Long term changes in the Baltic Sea phytoplankton community

Kalle Olli*, Riina Klais, Timo Tamminen, Robert Ptacnik, Tom Andersen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


During the last four decades the Baltic Sea phytoplankton went through a significant and gradual change in community composition. An analysis of several thousand quantitative samples from 1966 to 2008 reveals significant changes in the phytoplankton summer community in most parts of the Baltic Sea. By using community gradient analysis methods (NMDS, DCA), we found a strong correspondence between sample ordination scores and sampling year (R2 > 0.5). The association was stronger when the samples were geographically more confined and the temporal range sufficiently large (R2 > 0.8). Only in the southern Baltic Sea and the Kattegat had the salinity gradient stronger associations with the phytoplankton community composition as compared with the time effect over four decades. Eutrophication-related parameters (total and mineral nutrients) revealed low association with the phytoplankton community composition in all Baltic Sea sub-basins (R2 < 0.2). Also, known eutrophication gradients in the Baltic Sea had low association with phytoplankton community. The phytoplankton community in the Baltic Sea is not in a steady state or equilibrium, and is not the same today as it was decades ago.

Original languageEnglish
Pages (from-to)3-14
Number of pages12
JournalBoreal Environment Research
Issue numberSUPPL. A
Publication statusPublished - 2011

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