Eutrophication

The densely populated and industrialized coastal and hinterland areas of the Northwest Pacific produce increasing amounts of urban, industrial and agricultural wastes, which are overloading the region’s seas with nutrients, particularly nitrogen and phosphorous contained in urban sewage, factory and agricultural run-off.

Eutrophication

Too much nitrogen and phosphorus in the marine environment causes eutrophication with massive growth of nutrient-feeding algae which consume oxygen in the water column and, in extreme cases, create a dead water zone or hypoxia. The depleted oxygen levels impare or could kill fish in large numbers and change species composition. Eutrophication can contaminate water, decreasing seashore recreational opportunities. The number of dead zones in the world’s oceans increased from 10 in 1960 to more than 450 in 2008 and growing.

Some algal blooms contain toxins and bacteria. These harmful algal blooms (HABs) are commonly called red tides. Increase in sea temperatures from global warming can accelerate eutrophication, increasing the frequency of red tides.

Water and seafood contaminated by HABs are odourless and tasteless and the toxin cannot be destroyed by cooking or freezing.

Eutrophication is a growing concern in the Northwest Pacific and manifested in frequent red tides, ‘green tides’ caused by green algae, abundance of the giant jellyfish Nemopilema nomurai, hypoxia or anoxia, changes in phytoplankton communities and loss of marine biodiversity. 

HOW A RED TIDE IS CAUSED

Red tide

What NOWPAP does

By assisting Member States to protect the Northwest Pacific seas from eutrophication, NOWPAP activities supports regional progress towards the achievement of Sustainable Development Goal 14: Life Below Water. 

NOWPAP support includes development of a standardized eutrophication assessment procedure, countermeasures against HABs and eutrophication monitoring guidelines for local government coastal officials.

The NOWPAP Special Monitoring and Coastal Environmental Assessment Regional Activity Centre (CEARAC) has developed  an eutrophication assessment methodology or (Common Procedure) and conducted eutrophication studies in selected sea areas using this methodology. The NOWPAP common procedure consists of two steps: a screening procedure - applied to identify potential eutrophic zones by detecting symptoms of eutrophication using selected parameters; and a comprehensive procedure - which uses four categories of parameters, including the degree of nutrient enrichment, to assess the status and possible causes of eutrophication in the identified zones. Further findings have led to a classification of the eutrophication status in the selected sea areas and investigation of the possible causes.

The NOWPAP eutrophication assessment methodology is being continuously refined taking into account technical problems encountered during the studies.   An online map of potential eutrophic zones in the region has been published based on further assessments using the NOWPAP methodology. The latest CEARAC Expert Meeting on Eutrophication Assessment in the NOWPAP Region held in Qingdao, P.R. China in October 2017 reviewed progress in eutrophication assessments.

NOWPAP CEARAC has been making efforts - using remote sensing - to prepare long-term, consistent chlorophyll-a data sets to be used for the screening procedures described above. NOWPAPs current research regarding eutrophication combines chlorophyll-a threshold analysis with trend analysis in the long-term, combining data from multiple satellite sensors. The center also supports further development of global methodology on eutrophication and plastic debris assessment under SDG target 14.1: ‘’By 2025, prevent and significantly reduce marine pollution of all kinds, in particular from land-based activities, including marine debris and nutrient pollution’. Regional Ecological Quality Objectives (EcoQOs) indicators being developed by NOWPAP consider specific indicators of eutrophication.

Graphics credit: Northwest Pacific Region Environmental Cooperaiton Center (NPEC).