Distribución batimétrica, abundancia y diversidad de las poblaciones de moluscos bentónicos del litoral catalán

Resum

Bathymetric distribution, abundance and diversity of the benthic molluscan populations of the Catalan coast (NE Spain)
Nearly one hundred and fifty samples of the hard bottoms of six localities of the Catalan coast have been obtained using scuba diving equipment between 0 and 40 m deep. They have been studied quantitatively to acquire some knowledge of the distribution and ecology of nearly two hundred molluscan species. A first evaluation has been made of: the abundance of species in each leve1 (0, 5, 10, 20 and 40 m) and sampling locality (Cadaqués, Medes islands, Blanes, Vilassar de Mar, Garraf and I’Ametlla de Mar); the bathymetric distribution of each species, with an estimate of the exclussive forms in each of the considered depth levels; and the species diversity of the samples. Data on diversity follow the well-known pattern of increase with depth and/or environmental stability. The minimal sampling area (20 x 20 cm of hard substrates peeled off to obtain the associated flora and fauna), seems insufficient for deep (more than 15-20 m) and/or stable cornmunities, like the coralligenous. The abundance and bathymetric distribution of the molluscan species are given and discussed.