Three species of net-spinning caddisflies, Parapsyche cardis, Diplectrona modesta, and Dolophilodes distinctus were studied. Larvae of Dolophilodes are found at the lowest current velocities followed by Diplectrona, then Parapsyche, which prefer the higher velocities. Parapsyche larvae are most abundant on upper surfaces of stones while Diplectrona and Dolophilodes are found primarily on undersides of stones. These distribution patterns are probably related to capture net mesh dimensions which differ greatly for the three species, Parapsyche having the largest and Dolophilodes the smallest meshes. Significant correlations existed for mean foregut particle size and capture net mesh opening size between instars of all species within seasons, between instars of all species throughout the year, and between instars within species throughout the year. These correlations support the contention that particle size selection is an important aspect of feeding differences between species. There are large differences between mesh opening sizes of last-instar Dolophilodes and first- and second-instar Diplectrona larvae. However, based on mean particle size measurements of foregut contents, there is no corresponding gap in the spectrum of particle sizes used for food. Dietary composition also varied between species. Parapsyche consumed primarily animal material. Fine particulate detritus composed over 95% of Dolophilodes gut contents and Diplectrona consumed mostly vascular plant and detritus fragments in late instars and fine particulate detritus in early instars.
Bacterial community responses to a gradient of alkaline mountaintop mine drainage in Central Appalachian streams
