Finnish Institute of Marine Research, FIMR
Brown and turbid water suprised some divers when diving in an ice covered bay near Porvoo on the
coast of the Gulf of Finland last week. They contacted Finnish media and a sample was brought for
analysis to FIMR. Dr Guy Hällfors identified the dominating phytoplankton species, the dinoflagellate
Scrippsiella hangoei on 14.2..
This species occurs typically under the ice well before the actual vernal bloom in the open sea and can reach
very high cell concentrations. Later when the spring bloom has depleted nutrients Scrippsiella hangoei
forms resting cells that can colour water bright red. To our knowledge no harmful effects connected to
Scrippsiella hangoei blooms have been reported.
Also the haptophycean flagellate Chrysochromulina birgeri can form blooms that colour water and ice
brown during this time of the year. Even blue-green algae, in most cases senescent
Aphanizomenon flos-aquae, can colour ice and holes in the ice greenish blue or turquoise. Neither of
these species has been proven toxic in the Baltic Sea.
Figure 1: Cells of Scrippsiella hangoei.
Scale bar 30 µm. Photo Seija Hällfors.