Graduation Year

2023

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Marine Science

Major Professor

Mya Breitbart, Ph.D.

Co-Major Professor

Katherine Hubbard, Ph.D.

Committee Member

Gary Mitchum, Ph.D.

Keywords

Species assemblages, DNA fingerprinting, Species assemblages, Toxin

Abstract

Phytoplankton are abundant in both fresh and marine waters and can form harmful algal blooms (HABs) by producing potent toxins that have devastating effects on human, wildlife, and economic health. The HAB-forming diatom genus, Pseudo-nitzschia, occurs globally and approximately half of the 59 currently identified species can produce the neurotoxin, domoic acid (DA). DA accumulates in shellfish and finfish and can cause Amnesic Shellfish Poisoning (ASP) in humans and DA Poisoning (DAP) in several species of wildlife, resulting in severe neurological dysfunction and mortality. Along with these health threats, DA toxicity is a major economic threat for shellfish and fish farms and toxic Pseudo-nitzschia blooms have caused multi-million dollar losses in revenue in several regions due to the closures of seafood farms as a result of high DA levels. DA production varies across Pseudo-nitzschia species and strains therefore species identification and continuous monitoring are critical. The Gulf of Maine is an area with emerging DA issues. In 2016, the Gulf of Maine experienced its first shellfishery closure due to ASP in eastern Maine, coincident with the first observance of Pseudo-nitzschia australis in this region. Repeated shellfish closures due to P. australis presence occurred in 2017, 2018, and 2019. This thesis highlights temporal patterns of Pseudo-nitzschia species composition, environmental, hydrodynamic, and nutrient conditions in the Gulf of Maine, which provides potential mechanisms through which these changes are linked to DA production in this region. Findings from this research will enhance early detection capabilities of toxic Pseudo-nitzschia species, thus improving monitoring strategies for this HAB-forming genus.

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