4 Eutrophication

Download4 Eutrophication

What has been done?

Reduction targets set to tackle eutrophication

The presence of serious eutrophication effects in parts of the maritime area during the 1970s led North Sea countries to agree on the need for a reduction of nitrogen and phosphorus inputs to areas affected, or likely to be affected, by eutrophication. Agreement was reached on a target for reduction of the order of 50% between 1985 and 1995. This was endorsed by OSPAR in 1988 for its entire maritime area and has since formed an integral part of its Eutrophication Strategy.

Regular national reporting, supported by harmonised procedures for quantifying and reporting discharges and losses of nutrients, makes it possible to judge progress on reducing nutrient releases and achieving the 50% reduction target.

Agreed methodologies track eutrophication problems

In response to the need for a collective approach for evaluating the eutrophication status of the maritime area, OSPAR developed the Common Procedure for use by all OSPAR countries.

This was applied in 2002 for the period 1990–2000 and again in 2007 for the period 2001–2005 and has proved a good means for assessing the extent of marine eutrophication and for identifying problem areas, where the 50% nutrient reduction target applies. Joint modelling exercises have been used to test the effectiveness of current and projected nutrient reduction scenarios and to estimate transboundary nutrient transport in the North Sea.

The Common Procedure also supports the application of the eutrophication-related Ecological Quality Objective (EcoQO) for the North Sea Chapter 11.

Box 4.2 A Common Procedure to assess eutrophication

The Common Procedure for the Identification of the Eutrophication Status of the Maritime Area (‘Common Procedure’) provides the framework for a comprehensive, harmonised characterisation of marine areas by OSPAR countries in terms of ‘problem areas’, ‘potential problem areas’ and ‘non-problem areas’ with regard to eutrophication. Its second application, relating to the period 2001–2005, was restricted to areas that had previously shown eutrophication problems or non-problem areas which gave concern that their quality status may have deteriorated.

The Common Procedure links ten indicators for nutrient enrichment and direct and indirect eutrophication effects in an integrated cause-effect scheme. Applications of the Common Procedure have so far focused on assessing eutrophication status and change in area status over time. Assessments of regional trends in individual indicators will need to receive more attention in future to make it possible to track improvements.

The indicators cover excessive nuisance algal blooms, loss and changes in biodiversity (for macrophytes, zoobenthos, fish) and oxygen deficiency. Differences in environmental characteristics, such as salinity, mean that not all parameters are relevant or robust indicators for eutrophication in each area. Indicators are elevated if they exceed the acceptable deviation from area-specific background conditions which OSPAR countries determine through regionally agreed methodologies, taking into account natural variability. As a result they are not applied in the same way across the OSPAR area. Data availability also contributes to differences in their use. An area is generally classified as a problem area if an indicator for nutrient enrichment and an indicator for eutrophication effect are elevated. Monitoring of the indicators is coordinated across the OSPAR area through agreed methodological standards covering sampling, analysis, reporting and quality assurance. The work supports judgement about the quality of coastal and marine waters under the EU Water Framework Directive and the EU Marine Strategy Framework Directive.

Continued cooperation with other international bodies

To achieve OSPAR’s targets, OSPAR countries have agreed to implement a coordinated programme for the reduction of nutrient inputs from point sources and agriculture where eutrophication problems are identified. This is mainly being delivered through implementing measures adopted in the EU, the European Economic Area and other international forums. A wide range of European and international instruments aim at combating nutrient releases to surface waters and air through controlling discharges, emissions and losses at source and by setting environmental targets Table 4.1. Under EU legislation, stricter requirements apply to agriculture and urban waste water treatment plants discharging into areas designated as sensitive or vulnerable to nutrient inputs. These broadly coincide with OSPAR problem areas. EU legislation and OSPAR measures mutually support objectives to combat eutrophication.

Table 4.1

European and international instruments to combat eutrophication...