title: Increasing nitrogen limitation in the Bothnian Sea, potentially caused by inflow of phosphate-rich water from the Baltic Proper.
abstract: The study showed that the open water of the Bothnian Sea (BS) is likely to have shifted from altering nitrogen and phosphorous limitations of the spring bloom to more nitrogen-limited conditions during the last 20 years. This is affected by the by inflow of phosphate-rich and oxygen-depleted water from depths near the halocline in the northern Baltic Proper, where severe oxygen conditions currently cause extreme phosphate concentrations in the deep water. The change in relation between inorganic nitrogen and phosphorous in the BS occurs first in the deep water and then progresses to the surface water. The change can potentially cause increased production in the BS and more frequent cyanobacterial blooms. There does not appear to be any immediate concern in the short-term perspective for the state of the BS, but a progression of the processes may lead to a more eutrophic state of the BS.
authors.affiliation: Stockholm University Baltic Sea Centre, 106 91, Stockholm, Sweden. carl.rolff@su.se.
authors.forename: Carl
authors.initials: C
authors.lastname: Rolff
authors.affiliation: Stockholm University Baltic Sea Centre, 106 91, Stockholm, Sweden. tina.elfwing@su.se.
authors.forename: Tina
authors.initials: T
authors.lastname: Elfwing
mesh_terms: D005060:Europe; D005068:Eutrophication; D009584:Nitrogen / Q000378:metabolism*; D009792:Oceans and Seas; D010758:Phosphorus / Q000378:metabolism*; D012621:Seasons; D014872:Water Movements
chemical_list: D010758:Phosphorus; D009584:Nitrogen
keywords: Baltic; Bothnian Sea; Cyanobacteria; Eutrophication; Nutrient limitation; Redfield