Hidden threats: DNA testing reveals toxic algae in Queensland's Hervey Bay

Extensive genetic testing in Queensland's environmentally rich Hervey Bay coastal area has revealed the presence of toxic algae not detected in Australian waters before. The study is in Marine Pollution Bulletin.
James Cook University Ph.D. candidate Joseph Perkins led the study. He said harmful algal blooms (HABs) present severe risks to marine ecosystems, wildlife, human health and economies globally.
"We decided to investigate the diversity and abundance of the primary HAB group—dinoflagellates—in Hervey Bay, a region notable for its ecological uniqueness and high susceptibility to HABs," said Perkins.
He said testing for the microscopic creatures was thorough, incorporating not just water as in most studies, but also sand and macro-algae such as seaweed, accounting for dinoflagellates' complex life cycles.
The scientists discovered 15 species of toxic dinoflagellates (TD) in Hervey Bay, some of which were recorded in Australian waters for the first time.
"The TD not only pose direct threats to human health through contaminated seafood but also have potential repercussions for local marine life.
"The detection of species from the genus Karenia, for instance, is known to cause mortality in cetaceans, manatees, and turtles, and highlights a significant risk to local populations of whales, dugongs, dolphins and turtles.
"Hervey Bay is an ecologically unique and diverse ecosystem providing a sheltered stop-over point for migrating humpback whales that are nurturing calves and has extensive seagrass meadows that provide the ideal feeding grounds for large dugong and turtle populations," said Perkins.
He said there is no current evidence of such impacts in Hervey Bay from Karenia or any of the other toxic algae found, as scientists haven't specifically investigated this. However, the detection of Gambierdiscus species—associated with ciguatera poisoning—and other genera associated with shellfish poisonings, emphasizes the potential for human health risks in the region through contaminated seafood.
"The findings of this study underscore the critical need for enhanced management strategies and ongoing research to address the ecological and public health risks posed by toxic algae in Hervey Bay," said Perkins.
More information: Joseph C. Perkins et al, Assessment of dinoflagellate diversity using DNA metabarcoding reveals toxic dinoflagellate species in Australian coastal waters, Marine Pollution Bulletin (2024).
Journal information: Marine Pollution Bulletin
Provided by James Cook University