Seashell illustration – Joel Saget AFP
- Global warming will not prevent dinophysis, which is toxic to humans, from continuing to proliferate over the next hundred years.
- It could even do more damage due to its unpredictability and the risks discovered to oysters and fish.
At the end of spring or almost, it’s the same thing. For several days, even weeks, fishing and the consumption of seafood are regularly prohibited on certain French or European coasts. This is often the fault of dinophysis, this microalgae which is toxic to consumers of shellfish, causing diarrhea and other health risks in humans. Too bad for a family that is nevertheless beneficial for the planet, insofar as microalgae produce nearly half of the oxygen on Earth.
Since the 1980s, Ifremer researchers have been studying this dinohpysis, invisible to the naked eye and described as complex, and alert the authorities during outbreaks. Recently, for the first time, the European Coclime program has made it possible to isolate different strains of this harmful algae, in order to better understand it. Biologists wondered in particular if global warming could make it possible to get rid of it. And the answer, fruit of
a study which has just been published, is no: “By 2100, numerous blooms of toxic microalgae will persist in European coastal waters”, she concludes.
Unpredictable blooms
Because the little beast is tough: despite an acidification of the oceans, due to CO2 emissions, and a warming of the waters which could be + 2.5 ° C, the various tests show that it will always be necessary to deal with it and prey on which it feeds. While the blooms will not necessarily be larger, their consequences may be even more damaging, due to their unpredictability.
“Storms and all these extreme climatic episodes that we are experiencing could disrupt blooms,” suggests Philipp Hess, chemistry researcher and phycotoxins specialist at Ifremer in Nantes. If they arrive earlier or later, they will further disrupt economic activity, especially for shellfish farmers. The latter are obliged to work on solutions, such as on-land pools. We also talk about detoxifying seafood, but the feasibility is questionable insofar as shellfish generally purify themselves in a few weeks.
The potential damage may not end there since the study also showed that dinophysis was not only toxic to humans. Oysters and fish are also said to be victims. “We have shown in the laboratory that one of its toxins not only affects the gametes of oysters, affecting their fertilization rate, but also the gills of fish such as estuarine minnows,” observes Philipp Hess. Now that this link is established, we will be able to study it in detail, even if for the moment, we do not think that the effects are already very strong. “