Algae report number 8, 2023

Type: Report
Author: Marie Johansen, Anders Torstensson


The diversity and total cell numbers were generally high at most stations along the Swedish west coast. The only exception being Å17 where both biodiversity and total cell numbers were low.  Dinoflagellates were most commonly found in Skagerrak and diatoms in Kattegat. The integrated chlorophyll concentration (0-10 m) were above normal in Kattegat. The deeper integrated chlorophyll (0-20 m) were generally within normal range for this month at all stations.

The diversity and cell numbers of phytoplankton were normal at all stations in the Baltic Proper, with the highest abundances observed in the southern parts of the Baltic. Of the summer-blooming filamentous cyanobacteria Aphanizomenon flosaquae was common, mainly in the southern and northern parts of the Baltic Sea, but was observed in all samples. Also, smaller amounts of Nodularia spumigena* were present at some stations, primarily in the southern parts of the Baltic Proper. The diatom community was mainly dominated by Dactyliosolen fragilissimus in the southern parts of the basin, while Chaetoceros castracanei was common at the other stations. A few cells of the toxin producing dinoflagellate Dinophysis norvegica* were observed in the samples. The integrated chlorophyll concentrations (0-10 and 0-20 m) were generally within the normal range for this month at most stations, although the deeper integrated samples (0–20 m) were somewhat below the normal range for the Western Baltic.