.014
WOS© Times Cited 33
Keyword(s) Lucinids, Habitat mapping, ROV, Lophelia pertusa, Deep sea corals, Angola margin
Abstract The West African continental slope is an important theatre for geological survey prospecting and drilling for hydrocarbons but little is known about local deep-sea biological communities at these depths. While shallow-water reefs are common and well-known features in the tropics, only few records of deep-water corals exist at low latitudes, and most of them have been reported by historical oceanographic cruises undertaking circum-navigations of the world. This study, based on a multi-disciplinary approach, presents a description of newly discovered deep-water coral reef communities along the Angola margin. Data from ROV, multibeam bathymetry, side-scan sonar and seismics from a deep-towed acoustic system (SAR) were used to describe the morphology of the coral mounds and their relationship with the local geological setting. The reef-building scleractinian coral Lophelia pertusa has colonised carbonate mounds that reach heights of ca. 30 in and follow an orientation that is correlated with salt tectonic processes. Recent erosion is suggested as a process that influences the shape of the mounds. Sixteen fish taxa were identified during the ROV video surveys, with some of them likely to have a strong affinity with dense-living corals. The species observed belong to families commonly associated with deep-water corals (i.e. Sebastidae, Berycidae, Lophiidae and Chaunacidae), except an abundant species belonging to the family Zoarcidae, rarely observed in this type of environment. Lucinidae shells were found around mounds. As this bivalve family is indicative of reduced sediment and generally associated with cold-seep environments, this finding could revive the debate over the relationship between the distribution of cold-water coral habitat and gas seeps. However, there is no present-day nutritional relationship between living coral and chemosynthetic-derived biomass. The possible role of fluid expulsion in carbonate precipitation acting as the first step for coral colonisation is nevertheless discussed.
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