Coastal water quality

Good water quality is essential for the aquaculture industry and fisheries. It is also important for amenity use: beaches, swimming, surfing etc. and is critical for many coastal habitats.

Poor water quality is considered a coastal risk as place these socio-economic and environmental elements at risk. Coastal planners and decision makers must protect coastal water quality, and have obligations under a number of European instruments to prevent deterioration.

Direct discharges into coastal waters include urban wastewater, domestic sewage and industrial effluent inputs can affect water quality. Discharges such as agricultural run-off discharges or changes to riverine inputs are also known to have a detrimental effect on water quality.

The flow of nutrients into coastal waters from land-based sources has seen a European and worldwide increase over the last decades. The resulting change in water quality has many potential impacts on coastal and marine ecosystems. Phosphorus and nitrogen contribute to enhanced algae growth, and subsequent decomposition reduces oxygen availability to sea creatures like fish, shellfish and crustaceans.

Changes to nutrient loadings can also change the phytoplankton species composition and diversity. In extreme cases, this algal growth bloom or eutrophication can lead to oxygen-depleted “dead zones” once the algae clogs an area and then dies. It can also cause harmful algal blooms.

Other more direct water quality issues may include direct contamination of recreational waters by raw sewage or spills of chemicals or oil.

In December 2000, the European Parliament adopted the Water Framework Directive. By signing it, each Member State is committed to ensuring a good environmental quality of coastal and inland waters by 2015. A monitoring program has been set up to monitor the state of the water. The results obtained make it possible to take action to ensure that the objectives set are met. Subsequently, the Marine Strategy Framework Directive followed the same spirit in order to achieve a good ecological status of marine waters.

Resources

ANCORIM case study

Rías Baixas in Vigo

(Spain)

Case of study: The Rías Baixas in Vigo (Spain)Management and prevention of risks affecting the quality of coastal waters associated with aquaculture.

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