Exploring the Factors that Determine the Presence and Absence of Minytrema melanops in East Texas Using Environmental DNA
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Biological and Environmental Sciences
Date of Award
Summer 8-18-2025
Abstract
This study examines the presence and distribution of the spotted sucker, Mintrema melanops, a rare fish species, in the Cypress, Sabine, and Neches Rivers of East Texas, utilizing Environmental DNA (eDNA) technology. Traditional sampling methods often fail to detect rare species, making eDNA a valuable, non-invasive alternative. Water samples were collected from 49 sites across the three river basins and then analyzed using a qPCR assay with species-specific mitochondrial COI primers and hydrolysis probe. These primers were designed from a consensus sequence of 21 available sequences for the target species, and tested against a sequence database of 101 fish species from the region. Results of assay validation methods indicated a detection sensitivity of 1:1,000,000 dilution of positive control sample from fish tissue extraction, with a primer efficiency of 96%. Environmental parameters including width, substrate, flow, dissolved oxygen, pH, TDS, ORP, and temperature were collected in the field during eDNA collections. Correlation between presence of M. melanops eDNA was tested with logistic regressions, with model selection based on AIC score. Substrate was the most significant predictor of M. melanops presence in the dataset, with higher presence of the species in sites with more coarse substrates. ORP was also an important factor in the dataset, with increased presence at lower ORP sites, which may be related to water chemistry and degradation of eDNA (longevity of eDNA in systems). A regional analysis by Fisher’s exact test showed that the species did not have longitudinal clustering in abundance in the Cypress and Neches drainage, but did have significant clustering in the middle sections of the Sabine drainage. These findings not only confirm the utility of eDNA for detecting M. melanops in East Texas, but also contribute to insights for future research in conservation and habitat management strategies in these aquatic ecosystems.
Advisor
Bjorn Schmidt
Subject Categories
Biology | Life Sciences
Recommended Citation
Reid, Reagan C., "Exploring the Factors that Determine the Presence and Absence of Minytrema melanops in East Texas Using Environmental DNA" (2025). Electronic Theses & Dissertations. 1306.
https://lair.etamu.edu/etd/1306
