Hidden threats: DNA testing detects toxic algae in Queensland coastal waters

James Cook University PhD 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 Mr 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 Mr 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, emphasises 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 Mr Perkins.

Link to paper here.