Algae report number 3, 2023

Type: Report
Author: Ann-Turi Skjevik, Maria Karlberg


In the Skagerrak, the diversity of phytoplankton was low, especially at the outermost station, Å17. In the Kattegat however, the number of species and the total cell numbers were higher than in the Skagerrak area. Among the diatoms, Guinardia delicatula was the most numerous species, while Dinophysis norvegica* and Tripos muelleri were the most abundant dinoflagellates. The coccolithophorid Emiliania huxleyi was observed in elevated cell numbers in the Kattegat. The integrated chlorophyll concentrations were generally low, though within normal for this month in both areas. Only at Släggö in the Kattegat, the integrated concentrations (0-10 and 0-20 m) were below normal. Diversity and cell abundance of phytoplankton were low at most stations in the Baltic Sea, with the exception of the two southern stations, where the spring bloom was ready to start; BY2 and BY5. Otherwise, there were some, or few, chains of the diatom Skeletonema marinoi and mostly small cells such as Cryptomonadales and smaller Gymnodiniales, as well as various ciliates and colony-forming cyanobacteria. The integrated chlorophyll concentrations (0-10m and 0-20 m) were normal for the month at all stations except at BY2 where concentrations were lower than normal.