Date of Award

8-2026

Document Type

Thesis

Degree Name

Master of Science in Biology

Department

Biology

First Reader/Committee Chair

Heras, Joseph

Abstract

This study was developed to use aquatic environmental DNA (eDNA) as a tool to detect the presence of the Santa Ana sucker (Catostomus santaanae), a federally threatened fish species, across the Santa Ana River in Southern California. Environmental DNA is any genetic material that an organism sheds into the environment. We can get an idea of what aquatic species are present when sampling water at a given site. We sequenced the complete mitochondrial genome (mitogenome) of the Santa Ana sucker and designed custom DNA primers to improve eDNA detection accuracy. These primers were selected based on high genetic distances of 12-17%, in which these regions amplify two distinct gene fragments (Cytochrome b, and NAD5) of the mitogenome. These primers will allow us to detect the presence or absence of Santa Ana sucker, creating a novel and exciting alternative for surveying populations of the Santa Ana sucker. Some of the current traditional methods of population fish surveys involve electrofishing, visual observation, tagging, or video software, which can be stressful and cause potential harm to these sensitive species. Our method involves passive eDNA collecting, where  water from the river passes through a filter to capture the environmental DNA. This eDNA approach introduces a non-invasive biodiversity assessment and contributes to conservation efforts for this threatened species.

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