Search

The article reports on a study about the effects of aquatic weed or Ranunculus removal on freshwater pearl mussels and juvenile salmonids in the River Spey, Scotland. The conservation status of M. margaritifera in the River Spey is endangered by the rapid spread of invasive Ranunculus. Ranunculus roots appear to alleviate significant depositions of fine sand that are detrimental both to pearl mussels and salmonid fry. The study showed that the physical removal of Ranunculus had no substantial impact either on pearl mussels or on salmon and trout fry and that there are no realistic control solutions and complete eradication of the Ranunculus from the River Spey based on the methods available.

Atlantic salmon Salmo salar parr exposed to heated water effluent were larger than parr living upstream of the discharge. There was no effect, however, of temperature on the incidence of male parr maturation, despite the link between growth and maturation found in other studies. Mature parr upstream of the effluent were smaller than mature parr downstream of it, suggesting a higher size threshold for maturation in those parr exposed to the heated water. The small distance between upstream and downstream sampling sites probably precluded genetic differences between the parr, thus implying an environmental influence on the threshold size above which male parr matured. [ABSTRACT FROM AUTHOR]