Mussel Farming May Reduce Eutrophication at Sea

Under the EU Marine Strategy Framework Directive, Member States must agree on common environmental targets and should establish a programme outlining how these targets will be met. Researchers have demonstrated that mussel farming may be a cost-effective way to remove excess nutrients from the marine environment, reducing eutrophication its associated algal blooms, and should thereby be a method considered by EU Member States in meeting these targets.

Working in the Baltic Sea, researchers examined the cost of nutrient removal – nitrogen and phosphorus – using mussel farms, comparing this with: increasing cleaning at sewage plants; buffer strips; wetland construction and cultivation of catch crops. Four scenarios were modelled: with and without mussel sales options and in terms of low and high cost due to growth rates and nutrient content in mussels.

In all four scenarios, mussel farming was shown to cut costs in meeting stringent environmental targets. The overall cost savings of using mussels ranged from 20 – 138 million EUR. The mussels grown in this way could be used for fish meal in poultry feed.

Expansion of mussel farming in this way could have adverse impacts on marine ecosystems and this would need to be examined further before any widespread introduction to combat eutrophication in this way. If results are favourable the researchers propose that a ‘nutrient trading’ scheme could be introduced across Europe whereby, for example, a sewage treatment plant could trade nitrogen cleaning with a mussel farm.

Original Source: EU Science for Environment Policy

Gren, I-M., Lindahl, O. and Lindqvist, M. (2009). Values of mussel farming for combating eutrophication: An application to the Baltic Sea. Ecological Engineering. 35:935-945.