Microphytobenthos of the Dogger Bank: a comparison between shallow and deep areas using phytopigment composition of the sediment
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The surface sediment characteristics related to benthic microalgae primary production were studied at the Dogger Bank, North Sea, in order to evaluate the potential role of microphytobenthos as a food source for the macrobenthic fauna. Twenty-one stations were sampled in July 2001 and May 2002, with water depth ranging from 16.3 to 68.5 m. High-performance liquid chromatography pigment analyses revealed that concentrations of chlorophyll a, chlorophyll c and fucoxanthin are mainly associated with benthic diatom flora at most parts of the Dogger Bank. High percentage of phytopigments (>50%) was firmly attached to sand grains at the stations shallower than 40 m water depth. The deeper stations were characterized by a phytopigment composition originating from pelagic phytoplankton settled on the sea floor. Qualitative microscopy showed that the benthic microflora on top of the Bank mainly consists of small diatoms (5–10 μm), such as e.g., Diploneis spp., living attached to the sand grains. The results are discussed concerning possible implications for ecology and biogeochemistry of the Dogger Bank area.
KeywordsExtracellular Polymeric Substance Fucoxanthin Benthic Diatom Deep Station Total Organic Carbon Concentration
The authors wish to thank the captain and the crew of the RV “Senckenberg” for their help with sampling as well as T. Janßen and C. Plum for technical assistance. We are grateful to H. Freund, Research Centre Terramare Wilhelmshaven for identification of the diatoms and W. Ahlrichs and I. Notholt of the University of Oldenburg for providing the opportunity to use the SEM. We are also grateful to three anonymous referees for helpful comments on the manuscript.
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