Edaphisme et recrutement chez Venerupis decussata dans la lagune de Nador (Maroc) = Edaphism and recruitment in Venerupis decussata in Nador Lagoon (Morocco)
Zine, N.E.; Menioui, M.; Zaouali, J. (1997). Edaphisme et recrutement chez Venerupis decussata dans la lagune de Nador (Maroc) = Edaphism and recruitment in Venerupis decussata in Nador Lagoon (Morocco). Mar. Life 7(1-2): 17-28
In: Marine Life = Vie Marine. Institut Océanographique Paul Ricard: Marseille. ISSN 1168-3430; e-ISSN 2117-7368, more
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| Authors | | Top |
- Zine, N.E.
- Menioui, M.
- Zaouali, J.
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| Abstract |
The recruitment of the juvenile of the clam Venerupis decussata in the Nador lagoon was assessed in function of the variability of the edaphic and hydrologic conditions. Data analysis by the AFC was used to map this natural stock. There is an increasing gradient of abundance and of recruitment of the juvenile from stations where the substrate is muddy sand to the coarse sandy substrate. The granulometric optimum for the larval settlement In the Nador lagoon is a substrate constituted by at least 25 % of gravel, around 17 % of coarse sandy substrate and around 11 % of muddy sand. The survival of the larvas being fixed is dependent on a continuous food supply ensured by a permanent current of fresh water. The distribution of this species in the Nador lagoon is essentially of the agregative type. This is especially due to the relatively heterogeneous substrate in some sites and also to the limited fresh water supply. The direct discharge of used waters, the partial closing of its passes which prevents renewal of water inside the lagoon and installation of basins (17 ha) over much of the clam layer, have contributed of the silting up of the lagoon, to its confinment and, consequently, to the shrinkage of the clam natural stock. |
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