Depth segregation phenomenon and the macrofaunal diversity associated to Acanthocardia tuberculata (Linné, 1758) and Callista chione (Linnaeus, 1758), populations of the Northwest of Morocco.

Being a part of the Mediterranean ecosystem, the maritime zone included between M Diq and Ouad Laou ischaracterized by a biodiversity which has not hither to been studied, making difficult the implementation ofsuitable management measures. A study was undertaken to evaluate the existence of depth segregationbetween Acanthocardia tuberculata and Callista chione adults and juveniles in populations the Northwest ofMorocco, on the West part of its Mediterranean facades, and the macrofaunal diversity associated to this twospecies.Samples were collected from the infra-littoral zone between December 2009 and April 2010 at two samplingstations situated in the M fdiq lagoon and Kkaa srass. Sampling was undertaken at increasing depths (onetow per depth), between 0 metres and 20 depth, the tows were performed parallel to the shoreline. The sizefrequency distribution showed the predominance of smaller individuals ( 50 mm) in the intermediate deptharea (5-10 m depth) and the prevalence of larger individuals (.50 mm) at greater depths (15 m depth). Theclassic numeric descriptors were used for the characterization of the entities fauna and they indicatednaturally disturbed habitat, and that the species met in all of the stations resorts are fairly distributed.