Summary
This report is based on two cruises in December, covering the Baltic Sea and the Swedish West coast sampling stations. Typical winter situations were registered in the Kattegat and Skagerrak areas. The number of species was low, and the dinoflagelllate genus Ceratium and small flagellates were the only groups found in relatively high quantities. Even at the Baltic stations winter ruled in the phytoplankton samples. Cryptomonads, ciliates and colonies of small cyanobacteria were the most common groups. The potentially harmful species Prymnesium polylepis was observed at all stations from the first December cruise. The integrated (0-20 m) chlorophyll a concentrations were low, but within normal for this month in all sampling areas. This report is a shortened version because of lack of events in the phytoplankton world.