, Volume 269, Issue 1, pp 235–242

Diatoms in surface sediments of the Gotland Basin in the Baltic Sea


  • Tuulikki Grönlund
    • Geological Survey of Finland
Brackish water

DOI: 10.1007/BF00028022

Cite this article as:
Grönlund, T. Hydrobiologia (1993) 269: 235. doi:10.1007/BF00028022


A sediment core, 55 cm long, from station F81 in the Gotland Basin of the Baltic Sea was analysed for diatoms and ebridians. Chrysophyte stomatocysts found in the core were also counted but not identified. The aim was to trace environmental changes, e.g. eutrophication and salinity variations. There is evidence that eutrophication has been increasing in the Baltic Sea in recent decades.

Brackish-marine plankton diatoms dominate the entire core and reflect the local planktonic taxa rather well. The dominant taxon is the polyhalobous Actinocyclus octonarius. The main biostratigraphical change within the core analysed takes place at a depth of about 22 cm, where the abundance of diatoms, and especially of Chaetoceros spp., Thalassiosira hyberborea var. pelagica and T. baltica start to increase. This may reflect eutrophication which can be estimated to have started c. 200 years ago.

Key words

diatom floraebridiansmarine sedimentseutrophicationBaltic Sea

Copyright information

© Kluwer Academic Publishers 1993