JOURNAL OF PLANKTON RESEARCH | VOLUME 14 | NUMBER 1 | PAGES 107-125 | 1992
© Oxford University Press
research-article |
Spatial heterogeneity and dynamics of vernal phytoplankton species in the Baltic Sea in April–May 1986
Finnish Institute of Marine Research PO Box 33, SF-00931 Helsinki, Finland 1Institute of Ecology and Marine Research Paldiski Rd. 1, 200031 Tallinn, Estonia 2Institut für Meereskunde an der Universität Kiel Düsternbrooker Weg 20, D W-2300 Kiel 3Institut für Meereskunde Seestr. 15, D O-2530 Rostock-Warnemünde, FRG 4State Oceanographic Institute Kropotkinski 6, 119838 Moscow, USSR
Received on August 5, 1990; accepted on June 21, 1991 The mesoscale phytoplankton distribution was studied as part of an international joint Baltic Sea Patchiness Experiment (PEX'86) during April–May 1986 in the open Baltic Proper. The study period covered the peak phase of the phytoplankton spring bloom. The spatio-temporal dynamics of four dominating phytoplankton species, Achnanthes taeniata, Chaetoceros spp., Skeletonema costatum and Thalassiosira levanderi were studied within an area of 20x40 nmi with grids of 2 and 4 nmi spatial resolution. The results showed highly varying spatial distributions for all species, and the variability was accentuated on the synoptic space scale before the development of the seasonal thermocline. The maxima of Chaetoceros spp. and Thalassiosira levanderi coincided with the anticyclonic and cyclonic eddies prevailing in the area. Skeletonema costatum was found in high abundances only within a warmer water mass of higher salinity advecting into the area. The results pointed out that different successional stages can simultaneously be found even in adjacent water masses and both the phytoplankton growth and composition during the bloom peak phase in the Central Baltic depend on complex factors, mainly those connected with mesoscale hydrodynamic features (eddies, frontal zones, jet currents).