The discovery of deep water oyster banks on the French continental margin may indicate the presence of a unique hydrodynamic environment and could change the current understanding of oceans past.

On an expedition in the Bay of Biscay off the coast of France, the ROV Genesis, transmitted video observations back to the crew aboard the RV Belgica. At a depth of 650 m, they came across something unexpected: a reef of large oysters. While deep water banks of oysters had been reported in the past from dredge surveys, they had not been observed in their natural state at depth. Visually identified as belonging to the genus Neopynodonte, researchers surmise that these specific banks of oysters are comprised of a new species or sub-species. This is due to the fact that these specimens were observed at deeper depths than any recorded samples of Neopynodonte cochlear, the only deep-sea oyster known to inhabit the Atlantic Ocean and Mediterranean seas.

These deep-sea oyster communities, which inhabit the flanks of underwater canyons leading from the continental shelf waters down to the deep ocean basins, may be a component of a critical deep water ecosystem that has just been discovered through Census of Marine Life research. Potentially at risk of degradation from deep-sea fisheries activity and ocean acidification, these oysters could provide new insight into the ocean environment of the past. Because their presence may be indicative of a very specific set of environmental conditions such as a unique hydrodynamic environment, studies of fossilized Neopycnodonte (or closely related species) could provide more detail about the sea during time they lived. Thus, by gaining new knowledge about these communities and how they live today, we can develop a more complete picture of the seas of yesterday.

The most important aspect of this discovery is the observation of these oysters in their natural habitat. The video observations allowed researchers to visualize the 3-D nature of the reef structure, whereas past dredge samples only indicated their presence, giving no information regarding the morphology of the reef. Present technology has also allowed the mapping of these newly discovered reefs so that a clearer picture of the range and distribution of these oysters may be constructed. However, the visual nature of these observations still leaves many unanswered questions. Additional research has been planned to further investigate these communities and to attempt to sample live specimens so that phylogenetic analysis may be performed.

Discovery Location: On the La Chapelle continental slope off of France in ht Bay of Biscay, Northeast Atlantic Ocean.

• What: Discovery of deep water oyster banks may challenge how scientist view past ocean habitats.
• Who: COMARGE Scientists --> J.P. Henriet, D. Van Rooij, E. Le Guilloux, A. Foubert, V. Huvenne, and A. Wheeler
• When: June 2006
• Where: On the La Chapelle continental slope (7° 19'55" W / 47° 33'45"N) off of France in the Bay of Biscay, Northeast Atlantic ocean
• How: Video observation using the ROV Genesis
• References: No publication to date