Total phosphorus (TP) is assessed in 12 open sea assessment units for the period 2011-2016, of which good status (total phosphorus concentration below defined threshold value) was achieved only in the Great Belt. In the Kattegat, Gdansk Bay and Bothnian Bay the concentrations were only slightly above the threshold value (Key message figure 1 and Results table 1).
In the majority of coastal water assessment units, the threshold values set for total phosphorus were failed.
Key message figure 1. Status assessment evaluation of the indicator 'Total phosphorus' - annual monitoring (top), summer (middle) and winter (bottom). The assessment is carried out using Scale 4 HELCOM assessment units (defined in the HELCOM Monitoring and Assessment Strategy Annex 4). Please note that for some open sea areas threshold values still are under discussion, and that in coastal areas the assessment is based on annual data, summer data and winter data, as reported by HELCOM Contracting Parties, and these details are defined in Results table 2. Map 1 represents annual values, map 2 the values for summer and map 3 the values for winter. See Results section below for details. Click here to access interactive maps at the HELCOM Map and Data Service: Total phosphorus.
The confidence of the total phosphorus indicator status evaluation for the open sea areas is high in most of the assessed sub-basins. The confidence was moderate in the Quark and low in the Åland Sea. It should be noted that the confidence is only based on data availability, not the threshold confidence since the latter was not available for the indicator calculation.
The indicator is applicable in all coastal and open sea areas. The indicator period and method of calculation varies between open sea and coastal areas, and thus the threshold value- or assessment concentrations are not directly comparable between the open sea and coast, nor between all coastal assessment units where nationally binding threshold values may have been set.
The indicator is applicable in the waters of all countries bordering the Baltic Sea, though not operational in all assessment units yet as for some open sea areas threshold values still need to be agreed upon.
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 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.
D5 Human-induced eutrophication
- D5C1 Nutrient concentrations are not at levels that indicate adverse eutrophication effects
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.
HELCOM (2018). Total phosphorus. HELCOM core indicator report. Online. [Date Viewed], [Web link].
Total phosphorous HELCOM core indicator 2018 (pdf)