Date of Award

Summer 2019

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ocean & Earth Sciences

Program/Concentration

Ocean & Earth Sciences

Committee Director

H. Rodger Harvey

Committee Director

Margaret R. Mulholland

Committee Member

Shannon L. Wells

Abstract

Cyanobacteria are known to produce a variety of toxins that negatively impact both aquatic and terrestrial organisms. One putative neurotoxic compound is the non-protein amino acid β-N-methylamino-L-alanine (BMAA), which has epidemiological linkages to the development of several human neurological diseases. Three cyanobacterial species thought to produce BMAA —Microcystis aeruginosa, Synechococcus bacillaris, and Nostoc sp. —were grown in nutrient replete cultures to examine its synthesis and cellular distribution over a growth cycle. Production of BMAA was also examined in nutrient (nitrogen and phosphorus) deplete cultures of Microcystis aeruginosa. In addition, natural assemblages of phytoplankton dominated by cyanobacteria were collected from two Maryland Chesapeake Bay tributaries to determine whether natural cyanobacterial populations were producing BMAA. Blue crabs were also collected from the upper Maryland and lower Virginia Chesapeake Bay during the summer of 2018 to examine BMAA bioaccumulation in the stomach, hepatopancreas, and muscle tissues of these important benthic consumers. Concentrations of BMAA were determined via tandem high-performance liquid chromatography- mass spectrometry (HPLC-MS), a highly sensitive method that distinguishes between BMAA and analytically similar compounds, like the structurally related but non-toxic diaminobutyric acid (DAB). Although detection limits were between 25-106 pg wet weight for cyanobacteria and were 25 pg wet weight for blue crab tissues, BMAA was not found in any sample included in this study. Further research using similarly sensitive analytical methods are needed to determine the triggers for and variability of cyanobacterial BMAA production, and its potential transfer through the food web.

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DOI

10.25777/7fkq-6x96

ISBN

9781088396797

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