Argentina: toxic algae caused the death of 30 whales

BUENOS AIRES (HPD) — Harmful algal blooms in recent weeks in the Nuevo Gulf in the South Atlantic have killed some 30 southern right whales, according to Argentine researchers.

The toxic algae, also known as red tide, proliferated between the end of September and the beginning of October in the waters of the New Gulf of the Valdés Peninsula, in the southern province of Chubut, when 26 adult cetaceans and four juveniles were discovered dead, he indicated. the Whale Conservation Institute (ICB) in a statement.

Biologists and veterinarians from the Southern Right Whale Health Monitoring Program, which has been working in the Valdés Peninsula since 2003, performed necropsies on the six whales that were in the best conditions. In addition, they collected partial samples, without opening cavities, in another three found in areas of public use and could not be towed to another place.

All six whales tested had contents in their digestive tracts, indicating that they had recently fed prior to death.

“Every year we record and study the whales that die in the area. Although in previous years there have been calf deaths in greater numbers, this is the first time that we have registered 30 dead adult and juvenile whales in a season and in a period of a few days,” Mariano Sironi, Doctor of Zoology, told The Associated Press. and scientific director of the ICB.

In 2021, 20 were recorded, including 13 adults and seven juveniles.

The program’s experts will continue to work on the examination of eight cetaceans found in an advanced state of decomposition and on isolated beaches with difficult access in the Nuevo Gulf.

Concentrations of paralytic shellfish toxins were found in various tissues and fluids in five of the six necropsied whales.

Sironi explained that the latter “include several biotoxins naturally produced by marine phytoplankton microorganisms known as dinoflagellates.”

According to a statement published by ICB, there are records in the world of poisoning and death of marine fauna – often affecting a large number of animals – due to ingestion of the same paralyzing biotoxins that were found in the bodies of the whales that died in Península Valdés .

Sironi explained that harmful algal blooms are also known as red tides because in some cases the algae that produce them have a reddish color and can give that hue to the sea when they are in high concentrations. However, in many cases the water does not take on this color, as is currently the case in Península Valdés.

“Current evidence indicates that in the face of climate change, harmful algal blooms may increase in frequency and intensity at a global level, but this will depend on local conditions in each case,” said the scientist.

He pointed out that the increase in sea temperature, changes in marine currents and in the distribution and abundance of organic matter in coastal areas and other factors influence the dynamics of harmful algal blooms.

The sighting of southern right whales is one of the main tourist activities that take place in the Valdés Peninsula, where dozens of specimens gather every year. The cetaceans arrive during May and stay to breed and feed the calves until December.

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