The Rocky Branch stream ecosystem, NCSU campus, Raleigh: the beginning of a long-term study

Urbanization is a major source of stress for stream ecosystems. Streams draining urban areas carry large solute loads, have altered geomorphologies, and are inhabited mostly by tolerant aquatic fauna.  Physical restoration of channel features is a common alternative to improve the condition of stream ecosystems in urban areas.  Understanding how restored streams function as ecosystems is a priority to help improve our ability to restore them in urban landscapes. Our goal is to focus on Rocky Branch as a focal site to study urban stream structure and function after restoration. Rock Branch is a small urban stream that flows through NCSU campus. Its restoration was completed in 2011 with sequences of riffles and pools evident in the upper section, a middle section that was day-lighted, and a lower section that now has floodplain habitat.  We characterized macroinvertebrate and fish assemblages and assessed fish diets along Rocky Branch during 2019. Macroinvertebrates are abundant and dominated by tolerant taxa, including aquatic insects (dipterans and damselflies) and crayfish.  Fish assemblages are composed mostly of Green Sunfish, an introduced species dominant in urban streams, and Goldfish.  Sunfishes consume a wide variety of insect prey, with small individuals consuming mostly benthic insects and large individuals a variety of terrestrial prey.  Overall, the stream maintains signs of degradation, but has a functional ecosystem.  Our plan is to continue monitoring Rock Branch over time to understand how its ecosystem function.