Bioassessing lotic systems using benthic insect communities in southeast Wyoming.

摘要

Benthic macroinvertebrate communities are used widely to assess environmental conditions of aquatic ecosystems. To gain a good understanding of the macroinvertebrates that appear in certain locales as well as how they respond to anthropogenic disturbances, physical, chemical, and biological samples were collected with Surber and D-net in four southeastern Wyoming streams in the summer and autumn of 2001 and 2002. Based on a set of six criteria, six of 12 metrics generally reflected the contamination on Haggarty Creek from effluent that flows from the Ferris-Haggarty copper mine. They are the Shannon-Weiner index, random runs value, Ephemeroptera taxa richness, Ephemeroptera/Plecoptera/Trichoptera taxa richness, total taxa richness, and Plecoptera taxa richness.;The investigation of benthic insect communities in both the Medicine Bow River and Rock Creek showed that several differences occurred across different spatial scales. The differences in the structure of benthic macroinvertebrates between the montane and plains subbasins were caused from naturally-occurring variations in hydraulic and ecologic conditions. However, some differences existed between the two streams as well as between the substrates within subbasins; these differences were inconsistent across seasons and years. These findings suggest that, at the very least, the subbasin spatial scale should be considered when selecting both the metrics and their values for use in biomonitoring programs. In this study, an inventory was made of benthic insect communities that occurred in Medicine Bow River and Rock Creek.;Research suggested that, in a non-polluted stream (Big Sandstone Creek), differences in organic matter, time variables, and some metric values existed between the quantitative (Surber) and qualitative (D-net) sampling methods. However, with one exception, such differences were inconsistent across seasons and years. In contrast, no differences existed between results using the Surber sampler and D-net for sampling in a polluted stream (Haggarty Creek). This was probably due to pollutants reducing the number of benthic insects and amount of total organic matter to the extent that differences between the two sampling methods were not evident. Implications of these findings were discussed in the context of combining versus converting sample values that were collected with these two methods.