Environmental setting of deep-water oysters in the Bay of Biscay

• Published in: Deep-sea research. Part I, Oceanographic research papers Vol. 57; no. 12; pp. 1561 - 1572
• Main Authors: Van Rooij, D., De Mol, L., Le Guilloux, E., Wisshak, M., Huvenne, V.A.I., Moeremans, R., Henriet, J.-P.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-12-2010; Elsevier; Pergamon Press Inc
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; Autoecology; Bathymetry; Bay of Biscay; Biological and medical sciences; Biological oceanography; Canyons; Deep-water oysters; Fundamental and applied biological sciences. Psychology; Habitat; Invertebrates; Life Sciences; Marine; Marine ecology; Mollusca; MOW; Neopycnodonte; Neopycnodonte zibrowii; Oceans; Oysters; Protozoa. Invertebrata; Resuspension; Systematics. Geographical distribution; Bay of Biscay; Atlantic Ocean; North Atlantic; AN, North Atlantic; ANE, Atlantic, Mediterranean Outflow Water; ANE, Europe, Biscay Bay; Neopycnodonte zibrowii; Bay of Biscay; Resuspension; MOW; Canyons; Deep-water oysters; Habitat; Benthic organism; Gigantism; Deep water; Submarine canyon; Marine environment; Geographic distribution; Bivalvia; Invertebrata; Mollusca
• ISSN: 0967-0637; 1879-0119
• DOI: 10.1016/j.dsr.2010.09.002

We report the northernmost and deepest known occurrence of deep-water pycnodontine oysters, based on two surveys along the French Atlantic continental margin to the La Chapelle continental slope (2006) and the Guilvinec Canyon (2008). The combined use of multibeam bathymetry, seismic profiling, CTD casts and a remotely operated vehicle (ROV) made it possible to describe the physical habitat and to assess the oceanographic control for the recently described species
Neopycnodonte zibrowii. These oysters have been observed in vivo in depths from 540 to 846
m, colonizing overhanging banks or escarpments protruding from steep canyon flanks. Especially in the Bay of Biscay, such physical habitats may only be observed within canyons, where they are created by both long-term turbiditic and contouritic processes. Frequent observations of sand ripples on the seabed indicate the presence of a steady, but enhanced bottom current of about 40
cm/s. The occurrence of oysters also coincides with the interface between the Eastern North Atlantic Water and the Mediterranean Outflow Water. A combination of this water mass mixing, internal tide generation and a strong primary surface productivity may generate an enhanced nutrient flux, which is funnelled through the canyon. When the ideal environmental conditions are met, up to 100 individuals per m² may be observed. These deep-water oysters require a vertical habitat, which is often incompatible with the requirements of other sessile organisms, and are only sparsely distributed along the continental margins. The discovery of these giant oyster banks illustrates the rich biodiversity of deep-sea canyons and their underestimation as true ecosystem hotspots.
►
Neopycnodonte zibrowii oysters occur in a bathymetric range between 350 and 846
m. ►
N. zibrowii habitat requires steep slopes with overhanging banks and escarpments. ►This underestimated deep-water community occurs almost exclusively in canyons. ►Suitable habitats created by interplay between turbiditic and contouritic processes.