Feeding rate of the oysterCrassostrea gigasin a natural planktonic community of the Mediterranean Thau Lagoon

• Published in: Marine ecology. Progress series (Halstenbek) 2000-10, Vol.205, p.171-184
• Main Authors: Dupuy, Christine, Vaquer, André, Lam-Höai, Thong, Rougier, Claude, Mazouni, Nabila, Lautier, Jacques, Collos, Yves, Le Gall, Solange
• Format: Article
• Language: English
• Subjects: Agricultural resources; Agricultural situation; Carbon; Diatoms; Lagoons; Microbiota; Oysters; Plankton; Taxa; Zooplankton
• ISSN: 0171-8630; 1616-1599

The Mediterranean Thau Lagoon is an important oyster farming area in Europe. Oyster growth rates are among the highest in France, although chlorophyllaconcentration is low. Previous studies have demonstrated that picophytoplankton, nano-microphytoplankton, dinoflagellates and loricate ciliates such as tintinnids are abundant. However, heterotrophic flagellates and aloricate ciliates have not been investigated. The aim of this study was to assess picophytoplankton, protist and zooplankton abundances in the Lagoon and to investigate the particular structure of the microbial food web, which may explain such paradoxical oyster growth. In oligotrophic waters in the Thau Lagoon, the picoeukaryoteOstreococcus tauriis the dominant autotrophic picoplankter, with an abundance maximum in summer. On 17 August 1998, following a rainfall event, pico- and nanophytoplankton abundances were not as high as expected and we observed a high abundance of large diatoms. At this time, the available carbon resources were produced by microphytoplankton (84.5%), and picoplanktonic cells represented only 1.27% in terms of carbon. Heterotrophic cells were low in abundance and constituted 5 μm flagellates, microphytoplankton, dinoflagellates, ciliates and large zooplankton were retained by the oyster gills. Only flagellates