There are many reasons to love oysters, and now an NUI Galway scientist has suggested another one.
Apart from its nutritional benefits, the shellfish also provides a cost-effective solution to the impacts of climate change.
Natural reefs built from oysters are preferential to seawalls constructed as a flood and coastal erosion defence, according to research led by NUI Galway (NUIG) economist Prof Stephen Hynes.
Such natural reefs are not only cheaper to construct, but they have the added benefit of creating new habitats for marine life, Prof Hynes, who is director of the NUIG Socio-Economic Marine Research Unit, says.
Author Prof Stephen Hynes
“Nature-based solutions” to climate change are central to the European Green Deal, his research paper published in the science journal Ecological Economics notes.
Galway has long celebrated the oyster, and a coastal walk in Galway Bay was selected as a template for the study.
The coastal trail to Rinville point is three kilometres from Oranmore village in south Galway. As it lies at sea level, it is exposed to coastal flooding.
The research examined its recreational value and analysed two options for protecting it – the “hard engineering” rock armour solution versus constructing a natural reef from oysters cultivated locally.
Rinville bay was once nucleus for abundance of native oyster, dating from prehistoric times, but productive reefs have been overharvested to the extent that remaining stock is “close to functional extinction”.
However, community-based organisation, Cuan Beo, has been working with the Marine Institute on restoring the native oyster and the first effort to rebuild several oyster reefs began in late 2020.
Cuan Beo used 200 tonnes of empty Pacific oyster shells covering a 50-metre radius and one metre in height from the seabed, which was then seeded with native oyster stock.
Although these structures are not close enough to the point to protect the walk, a similar natural protective reef could be created if given legislative approval, Cuan Beo spokesman Diarmuid Kelly confirmed.
Natural oysters
The oyster “bar” would be covered by sea most of the time, except at low tide, and would involve sowing seed oysters on top of empty oyster shell substrate
Prof Hynes’s study found that both protection options resulted in a positive net benefit over a 20-year time horizon.
However, the study found the nature-based solution had a benefit-cost ratio multiple times larger than the “grey infrastructure” seawall alternative.
Artificial oyster reefs have been piloted along the US Gulf Coast to protect and restore shoreline habitat and create living oyster beds, Prof Hynes notes.
The results of the research “suggest a compelling case for embedding nature-based solutions in climate adaption and flood management planning for low lying coastal areas where recreational resources are under threat”, his paper says.
“The fact that oyster reefs can also adapt to sea-level rise with vertical growth rates that are faster than the expected rate of sea-level rise also makes them a good nature-based solution,” he adds.
The full paper is here
