Imagine walking over the Scottish hills into a remote Highland glen and discovering an entire ecosystem little changed in more than 2,000 years.
As previously reported (e.g. Cosgrove et al. 2000, 2012), the Freshwater Pearl Mussel Margaritifera margaritifera has suffered significant declines throughout its Holarctic range and is now classified as Endangered in its world range (Mollusc Specialist Group 1996).