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The mussel Margaritifera margaritifera, commonly known as the Eastern Pearlshell, produces fine pearls with lustrous nacre and physical properties similar to those of most nacreous pearls. Over the past few centuries, rare examples of these freshwater pearls have been harvested from the cool streams and rivers of eastern Canada. The Collections of the Canadian Museum of Nature hold historic specimens, as well as a more recently acquired necklace and brooch that contain a total of 72 pearls. These represent one of the most significant records of this type of pearl. The long-term survival of the Eastern Pearlshell mussel is under threat in many river systems, primarily because of human development, acid rain, and the decline of wild Atlantic Salmon (the salmon being the primary host fish used by M. margaritifera). Rivière du Gouffre, the locality for the pearls described here, is still unpolluted with a healthy and reproducing Eastern Pearlshell population. [ABSTRACT FROM AUTHOR]

Potamilus alatus (Pink Heelsplitter) is a rare freshwater mussel in the Ottawa River drainage (Ontario/Quebec, Canada), at the northeastern limit of its distribution. There are few historical records, and one old specimen from an uncertain locality. The discovery of the Pink Heelsplitter in the Ottawa River drainage dates from 1863. A few specimens were reported up to 1901, but it was August 2001 before another specimen was found in the Ottawa River, as an empty shell at Upper Duck Island, near Ottawa. From 2001 to 2005, the authors found this freshwater mussel at four localities along the Ottawa River, and two in the tributary South Nation River. Records include 4 living specimens and 12 empty shells, of which 8 were in fresh condition. The Pink Heelsplitter seems to persist sparsely in the Ottawa River, but it may have been extirpated from one of its tributaries (South Nation River) before its discovery due to mortality associated with Dreissena polymorpha (Zebra Mussel). [ABSTRACT FROM AUTHOR]