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Technical data
Metadata
Technical information
Data source:
The HELCOM countries have provided status concentrations for 2003-07. See the technical data for the individual core set indicators on water clarity, nutrient concentration, chlorophyll-a and benthic invertebrate fauna for more information.
Description of data: See the technical data for the individual core set indicators on water clarity, nutrient concentration, chlorophyll-a and benthic invertebrate fauna for more information.
Geographical coverage: All regions of the Baltic Sea.
Temporal coverage: : The data used here are based on average values for 2003-2007 (for more details see the technical data for the individual core set indicators on water clarity, nutrient concentration, chlorophyll-a and benthic invertebrate fauna for more information.
Methodology and frequency of data collection: See the technical data for the individual core set indicators on water clarity, nutrient concentration, chlorophyll-a and benthic invertebrate fauna for more information.
Methodology of data analyses: Status classifications for 189 assessment units on water transparency, nitrogen and phosphorus concentrations, chlorophyll concentrations and benthic invertebrate fauna have been weighted and combined using the HELCOM Eutrophication Assessment Tool (HEAT) to produce a final integrated eutrophication classification of bad to high status.
The status of the Baltic Sea according to the different indicators has been classified using the multi-metric indicator-based HEAT tool. Each area was assessed using information on reference conditions (RefCon) and acceptable deviation from reference condition (AcDev) combined with national monitoring data from the period 2003–2007. The basic assessment principle is RefCon ± AcDev = EutroQO, where the latter is a "eutrophication quality objective" (or target) corresponding to the boundary between good and moderate ecological status. When the actual status data (average for 2003-2007) exceeds the EutroQO or target, the area in question is regarded as affected by eutrophication.
The Ecological Quality Ratio (EQR) is a dimensionless measure of the observed value (AcStat) of an indicator compared with the reference value (RefCon). The ratio is equal to 1.00 if actual status is better than or equal to reference conditions and approaches 0.00 as deviation from reference conditions becomes large. The value of EQR is used to assign a quality class to the observed status. The classes in descending order of quality are RefCon, High, Good, Moderate, Poor, Bad. The central definition of the quality classes is given by the value of acceptable deviation (AcDev).
For a complete explanation of the methodology used, please see Andersen et al (2010) and thematic integrated assessment on eutrophication of the Baltic Sea (HELCOM 2009).
The eutrophication status maps were produced by spatially interpolating the values for the areas listed in the data table. ArcGIS 9.3.1 was used to interpolate the open and coastal areas. The coastal areas interpolation was delimited by a 6 nautical miles buffer along the coastline. The result was then joined to the open sea areas and the final map was processed to add a smoother transition between coast and open sea areas.
Strength and weaknesses of data: See the technical data for the individual core set indicators on water clarity, nutrient concentration, chlorophyll-a and benthic invertebrate fauna for more information.
Reliability, accuracy, robustness, uncertainty (at data level): The accuracy of classification results was tested in the thematic integrated assessment on eutrophication of the Baltic Sea. The accuracy was found to be in general good although there is some room for improvement. This has been documented indirectly via the secondary assessment of confidence where the data on which the classification is based on is scored in terms of accuracy. The secondary assessment found that 145 of 189 areas had an acceptable confidence while the remaining 44 areas had an unacceptable low confidence. Areas with low confidence in general are found in the southeastern or northern parts of the Baltic Sea.
Further work required (for data level and indicator level): The integrated eutrophication indicator report will be updated annually based on updated and new data from the core set of eutrophication indicators.
References
Andersen, J.H., P. Axe, H. Backer, J. Carstensen, U. Claussen, V. Fleming-Lehtinen, M. Järvinen, H. Kaartokallio, S. Knuuttila, S. Korpinen, M. Laamanen, E. Lysiak-Pastuszak, G. Martin, F. Møhlenberg, C. Murray, G. Nausch, A. Norkko, & A. Villnäs. 2010. Getting the measure of eutrophication in the Baltic Sea: towards improved assessment principles and methods. Biogeochemistry. DOI: 10.1007/s10533-010-9508-4.
HELCOM 2009. Eutrophication in the Baltic Sea – An integrated thematic assessment of the effects of nutrient enrichment in the Baltic Sea region. Helsinki Commission. Baltic Sea Environment Proceeding No. 115B.
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Last updated: 26 May 2010