An analysis of the community structure of subtidal and intertidal benthic mollusks of the Inlet of Bano (Ria de Ferrol) (northwestern Spain)

A study of the benthic communities of the Inlet of Bano (Ria de Ferrol) (no rthwestern Spain) was carried out, encompassing the examination of 75 sampl ing stations (35 subtidal and 40 intertidal). Data were subjected to classi fication and ordination techniques. Two major assemblages were identified, and divided into five subgroups in terms of dominance of the species, const ancy, and fidelity, The subtidal zone was characterized by the Abra alba (W ood, 1802) community. It was structured in facies as follows: The Nucula ni tida Sowerby, 1833-Thyasira flexuosa (Montagu, 1803) facies, was the innerm ost, in the eastern area of the inlet; another facies existed in the transi tion toward the Clausinella fasciata (da Costa, 1778) community in the oute r inlet area. In the intertidal zone the Cerastoderma edule (Linne, 1758)-S crobicularia plana (da Costa, 1778) community was defined, which was also s tructured in facies: one facies, located at the mouth of the river, was dom inated by Hydrobia ulvae (Pennant, 1777); another facies, found in the inne r inlet area associated with a meadow of the seagrass Zostera noltii Hornem ., 1832, characterized by Bittium reticulatum (da Costa, 1778), Loripes lac teus (Linne, 1758), C. edule, Venerupis senegalensis (Gmelin, 1791), and Ri ssostomia membranacea (Adams, 1800), and a third facies, situated at the bo rder of the inlet, included Gibbula unbilicalis (da Costa, 1778), Littorina littorea (Linne, 1758), L. obtusata (Linne, 1758), V. senegalensis, etc., as dominant species. The analyses showed that sediment parameters (mainly g rain size), organic matter in the subtidal stations, and grain size and dep th are the most important factors governing the distribution and abundance of the communities.