, Volume 363, Issue 1–3, pp 169–177 | Cite as

Impact of increased river discharge on the phytoplankton community in the outer Oslofjord, Norway

  • Svein Kristiansen


An extraordinary flood event occurred in SouthernNorway in May–June 1995. The impact of fresh waterdischarge from the river Glomma on phytoplanktonspecies composition and on primary production duringthe flood was studied. The phytoplankton community wasdominated by species usually found in the fjord, thediatom Skeletonema costatum dominated thecommunity together with cyanobacteria. Potentiallyharmful species (e.g. Chrysochromulinapolylepis) were found in low cell densities. No largeincrease in nutrient concentrations were found.Primary production and uptake rates of nitrate andammonium were very low in low-salinity water near theriver outlet. Nutrients from the river water wereefficiently utilized in the open part of the fjord.The flood trigged a phytoplankton bloom dominated byharmless species commonly observed in the fjordplankton.

bloom flood harmful toxic Skeletonema costatum 


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Copyright information

© Kluwer Academic Publishers 1998

Authors and Affiliations

  • Svein Kristiansen
    • 1
  1. 1.Section for Marine Botany, Department of BiologyUniversity of OsloOsloNorway

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