Scientists Say Toxic Algae Caused Ancient Whale Graveyard in Northern Chile

Posted on February 28, 2014

Ancient Whale Graveyard Analysis

Smithsonian and Chilean scientists have examined a large fossil site of ancient marine mammal skeletons in the Atacama Desert of Northern Chile. The site at Cerro Ballena has become known as a whale graveyard. It is the first definitive example of repeated mass strandings of marine mammals in the fossil record. The site reflects four distinct strandings over time. The researchers say toxic algae is the culprit.

The amazing site was first discovered during an expansion project of the Pan-American Highway in 2010. It dates to 6 million to 9 million years ago. The scientists recorded their findings before the site was paved over. At least two species of extinct whales were discovered at the site as well as skeletons of billfishes, seals and aquatic sloths.

The scientists say toxins generated by harmful algal blooms most likely poisoned many ocean-going vertebrates near Cerro Ballena in the late Miocene, 5-11 million years ago. The creatures were poisoned either by consuming contaminated prey or through inhalation. This would have caused relatively rapid death at sea. The carcasses then floated toward the coast, where they were washed into a tidal flat by waves. Once stranded on the tidal flat, the dead or dying animals were protected from marine scavengers. There were also no large land scavengers in South America at this time to eat the carcasses. Eventually, the carcasses were buried by sand. Because there are four layers at Cerro Ballena, the scientists believed this same pathway from sea to land occurred four different times.

Nicholas Pyenson, paleontologist at the Smithsonian's National Museum of Natural History and lead author of the research, says in a statement, "There are a few compelling modern examples that provide excellent analogs for the patterns we observed at Cerro Ballena - in particular, one case from the late 1980s when more than a dozen humpback whales washed ashore near Cape Cod, with no signs of trauma, but sickened by mackerel loaded with toxins from red tides. Harmful algal blooms in the modern world can strike a variety of marine mammals and large predatory fish. The key for us was its repetitive nature at Cerro Ballena: no other plausible explanation in the modern world would be recurring, except for toxic algae, which can recur if the conditions are right."

The team's findings were published here in the Proceedings of the Royal Society B. Take a look:

Photo: Smithsonian Institute

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