Summer mortality of Crassostrea gigas (Thunberg) in relation to environmental rearing conditions

Type Article
Date 2005
Language English
Author(s) Soletchnik Patrick1, Lambert Christian2, Costil Katherine3
Affiliation(s) 1 : IFREMER, Lab Environm Ressources Poitou Charentes, F-17390 La Tremblade, France.
2 : Univ Bretagne Occidentale, Inst Univ Europeen Mer, Lab Sci Environm Marin, F-29280 Plouzane, France.
3 : Univ Caen Basse Normandie, IFREMER, UMR, Lab Biol & Biotechnol Marine, F-14032 Caen, France.
Source Journal of Shellfish Research (0730-8000) (The National Shellfisheries Association), 2005 , Vol. 24 , N. 1 , P. 197-207
WOS© Times Cited 56
Keyword(s) Summer mortality, Hydrology, Sediment, Marine ecosystem, Marennes Oleron Bay, Crassostrea gigas
Abstract The purpose of this study is to investigate summer mortality of the cupped oyster, Crassostrea gigas, in relation to culture practices in the traditional oyster production region of Marennes-Oleron (France). Four oyster rearing conditions, varying culture location ("on-" or "off-bottom"), and site depth (65% to 80% daily immersion termed "deep" or 45% to 65%, termed "shallow") were studied to compare biologic performance and maturation status of oysters, in relation to sediment and water column parameters. The most severe mortality occurred in June to July in "on-bottom" reared oysters (25%), as compared with 10% mortality in "off-bottom" cultured oysters. Oysters (shell and meat) grew significantly better when reared "off-bottom" than "on-bottom." Reproductive effort was almost double in "off-bottom" reared oysters, compared with those "on-bottom"; thus, reproduction cannot be directly related to mortality in this summer mortality event. Low glycogen content recorded for both "on" and "off-bottom" reared oysters in summer, confirmed the probable lack of food and/or the overstocking in the Marennes-Oleron Bay, but did not discriminated among culture conditions. Whatever the immersion depth ("deep" or "shallow" conditions), "on-bottom" cultured oysters were adversely affected in growth, reproductive effort, and survival suggesting a direct effect of the mud (the so called "mud effect") on the biologic performance of oysters cultured on the bottom. Data from monitoring of sediment redox potential, organic content, and ammonium release did not support hypotheses that these parameters were alone responsible for the observed differences in mortality events.
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Soletchnik Patrick, Lambert Christian, Costil Katherine (2005). Summer mortality of Crassostrea gigas (Thunberg) in relation to environmental rearing conditions. Journal of Shellfish Research, 24(1), 197-207. Open Access version :