Research from the University of Exeter and the University of Edinburgh reveals that extensive oyster reefs once thrived along Europe’s coastlines but were largely destroyed over a century ago. Based on 18th—and 19th-century documents, the study indicates that these reefs, made up of living and dead oyster shells, provided vital habitats for diverse marine life.
Today, oysters are primarily found as isolated individuals, but evidence of these reefs spans from Norway to the Mediterranean, covering at least 1.7 million hectares. The native oyster reefs fostered rich ecosystems, supporting more species than surrounding areas.
Oysters provided habitat for nearly 200 fish and crustacean species and played crucial roles in stabilizing shorelines, cycling nutrients, and filtering water—each adult oyster can filter up to 200 liters daily.
Restoration initiatives, such as The Wild Oyster Project led by ZSL and partners, are essential for reviving these ecosystems across Europe. However, these efforts must be expanded with support from governments and decision-makers throughout the continent to be effective.
Oysters struggle with noisy Oceans
Dr Ruth Thurstan, from the University of Exeter and part of the Convex Seascape Survey, an ambitious five-year project examining ocean carbon storage, said, “Human activities have affected the ocean for centuries. This makes it difficult to discover what our marine ecosystems used to look like, which in turn hampers conservation and recovery.”
“Few people in the UK today will have seen a flat oyster, our native species. Oysters still exist in these waters, but they’re scattered, and the reefs they built are gone.”
“We tend to think of our seafloor as a flat, muddy expanse, but in the past, many locations were a three-dimensional landscape of complex living reefs – now completely lost from our collective memory.”
Oysters are of economic and cultural importance, as reflected in historical records such as newspapers, books, travel writings, landing records, nautical charts, and early scientific investigations.
By analyzing these diverse sources, scientists can reconstruct the historical state of marine ecosystems. The North Sea was found to have the highest concentration of oyster reefs, with extensive reefs also recorded along the coasts of modern France, Denmark, Germany, the Netherlands, the Republic of Ireland, and the UK.
Dr Philine zu Ermgassen, an honorary researcher at the University of Edinburgh, said, “Oyster reefs are slow to develop, with layers of new oysters building up on the dead shells of their predecessors, but their destruction through overfishing was relatively rapid.”
“This has caused a fundamental restructuring and ‘flattening’ of our seafloors – removing thriving ecosystems and leaving an expanse of soft sediment behind.”
“Thanks to this historical ecology research, we can now quantitatively describe what oyster reefs looked like before they were impacted and the spatial extent of the ecosystems they formed.”
“These were huge areas that were thickly crusted with oysters and crawling with other marine life.”
Journal Reference:
- Thurstan, R.H., McCormick, H., Preston, J. et al. Records reveal the vast historical extent of European oyster reef ecosystems. Nat Sustain (2024). DOI: 10.1038/s41893-024-01441-4