Seasonal dynamics of bacteria, autotrophic picoplankton and small nanoplankton in the Inner Oslofjord and the Skagerrak in 1993
Ypma, J.E.; Throndsen, J. (1996). Seasonal dynamics of bacteria, autotrophic picoplankton and small nanoplankton in the Inner Oslofjord and the Skagerrak in 1993. Sarsia 81: 57-66
In: Sarsia. University of Bergen. Universitetsforlaget: Bergen. ISSN 0036-4827; e-ISSN 1503-1128, meer
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| Abstract |
Seasonal dynamics of bacteria, autotrophic picoplankton and small nanoplankton (< 5 µm) were studied by direct counts using an epifluorescence microscope. Samples were collected from the euphotic zone in the inner Oslofjord from April to September and in the Skagerrak from May to August during 1993. The first exponential growth period of picocyanobacteria was observed during May and June in the Skagerrak and 2 to 3 weeks later in Oslofjorden. Eukaryotic picoplankton isolated by serial dilution cultures were dominated by the prasinophyte Micromonas pusilla (Butcher) Manton & Parke with cell numbers > 10 4 cells ml -1 from April to May. Biomass of phytoplankton (< 5摯瑬敳獩m) and heterotrophic bacteria were 25-56 µg C litre -1 in Oslofjorden, with increasing biomass of small nanoplankton towards the inner fjord. In the Skagerrak biomasses were 17-52 µg C litre -1 , with increasing biomass of picocyanobacteria from May to August. The importance of competition for nutrients between autotrophic picoplankton and heterotrophic bacteria is discussed. |
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