SANTIAGO – Scientists investigating a graveyard of marine mammal fossils near Chile’s northern coast say toxins generated by algal blooms most likely poisoned the animals millions of years ago.
The study by a team of Chilean and Smithsonian Institution scientists was published in the British journal Proceedings of the Royal Society B.
The experts traveled to Chile’s Atacama region in 2011 to unearth one of the world’s best-preserved graveyards of prehistoric whales. Their findings help solve a mystery about how dozens of whales and other marine mammals congregating off South America’s Pacific coast died, only to emerge again atop a desert hill a kilometer from the surf.
“There are hundreds of whale skeletons yet to be found,” said Nick Pyenson, curator of fossil marine mammals at the Smithsonian’s National Museum of Natural History. “This is a site on par with Dinosaur National Monument here in the United States, a whole hillside littered with dinosaur skeletons. We seem to have the same thing, except with whales, here in Chile.”
The remains were first found by construction workers in 2010 during the widening of the Pan American Highway, or Route 5, which is Chile’s main north-south road. Other unusual creatures found at the “Whale Hill” site include an extinct aquatic sloth and a walruslike toothed whale.
Scientists say the skeletons show the animals were poisoned by toxins some 5 million to 11 million years ago and “died at sea, prior to burial on a tidal flat.”
“Based on the orientation of the skeletons and other information, these whales likely died from harmful algae blooms, which we know in the modern world can be a killer,” Pyenson said.
Poisons created by algal blooms can be ingested or inhaled, causing organ failure in marine mammals. Blooms are common along coasts and are enriched by nutrients like iron carried by rivers into the ocean. Scientists say that for more than 20 million years, runoff from the iron-rich Andes Mountains has created ideal conditions for harmful algal blooms along South America’s west coast.