Nutrients stimulate the growth of algae and plants causing undesirable disturbance to the balance of organisms present in the water and to the quality of the water concerned. This environmental problem is present in various parts of the OSPAR area.
To asses the level of eutrophication, several interlinked indicators are used such as the occurrence of nuisance algae, oxygen deficiency and kills of fish and sediment organisms. Management measures have been taken to reduce the enrichment with nutrients and this should result in a healthy environment where eutrophication does not occur.