Image: Kristina Viklund
Research project The Bothnian Bay does not currently have any major problems with eutrophication, but phosphorus levels are increasing and the ratio between readily available nitrogen and phosphorus is decreasing. The probable cause is the inflow of phosphorus-rich water from the Bothnian Sea. Studies focused on the Northern Quark are almost completely lacking, and more detailed knowledge about this is necessary to be able to predict and, if necessary, be able to act against any negative environmental effects.
Eutrophication is one of the biggest environmental problems facing the Baltic Sea, but the Bothnian Bay has so far been spared from the harmful effects of this. This is most likely because the distribution between phosphorus and nitrogen is different in the Bothnian Bay than in other parts of the Baltic Sea. Monitoring data now indicate that phosphorus levels in the Bothnian Bay are increasing, which in the long term may cause the same eutrophication problems as in the rest of the Baltic Sea. The probable cause is the inflow of phosphorus-rich water from the Bothnian Sea. This project aims to clarify how transport from the Bothnian Sea affects the Bothnian Bay, how it is done, and if or when the Bothnian Bay may be affected by eutrophication.
Water sampling in the Gulf of Bothnia from the research vessel KBV 181.
Image Marlene JohanssonThe aim of the project is to clarify and quantify the transport of nutrients from the Bothnian Sea to the Gulf of Bothnia across the Northern Quark. This includes both total concentrations of phosphorus and nitrogen as well as the readily available fractions phosphate, ammonium, nitrite, and nitrate, as well as a complete spatial and temporal coverage of the area. This will form the basis for modelling current and future nutrient transport across the Northern Quark, as well as predictions for possible future cyanobacterial blooms. The goal is to clarify if, and if so, when, the Bothnian Bay will switch to a nitrogen limited system, with the eutrophication problems in the form of, for example, harmful algal blooms this can cause.
Sampling will be performed in both the western and the eastern parts of the Northern Quark.
Image Joakim AhlgrenThe project consists of two main parts; a field-based sampling part focused on sampling, chemical analyses and hydrographic investigations, and a subsequent modelling and data analysis part.
The sampling will be carried out monthly during 2025 starting in February. The sampling will primarily be coordinated with Umeå Marine Sciences Centre's sampling expeditions within the national environmental monitoring programme for the free water mass. Sampling and analyses are carried out using the same methods and execution as in the national–regional monitoring programme for the free water mass in the Gulf of Bothnia.
