Comparison of Macroinvertebrate communities between Forested and Urban streams

Sam Dormady

sdormady@unca.edu

ENVIRONMENTAL STUDIES

Urbanization has been known to impact watersheds negatively in a number of ways. For streams, this often includes poor water quality and increased sediment concentration. Macroinvertberates respond to these changes and will likely be found where they can tolerate certain levels of environmental stress. Forested streams, being the natural habitat of pollution, temperature, and oxygen sensitive taxa will likely have a community representative of cleaner stream conditions. The study aimed to analyze the macroinvertebrate community for eight stream sites within the Swannanoa River basin and to compare communities between urban and forested sites. We found that urban sites had a higher Family Biotic Index (FBIBI) than forested sites, indicating less than tolerable environmental conditions for common bio-indicators such as Ephemeroptera, Trichoptera, and Plecoptera families. Research on urban streams suggests that this is the normal pattern, citing sediment pollution and nutrient enrichment to be the top concerns. Conductivity was highest in urban sites downstream and the inverse was true for dissolved oxygen. Scoured banks and incised channels found at urban sites with high conductivity are indicative of increased flow volume and velocity during precipitation events eroding soil. Communities were more diverse within forested sites compared to urban sites. Two sediment tolerant taxa, Chironomidae and Oligochaete, composed most of the community for two urban sites Grassy Branch and Sweeten Creek. Forested sites had higher diversity including abundances of EPT. Higher habitat diversity increases available niches which can lead to higher community diversity, whereas sedimentation can decrease habitat heterogeneity. The differences in community diversity is likely due to the differences in habitat quality. Introduction

May-14-2024