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Have scientists discovered reason for baby right whale deaths?

By Karen Graham     Oct 26, 2015 in Environment
From 2005 until 2014, the massive die-off of baby right whales off Argentina's Patagonian coast had experts puzzled. While several causative events were suggested, scientists now think they have found the culprit, and it may be toxic algae.
After finding 308 right whale carcasses in the waters around Peninsula Valdes along Argentina's Patagonian Coast between 2005 and 2010, observers estimated 90 percent of the deaths represented calves less than three months of age. The number of deaths between 2005 and 2014 now averages around 65 deaths per year.
In March 2010, the scientific committee of the International Whaling Commission (IWC) convened a special meeting and workshop in Puerto Madryn, Argentina. At that time, there were few clues to go on. But experts knew that right whales are baleen feeders, filtering their prey from the waters with comb-like mouths.
Killer whale attacks were dismissed, as were fishing vessels, whale-watching boats or fishing net entanglement. This left scientists looking into a lack of prey, toxic algae blooms, disease, parasites or environmental factors. And researchers have zeroed in on a likely culprit for the deaths, toxic algae blooms, the same kind of algae blooms that cause the closing of clamming and other kinds of shellfish harvesting.
NOAA ocean service scientists correlated the deaths of the right whales with the concentrations of the toxic algae, Pseudo-nitzschia. The higher the density of the toxic algae — which in some species produce a potent neurotoxin called domoic acid — the greater the number of baby right whale deaths. When algae density dropped, so did the deaths. While this is not definitive proof, it certainly bears further research.
"The numbers hinge at the same point and have the same pattern," said Cara Wilson, an oceanographer at NOAA Fisheries' Southwest Fisheries Science Center and lead author of the paper. "What's unusual about this is how long these bloom events continued to reoccur. You don't usually have deaths every year but the calves died in high numbers every year from 2007 to 2013."
This finding is significant in a number of ways because it shows us that even the ocean's largest creatures are vulnerable to algae blooms, and these blooms are projected to increase as the oceans warm. One of the largest algae blooms recently was seen off the West Coast of the United States earlier this year.
Scientists are also looking at whether a toxic algae bloom may have been responsible for the deaths of 30 adult whales off the coast of Alaska in May this year, prompting NOAA to call the deaths an "unusual mortality event."
This study, "Southern right whale (Eubalaena australis) calf mortality at Península Valdés, Argentina: Are harmful algal blooms to blame?" was published in the online journal, Marine Mammal Science, September 4, 2015.
More about baby right whale deaths, patagonian coast, Toxic algae, alaska whale deaths, highly suggestive
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