Study uncovers vivid and poignant accounts of reefs as high as houses off countries including UK, France and Ireland

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.