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Seasonal fluctuations of benthic protozoan populations at different depths in marine sediments
Bak, R.P.M.; Nieuwland, G. (1989). Seasonal fluctuations of benthic protozoan populations at different depths in marine sediments. Neth. J. Sea Res. 24(1): 37-44
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579, more
Peer reviewed article  

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  • Bak, R.P.M.
  • Nieuwland, G.

    We used epifluorescence microscopy to enumerate small (< 20 µm) protozoa in extracts of flushed fixed sediment samples. This method retrieved 91±4% (x±se) of cultured flagellates from sediments. Protist densities at different depths in the sediments were studied over 1 year at 3 intertidal flats in the Wadden Sea. There was a general pattern of seasonal density fluctuation at all sites with a marked increase in March from winter density levels (50 to 100·103·cm-3) to 2 to 3 times higher summer levels (150 to 300·10³·cm-3). Deeper in the sediments (30 to 33 and 60 to 63 mm) densities were throughout the year 2 to 3 times lower than in the sediment surface layer. Fluctuations in densities at the surface were generally mirrored at greater depths. At least 50% of the cells were in the size class of 2 to 5 µm. Estimates for total biomass ranged between 1.2 and 8.5·10-6 g C·cm-3. About 33% of the protists contained chlorophyll. There were no obvious correlations with concurrently measured parameters such as porosity, POC, bacterial numbers or biomass. Increased bacterial productivity, however, was invariably parallelled by increased protist densities. This suggests that high benthic protist densities are indications of high benthic microbial growth.

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