Seasonal study of caddis fly populations in the South Dry Sac River.

This study focused on assessing the similarities of Caddisfly populations in different riffles over several seasons within a two-year period between 2003 and 2004 and was conducted within the intermittent stream of the South Dry Sac River in Springfield, Missouri. The focus was to determine if riffles themselves show consistent caddisfly population size across seasons or if other factors may be involved in the success of caddis fly populations. Samples were taken every six weeks within a four-day period using a Surber net with a 500 [mircro]m mesh. One square foot quadrant within the surber was agitated for one full minute at a depth of about fifteen centimeters. Preservation of samples took place in 75% ethanol and each individual was identified to genus using Merritt & Cummins 1996 and Thorp & Covich 2001. For this particular study, the data analyzed was specific to the Hydropsychidae population. Data showed that there were more individuals located in the more consistently flowing riffles during the August-September 2003 season than in February-March 2004. Dendrograms representing patterns in distribution of Hydropsychidae populations revealed a noticeable degree of dissimilarity spatially between the riffles as well as temporally between consistent and low flow seasons; mirroring flow patterns in the South Dry Sac River. These patterns are reflective of the effects of water availability on the distribution of aquatic larval Caddisflies and show that population size is not consistent across seasons but may very well be directly linked to water availability.

* Buffington, A.K., Carroll, T.M. Department of Biology, Drury University.