Heterosigma cyst formation and longevity 

Troubled Sediments: Heterosigma Cyst Formation and Longevity 

Using a broad, integrated toolbox of techniques, researchers uncovered important information about Heterosigma’s behavior, life-history parameters, and metabolism. These findings can be used to build a testable model for predicting harmful algal blooms.

Principal Investigator

Rose Ann Cattolico, University of Washington, Department of Biology


WSG researchers used a broad range of techniques to analyze Heterosigma’s change from an active to resting state, including high-resolution videography to track swimming behavior, and a suite of instruments and biochemical procedures to measure lipid quantity and quality and examine transitions in metabolic pathways.

Research Updates


The single-celled alga Heterosigma forms massive toxic blooms, which have caused fish kills and destroyed millions of dollars’ worth of farmed salmon in Puget Sound and neighboring waters. Heterosigma is elusive and resilient; it can go into a resting state for months in deep, cold waters, then change to a vigorous active state when growth conditions improve, swim back to the photic zone, and initiate new blooms. How exactly Heterosigma makes this switch remains unknown, but it is important for understanding and anticipating toxic blooms.


This effort has produced the only highly integrated study of both the behavioral and metabolic responses of Heterosigma’s two life-history profiles. The data show a correlation between lipid production and swimming capacity. Results can be used to build a testable model using cell-activation responses to predict bloom formation. They also suggest the possible presence of a sexual cycle and give new insight into the metabolic shifts that insulate harmful algal species from unfavorable conditions.


Bigelow N, Barker J, Ryken S, Patterson J, Hardin W, Barlow S, Deodato C, Cattolico RA (2013) Chrysochromulina sp.: a proposed lipid standard for the algal biofuel industry and its application to diverse taxa for screening lipid content. Algal Research, 2(4):385-393.

Park BS, Cattolico RA, Baek SH, Ki JS, Han MS (2012) Assessment of EvaGreen-based quantitative real-time PCR assay for enumeration of the microalgae Heterosigma and Chattonella (Raphidophyceae). Journal of Applied Phycology, 24:1555-1567.