River Dee’s pearl mussels get a helping hand – or gill

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The sun shines on clear river water running through a valley in the Cairngorms, bringing the stones on the river bed into colourful focus. Here and there are dark shadows, half-buried clusters of dull black shells, lined and gouged by decades of shifting water and gravel: the pearl mussels of the river Dee.

The pearl mussel is one of the most ancient invertebrates on the planet, a freshwater shellfish that has helped to shape the history of Britain. One pearl mussel in every 1,000 or 5,000 - no one can be sure - lives up to its name and contains a lustred treasure. Julius Caesar's biographer, Suetonius, cites a desire for pearls as one of the reasons why the Romans invaded Britain in 55BC.

Read More  :  https://www.theguardian.com/environment/2016/aug/13/river-dee-pearl-mussels-habitat-restoration