An International Journal of Ecology, Evolution and Environment

346 THE AMERICAN MIDLAND NATURALIST 163(2)FIG. 5.—Age-frequency histograms of Lemiox rimosus populations in the Clinch and Duck rivers; sexratio was 2:1 and 3:1 in favor of males, respectivelyPopulation trends and juvenile recruitment.—Most of the live specimens found in both riversbetween 2004 and 2007 were of small and medium sizes, indicating that these populationsare recruiting. Age histograms showed multiple age classes of young mussels (1–3 y),collectively comprising about 16% of sampled individuals in the Clinch River, and about12% in the Duck River (Fig. 4). Furthermore, the time-series of historical densities of Lemioxrimosus from 1979–2004 reported by Ahlstedt et al. (2004, 2005) indicated stable orincreasing population trends in each river, respectively (Fig. 6). Although these data werecollected using a different sampling design, the protocol was implemented consistently ateach time interval, thus providing additional insights into density trends over longer timeperiods. However, because the protocol sampled areas of best available habitat, density mayhave been over-estimated relative to total available habitat. Increasing abundance of L.