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Id Hall M.,National Institute for Fisheries Research | Serghini M.,National Institute for Fisheries Research | Houssa R.,National Institute for Fisheries Research
Journal of Materials and Environmental Science | Year: 2011

A companion assessment of natural accumulation of sea urchin Paracentrotus lividus realized in June 2009 in the region of El Jadida-Safi. This assessment has revealed the existence of a coast-wide gradient of density and size that proportionate inversely with 80% of individuals covering the first 10 m while individuals of intermediate size and large live in medium to large depths. In contrast this study clearly reveals the interrelationship urchin / algae on one hand and the nutritional aggregation on the other hand. It notes that young individuals whose size <30 mm are generally fed of Ulva lactuca, Halopitys incurvus, Cystoseira baccata and Bifurcaria bifurcata. While Gracilaria multipartita, Laminaria digitata, Plocamium cartilagineum and Geliduim sesquipedale are feeding individuals of average size. Plocamium cartilagineum and Geliduim sesquipedalen which persist in the great depths feed bigger echinoids.

Rharrass A.,National Institute for Fisheries Research | Talbaoui M.,National Institute for Fisheries Research | Idhalla M.,National Institute for Fisheries Research
Journal of Materials and Environmental Science | Year: 2011

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

Somoue L.,National Institute for Fisheries Research | Ettahiri O.,National Institute for Fisheries Research | Makaoui A.,National Institute for Fisheries Research
Journal of Materials and Environmental Science | Year: 2011

The marine phytoplankton was studied in january and july 2002 in four transects: 32°30'N, 29°N, 24°30'N and 24°N. Water samples were collected at four depths (surface, 10m, 30m and 50m).The total microalgal density shows that the southern area is more productive than the northern. The maximum of density is recorded at -30m depth in winter and -10m in summer in all transects. The analysis of the spatiotemporal variation of the physicochemical parameters shows an activity of upwelling during summer in whole transects, while in winter no marked gradient of physicochemical parameters was detected, except in Dakhla (24°N), where a cold filament was observed. Generally, the upwelling activity, the presence of filaments and the morphology of the coast determine largely the spatiotemporal variability of phytoplankton in the studied areas.

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