THE EFFECT OF FLASHINESS ON MACROINVERTEBRATE POPULATIONS IN 1ST ORDER STREAMS NEAR DAVIDSON, NC

We examined 17 headwater streams in the North Carolina Piedmont to explore if there is a relationship between a stream’s flashiness and biotic index of the macroinvertebrate community. We hypothesized that flashier streams would show macroinvertebrate communities with higher tolerance toward sedimentation and organic pollution, and that land use in a drainage basin would affect the stream’s flashiness. Stream gauges were installed on 17 headwater streams in the Davidson, NC area using HOBO sensors to determine water depth and temperature every 15 minutes. Depth was converted to discharge using ratings curves developed for each site. To measure flashiness, we calculated the Richards Baker Index for each gauge site by season and for the whole data collection period. At each site we collected two kick net samples seven times between May and July and calculated the Hilsenhoff Biotic Index for the macroinvertebrates based on the per site per date data. We found no correlation between macroinvertebrate biotic tolerance index and flashiness but we did find a relationship between land use and flashiness. From this study, we conclude that streams located in residential areas tend to be flashier than streams located in mixed use or forested areas. However, flashiness does not seem to impact summer macroinvertebrates as measured by the Hilsenhoff Biotic Index. Further work is needed to determine if flashiness has an impact on invertebrates in other seasons and more detailed analysis is necessary to determine the impact on individual species and biodiversity during the summer.