Indicator Specification

Nutrients in transitional, coastal and marine waters

Indicator Specification
  Indicator codes: SEBI 015
Published 21 May 2010 Last modified 09 Feb 2021
6 min read
This page was archived on 09 Feb 2021 with reason: Other (Discontinued indicator)
The indicator illustrates trends in, and concentrations of, winter nitrate and phosphate (microgram/l), as well as Nitrogen/Phosphorous ratio in the seas of Europe.

Assessment versions

Published (reviewed and quality assured)
  • No published assessments


Justification for indicator selection


The indicator is based in a well-established data flow from a wide geographic coverage of countries and regional seas.

The indicator is based on an EEA priority data flow and the information is timely as it is updated annually.

The data are in Waterbase and are freely available on the EEA website. The EEA is Europe's water data centre and hosts the Water Information System for Europe (WISE) which will incorporate Waterbase. The data flows for Marine Conventions may also be incorporated into WISE in the future.

Scientific references

  • No rationale references available

Indicator definition

The indicator illustrates trends in, and concentrations of, winter nitrate and phosphate (microgram/l), as well as Nitrogen/Phosphorous ratio in the seas of Europe.


Concentrations in micromol/l


Policy context and targets

Context description

Nitrogen (N) and phosphorus (P) enrichment can result in a chain of undesirable effects, starting from excessive growth of plankton algae that increases the amount of organic matter settling to the bottom. This may be enhanced by changes in species composition and functioning of the pelagic food web (e.g. growth of small flagellates rather than larger diatoms), which leads to lower grazing by copepods and increased sedimentation. The consequent increase in oxygen consumption can, in areas with stratified water masses, lead to oxygen depletion, changes in community structure and death of the benthic fauna. Eutrophication can also increase the risk of algal blooms, some of them consisting of harmful species that cause the death of benthic fauna, wild and caged fish, or shellfish poisoning of humans. Increased growth and dominance of fast-growing filamentous macroalgae in shallow sheltered areas is another effect of nutrient overload which can change the coastal ecosystem, increase the risk of local oxygen depletion and reduce biodiversity and nurseries for fish.

Measures to reduce the adverse effects of excess anthropogenic inputs of nutrients and protect the marine environment are being taken through various initiatives at all levels - global, European, national, regional conventions and Ministerial Conferences.

There are a number of EU Directives aimed at reducing the loads and impacts of nutrients, including the Nitrates Directive (91/676/EEC); the Urban Waste Water Treatment Directive (91/271/EEC); the Integrated Pollution Prevention and Control Directive (96/61/EEC); and the Water Framework Directive (2000/60/EC) which requires the achievement of good ecological status or good ecological potential of transitional and coastal waters across the EU by 2015.

The EU Thematic Strategy on the Protection and Conservation of the Marine Environment and its associated proposed Marine Strategy Directive are of key relevance with regards to the achievement of good environmental status in marine waters.

Additional measures arise from international initiatives and policies including: the UN Global Programme of Action for the Protection of the Marine environment against Land-Based Activities; the Mediterranean Action Plan (MAP) 1975; the Helsinki Convention 1992 (HELCOM); the OSPAR Convention 1998 (Convention for the Protection of the Marine Environment of the North-East Atlantic); and the Black Sea Environmental Programme (BSEP).

Relation of the indicator to the focal area

Undesirable effects caused by Nitrogen (N) and phosphorus (P) (have a direct impact on ecosystem integrity and functioning (e.g. changes in species composition, oxygen depletion, changes in community structure) and the delivery of ecosystem services (death of commercial fish species or shellfish poisoning).


No targets have been specified

Related policy documents

No related policy documents have been specified



Methodology for indicator calculation

Consistent time series are used as the basis for assessment of trends over time. The trend analyses are based on time series 1985-2004/2005 from stations having at least 3 years data in the period 1999-2004 and at least five years data in all. For nitrogen the combined concentrations of nitrate and nitrite are used, but gaps may be populated with nitrate alone to complete the time series.

Winter concentrations are used because in summer all inorganic nutrients are used for plankton growth.

The following steps are undertaken for the calculation. For a detailed description of methodology, reference is made to the EEA core set indicator 'Nutrients in transitional, coastal and marine waters' ( ISpecification20041007132008/full_spec).

1. Primary aggregation of sea water TCM data

The primary aggregation consists of identifying stations and assigning them to countries and sea regions and creating statistical estimates for each combination of station and year.

2. Geographical classification: sea region, coastal/offshore

All geographical positions defined in the data are assigned to sea region by coordinates, and classified as coastal or off-shore (> 20 km from coast) by checking them against the coastal contour.

3. Defining stations

Eionet-Water stations
TCM data reported directly from countries are assigned to station identifiers that are listed with coordinates. For these data, which are mostly along the coast of the reporting country, stations are kept as defined.

Marine convention data from ICES
The data reported through ICES has no consistent station identifiers (i.e. station names), only geographical coordinates (longitude and latitude).

Methodology for gap filling

No methodology for gap filling has been specified. Probably this info has been added together with indicator calculation.

Methodology references

No methodology references available.


Data specifications

EEA data references

Data sources in latest figures



Methodology uncertainty

No uncertainty has been specified

Data sets uncertainty

No uncertainty has been specified

Rationale uncertainty


  • Data for this assessment are still scarce considering the large spatial and temporal variations inherent to the European transitional, coastal and marine waters. Long stretches of European coastal waters are not covered in the analysis due to lack of data. Trend analyses are consistent only for the North Sea and the Baltic Sea (data updated yearly within the OSPAR and HELCOM conventions) and Italian coastal waters. The accuracy on regional level is largely influenced by the number of stations for which data are available.


The indicator is an EEA core set indicator. The information basis for the indicator and the assessments possible will improve in time as the WFD and Marine Strategy Directive assessments are implemented by Member States.

Further work

Short term work

Work specified here requires to be completed within 1 year from now.

Long term work

Work specified here will require more than 1 year (from now) to be completed.

Work description

SUGGESTIONS FOR IMPROVEMENT Showing European time trends in pollutant load presenting mean concentration from the year 1995 will be considered. It will be necessary to get access to more data, in terms of better spatial coverage and longer time series, in order to improve the assessment. Methods for comparing data from the same region over different years should be developed to improve the assessment, and techniques for visualising the differences in nutrient levels over the entire region should be investigated. Indicators could make use of salinity data at stations as a co‑variate in order to compensate for inter-annual variations in salinity. It might also be necessary that data are accompanied by information on methodology and estimated uncertainty. In relation to the Water Framework Directive, work is ongoing defining good ecological quality for all coastal waters. Monitoring will provide more coastal nutrient data, and locally defined targets and thresholds will improve this indicator.

Resource needs

No resource needs have been specified


Not started


2099/01/01 00:00:00 GMT+1

General metadata

Responsibility and ownership

EEA Contact Info

Katarzyna Biala


European Environment Agency (EEA)


Indicator code
SEBI 015
Version id: 1

Frequency of updates

Updates are scheduled every 2 years


DPSIR: Pressure
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)


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