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Eutrophication and Hypoxia in Coastal Areas

A Global Assessment of the State of Knowledge

Eutrophication---the overenrichment of water by nutrients such as nitrogen and phosphorus---has emerged as a leading water quality problem. This report identifies over 415 areas worldwide that are experiencing eutrophication symptoms, and there are significant information gaps in many regions.

Key Findings

Executive Summary

Eutrophication -- the overenrichment of waters by nutrients -- threatens and degrades many coastal ecosystems around the world. The two most acute symptoms of eutrophication are hypoxia (or oxygen depletion) and harmful algal blooms, which among other things can destroy aquatic life in affected areas.

Of the 415 areas around the world identified as experiencing some form of eutrophication, 169 are hypoxic and only 13 systems are classified as "systems in recovery."

Mapping and research into the extent of eutrophication and its threats to human health and ecosystem services are improving, but there is still insufficient information in many regions of the world to establish the actual extent of eutrophication or identify the sources of nutrients. To develop effective policies to mitigate eutrophication, more information is required on the extent of eutrophication, the sources of nutrients, and the impact of eutrophication on ecosystems.

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