Offshore brachiopods investigated by submersible

摘要: The distributional limits and densities of the brachiopod Gryphus vitreus (Born) are investigated for first time by submersible, along transects over “Banc du Magaud” (east Hyeres islands, Provence, France). offshore bottoms, on which G. biocoenosis occurs (110 to 250 m), can be divided into three zones. highest density (up 600 individuals·m−2) is observed in large ripplemarks under strong bottom currents (1.5-2 knots) Zone 2 (130–180 while lower (< 10·m−2) 1 (110–130m) 3 (180–250 m, a Quaternary thanatocoenosis) where weaker (0.5-1 knot). ecological requirements vitreus, stenotopic species, high hydrodynamic conditions (inducing weak sedimentation, nutrients supplies, sandy sediment with small hard substrata) an annual constancy temperature salinity. arrangement shells relation current (Zone 2) analysed. Paleoecological implications branchiopods suggested. A green alga recorded depths 190 m.