The Application of Longline Mussel Aquaculture to Establish Subtidal Reefs: New Solutions in Coastal Defense

Peter Benham

Nations with low lying coastlines are under increased threat from erosion, flooding and saltwater intrusion. In response, the Coastbusters group was formed to find nature based solutions (NBS) to these threats. In 2018 they implemented a project modeled off of mussel longline aquaculture for a new purpose: to establish mussel beds off of the coast of Belgium.

            We investigated the effectiveness of the project design, including which material type works best to attract and grow new mussels, the effects of a longer immersion period, and the influence of the fouling community on both the mussels and the benthic community.

            We determined that a filamentous material leads to higher density of mussels but at smaller sizes. In contrast, non-filamentous materials provide a lower number of larger mussels, that are not as firmly attached. Time had an effect, lines immersed for multiple years may be less effective at recruitment. Finally, there seems to be no effect of fouling on the mussels, or on the benthic community at the time of sampling. We conclude that a semi-filamentous bio-degradable material is the best to use. However future study is needed, with a larger sample size and samples taken over a longer period of time.