Spatio-temporal variability in benthic mineralization processes in the eastern English Channel |
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Authors: | Mathieu Rauch Lionel Denis |
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Institution: | 1. Station Marine de Wimereux, Laboratoire Ecosystèmes Littoraux et C?tiers, FRE ELICO CNRS n°2816, Université des Sciences et Technologie de Lille-Lille 1, 28 Avenue Foch, BP 80, 62930, Wimereux, France
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Abstract: | The effect of phytodetritus derived from Phaeocystis sp. bloom on benthic mineralization processes has been determined at four intertidal stations along the French coast of the
eastern English Channel. Sites were chosen to offer a diversity of sediment types, from permeable sandy beach to estuarine
mudflats. Sediment Oxygen Demand (SOD) as well as total fluxes of Dissolved Inorganic Nitrogen (DIN) at the sediment–water
interface were determined by using whole core incubation technique and diffusive fluxes were predicted from interstitial water
concentrations. In the absence of phytodetritus deposits, a marked gradient of granulometric characteristics and organic matter
contents were observed, and resulted in more intensive mineralization processes in muddy sediments. Highly significant correlations
(P < 0.05) were evidenced between SOD and porosity, bacterial biomass, Organic Carbon and Organic Nitrogen, evidencing the direct
link between sediment texture, organic matter accumulation and microbial activity. The spring bloom led to a massive input
of organic matter in surficial sediments and mineralization rates significantly increased while higher DIN release towards
the water column was observed. A modification of the mineralization pathways was evidenced but clearly depended on the sediment
type. With a global view, benthic mineralization processes in the intertidal zone provided significant a part of DIN inputs
in the coastal zone while water column was depleted in nutrients. |
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Keywords: | Intertidal Organic matter mineralization Phaeocystis sp Sediment– water fluxes |
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