Glochidium morphology of the freshwater pearl mussel ( Margaritifera margaritifera) and glochidiosis of Atlantic salmon ( Salmo salar): a study by scanning electron microscopy

• Published in: Canadian Journal of Zoology
• Main Authors: Nezlin, L. P., Cunjak, R. A., Zotin, A. A., Ziuganov, V. V.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1994
• Subjects: Varzuga; Atlantic salmon; Salmo salar
• Online Access: http://dx.doi.org/10.1139/z94-003; http://www.nrcresearchpress.com/doi/pdf/10.1139/z94-003

The morphology of glochidia of the freshwater pearl mussel Margaritifera margaritifera L. and the development of the cyst for 50 days after glochidial infection of wild and hatchery-reared Atlantic salmon (Salmo salar L.) parr were studied using scanning electron microscopy. The microvillar surface of the inner epithelium of the glochidium, which may function in nutrition, respiration, and osmoregulation, is described. Glochidia were found to have five sensory tufts as well as marginal ciliary bands which are believed to function in directing water currents. After artificial infection of salmon parr, cyst formation was the result of shape change and migration of gill epithelial cells, but not hyperplasia. The process of cyst formation lasted from 9 to 12 h. No mortality of salmon parr occurred during the experiment. Based on our study, glochidia appear to have a negligible effect on the gills of Atlantic salmon, its preferred fish host. These results are discussed in the context of the possibility of a mutually beneficial coexistence of Atlantic salmon and pearl mussels in northern European rivers such as the Varzuga River in Russia.