Effects of aquatic weed removal on freshwater pearl mussels and juvenile salmonids in the River Spey, Scotland

1.Experiments were carried out in the River Spey, Scotland to determine the effects of aquatic weed (Ranunculus spp.) removal on populations of freshwater pearl mussels (Margaritifera margaritifera) and juvenile salmonids (Salmo salar, Salmo trutta) and their river-bed habitats.2.Physical removal of Ranunculus had no significant impact either on pearl mussels or on salmon and trout fry.3.Regrowth of Ranunculus post-removal was negligible for one year, indicating that hand-removal may be an effective control measure.4.Ranunculus roots appear to facilitate substantial depositions of fine sand that are detrimental both to pearl mussels and salmonid fry.5.The rapid spread of invasive Ranunculus is a potential threat to the conservation status of M. margaritifera in the River Spey. Copyright © 2007 John Wiley & Sons, Ltd.