An unusual bloom of the toxin-producing organism Alexandrium in Hood Canal has presented a new mystery for researchers. Associate Professor Cheryl Greengrove of the University of Washington Tacoma is studying the event, which challenges previous scientific understandings of the organism.
The Alexandrium bloom is significant because the microscopic phytoplankton produces a neurotoxin that can concentrate in filter-feeding shellfish. When humans ingest such shellfish, it can cause paralytic shellfish poisoning. Such blooms can result in shellfish harvest shutdowns, impacting public health and the Washington shellfish industry, which is the nation's leading producer of farmed shellfish.
This year's event in Hood Canal is considered unexpected because previous blooms generally originated further north. This specific bloom appeared to begin in the southern portion of the canal, an area where Alexandrium cysts are typically less likely to occur. Greengrove stated that the current mechanism challenges assumptions developed through years of observation.
Greengrove, an oceanographer who has studied the Puget Sound for decades, investigates the life cycle of Alexandrium. The organism can form tiny cysts as a protective measure to survive harsh environmental changes, allowing them to remain viable in marine sediments for years. By mapping where these cysts settle, researchers aim to better understand where future blooms might develop.
Greengrove's research involves collaboration with sedimentologist Julie Masura. The process includes collecting sediment samples and processing mud in a laboratory to count cysts, which appear like little yellow jelly beans under a microscope.
Greengrove has been with UW Tacoma since 1996, when she was one of the institution's first two science faculty members. At that time, the campus lacked degree programs, a library, and dedicated teaching buildings. Over three decades, she has helped build science programs, design campus science buildings, and develop environmental science degree programs.
In 2014, a marine heat wave known as "The Blob" contributed to one of the first major Alexandrium blooms in Hood Canal. While waters have since cooled, they have not yet returned to original temperatures.
Greengrove's research in the Greengrove Lab involves undergraduate students who participate in field expeditions and data processing. She aims to provide students with the confidence to trust their skills in the field of science.
