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Publication Date


Document Type

Honors Project


Biological Sciences


Amnesic shellfish poisoning, Diatoms, Domoic acid, Determinants, Maine, Gulf of, Phytoplankton-Variation, Pseudo-nitzschi, Species diversity, Time-series analysis, ARISA, Environmental determinants, Gulf of Maine, Phytoplankton, Time series


The pennate diatom genus, Pseudo-nitzschia, commonly occurs in US coastal waters and includes several species that produce the neurotoxin domoic acid (DA). Human consumption of DA causes the syndrome, Amnesic Shellfish Poisoning. In the Gulf of Maine, little is known about the seasonal shifts in abundance and toxicity of the species in this genus, although at least 14 Pseudo-nitzschia species have been documented there. To understand bloom development in the eastern/central Gulf of Maine, shifts in the abundance of Pseudo-nitzschia spp. and toxicity, along with environmental factors (salinity, water temperature, transparency, dissolved oxygen and nutrient levels), were monitored over a 20-week period from June 10th- October 24th, 2013 at 3 locations. The DNA fingerprinting approach ARISA was used to characterize Pseudo-nitzschia community composition. Positive ASP Jellett tests first indicated the presence of DA, and LC-MS/MS was used to quantitate particulate DA levels. Temporal and spatial variations were observed in abundance, species composition and particulate DA over the sampling period, indicating clear successions of dominant species over time. In addition, correlations were observed between identified toxic species (P. seriata and P. plurisecta) and pDA. Significant correlations were observed between environmental and biological factors, such as water temperature and both cell abundance and pDA concentration. Salinity correlated to cellular abundance, pDA concentration and select Pseudo-nitzschia species. Select nutrients were also correlated to cellular abundance and pDA. Insights from this study reveal the impact of both biological and environmental factors on toxic blooms of Pseudo-nitzschia spp. in the Gulf of Maine.




79 pages : illustrations (some color), color map. Honors Project-Smith College, 2014. Includes bibliographical references (pages 67-72)