PRELIMINARY ASSESSMENT OF FUNCTIONAL AND FAMILY DIVERSITY OF MACROINVERTEBRATES IN THE MAIN STREAM, SIDE CHANNEL, AND BACKWATER AREAS OF THE SAINT CROIX RIVER, JUNE 2009

C. A.DeGuire, Student, Edgewood High School, Madison WI
C. M. Kuecker, Student, Edgewood High School, Madison WI
M. A. Wiederholt Meier, Director, Advanced Environmental Field Education, Edgewood High School, Madison WI
Toben D. Lafrancois, Research Associate, St. Croix Watershed Research Station, Marine on St. Croix MN

Macroinvertebrates play a significant role in their ecosystems and are important bioindicators. Different habitats within a stream can affect the distribution and abundance of macroinvertebrate taxa and functional groups. The purpose of this study was to examine macroinvertebrate communities in three major sub-habitats of the upper St. Croix River (Pine Co., MN) in June of 2009. Main stream, side channel, and backwaters sites were defined by physical parameters. Two sites of each type were sampled along the St. Croix from HWY 48 (MN) to the confluence with the Kettle River. Macroinvertebrate taxonomic and functional diversity were measured along with basic water chemistry and water speed. Invertebrates were identified to Family level and assigned a functional group. It was expected that the backwater and main channel sites would be the most different, but these areas were very similar in taxonomic diversity. The side channel areas had the lowest taxonomic diversity. There were not significant differences in the number or kind of functional groups found at the three site types (means of 5.0, 4.5, and 5.0 respectively). The average water speeds of the three types of areas shows that flow is different over site types(means of 0.30, 0.15, and 0.00 m/s respectively). Results may change at lower taxonomic resolution, if more sites are sampled, or if the survey is carried out at different times of the year. However, the finding that different types of stream section in the upper St. Croix River support similar taxonomic and functional diversity is ecologically significant. This work was completed as part of the Advanced Environmental Field Education course (#7095C) run by Edgewood High School, Madison WI.