Algae report number 5, 2023

Type: Report
Author: Marie Johansen, Maria Karlberg


The diversity and total cell numbers were generally low at all stations along the Swedish West coast. Small cells dominated in cell numbers which is common during late spring. At Å17 the coccolithophore Emiliania huxleyi was found in high cell numbers. The samples from the Kattegat still contained a lot of cells of the diatom Guinardia delicatula, just like in April. At N14 some cells of Tripos muelleri was found but besides that the samples mainly contained small cells of different sorts. The integrated chlorophyll concentration (0-20 m) was slightly above normal for this month at Släggö, and within normal at all other stations. The diversity and cell abundances of phytoplankton were normal at all stations in the Baltic Sea with a post spring bloom community. Several dinoflagellate genera were present in high numbers at most stations, such as Gymnodiniales, Heterocapsa rotundata, and Peridiniella catenata. There were also plenty of the golden algae Dinobryon balticum and the filamentous cyanobacterium Aphanizomenon sp. Both Dinophysis acuminata* and D. norvegica* were present at almost all stations, at BCSIII-10 in quite high amounts. The integrated chlorophyll concentrations (0-10m and 0-20 m) were normal for the month at all stations, except at BY38 where they were above the normal range.