It’s a sad number. Blue whales ingest up to 10 million pieces of microplastic a day, according to an estimate released Tuesday, suggesting a greater impact of this pollution on the world’s largest animal than previously thought.
Tiny fragments of plastic have been found from the deepest oceans to the highest mountains and even in human organs and blood. To estimate the amount of microplastics ingested by whales, researchers conducted a modeling study published in the journal Nature Communications.
modelling
These scientists tagged 191 blue, fin and humpback whales living off the coast of California with some kind of tag to track their movements. “Like an Apple Watch on the back of a whale,” says Shirel Kahane-Rapport, a researcher at California State University at Fullerton and the study’s lead author.
According to the data collected, the whales fed mainly at depths between 50 and 250 meters, where “the greatest concentration of microplastics is in the water column,” this whale specialist told AFP. The researchers then estimated the size and number of the whales’ daily bites and what they filtered out by modeling three scenarios. In the most likely scenario, blue whales ingested up to 10 million pieces of microplastics per day.
“This worries us”
The largest animal that has ever lived on earth would probably be the largest consumer of microplastics and, according to the study, consumes up to 43.6 kilograms a day. Although it is spontaneously assumed that whales ingest large amounts of microplastics as they make their way through the ocean, researchers have found that this is not the case.
In fact, 99% of microplastics ended up in whales’ bodies because they were already in their prey. “It’s of concern to us,” Shirel Kahane-Rapport said, because humans also eat this prey. “We also eat anchovies and sardines,” she noted, adding that “krill[small shrimp-shaped crustaceans ed.]are the base of the food web” of the marine food chain.
Previous research has shown that krill “get eaten” in a tank of microplastics, the scientist said. Now that the researchers have estimated the amount of microplastics that the whales have ingested, they want to determine the extent of the damage. “The dose makes the poison,” says Shirel Kahane-Rapport.