After lead and invasive crabs, microplastics colonize Antarctica

Plastic garbage has colonized the most remote corner of the planet: Antarctica. The debris has recently been detected in snow on the mainland so there is no environment left uninfected. The sea, sea ice, sediments, glaciers, snowfields...

After proving how lead pollution from the 19th century industrial revolution settled on the continent o fish for the North Atlantic spider crab in the extreme southinvestigations – one of them Spanish – have proven that there are microplastics in Antarctic freshwater.

"They have already arrived. Now we have to study if they are affecting", reflects Miguel González Pleiter, one of the researchers who detected the presence of these remains in a stream in the Byers Peninsula Special Protection Area. "An area without tourism and with restricted scientific access that makes it considered a reference for the study of inland waters", explains the researcher from the Autonomous University of Madrid.

The biologist also participated in the detection of plastic trash on collins glacier on King George Island (South Shetlands). "There we also found mesoplastics, larger than five millimeters, and remains of polystyrene in the ablation zone of the glacier."

Microplastics come floating from the great plastic soups of the oceans, on ships or human activities within the continent. In addition, González Pleiter explains that "the wind can also play a role in the arrival of waste."

So these tiny fragments are in both liquid and solid freshwater. It remained to endorse the snow. The first evidence of microplastics in that medium has been made public this month. A New Zealand team identified microplastics in samples collected from 19 different locations on Ross Island. Six points near scientific stations and 13 in remote locations "with minimal human disturbance."

The researchers found the presence of 13 types of plastic at a rate of 29 microplastic particles per liter of snow. "The most common have been fibers and the most common compound is PET, the one used in clothing and soft drink bottles."

"The implications of microplastics reaching remote regions like Antarctica are huge," this study concludes. "Antarctic organisms have adapted to their conditions for millions of years and sudden changes due to anthropogenic influence are threatening unique ecosystems," the work states.

Plastic pollution is highly mobile and ubiquitous. "Although since 1995 there were signs of plastics approaching Antarctica, it was in 2017 when irrefutable evidence of their presence in the water of the Antarctic sea was obtained," says González Pleiter. "Then it was tested in marine sediments, in sea ice, in fresh water, in soils, glaciers and the atmosphere."

But it was not the first Antarctic pollution caused by humans. Lead released by the Industrial Revolution reached Antarctica more than 130 years ago and has been there ever since.. The first traces of lead detected in the ice records in Antarctica date back to 1889, 22 years before Roald Admundsen reached the south pole for the first time in 1911, as demonstrated in 2014 by a team from the University of Nevada (USA). "A long and persistent history of heavy metal contamination," the scientists called it.

The researchers were able to trace the origin of the lead that accumulated in that frozen water two centuries ago. They compared the isotopes of the heavy metal and the composition matched that which could be detected in lead from the mining town of Broken Hills in New South Wales, Australia.

Lead has marked two peaks on the frozen continent: one at the end of the 1920s that fell due to the economic crisis and World War II. And another around 1975. "During the 21st century the concentrations are lower, but well above the levels prior to the Industrial Revolution."

In 1986, a scientific vessel from the São Paulo Oceanographic Institute (Brazil) demonstrated that the marine ecosystems of Antarctica, until then considered uncolonized, were no longer safe from invasive species: they extracted a male and a female spider crab, native of the North Atlantic and the Arctic. Literally the other side of the planet.

It was the first record of an exotic marine species in those latitudes and it is not known whether the variety has taken root or not. Biologically, Antarctica has evolved in isolation for some 25 million years. As they settled, barriers arose that maintained that separation, such as the most powerful ocean current: the Antarctic circumpolar. Everything there has evolved in a way that is unique in the world and adapted to the extreme conditions of the continent.

That is why invasive species are a scientific concern. "Its isolation has been broken by various varieties", counted a recent Australian Government assessment. They arrive with the increase in marine traffic and the new environmental conditions created by climate change.

The account includes 11 types of invertebrates (mites, mosquitoes, springtails and worms). A grass and microbes. Regarding the spider crab: "Stable populations of marine species have not been documented."

Microplastics, smaller than 5 millimeters, cause a cascade of effects. The biologist García Pleiter lists them: "The first are physical, being ingested by the fauna." Three species of penguins, the Adelie, the Chinstrap and the Gentoo, eat them for sure, as proved by an expedition of the National Museum of Natural Sciences. These birds feed especially krillbut the scientists found relevant percentages of plastic debris in their depositions in different colonies and in different years.

In addition, these minuscule portions have contaminants attached: "They are like a bus that can release them when they reach Antarctica," explains the Autonomous biologist. In this way, they also transport additives that later "when they reach the stomach of animals, where conditions change, they are released."

And the passage embedded in the garbage is completed by "microorganisms from the plastisphere that will travel thousands of kilometers to these ecosystems." All these possible effects are what we have to evaluate. "It can also be remembered that 40% of the plastic used in Europe is destined for single-use packaging. If that is tackled, almost 40% of the problem is tackled," García Pleiter underlines.

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