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Pelagic-benthic coupling in the North Sea: short-term dynamics in phytopigment sedimentation and the response of benthic bacteria
van Duyl, F.C.; Duineveld, G.C.A.; Kop, A.J.; Kraay, G. (1996). Pelagic-benthic coupling in the North Sea: short-term dynamics in phytopigment sedimentation and the response of benthic bacteria, in: (1991). Proceedings of the International Symposium on Hydro- and Aerodynamics in Marine Engineering HADMAR '91, Varna, Bulgaria, 28 October - 1 November 1991. pp. 1-32
In: (1991). Proceedings of the International Symposium on Hydro- and Aerodynamics in Marine Engineering HADMAR '91, Varna, Bulgaria, 28 October - 1 November 1991. Bulgarian Ship Hydrodynamics Centre: Varna. 2 vol. pp., more

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Document type: Project report

Keyword
    Marine

Authors  Top 
  • van Duyl, F.C.
  • Duineveld, G.C.A., more
  • Kop, A.J.
  • Kraay, G.

Abstract
    A temperature stratified water column including the sediment surface layer in the Oyster Ground, North Sea was studied in July 1994. Twice a day (once during slack tide and once during full tide) samples were taken for phytopigments at different depths, sedimentation of phytopigments was assessed just above the bottom, and the phytopigment content in the 3 mm sediment surface layer was determined. In addition benthic bacterial production and abundance were measured. Semi-permanent registration of current velocity and direction was conducted close to the bottom, and fluorescence was measured intermittently at 13 and 38 m depth. The aim of the study was to assess the pelagic-benthic coupling for phytopigments and the response of benthic bacteria to changes in phytopigment input in the bottom. During the cruise mixing events which resulted in enhancement of the phytopigment content in the bottom mixed layer did not occur. There were no evident indications of net sedimentation of phytopigments on the bottom. The bulk of the material which settled during slack tide was resuspended during full tide. Due to the absence of substantial variations in net pigment input in the bottom, the benthic phytopigment inventory gradually decreased during the cruise (half-life of 10-13 days). This was not reflected by benthic bacterial variables which did not significantly change. As a consequence short-term temporal relations between bacterial variables and phytopigments in the sediment were not found. The pigment content apparently lost its role of indicator of available substrate for bacteria in the absence of substantial input of fresh algal material. However the benthic spatial variations in phytopigments due to the heterogeneity of the study were significantly reflected by the bacterial variables. It was concluded that bacterial variables are spatially related to phytopigments in North Sea sediments in an area with a comparable recent history of phytodetritus sedimentation. Benthic bacterial production may only be temporally related to phytopigments when fresh material is available in the sediment.

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