Influence of a Lentic Area on Condition Indices of Corbicula fluminea in the Wolf River, Tennessee

ABSTRACT

This study tested the hypothesis that filter-feeding organisms have higher condition indices downstream from a swamp than those upstream at a location not receiving lentic drainage. Sampling was performed monthly in the Wolf River in western Tennessee, USA from February to August, 2002. Condition of the Asian clam, Corbicula fluminea (Müller), was measured as glycogen concentration, tissue percent water content, tissue dry mass: shell mass, tissue dry mass: shell cavity volume, ash-free dry mass: shell mass, and ash-free dry mass: shell cavity volume. All condition indices, except glycogen concentration, were significantly greater (P<0.05) at the downstream location but converged during the summer. Downstream individuals also had significantly heavier shells (P<0.05) for a given cavity volume. The most discriminating condition index was tissue ash-free dry mass: shell cavity volume. The higher condition of individuals immediately downstream from the swamp, compared to upstream individuals, supports the hypothesis that the swamp benefits filter-feeding organisms by exporting seston.