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Date Permissions Signed


Date of Award

Fall 2020

Document Type

Masters Thesis

Department or Program Affiliation

Environmental Sciences

Degree Name

Master of Science (MS)


Environmental Sciences

First Advisor

McPhee-Shaw, Erika E.

Second Advisor

Moore, Stephanie K.

Third Advisor

Greengrove, Cheryl

Fourth Advisor

Bodenstein, Leo R., 1957-


Since the 1950s, the Washington State Department of Health has routinely monitored the suite of toxins in shellfish associated with Paralytic Shellfish Poisoning. These toxins, known collectively as Paralytic Shellfish Toxins, are produced by species of the marine dinoflagellate in the genus Alexandrium. The role of the monitoring program is primarily to protect public health and safety; and therefore, use of these data for long-term statistical analysis has been limited due to opportunistic and irregular sampling of various shellfish species in space and time. However, some studies suggest that initiation of these toxic events have recently shifted to earlier in the year (Hanein and Borchert, 2015). To test this hypothesis, I extracted a subset of these data to analyze for trends in timing of bloom initiation and location of Paralytic Shellfish Toxins after the first annual appearance. I did not find that bloom initiation to be occurring earlier in the year in any subbasins or regulatory closure zones which may indicate that a shift is either absent or undetectable. This contrasts with the finding of others that Paralytic Shellfish Toxins are being detected earlier in the year and indicate that endogenous conditions are a stronger driving factor in bloom initiation than larger climatic shifts. Additionally, although PST has been observed to be more widespread in recent years, I observed no clear progression of shellfish toxicity from one basin to another within any particular year. There was also no clear spatial relationship between the locations of cyst beds (i.e., areas with high concentrations of dormant cysts in sediments) and locations where PST is first detected in shellfish.




Alexandrium, Paralytic Shellfish Poison, Paralytic Shellfish Toxin, Puget Sound, Salish Sea


Western Washington University

OCLC Number


Subjects – Names (LCNAF)

Washington (State). Department of Health.

Subject – LCSH

Algal blooms--Monitoring--Washington (State)--Puget Sound; Paralytic shellfish poisoning--Washington (State)--Puget Sound; Poisonous shellfish--Washington (State)--Puget Sound

Geographic Coverage

Puget Sound (Wash.)




masters theses




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