Determining Stream and Wetland Health in an Urban Restored Riparian Ecosystem in Durham NC through Benthic-macroinvertebrate Surveys

Abstract

Water and aquatic habitat quality are frequently assessed by analyzing the structure of benthic macroinvertebrate communities in streams and other bodies of water. The Stream and Wetland Assessment Management Park (SWAMP) in Durham, NC, part of Sandy Creek, is a restored stream and wetland complex started in 2003. Restoration phases have been constructed to target both improvements in water quality and habitat. The two focal phases of restoration for this project were a re-sculpting of the geomorphology of the main stem of Sandy Creek and the creation of a braided or anabranched stream pattern. The anabranching stream pattern allows stream water to frequently come in contact with the soils in the floodplains for a prolonged period, promoting beneficial biogeochemical processes. This project tested both the change in water and habitat quality over time, as well as the difference in water and habitat quality between the restoration phases. Chemical and microbial laboratory analyses have shown that the water quality has improved since the restoration. Benthic macroinvertebrate data over an 8-year period demonstrate dissimilar results. The macroinvertebrate community analysis shows an overall decrease in both water and habitat quality since the restoration. There is also a significant difference in the macroinvertebrate communities found between restoration phases, specifically, the stream channel in the anabranching phase is shown to have lower water and habitat quality than that of the main stem. These findings are contrary to the expected results for a stream and wetland restoration project, but may be due to unusually high stream discharges in 2013 compared to earlier survey periods.