In 2016, the algae bloomed along the East Coast for the first time, spreading a neurotoxin in its wake. The neurotoxin contaminates shellfish, causing amnesic shellfish poisoning in those who eat the affected seafood. It can be deadly to humans and cause aggressive behavior in marine mammals. Shellfish farms from the Bay of Fundy to Rhode Island halted harvesting for weeks and recalled products. While a major event like this has not occurred in the Gulf of Maine since, P. australis<\/em> continues to threaten hatcheries and Maine\u2019s working waterfront.<\/p>\n\n\n\n The team developed a test that uses a quantitative version of the Polymerase Chain Reaction (qPCR) to detect P. australis <\/em>in environmental DNA (eDNA) samples. The test builds on Pseudo-nitzschia <\/em>research conducted over the past decade in Countway\u2019s lab, where Greenlee is based, and offers a more accurate approach to monitoring these toxic algae. As a result, this test can help the shellfish industry better track and respond to harmful algae blooms. <\/p>\n\n\n\n \u201cGenetic tools like this are becoming an important tool in our monitoring efforts for the Marine Biotoxin Monitoring Program within the Department of Marine Resources\u2019 Bureau of Public Health and Aquaculture,\u201dsaid Tyler Spillane, a marine resource scientist with Maine\u2019s Department of Marine Resources. \u201cThis assay will help us in better identifying toxin forming blooms of Pseudo-nitzschia<\/em> phytoplankton, allowing us to refine our management practices to better protect public health and potentially minimize growing area closures that impact the shellfish industry in Maine.\u201d<\/p>\n\n\n\n Approximately half of Pseudo-nitzschia <\/em>species are toxic, with P. australis<\/em> producing the highest levels of domoic acid, the neurotoxin that causes amnesic shellfish poisoning. Harmful algal blooms occur when a toxic species becomes more abundant than normal, sometimes taking over an ecosystem. While the bloom species is dominant, its toxins accumulate in shellfish, and when humans and other animals ingest those shellfish, it can lead to dangerous and even lethal consequences. The dangers of P. australis<\/em> in Maine loomed after its unexpected arrival in 2016, especially as scientists did not have the tools to best monitor and understand the species. <\/p>\n\n\n Currently, researchers use light microscopy to monitor samples of seawater for Pseudo-nitzschia<\/em>. While not all Pseudo-nitzschia <\/em>produce toxins like P. australis, <\/em>it is nearly impossible to differentiate toxic and non-toxic species visually, even based on observations by a skilled technician. When Pseudo-nitzschia <\/em>cells reach a certain abundance in the water, precautionary measures are taken within the shellfish industry to avoid selling contaminated products. <\/p>\n\n\n\n These measures remain in place until resource managers determine whether shellfish meat contains domoic acid. Collectively, this makes the benefits of identification costly to resource managers and other stakeholders.<\/p>\n\n\n\n![\"A](\"https:\/\/umaine.edu\/news\/wp-content\/uploads\/sites\/3\/2025\/12\/p-australis-cells-16x9-1-1024x576.png\")