Benthic primary production, respiration and remineralisation: in situ measurements in the soft-bottom Abra alba community of the western English Channel (North Brittany) |
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Authors: | Aline Mign Dominique Davoult Jean-Jacques Bourrand Guy Boucher |
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Institution: | aUMR 5178 (MNHN-CNRS-Paris VI), DMPA, CP 53, 57 rue Cuvier, 75231 Paris cedex 05, France;bUMR 7127, Station Biologique, Université Paris VI, place G. Teissier, BP 74, 29682 Roscoff cedex, France;cLaboratoire de Géochimie des isotopes stables, UFR des Sciences Physiques de la Terre, Université Paris VII, 4 place Jussieu, Tr 54-64 1er ét., 75251 Paris cedex 05, France |
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Abstract: | In situ measurements of ammonium and carbon dioxide fluxes were performed using benthic chambers at the end of spring and the end of summer in two soft-bottom Abra alba communities of the western English Channel (North Brittany): the muddy sand community (5 m, about 10% of surface irradiance) and the fine-sand community (19 m, about 1% of surface irradiance). High rates of ammonium regeneration were measured in the two communities at the end of summer (296.03±40.07 and 201.7±62.74 μmolN m−2 h−1, respectively) as well as high respiration rates (2.60±0.94 and 2.23±0.59 mmolC m−2 h−1, respectively). Significant benthic gross primary production (up to 6.11 mmolC m−2 h−1) was measured in the muddy sand community but no benthic primary production was measured in the fine-sand community. It suggests that microphytobenthic production values used in simulations previously published for these two communities were overestimated while values of community respiration were underestimated. The study confirms that this benthic system is heterotrophic and strengthens the idea that an important pelagic-benthic coupling is required for the functioning in such coastal ecosystems. |
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Keywords: | Sediment-water interface Carbon dioxide exchange Ammonia Benthic Respiration rates Primary production English Channel |
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