Low settlement of the pacific oysters Crassostrea gigas in the Thau lagoon reflects competition for space and food
The objective of this work is to understand why oysters Crassostrea gigas shows low settlement success in the Thau lagoon despite the fact that biomass of adults is elevated and that larvae show normal development in the water column. Our hypotheses are that oysters compete for food or space with ot...
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Pysiomar 2010, October 31st to November 4th, Québec, Canada
2010
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ftarchimer:oai:archimer.ifremer.fr:12665 2023-05-15T15:58:20+02:00 Low settlement of the pacific oysters Crassostrea gigas in the Thau lagoon reflects competition for space and food Rayssac, Nathalie Malet, Nathalie Pernet, Fabrice 2010-10 application/pdf https://archimer.ifremer.fr/doc/00015/12665/9555.pdf https://archimer.ifremer.fr/doc/00015/12665/ eng eng Pysiomar 2010, October 31st to November 4th, Québec, Canada https://archimer.ifremer.fr/doc/00015/12665/9555.pdf https://archimer.ifremer.fr/doc/00015/12665/ 2010 Ifremer info:eu-repo/semantics/openAccess restricted use text Poster info:eu-repo/semantics/conferenceObject 2010 ftarchimer 2021-09-23T20:18:41Z The objective of this work is to understand why oysters Crassostrea gigas shows low settlement success in the Thau lagoon despite the fact that biomass of adults is elevated and that larvae show normal development in the water column. Our hypotheses are that oysters compete for food or space with other filter-feeders animals such as sponges, ascidians and other bivalves. To test the trophic hypothesis, we analysed the entire settler community harvested on four-month-old collectors deployed in the Thau lagoon during the summer 2009 for stable isotopes and fatty acids. Based on the isotopic, crustacean amphipods and barnacles can be rejected as a potential food competitor of juvenile oysters. However, other bivalves such as Mytilus sp., Anomia sp., and sponges seem to feed on the same diet. Our results also suggest that the ascidian Ascidiella sp. is the major food competitor of oysters followed by two other ascidian species and the bivalve Lima sp. To test the space hypothesis, sets of collectors were (1) maintained always underwater, which is normally the case in the Thau lagoon where tides are marginal, or (2) manually emerged every weeks to reduce the development of subtidal species. After few weeks, the collectors maintained underwater were dominated by sponges and ascidian whereas the regularly emerged collectors were successfully colonised by oysters and barnacles. This experiment clearly suggests that settlement of pacific oysters in the Thau lagoon is constrained by competition for space with other subtidal species. From a practical standpoint, it seems that it is possible to enhance spat collection of oysters until attaining commercial profitability by regularly emerging the collectors. Conference Object Crassostrea gigas 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 |
description |
The objective of this work is to understand why oysters Crassostrea gigas shows low settlement success in the Thau lagoon despite the fact that biomass of adults is elevated and that larvae show normal development in the water column. Our hypotheses are that oysters compete for food or space with other filter-feeders animals such as sponges, ascidians and other bivalves. To test the trophic hypothesis, we analysed the entire settler community harvested on four-month-old collectors deployed in the Thau lagoon during the summer 2009 for stable isotopes and fatty acids. Based on the isotopic, crustacean amphipods and barnacles can be rejected as a potential food competitor of juvenile oysters. However, other bivalves such as Mytilus sp., Anomia sp., and sponges seem to feed on the same diet. Our results also suggest that the ascidian Ascidiella sp. is the major food competitor of oysters followed by two other ascidian species and the bivalve Lima sp. To test the space hypothesis, sets of collectors were (1) maintained always underwater, which is normally the case in the Thau lagoon where tides are marginal, or (2) manually emerged every weeks to reduce the development of subtidal species. After few weeks, the collectors maintained underwater were dominated by sponges and ascidian whereas the regularly emerged collectors were successfully colonised by oysters and barnacles. This experiment clearly suggests that settlement of pacific oysters in the Thau lagoon is constrained by competition for space with other subtidal species. From a practical standpoint, it seems that it is possible to enhance spat collection of oysters until attaining commercial profitability by regularly emerging the collectors. |
format |
Conference Object |
author |
Rayssac, Nathalie Malet, Nathalie Pernet, Fabrice |
spellingShingle |
Rayssac, Nathalie Malet, Nathalie Pernet, Fabrice Low settlement of the pacific oysters Crassostrea gigas in the Thau lagoon reflects competition for space and food |
author_facet |
Rayssac, Nathalie Malet, Nathalie Pernet, Fabrice |
author_sort |
Rayssac, Nathalie |
title |
Low settlement of the pacific oysters Crassostrea gigas in the Thau lagoon reflects competition for space and food |
title_short |
Low settlement of the pacific oysters Crassostrea gigas in the Thau lagoon reflects competition for space and food |
title_full |
Low settlement of the pacific oysters Crassostrea gigas in the Thau lagoon reflects competition for space and food |
title_fullStr |
Low settlement of the pacific oysters Crassostrea gigas in the Thau lagoon reflects competition for space and food |
title_full_unstemmed |
Low settlement of the pacific oysters Crassostrea gigas in the Thau lagoon reflects competition for space and food |
title_sort |
low settlement of the pacific oysters crassostrea gigas in the thau lagoon reflects competition for space and food |
publisher |
Pysiomar 2010, October 31st to November 4th, Québec, Canada |
publishDate |
2010 |
url |
https://archimer.ifremer.fr/doc/00015/12665/9555.pdf https://archimer.ifremer.fr/doc/00015/12665/ |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
Crassostrea gigas |
genre_facet |
Crassostrea gigas |
op_relation |
https://archimer.ifremer.fr/doc/00015/12665/9555.pdf https://archimer.ifremer.fr/doc/00015/12665/ |
op_rights |
2010 Ifremer info:eu-repo/semantics/openAccess restricted use |
_version_ |
1766394056987901952 |