26. Effects of Road Crossings on Macroinvertebrate Communities in Tropical Cloud Forest Streams

Abstract

Monitoring water quality is imperative to safeguarding the health and quality of streams because they provide habitat to organisms and water resources to the surrounding area. To measure and assess stream health, investigators may utilize physical and chemical indicators including pH, dissolved oxygen, temperature, flow, and turbidity, as well as biological indicators such as macroinvertebrate counts. Our goal was to assess the impact of two road crossings on their respective streams and, in particular, to assess possible anthropogenic influences on the macroinvertebrate community of each stream. At UGA’s Costa Rica campus in Monteverde, samples were collected from six riffles of an ephemeral and a second order stream using standard D-frame net sampling technique. Samples were then examined and classified to the family level. A Shannon Diversity Index, Hilsenhoff Family Biotic Index, and the BMWPCR, an index developed for Costa Rican streams, were used to assess and compare the effect of the different road crossings on the macroinvertebrate communities of each stream. Our two-way ANOVA suggests that there is no statistical difference between upstream and downstream macroinvertebrate communities in the two streams sampled. Infrequent use of the road crossings due to a small human population in Monteverde may help explain these results. Our data suggest that human activity near the campus and surrounding area may have a minimal impact on stream macroinvertebrate communities.