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Distribution of Cryphus vitreus (Born, 1778) (Brachiopoda) on transect P2 (Continental margin, French Mediterranean coast) investigated by submersible
Christian C. Emig and M.A. García-Carrascosa

Direct observations by submersible are recorded on a Provence transect, between 88 to 603 m. On the Bathyal detritic sand biocoenosis, characterized by the brachiopod Gryphus vitreus, extending from the shelf edge (103 m) down to 260 m, they corroborate the five distributional density zones of this brachiopod (in density, but not for all their bathymetric limits), previously estimated from dredging data, and the environmental factors responsible for this distribution. Nervertheless, the two deepest density zones have quite different bathymetric limits, i.e. Zone 4: 151-245 m (previously estimated 150-200 m), and Zone 5: 245-260 m (estimated 200-250 m). Near-bottom currents are directly responsible for the density zone extension and depht range of this biocoenosis, which corresponds to the intermediate Mediterranean water layer. The currents move perpendicular to the slope and their strongest velocity occurs over the offshore-shelf where the highest brachiopod density is recorded; however, according to the larger extension of Zone 4, the currents have a larger influence downwards than previously expected.

Keywords: Bathyal, Currents, Brachiopoda, Distribution, Mediterranean.
Contents of this volume Sci. Mar. 55(2) : 385-388 Back PDF
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