| Summary: | Thesis (Master's)--University of Washington, 2019 Environmental DNA is a rapidly developing tool that offers a unique opportunity to sample the communities of an ecosystem in greater depth than other sampling methods. When analyzing environmental samples using general primers and a metabarcoding method, researchers are able to detect a multitude of taxa, such as plankton, invertebrates, fish, and mammals, even at low concentrations. Given the changing environment in Puget Sound, biological responses such as the increasing frequency of harmful algal blooms, are a concern. Environmental DNA can help detect and track harmful algal species, as it has been used for other harmful or invasive species. In this study, I use environmental DNA to detect a potentially toxic dinoflagellate in the family Kareniaceae, which is not well reported in Puget Sound, and assess the environmental conditions with which it is associated. In the present dataset, the species occurs only at depth, and in particular, in low-pH, low-dissolved-oxygen, and high-salinity conditions. I then use logistic regression to predict the presence of the dinoflagellate given the data in hand; the resulting model suggests that a change in water pH from 7.8 to 7.4 increases the probability of Kareniaceae sp. presence by from 29% to 95%. With decreasing pH levels within Puget Sound, the continuing progression of ocean acidification could lead to bloom conditions for the taxon. This method could become a first-step monitoring tool for species such as Kareniaceae sp. and to focus investigative efforts to prevent HABs.
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