Algae report number 7, 2020

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 suitable for identifying larger and more robust cells whereas smaller cells and fragile cells are difficult to determine taxonomically or 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 the most abundant. The dinoflagellates were represented by different species belonging to the genus Tripos. This genus was especially common in the fluorescense peaks found at about 20m at a couple of stations. The Baltic Sea: No large surface accumulations were noted in the south of the Baltic. The wind and waves kept the filaments dispersed in the water column. The small grains of aggregations that were seen at all stations mainly contaied Aphanizomenon but also some filaments of the toxic species, Nodularia spumigena*. In the eastern part of the Baltic, outside the east coast of Gotland, larger areas of surface accumulations were noted in form of streaks. The toxic species N. spumigena* was more common here. The wind increased on the way between Öland and Gotland and the aggregates were seen as grains in the water column. At Karlsö deep the ship stopped the wind close to the ship and the grains quickly accumulated as small streaks at the surface. South of Öland, in Kalmar sound and Hanö bight the wind stress was high enough to keep the filaments dispersed in the water column. The total concentration of filaments were overall lower in these areas and mainly Ahanizomenon flosaquae was found.