November 15, 2022 at 2:30 p.m,
Updated November 16, 2022 at 9:56 am
Reading time: 3 minutes
Zoology, animal science
Disastrous Fate of Whales. Filtering thousands of cubic feet of water through their baleen, these large marine mammals are at the forefront of exposure to microplastics that pollute the oceans. According to a new study published in Nature Communications on November 1, 2022, the blue whale can ingest 10 million plastic particles smaller than 5mm per day. Its cousin, the fish-feeding humpback whale, would be less at risk despite the contamination of its prey. His daily intake is still 200,000 particles.
To arrive at these ratings, the Californian team that wrote the study estimated the amounts of fish ingested, the amounts of water ingested, the concentrations of microplastics in the water and in the prey… information obtained by tracking more than 200 specimens for ten years and by directly measuring the various concentrations in California waters. All of this data was then integrated into a model that allowed the researchers to estimate the amounts of plastic particles ingested.
- Blue whales ingest millions of plastic particles every day. public domain / US National Oceanic and Atmospheric Administration
Although notable for its scope, this study is not the first of its kind. Several scientific studies have been conducted in different regions of the world with very different estimates of the amounts of microplastics ingested, from hundreds to millions of particles per day. A team from New Zealand therefore spent five years analyzing whale excrement off the coast of Auckland. Their findings, published in Science of the Total Environment in April 2022, estimated the number of microplastic particles ingested at 3 million per day.
“ The differences in magnitude from study to study can be explained by the different geographical areas, the whale species affected, but also the different concentrations of microplastics in the sea. », explains Céline Tardy from the Miraceti association, dedicated to the knowledge and conservation of cetaceans. Between 2016 and 2019, the cetologist studied the contamination of cetaceans by phthalates in the Mediterranean Sea, substances often used as plasticizers in plastics: “ The concentrations of phthalates found varied greatly from person to person in the same year and geographical area. »
- The effects of this massive ingestion of plastics on the health of cetaceans and cetaceans are still unknown and worrying scientists. © Jérémie Silvestro / Wikimedia Commons / CC THROUGH–YOU 4.0
A Canadian study published in 2020 in collaboration with Inuit hunters examined belugas in the Beaufort Sea. As a result, half of the thousands of microplastics found in whales were polyester fibers. A large proportion of the microplastics found in the ocean would actually come from synthetic clothing. The microfibers released during washing end up in wastewater and then in the oceans.
polyester and heavy metals
The consequences of this contamination are still largely unknown. “ To my knowledge, very little is known about the exact effects of microplastics on cetacean health. »agrees Zhe Lu, professor of marine ecotoxicology at the University of Quebec at Rimouski, in charge of a program on microplastics in the Bay of St. Lawrence.
This does not prevent scientists from predicting toxic effects. “ Microplastics, due to their lipophilic nature, have the potential to absorb persistent organic pollutants present in contaminated regions. For example heavy metals, polychlorinated biphenyls (circuit board), pesticides »says Zhe Lu. Another risk is the presence of reproductively toxic additives and endocrine disruptors such as bisphenol A or phthalates, which are known to be harmful to another mammal, man.