Data/hora: 01/06/2024 18:05:49

Provedor de dados: | 5
País: | France
Título: | Benthic microphytic activity at 2 mediterranean shellfish cultivation sites with reference to benthic fluxes
Autores: | Barranguet, C; Alliot, E; Plantecuny, Mr.
Data: | 1994
Ano: | 1994
Palavras-chave: | MICROPHYTOBENTHOS; FLUXES; PRIMARY PRODUCTION; SHELLFISH CULTIVATION.
Resumo: | Microphytobenthos activity in coastal waters has been studied at two shellfish fanning sites: an oyster farm in Thau lagoon and a mussel farm in Carteau bay (NW Mediterranean coast). In both cases, shellfish are cultivated on ropes hanging from rigid structures (tables) in shallow waters (- 5 m). An ''under table'' station and an ''outside table'' (reference) station were chosen at each site. Oxygen and ammonia fluxes at the water-sediment interface were measured in dark and transparent benthic chambers. Chlorophyll a concentrations were two- to threefold higher in ''under table'' sediments than outside (260 mg Chl a m(-2) under the oyster table, 436 mg Chl a m(-2) under the mussel table in winter). Net oxygen fluxes were negative at all stations, except at the Carteau reference station and under the oyster table at the beginning of the summer (+ 20 mg O-2 m(-2) h(-1)). Maximum negative fluxes (- 70 mg O-2 m(-2) h(-1) under a mussel table) were recorded during spring at all stations, when mollusc trophic activity was maximal as reflected in high phaeopigment content under the tables. Gross primary production was lowest in spring at the Thau stations as well as at the Carteau reference station. Under the mussel table, primary production increased steadily from autumn to summer, from 0 to 100 mg O-2 m(-2) h(-1). Ammonia release was higher under shellfish farming structures (200 mu mol N-NH4+ m(-2) h(-1)) than at the reference stations (70 mu mol N-NH4+ m(-2) h(-1)). The discrepancy between O-2 production and microphytic biomass suggests that mechanisms other than photosynthesis prevail under shellfish structures. Mussel cultures were shown to have a stronger impact on benthic fluxes below the tables than oysters. In localities with shellfish farms, oxygen produced by microphytobenthos activity cannot always meet the total oxygen demand of the sediment, increased by accumulation of mollusc biodeposits and, sometimes drastically in the lagoon, by macroalgae decay.
Tipo: | Text
Idioma: | Inglês
Identificador: | http://archimer.ifremer.fr/doc/00098/20884/18498.pdf
Editor: | Gauthier-Villars
Relação: | http://archimer.ifremer.fr/doc/00098/20884/
Formato: | application/pdf
Fonte: | Oceanologica Acta (0399-1784) (Gauthier-Villars), 1994 , Vol. 17 , N. 2 , P. 211-221