Spatio-temporal changes in mortality, growth and condition of the pacific oyster, Crassostrea gigas, in Normandy (France)
Summer mortalities have been observed in French shellfish areas (including Normandy) since 1994, but origin of this syndrome remains unclear and is suspected to be caused by a combination of several interacting extrinsic (biotic and abiotic) and intrinsic (genetic, physiological, immunological) fact...
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ftarchimer:oai:archimer.ifremer.fr:4733 2023-05-15T15:58:32+02:00 Spatio-temporal changes in mortality, growth and condition of the pacific oyster, Crassostrea gigas, in Normandy (France) Royer, J Ropert, Michel Costil, K 2007-12 application/pdf https://archimer.ifremer.fr/doc/2007/publication-4733.pdf https://archimer.ifremer.fr/doc/00000/4733/ eng eng National Shellfisheries Association https://archimer.ifremer.fr/doc/2007/publication-4733.pdf https://archimer.ifremer.fr/doc/00000/4733/ 2007 National Shellfisheries Association info:eu-repo/semantics/openAccess restricted use Journal of Shellfish Research (0730-8000) (National Shellfisheries Association), 2007-12 , Vol. 26 , N. 4 , P. 973-984 France English Channel Growth Summer mortality Crassostrea gigas Oyster text Publication info:eu-repo/semantics/article 2007 ftarchimer 2021-09-23T20:16:18Z Summer mortalities have been observed in French shellfish areas (including Normandy) since 1994, but origin of this syndrome remains unclear and is suspected to be caused by a combination of several interacting extrinsic (biotic and abiotic) and intrinsic (genetic, physiological, immunological) factors. The French research program, MOREST aimed to identify the origin of oyster summer mortality along the French coast, focusing on the interactions between oysters, their pathogens, and the environment. The present study analyzed spatio-temporal variation in growth, condition and mortality in spat, and half-grown and market-sized oysters reared from February 2000 to October 2003 at six stations within two different areas in the Bay of Veys, Normandy: Grandcamp (GR), and Gefosse (GE) that is more estuarine. These biological parameters were compared between years, age groups, and areas. Results showed that shell growth was significantly lower in the station highest on the shore and similar in the four other sites, whereas tissue growth and condition index were higher in the Gefosse area. Results also showed large interannual, interage, seasonal and spatial variation in oyster mortality. In 2001, mortalities were markedly higher than in other years and all batches and sites were affected by high mortality rates. Moreover oysters suffered much higher mortalities in their second and third years than as spat, and the difference between age classes was accentuated when mortality was high. Increases in mortality occurred when the gonad was most extensively developed and the peak coincided with the spawning and postspawning periods when gonad volume began to decrease. Spatial variability showed that mortality was higher in Gefosse than Grandcamp. Chronology and spatial variations in mortality highlighted the importance of timing and confirmed that mass mortalities may be closely linked to reproduction. The risk seems to be associated with high reproductive effort, partial spawning, and/or slow gonad resorption. Spatial variation also suggests that the study sites experience varying degrees of stress caused by biological changes and probable differences in water quality reflecting the influence of freshwater input in Gefosse where mortality is higher. Article in Journal/Newspaper Crassostrea gigas Pacific oyster Archimer (Archive Institutionnelle de l'Ifremer - Institut français de recherche pour l'exploitation de la mer) Pacific |
institution |
Open Polar |
collection |
Archimer (Archive Institutionnelle de l'Ifremer - Institut français de recherche pour l'exploitation de la mer) |
op_collection_id |
ftarchimer |
language |
English |
topic |
France English Channel Growth Summer mortality Crassostrea gigas Oyster |
spellingShingle |
France English Channel Growth Summer mortality Crassostrea gigas Oyster Royer, J Ropert, Michel Costil, K Spatio-temporal changes in mortality, growth and condition of the pacific oyster, Crassostrea gigas, in Normandy (France) |
topic_facet |
France English Channel Growth Summer mortality Crassostrea gigas Oyster |
description |
Summer mortalities have been observed in French shellfish areas (including Normandy) since 1994, but origin of this syndrome remains unclear and is suspected to be caused by a combination of several interacting extrinsic (biotic and abiotic) and intrinsic (genetic, physiological, immunological) factors. The French research program, MOREST aimed to identify the origin of oyster summer mortality along the French coast, focusing on the interactions between oysters, their pathogens, and the environment. The present study analyzed spatio-temporal variation in growth, condition and mortality in spat, and half-grown and market-sized oysters reared from February 2000 to October 2003 at six stations within two different areas in the Bay of Veys, Normandy: Grandcamp (GR), and Gefosse (GE) that is more estuarine. These biological parameters were compared between years, age groups, and areas. Results showed that shell growth was significantly lower in the station highest on the shore and similar in the four other sites, whereas tissue growth and condition index were higher in the Gefosse area. Results also showed large interannual, interage, seasonal and spatial variation in oyster mortality. In 2001, mortalities were markedly higher than in other years and all batches and sites were affected by high mortality rates. Moreover oysters suffered much higher mortalities in their second and third years than as spat, and the difference between age classes was accentuated when mortality was high. Increases in mortality occurred when the gonad was most extensively developed and the peak coincided with the spawning and postspawning periods when gonad volume began to decrease. Spatial variability showed that mortality was higher in Gefosse than Grandcamp. Chronology and spatial variations in mortality highlighted the importance of timing and confirmed that mass mortalities may be closely linked to reproduction. The risk seems to be associated with high reproductive effort, partial spawning, and/or slow gonad resorption. Spatial variation also suggests that the study sites experience varying degrees of stress caused by biological changes and probable differences in water quality reflecting the influence of freshwater input in Gefosse where mortality is higher. |
format |
Article in Journal/Newspaper |
author |
Royer, J Ropert, Michel Costil, K |
author_facet |
Royer, J Ropert, Michel Costil, K |
author_sort |
Royer, J |
title |
Spatio-temporal changes in mortality, growth and condition of the pacific oyster, Crassostrea gigas, in Normandy (France) |
title_short |
Spatio-temporal changes in mortality, growth and condition of the pacific oyster, Crassostrea gigas, in Normandy (France) |
title_full |
Spatio-temporal changes in mortality, growth and condition of the pacific oyster, Crassostrea gigas, in Normandy (France) |
title_fullStr |
Spatio-temporal changes in mortality, growth and condition of the pacific oyster, Crassostrea gigas, in Normandy (France) |
title_full_unstemmed |
Spatio-temporal changes in mortality, growth and condition of the pacific oyster, Crassostrea gigas, in Normandy (France) |
title_sort |
spatio-temporal changes in mortality, growth and condition of the pacific oyster, crassostrea gigas, in normandy (france) |
publisher |
National Shellfisheries Association |
publishDate |
2007 |
url |
https://archimer.ifremer.fr/doc/2007/publication-4733.pdf https://archimer.ifremer.fr/doc/00000/4733/ |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
Crassostrea gigas Pacific oyster |
genre_facet |
Crassostrea gigas Pacific oyster |
op_source |
Journal of Shellfish Research (0730-8000) (National Shellfisheries Association), 2007-12 , Vol. 26 , N. 4 , P. 973-984 |
op_relation |
https://archimer.ifremer.fr/doc/2007/publication-4733.pdf https://archimer.ifremer.fr/doc/00000/4733/ |
op_rights |
2007 National Shellfisheries Association info:eu-repo/semantics/openAccess restricted use |
_version_ |
1766394287457566720 |