Study: Europe's Oyster Reefs Were Once The Size Of Northern Ireland; Today's Remnants Are A Few Meters Square

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Only a handful of natural oyster reefs measuring at most a few square metres cling on precariously along European coasts after being wiped out by overfishing, dredging and pollution. A study led by British scientists has discovered how extensive they once were, with reefs as high as a house covering at least 1.7m hectares (4.2m acres) from Norway to the Mediterranean, an area larger than Northern Ireland.

The study involved dozens of researchers poring over government records, nautical charts, fishery reports, customs documents, naturalists’ accounts, scientific journals and newspapers from the 18th, 19th and early 20th centuries to piece together the spread of the European flat oyster (Ostrea edulis). They found vivid – and poignant – accounts of often sprawling reefs at 1,196 locations off countries including the UK, France, Ireland, Denmark, Spain, Germany and the Netherlands. One report from a scientific article mentioned oyster reefs reaching 7 metres in height in the Black Sea.

Ruth Thurstan from the University of Exeter, the joint lead author of the report, said she was “blown away” by the extent of the reefs. “I knew that oysters used to be caught in huge quantities, so we suspected that these reefs could be large, but to find information that evidenced such coverage of reefs, amazed me. “Few people in the UK today will have seen a flat oyster, which is 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.”

The reefs created rich ecosystems, providing a habitat for almost 200 fish and crustacean species including the common stingray, the short-snouted seahorse and the European sturgeon. They also played a vital role in stabilising shorelines, nutrient cycling and water filtration. Thurstan said: “There are a handful of remnant reefs in a few parts of Europe, including the coast of Brittany and the west coasts of Ireland and Scotland. But these are at most a few square metres in extent, as opposed to square kilometres in the past. The significant ecological functions these reefs used to provide no longer exist, which is what we mean by functionally extinct.”

EDIT

https://www.theguardian.com/environment/2024/oct/03/europe-oyster-reefs-study