​​​​​​​​​​​​​​​​​​KEY MESSAGE​

The core indicator evaluates average dissolved inorganic nitrogen concentration in the surface (0 – 10 m) during winter (December – February) during the assessment period 2011-2015.

Of the 17 assessed open-sea assessment units, good status has been achieved only in the Gdansk Basin (DIN concentration below defined threshold value, which reflects good conditions).Though the winter-time DIN is still at elevated levels in the remaining 16 sub-basins, it has decreased in the 1990s or the early 2000s and remained since then on the same level.

Key message figure 1: Status assessment results based evaluation of the indicator ‘DIN'. The assessment is carried out using Scale 4 HELCOM assessment units (defined in the HELCOM Monitoring and Assessment Strategy Annex 4).

The confidence of the presented DIN status estimate is moderate in all 17 open sub-basins. Of all coastal waters where DIN was assessed, good eutrophication status was only found in Polish coastal waters and around the Swedish islands in Gotland Basin.

The indicator is applicable in the waters of all countries bordering the Baltic Sea.


Eutrophication is caused by excessive inputs of nutrients (nitrogen and phosphorus) resulting from various human activities. High concentrations of nutrients and their ratios form the preconditions for huge algal blooms, reduced water clarity and increased oxygen consumption. Long-term nutrient data are key parameters for quantifying the effects of anthropogenic activities and evaluating the success of measures undertaken.


BSAP segment and objective​​s

MSFD Descriptor and Criteria

Primary link

Baltic Sea unaffected by eutrophication

D5  Human-induced eutrophication

- D5C1 Nutrient concentrations are not at levels that indicate adverse eutrophication effects​​

Secondary link

D1 Biological diversity of species and habitats

Theme: Pelagic habitats

-D1C6  The condition of the habitat type, including its biotic and abiotic structure and its functions, is not adversely affected due to anthropogenic pressures.

Theme: Benthic habitats

-D6C5 The extent of adverse effects from anthropo­genic pressures on the condition of the habitat type, including alteration to its biotic and abiotic structure and its functions, does not exceed a specified proportion of the natural extent of the benthic habitat type in the assessment area.

Other relevant legislation: EU Water Framework Directive


HELCOM (2017). Dissolved inorganic nitrogen (DIN). HELCOM core indicator report. Online. [Date Viewed], [Web link].

ISSN 2343-2543