Julius Caesar was said to have invaded Britain at least partly due to his love of pearls.

The Holy Roman Empire’s most able military commander launched his first invasion in 55BC, according to his biographer, Suetonius. Chariots were a feature of the Roman war machine, and their modern-day equivalents have been an intriguing aspect of the latest round in the battle to save our rare freshwater pearl mussels.

1975 Ford Capri JPS Special, (C) Gartenmeister, Creative Commons.

A number of cars – including a 1970s Ford Capri John Player Special – have been hauled up from the depths of the River Dee, Aberdeenshire, during work to remove obstacles and help save freshwater pearl mussels.

The finds stem from work in 1984 when a 100 metre gap in the riverbank on the Mar Lodge Estate, now owned by the National Trust for Scotland, was filled with trees, old cars, and large quantities of rubble.

©Lorne Gill/SNH

Up to 16 cars and many tonnes of concrete waste, rocks and boulders were removed from the bank of the River Dee as work to help reduce pollution risk to the mussels, and salmon, got underway. Work will also remove an eyesore as the corrugated iron facing on the stretch of riverbank mars the otherwise unspoilt landscape.

©Lorne Gill/SNH

David Frew, property manager for Mar Lodge Estate, explains: “The car embankment has been a blot on an otherwise iconic landscape for many years, and it will be fantastic to see this restoration work finally take place. The project demonstrates how partnership working between landowners and public agencies can deliver real results for the environment.”

The work was initiated by the Dee Catchment Partnership and is being carried out as part of a £3.5 million Pearls in Peril (PIP) project. PIP is an EU-funded LIFE project to improve habitat for freshwater pearl mussels and salmon, co-ordinated by Scottish Natural Heritage with the Dee District Salmon Fishery Board and the River Dee Trust.

©Lorne Gill/SNH

Once all the waste that makes up the car barrier has been removed from the riverbank, and the cars sent to be scrapped, the bank will be re-profiled to a more natural shape which blends in with the surrounding landscape.

©Lorne Gill/SNH

Other PIP work on the River Dee includes planting woodland along a 70km stretch of riverbank to protect against the effects of future climate change; installing 45km of buffer strips in the middle catchment to protect watercourses from soil and nutrient runoff; and an education programme will be run in local schools. This will all benefit the river system by improving water quality and helping restore natural flow patterns.

©Lorne Gill/SNH

The exploitation of freshwater pearl mussels, the fascinating mollusc which may, or may not, yield the elusive pearl, has gone on since pre-Roman times. In Scotland the earliest reference is from the 12th century when Alexander I, King of Scots, was said to have the best pearl collection of any man living.  There are further references later that indicate a growing exploitation of Scottish pearl mussels and by the 18th century the first note of a decline in pearl mussel numbers can be seen. More recently evidence emerged that pearl mussels had become extinct from an average of two rivers every year in Scotland between 1970 and 1998 (when the species gained full legal protection).

Freshwater pearl mussels (Margaritifera margaritifera) ©Sue Scott/SNH

Freshwater pearl mussels are rare molluscs that live in the gravel beds of clean rivers. They feed by filtering water and removing fine particles and so help to keep our rivers clean. The mussels are critically endangered and Scotland is one of their few remaining strongholds. Mussel larvae spend the first few months of their lives attached to the gills of young salmon and trout, so healthy fish populations are vital to their lifecycle.

Freshwater pearl mussels have historically been fished for the pearls they can produce. However, they very rarely contain pearls and they are fully protected under law – it a crime to kill, injure, take or disturb them.

Freshwater pearl mussels ©Sue Scott/SNH

PIP is working hard to ensure that the freshwater pearl mussel remains an important component of Scotland’s biodiversity. Given its place in our cultural history it would be doubly tragic if the final chapter in that history was to see the species become extinct in our rivers.

For more information visit the freshwater pearl mussel pages of our website.