Distribution of Rotifera and Cladocera in a regulated river system

The purpose of this study was to determine distributions of Rotifera and Cladocera in the Kanawha River in West Virginia. Rotifera were sampled monthly for twelve months with a Juday trap in the more lotic upstream end of Winfield pool (UW), and the more lentic downstream end of Winfield pool (LW) to determine seasonal distribution. During the period of peak rotifer abundance, rotifers were sampled along a longitudinal transect of Winfield pool and lower Marmet pool to determine longitudinal distribution. Cladocera were sampled with funnel traps at Marmet and Winfield Locks and Dams from lock wall, mid channel, and near shore sites.

The seasonal study showed that both UW and LW total rotifer densities were characterized by a single summer population peak. The same physical and/or chemical parameters did not account for equivalent variation in rotifer densities at the two stations. The longitudinal profile showed that a shift in species composition occurred from bacteriophages and detritivorous species upstream to herbivorous species downstream. A new species of the genus Lecane Nitzsch 1827 (Lecanidae: Rotifera) was discovered, namely Lecane arietii n. sp. This species was found to have fungal parasites which apparently effect its distribution. The Cladocera study showed shore and lock wall areas had greater numbers of Cladocera from mud and vegetative habitats than mid channel areas, apparently due to differences in periphyton between the sites. Cladocera from mud and vegetative habitats in lotic systems may be useful organisms to study tow boat perturbations.