We investigated the spatial distribution, size structure, shell orientation and valve colonization by epibionts of the endangered Mediterranean bivalve Pinna nobilis in three continuous but different habitats in the Gulf of oristano (sardinia, western Mediterranean). the sampling stations chosen were: an estuarine area (e) of coastal salt-marshes characterized by unvegetated sea-bottoms; and two areas in a seagrass meadow characterized by an extensive Posidonia oceanica meadow (Mw) and patched mixed meadows of P. oceanica and Cymodocea nodosa (Me). We found significantdifferences in mean densities among stations and the highest value was found in the estuarine area. shell orientation showed that there was uniform circular distribution of specimens in the Mw station and a unimodal distribution in the Me and e stations, where specimens were set at 0°n and 10°nne, which is a pattern related to sea drift. shell epibiosis displayed differences between habitats. the highest valve colonization was in the estuary, with filamentousdark algae and Ostrea edulis reaching almost 90 percent of shell coverage. this study provides new information on habitat preferences and data for assessing local populations of P. nobilis that is useful for its conservation and improving the knowledge of its ecology.

Density, size structure, shell orientation and epibiontic colonization of the fan mussel Pinna nobilis L. 1758 (Mollusca: Bivalvia) in three contrasting habitats in an estuarine area of Sardinia (W Mediterranean)

ADDIS, PIERANTONIO
;
SECCI, MARCO;CAU, ANGELO
2009-01-01

Abstract

We investigated the spatial distribution, size structure, shell orientation and valve colonization by epibionts of the endangered Mediterranean bivalve Pinna nobilis in three continuous but different habitats in the Gulf of oristano (sardinia, western Mediterranean). the sampling stations chosen were: an estuarine area (e) of coastal salt-marshes characterized by unvegetated sea-bottoms; and two areas in a seagrass meadow characterized by an extensive Posidonia oceanica meadow (Mw) and patched mixed meadows of P. oceanica and Cymodocea nodosa (Me). We found significantdifferences in mean densities among stations and the highest value was found in the estuarine area. shell orientation showed that there was uniform circular distribution of specimens in the Mw station and a unimodal distribution in the Me and e stations, where specimens were set at 0°n and 10°nne, which is a pattern related to sea drift. shell epibiosis displayed differences between habitats. the highest valve colonization was in the estuary, with filamentousdark algae and Ostrea edulis reaching almost 90 percent of shell coverage. this study provides new information on habitat preferences and data for assessing local populations of P. nobilis that is useful for its conservation and improving the knowledge of its ecology.
2009
Se investigó la distribución espacial, la estructura de tallas, la orientación de las conchas y la colonización de las valvas por parte de epibiontes, de la especie protegida Pinna nobilis en el Golfo de Oristano (Cerdeña, Mediterráneo Occidental). Las estaciones de muestreo se encontraban en tres hábitats continuos pero diferentes: una zona estuarina (E) de humedales costeros caracterizada por un fondo sin vegetación; una zona caracterizada por una amplia pradera de Posidonia oceanica (Mw) y una tercera compuesta de una pradera mixta parcheada de P. oceanica y Cymodocea nodosa (Me). La máxima densidad media se encontró en el estuario. La orientación de las conchas indicó una distribución circular y uniforme de los ejemplares en la estación Mw, y una distribución unimodal en las estaciones Me y E, donde los ejemplares estaban orientados a 0°N y 10°N-NE, patrón relacionado con las corrientes dominantes. La epibiosis de las conchas mostró diferencias entre los hábitats. La máxima colonización de las valvas fue en el estuario, con algas brunas filamentosas y Ostrea edulis, llegando a casi el 90% de cobertura de la concha. Este estudio ha permitido obtener nuevos datos sobre el hábitat preferencial de P. nobilis, y evaluar las poblaciones locales proporcionando informaciones útiles para el conocimiento de la ecología y mejorar la conservación de esta especie.
Pinna nobilis; Bivalvia; Endangered species; Population density; Size distribution; Epibiosis; Sardinia; Western Mediterranean
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11584/95613
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