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THREE YEAR VARIATION IN SHELL GROWTH OF THEMUSSEL, ELLIPTIO WACCAMAWENSIS (LEA), IN LAKEWACCAMAW, A BAY LAKE IN NORTH CAROLINA
Citation:
DiDonato, G. T. AND A. E. Stiven. THREE YEAR VARIATION IN SHELL GROWTH OF THEMUSSEL, ELLIPTIO WACCAMAWENSIS (LEA), IN LAKEWACCAMAW, A BAY LAKE IN NORTH CAROLINA. JOURNAL OF THE ELISHE MITCHELL SCIENTIFIC SOCIETY 116(4):324-333, (2000).
Impact/Purpose:
Our separate experiments during years 1993-1996 provide an opportunity to combine parts of our data and test for between-year variation in mussel growth parameters and to examine possible causes of inter-year variation.
Description:
Freshwater mussels (Bivalvia: Unionidae) are one of the most endangered animal taxa in North America, and continued research on unionids will improve management decisions regarding their conservation. One unexplored aspect of unionid ecology is the magnitude of interannual variation in growth. Investigations of a freshwater mussel population in Lake Waccamaw (North Carolina, USA) over a 3-year period (1993-1996) found significant between-year variation in several growth characteristics. Individual Elliptio waccamawensis demonstrated growth rates in shell length of 3.38 mm/yr during 1993, half that observed in 1994 (6.61 mm/yr) and 1995 (6.46 mm/yr). Growth calculated from shell height and width showed similar differences. Tissue dry weight in 1993 was reduced by one-third compared to the other study years. Methodological factors like variable mussel density and exposure period do not account for these observed differences. Variation in lake level, however, appears congruent with growth, and this observation forms the basis of an hypothesis concerning this mussel population and lake level. The mark-recapture technique used in these studies directly estimates mussel growth rates and discerns temporal variability, and those data like these are significant for unionid research and management.