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8025831 
Journal Article 
DISTRIBUTION, AGE STRUCTURE, AND MOVEMENTS OF THE FRESH-WATER MUSSEL ELLIPTIO-COMPLANATA (MOLLUSCA, UNIONIDAE) IN A HEADWATER STREAM 
Balfour, DL; Smock, LA 
1995 
Yes 
Journal of Freshwater Ecology
ISSN: 0270-5060
EISSN: 2156-6941 
10 
3 
255-268 
WOS:A1995RZ11300007 
The distribution, age structure, and movements of the unionid mussel Elliptic complanata (Lightfoot) were studied in a first-order stream in Virginia, USA. Mean density of the mussel in this low-gradient, sand-bottomed stream was 2.5 individuals/m(2) and biomass was 3.4 g dry mass/m(2). About 87% of the population had a shell length of 6-9 cm, or age of 4-6 years. Only 11% of the population was less than four years old; the age of the oldest individuals encountered was only eight years. Distribution of the mussels was highly clumped, but no physical, chemical, or hydrologic factors examined were significantly correlated with mussel abundance. All young mussels (age < three years) were burrowed into the sediment, whereas older individuals occurred both below and at the sediment surface, depending on time of year. About 90% of the population was burrowed below the surface during the winter, but a high of 80% of the mussels moved to the surface in March and April, the time of peak reproductive activity. Tagged mussels moved an average of 2.9 m during one year. Although the direction of those movements was erratic, the overall movement of the population was a net 27 cm downstream, indicating no directed upstream movement to compensate for downstream displacement during storms.