An undergraduate student project by Suzanne Gilmore,
Central Coast Watershed Studies (CCoWS)
Watersheds are an integral and driving component of many terrestrial cycles.
Fresh water resources are becoming increasingly valuable to local communities
for urban development, agriculture, and recreation. Assessing environmental
changes over time is important in evaluating impacts of human usage on our declining
water resources. Benthic macro-invertebrates have been found to be an effective
measure of changes in local waterways. In the Arroyo Seco watershed, located
east of Big Sur in Central California, a study was conducted to assess changes
in the environment and their related changes in benthic macro-invertebrate diversities.
By comparing differences in substrate to the corresponding diversity levels
of insect communities, a relationship between substrate and biological metrics
can be formed. To better understand this relationship, macro-invertebrate abundance
levels, taxa richness, EPT taxa (number of taxa found in the orders: Ephemeroptera
(mayflies), Plecoptera (stoneflies), and Trichoptera (caddis flies)), EPT taxa
composition and dominant taxa composition were analyzed given a cobble versus
sand dominated substrate. EPT taxa, EPT composition, and taxa richness measures
were higher in the upper site and decreased in the lower site. Dominant taxa
composition was found to be higher in the sandy substrate than the cobble substrate.
Overall, less diversity was found in the sandy substrate (lower site) than in
cobble substrate (upper site).
A level II or III taxonomic effort would be necessary to further clarify EPT
measures and associated ramifications found in both