The use of artificial substrates to ascertain the faunal difference between an agricultural drainage ditch and a third order river in south central Minnesota

The purpose of this study was to ascertain which of three artificial substrate samplers best discriminated between a river and an agricultural drainage ditch environment in south central Minnesota. The aquatic macro-invertebrates associated with three different artificial substrates, multi-plate (MP), rock filled basked (RFB) and nylon mesh bag on a brick (MBB) were collected to determine the effectiveness of the artificial substrate in a variety of sediment conditions. Using species diversity, total taxa, unique taxa and total organism analysis data, from the MBB sampler, revealed; of 48 taxa collected in the study area, 38 taxa were collected in the river and 25 taxa were collected in the ditch. Only 15 of the 48 taxa were common to both ditch and river. Of the 38 taxa were collected in the river, 11 orders and 17 families were represented. Then orders and 15 families were common to both ditch and river. All but one order and two families collected in the ditch were also found in the river, yet the river had one order and 13 families were not found in the ditch. This indicates that the ditch and river appear to have different habitat in relation to aquatic macroinvertebrate colonization. This investigation also indicates that aquatic macorinvertebrates should be used to assess environmental quality rather than water quality.