Optical Tools for HAB Detection
Researchers created new imaging technology for monitoring harmful Alexandrium and Heterosigma algae, and developed a new model for predicting when and where Heterosigma will form HABs.
Daniel Grünbaum, University of Washington, School of Oceanography
Washington Sea Grant-funded researchers developed and deployed high-resolution, low-cost, low-power micro-imaging technology using embedded computers and high-definition cameras to detect, quantify, and characterize swimming algal cells. The imagers can work autonomously, storing data onboard, or be integrated into sensor networks, streaming real-time data to an online server.
The toxic algae Heterosigma and Alexandrium are common and costly sources of harmful algal blooms (HABs) in Puget Sound. Alexandrium is a toxin that can accumulate in shellfish and cause paralytic shellfish poisoning in humans and other animals. Heterosigma is a microscopic raphidophyte that relies upon its vigorous swimming ability to aggregate into toxic blooms that kill fish and other marine life.
In field tests, prototype imagers distinguished Alexandrium chains and quantified their abundance and swimming velocities. They enabled the team to publish new observations of Heterosigma cells emerging from sediment to water column. When conditions became supportive, resting cells could emerge and divide within hours, suggesting a tradeoff between swimming speed and efficient transition to the water column, both of which are metabolically demanding. The research team developed a numerical model based on this tradeoff that predicts the conditions under which different Heterosigma strains are likely to dominate HAB populations as well as conditions under which no strains will likely bloom.
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