Stream and Wetland Biological Survey

Abstract

A biological monitoring survey was conducted on four stream sites and two wetlands in the vicinity of a proposed mining operation in northern Minnesota. Fish and macroinvertebrate community composition, habitat characteristics, and water chemistry parameters were examined to establish biological condition at four stream reaches and two wetland complexes. Fish assemblages were sampled in streams by electrofishing, and in wetlands with 24-hour trap net sets. Macroinvertebrates were collected qualitatively with D-frame kick nets, and quantitatively with Hess, Ekman, or Petite Ponar dredge sampling gear. Total number of fish and total lengths per species were determined within each stream reach to estimate catch per unit effort (CPUE). Macroinvertebrates were identified, enumerated, and the relative abundance and taxa richness per site determined. Stream habitat characteristics and water quality parameters at each site were summarized by point estimates along randomly placed transects. Invertebrate community composition between sites was predictable, with two wetland communities sharing similar characteristics (B5 and B7). The number of macroinvertebrate taxa was similar among stream sites (B1, B2, B3, and B6), but much higher than found in both wetland habitats. Three stream sites, including a designated reference reach located within the same drainage area (B1), provided similar community compositions. The remaining stream sampling location (B6) contained a macroinvertebrate and fish community that was unlike the previous three stream sites, and more similar to the wetland habitats based on the fish community composition. Fish communities among all sites were similar in respect to the functional proportions of taxa present. This survey suggests that the biological characteristics associated with stream and wetland sites sampled at the proposed NorthMet Mining Project site varied with respect to the distribution of fish and invertebrate functional categories between sites, but the overall community composition was typical of other systems in the region.