EnvORG Environmental Observations and Research Group

Trampling through streams and creeks may disrupt aquatic ecosystems by altering the landscape and displacing wildlife. Aquatic invertebrates are often used as indicators of water quality in stream ecosystems. We examined the effects of trampling on the aquatic invertebrate community and measured the absolute abundance, relative abundance, species richness, and species diversity at two (upper and lower) sites on Bell Creek in Orange County, CA. We used the California Streamside Biosurvey Protocol of aquatic invertebrates as guidelines for sampling and to determine creek health. We hypothesized that trampling would decrease the absolute abundance of the aquatic invertebrates and lower water quality in this stream. We simulated a 20-person hiking group trampling through the selected sites. Samples of aquatic invertebrates were collected from control sites (n=6) and trampled sites (n=12).
Trampled sites were sampled 12 and 36 hours after trampling. Three samples were collected from each treatment using a D-frame kick net. Relative to the controls, the upper creek community had a significant decline in absolute abundance, increase in diversity, increase in richness, and an increase in water quality 12 hours after trampling. The lower creek site had a decrease in absolute abundance, decrease in diversity, increase in richness, and an increase in water quality 12 hours after trampling. Similar trends were observed 36 hours after trampling with the exception of mayflies (Ephemeroptera) and caddisflies (Trichoptera). Our results show that trampling adversely affects aquatic invertebrates within this creek community.