Central Coast Watershed Studies Team

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Benthic Macroinvertebrates in Arroyo Seco River

An undergraduate student project by Suzanne Gilmore,

Central Coast Watershed Studies (CCoWS) team, CSUMB.


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


Project author: Suzanne Gilmore
Advisors: Dr Suzy Worcester, Dr Fred Watson

Final product

Brief report (317 KB PDF file)


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