This is the main conclusion of a new study in participation with the Institut de Ciències del Mar (ICM-CSIC) that reveals the loss of these key ecosystems for marine biodiversity in Europe.
A new study led by the University of Exeter, the University of Edinburgh, and with the collaboration of the Institut de Ciències del Mar (ICM-CSIC), has revealed that the extensive oyster reefs that once populated European coastlines have almost completely disappeared. This study, published in the journal Nature Sustainability, details how the European flat oyster (Ostrea edulis) once formed large reefs that hosted extraordinary biodiversity, but these ecosystems were destroyed more than a century ago due to overexploitation and human activity.
Researchers found that, at their peak, oyster reefs covered at least 1.7 million hectares of European coasts, from Norway to the Mediterranean, an area larger than Northern Ireland. Today, native oysters are scattered, and their ecosystems have almost completely disappeared.
“Native oysters not only provided a home for nearly 200 species of fish and crustaceans, but also stabilized coastlines and filtered enormous amounts of water, which contributed to the cleaning of marine ecosystems,” notes Ruth Thurstan from the University of Exeter, who is part of the Convex Seascape Survey, an ambitious five-year project examining carbon storage in the oceans. “It is crucial to understand how our ecosystems were in the past to effectively restore them,” she adds.
Push for habitat restoration
Various restoration projects are currently being carried out in Europe, such as “Wild Oyster,” an initiative led by the Zoological Society of London (ZSL). At a national level, the RemediOS2 project, funded by the Fundación Biodiversidad under the Pleamar program, also studies how to restore the Mar Menor with flat oysters to help improve the health of its ecosystems. With the results of this study in hand, researchers call for these efforts to be expanded with the support of governments and policymakers.
Eve Galimany, a researcher at the ICM-CSIC and ICATMAR, also involved in the study, highlights the importance of the findings:
“This study allows us to understand the true magnitude of what we have lost. Oyster reefs were key components in the health of our seas. Their restoration would not only bring back an iconic species, but also provide shelter for numerous species and help fight the climate crisis by improving water quality and strengthening coastal protection. It is essential that we scale up these restoration efforts across Europe if we are to reverse the historical damage we have caused to our marine ecosystems.”
The future of oyster reefs
The study reveals that historical records, such as newspapers, nautical charts, and fishermen’s accounts, documented the existence of vast reefs along the coasts of countries such as France, Denmark, Germany, the Netherlands, the Republic of Ireland, and the United Kingdom. However, overfishing and intense exploitation caused the rapid disappearance of these ecosystems, resulting in a significant loss of biodiversity.
Philine zu Ermgassen, researcher at the University of Edinburgh, explains: “Now, thanks to this research, we can accurately describe what these reefs looked like before they were destroyed and the extent of the ecosystems they formed.” According to Ermgassen, these European reefs covered vast areas, densely packed with oysters and teeming with marine life. “It’s a great loss that we must begin to reverse,” concludes the researcher.