Date

Summer 2026

Document Type

Master's Thesis (Open Access)

Degree Name

Master of Science (M.S.)

Department

Applied Environmental Science

Abstract

Rivers are dynamic freshwater systems that can experience shifts in flood regime that are driven by anthropogenic activity and climate change. These changes may no longer support the native species in the ecosystem and can favor invasive generalist species. The Pajaro River supports a range of urban, agricultural, and natural habitats and is prone to seasonal flooding that can affect habitat conditions and biodiversity. Current vertebrate diversity in the Pajaro River is not well understood, although traditional surveys have documented both rare and invasive species. Environmental DNA, or eDNA, can help address gaps in traditional monitoring by detecting elusive or difficult to survey species and establishing a new baseline for future biodiversity monitoring. This research utilized eDNA metabarcoding to characterize existing vertebrate biodiversity in the Pajaro River and examine how abiotic factors, such as surrounding land cover, may influence patterns of diversity along the river. We identified a total of 45 species across 10 sites, 6 of which were invasive species that had been traditionally observed. Our exploratory random forest analysis suggested that land cover and temperature variables did not have strong relationships with alpha diversity, beta diversity, and species richness. The species identified provide an updated biodiversity baseline that can inform future levee modifications and restoration efforts.

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