Effects of distance downstream from a wetland source on Hydropsychidae and Brachycentrus abundances.

Abstract

The purpose of this study was to determine the changes in filter feeder abundance, specifically Hydropsychidae and Brachycentrus, downstream from a wetland stream source. An increase in collector abundance was expected with respect to increasing current velocity and increasing fine particulate organic matter (FPOM). Eight sites were sampled downstream from a wetland. At each site, a viewing bucket with a sample area of 100 cm2 was used to count caddisfly abundance on six different logs. It was found that the number of Hydropsychidae did not change with downstream distance, however abundance did increase with an increase in velocity and FPOM. The number of Brachycentrus were found to increase with distance downstream and with current velocity, however FPOM had no affect on abundance. Light had no significant affect on relative abundance of either species. It is speculated that microhabitat space affects distribution of caddisfly collectors.