Algae report number 7, 2021

Type: Report
Author: Marie Johansen


The analyses were made on bord the ship Svea during the cruise. Water from integrated sampels or discrete depths were filtrated down to filters with 5μm pore size. The method is most suitebale for identifying larger and more robust cells whereas smaller cells and fragile cells are difficult to determine taxonomically are missed to a higher degree.

West coast

All stations along the west coast had low to moderate cell numbers and biodiversity. At most stations diatoms dominated where Proboscia alata was most abundant. The dinoflagellates were mainly represented by different species belonging to the genus Tripos. This genus was especially common in the fluorescense peaks found at several stations along the Å-transect and at Å17 Tripos macroceros dominated.

Baltic Sea

Small sporadic aggregations were already seen in the Sound. In the southwestern parts of the Baltic proper grains were noted in the upper water column. West of Bornholm larger areas with surface accumulations appeared and increased in size and coverage going north of Bornholm. All samples from these areas were clearly dominated by the potentially toxic filamentous cyanobacteria Nodularia spumigena*. Going onward towards the southeastern part of the Baltic the accumulations decreased to thin streaks. The eastern part of the Baltic proper, alongside Gotland, the surface accumulations were sporadic and far away from the boat. Still N. spumigena* dominated among the filamentous cyanobacteria but less filaments were found. North of Gotland the water was calm but no aggregations were seen. The samples contained all three major groups of filamentous cyanobacteria so a potential surface bloom in the near future is possible. Between Gotland and Öland small sporadic streaks and grains were noted. The windstress were mixing the waters around the south of Öland, Kalmar sound and at Hanö bight. Even so grains were noted in the upper water column in different amounts in this area. Surface samples revealed that all three groups were present in these water.