Growth and survival of juvenile freshwater mussels in streams: Implications for understanding enigmatic mussel declines
We used in situ exposures of juvenile mussels (96-d average, May–September) to investigate the causes of mussel declines. We measured survival and growth of mussels exposed to ambient conditions in 23 streams in Kentucky, USA. Our set of streams included both those that support diverse mussel assemblages (occupied streams) and those that have lost nearly their entire mussel fauna (defaunated streams). We used 2 types of enclosures in each stream: silos, which primarily expose mussels to water, and sediment cages, which provide greater exposure to sediments. We used both enclosure types because some contaminants are more prevalent either in water or sediments. We collected extensive water and sediment chemistry data (163 and 144 analytes, respectively ) monthly at each stream and landscape data for each watershed. We found no evidence of acute toxicity. Survival averaged 90% in silos and was only 68% in cages.