Observations of resuspended diatoms in the turbid tidal edge
In: Journal of Sea Research. Elsevier/Netherlands Institute for Sea Research: Amsterdam; Den Burg. ISSN 1385-1101; e-ISSN 1873-1414, meer
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| Trefwoorden |
Algae > Diatoms
Motion > Sediment movement > Sediment gravity flows > Turbidity currents
Suspended organic matter
Suspension > Resuspension
Topographic features > Landforms > Coastal landforms > Tidal flats
Coscinodiscus C.G. Ehrenberg, 1839 [WoRMS]
ANE, Ems-Dollard estuarium [Marine Regions]; ANE, Nederland, Westerschelde, Molenplaat [Marine Regions]
Marien/Kust |
| Author keywords |
resuspension; benthic diatoms; tidal flats; HPLC; Westerschelde;Ems-Dollard |
| Abstract |
Observations of resuspended diatoms in the shallow waters (<60 cm) of the turbid tidal edge are described for single sites on two tidal flats-the Molenplaat in the Westerschelde estuary, and the Hond in the Ems-Dollard estuary, The Netherlands. High concentrations of chlorophyll-a (chl-a) were observed in the trailing edge of the ebbing tide in water depths of <20 cm, after which concentrations decreased markedly. Peak mean values were 19 µg chl-a l-1 in 10 cm of water at the Molenplaat, and 45 µg chl-a l-1 in 5 cm of water at the Hond. Similar trends were observed on the flooding tide, although peak values were far less pronounced (6 and 30 µg chl-a l-1 respectively). Microscopic examination of the diatom community within the turbid tidal edge at the Molenplaat revealed that peaks in biomass were caused by suspended benthic diatoms, as well as the large centric diatom Coscinodiscus sp., particularly on the ebb tide. Planktonic diatoms other than Coscinodiscus sp. were more randomly distributed and did not appear to follow any particular trend. It would seem that as the tide recedes, resuspended benthic diatoms and large Coscinodiscus sp. cells become concentrated in the shallow water. However, the virtual absence of Coscinodiscus sp. from the leading edge of the flooding tide suggests that most of the resuspended cells do not settle to the seabed, but are washed away into the channels. The small peak of benthic diatoms at the leading edge of the flood tide is most likely resuspended locally from the sediment, along with large numbers of diatom frustules. |
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