Phases of microalgal succession in sea ice and the water column in the Baltic Sea from autumn to spring

• Published in: Marine Ecology Progress Series
• Main Authors: Enberg, Sara, Majaneva, Markus, Autio, Riitta, Blomster, Jaanika, Rintala, Janne-Markus
• Other Authors: Environmental Sciences, Tvärminne Zoological Station, Ecosystems and Environment Research Programme, Jaanika Blomster / Principal Investigator, Life Science Education, Helsinki Institute of Sustainability Science (HELSUS), Marine Ecosystems Research Group, Institute for Atmospheric and Earth System Research (INAR), Teachers' Academy
• Format: Article in Journal/Newspaper
• Language: English
• Published: INTER-RESEARCH 2019
• Subjects: Microalgae; Cold-water season; Succession; Sea ice; Baltic Sea; COASTAL ARCTIC-OCEAN; BACTERIAL COMMUNITIES; PHYTOPLANKTON BIOMASS; ENVIRONMENTAL-FACTORS; SUMMER TRANSITION; BRINE COMMUNITY; CLIMATE-CHANGE; MCMURDO SOUND; BLOOM; ALGAL; 1172 Environmental sciences; Arctic; Arctic Ocean; McMurdo Sound; Climate change; Global warming; ice algae; Phytoplankton
• Online Access: http://hdl.handle.net/10138/308486

The phytoplankton biomass in the Baltic Sea is low during the cold-water season (October to May) compared to the warm-water season(June to September). However, the sea ice is a habitat for diverse assemblages in polar and subpolar areas. These areas, including the Baltic Sea, are subject to changing environmental conditions due to global warming, and temporal and spatial studies are required to understand changes in the processes the organisms are involved in. We delineated microalgal succession in the northern Baltic Sea during the cold-water season using a weekly collected data set. Microscopy results together with molecular methods showed that 5 microbial groups could be distinguished: the sea-ice microalgal assemblage and 4 phytoplankton assemblages(fall, winter, under-ice water and spring). Based on cell enumeration, the microalgal biomass in the water column remained low until the end of the ice-covered season and was dominated by small flagellates and dinoflagellates. The young-ice assemblage in January resembled the water-column assemblage, but indicated a partly selective species-concentrating mechanism during ice formation due to lower species richness in ice than in the water column. Biomass of microalgae increased in the ice and water column during the March to May period, and the assemblage changed from flagellate-dominated to diatom-and dinoflagellate-dominated. The result that the spring phytoplankton, based on species and biomass, formed a separate as semblage indicates that sea-ice algae did not contribute to the spring bloom phytoplankton assemblage. Peer reviewed