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Feeding rate of the oyster Crassostrea gigas in a natural planktonic community of the Mediterranean Thau Lagoon

2000; Inter-Research; Volume: 205; Linguagem: Inglês

10.3354/meps205171

1616-1599

Christine Dupuy, André Vaquer, T. Lam-Hoai, C. Rougier, Nabila Mazouni, Jacques Lautier, Yves Collos, Solange Le Gall,

Algal biology and biofuel production

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 205:171-184 (2000) - doi:10.3354/meps205171 Feeding rate of the oyster Crassostrea gigas in a natural planktonic community of the Mediterranean Thau Lagoon Christine Dupuy1,2,* André Vaquer3, Thong Lam-Höai3, Claude Rougier3, Nabila Mazouni4, Jacques Lautier3, Yves Collos3, Solange Le Gall1 1CNRS/IFREMER, UMR 10, CREMA L¹Houmeau, BP 5, 17137, L¹Houmeau, France 2LBEM, Université de La Rochelle, EA 3168 Pôle Science Av. Michel crépeau, 17042 La Rochelle, France 3Laboratoire d¹Hydrobiologie, UMR 5556 and URM 5, Université Montpellier II, 34095 Montpellier Cedex 05, France 4IFREMER-Sète, BP 171, 34203 Sète, France *E-mail: cdupuy@ifremer.fr ABSTRACT: The Mediterranean Thau Lagoon is an important oyster farming area in Europe. Oyster growth rates are among the highest in France, although chlorophyll a concentration 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 picoeukaryote Ostreococcus tauri is 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\#000), and picoplanktonic cells represented only 1.27\#000 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 <5 µm and O. tauri were not very well retained (45 and 2\#000 respectively). The high clearance rates of C. gigas found in this experiment can be explained by a low concentration of suspended particulate matter (0.65 mg l-1). The oysters adapted their retention mechanism when they lived in oligotrophic waters. These results indicate that, under the given experimental conditions, picophytoplankton did not represent a valuable trophic resource for farmed oysters because (1) C. gigas cannot retain picoparticles and (2) the picoplankton represented a poor carbon resource capable of being transferred via a weak heterotrophic protist community. In the oyster pens of the Thau Lagoon during this study, microphytoplanktonic primary producers, in particular diatoms, were the main food sources for bivalve suspension feeders. KEY WORDS: Bivalve · Oyster · Food source · Thau Lagoon · Microbial food web · Heterotrophic protist · Picophytoplankton · Trophic link Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 205. Online publication date: October 19, 2000 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2000 Inter-Research.