Graduation Date

Spring 2020

Document Type



Master of Science degree with a major in Natural Resources: option Environmental Science and Management

Committee Chair Name

Alison O'Dowd

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Darren Ward

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Nicholas Som

Third Committee Member Affiliation

HSU Faculty or Staff

Subject Categories

Environmental Science and Management


Benthic macroinvertebrate (BMI) drift, species composition and abundance are specific to local hydrologic and habitat conditions, which can restrict or enhance availability to salmonids as a food resource. Currently, a knowledge gap exists on the Trinity River (northern California) in how flow releases from Lewiston Dam potentially impact BMI drift and feeding opportunities for juvenile salmonids. Samples of BMIs from drift, benthos, and diets of juvenile Chinook salmon (Oncorhynchus tshawytscha) were collected from two sites in the upper Trinity River February-April 2018, during stable flow conditions (~8 ) and two increased flow conditions peaking at ~50 . Chironomidae (Diptera) and Baetidae (Ephemeroptera) were dominant BMI taxa in the drift, benthos and diets. Although contributions to biomass were more even across BMI taxa in the drift, biomass consumed by fish was dominated by Chironomidae and Baetidae at both study sites. BMI taxonomic composition was more similar between benthic, drift and diet samples at the upstream study site below Lewiston Dam, whereas compositional similarities diverged during peak discharge conditions at the downstream study site. Although standardized drift rates (ex. mg/m3) did not increase with increased flow, the total export of BMI drift increased significantly with increased flow (p


Original degree title: Master of Science degree with a major in Natural Resources, option Environmental & Natural Resource Sciences

Citation Style



Thesis/Project Location