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Abstract
This thesis examines bioavailability of dissolved organic carbon (DOC) and the dynamics of Actinobacteria in the California State Water Project (SWP). DOC bioavailability was low throughout the SWP. Exposure to the equivalent of a one day of solar irradiation did not change aqueduct DOC bioavailability, but caused a slight increase in reservoir DOC bioavailability. Actinobacteria relative abundance was measured using real-time PCR; changes in assemblage composition were assessed by PCR/DGGE, and phylogenetic affinities of Actinobacteria populations were determined by sequencing cloned 16S rRNA genes. Actinobacteria relative abundance was 22% (range, 9-34%). Actinobacteria in water samples were not closely related to those in soil samples but were closely related to Actinobacteria found in the Sacramento-San Joaquin Delta. Reservoir and aqueduct assemblages differed. Aqueduct Actinobacteria assemblages varied seasonally. Changes in October assemblages correlated with conductivity and optical and chemical properties of DOC, while February assemblages varied with pH, temperature and conductivity.