Monaco – At a workshop organized by the IAEA and its partners last month, 60 scientists from over 30 countries learned how nuclear techniques can be used to combat biotoxins from harmful algal blooms.
Microscopic algae at the base of the marine food chain provide nutrients for marine organisms and are responsible for producing more than half of the earth’s oxygen supply. However, factors such as the natural movement of water towards the surface and the accumulation of agricultural run-off into the sea can increase nutrient levels in coastal waters and trigger algal blooms, which can sometimes include toxic species.
Each year, these harmful algal blooms (HABs) are responsible for the poisoning of thousands of people worldwide due to the consumption of contaminated seafood and the inhalation of toxins in the air. “Faced with the apparent increase in frequency, geographical distribution and intensity of such blooms, addressing them on a global scale has become urgent,” said Marie-Yasmine Dechraoui Bottein, a research scientist at the IAEA Environment Laboratories in Monaco.
Although strategies to control the impact of planktonic toxic HABs, which float in the water, are well-defined, there remain gaps in the scientific understanding of those on the ocean floor, known as benthic species. Environmental changes linked to climate change could make matters worse, as dead coral reefs constitute good habitats for macroalgae, said Clemence Gatti, a research scientist at the Louis Malardé Institute in French Polynesia, and a speaker at the meeting. With the increasing number of corals dying, a proliferation in benthic harmful algal blooms and associated health risks are likely.
One of the most common illnesses is ciguatera fish poisoning — a non-bacterial seafood intoxication caused by ingesting fish that has been contaminated by ciguatera toxin that comes from benthic harmful algal blooms.
“It is a complex disease still poorly understood,” Gatti said. “It can express itself through 175 different symptoms that can last for months or even decades, which makes its diagnosis and management a challenge for physicians.” She highlighted the threat that ciguatera poses to populations, adding that some people may have 10 to 15 ciguatera poisonings in their life. Some fish such as red snapper can remain toxic for up to 30 months.
