Microplastics found in Antarctic seals

The idea of ​​Antarctica as an immaculate and pristine environment, far from human intervention and where nature exists with only the company of itself is, at the very least, naive. In fact, it is unrealistic, not only because of the length of time that the site has been occupied (Argentina was the first country to install a permanent base, in 1904) but, above all, because of the multiple communications and global mobility that shorten the distances between continents and connect the most isolated corners with the rest of the world. Garbage pollution is one of the main examples of this reality, and concern is now rekindled after recent research demonstrating the presence of microplastics in the feces of seals that inhabit the Antarctic Peninsula. The results of the study leave no room for doubt: the particles were detected in one hundred percent of the samples analyzed.

The study is the work of a team in which the National Scientific and Technical Research Council (CONICET) of Argentina participated.

The species studied were three: crabeater seal (Lobodon carcinophaga), leopard seal (Hydrurga leptonyx), and Weddell seal (Leptonychotes weddellii), based on 29 samples of excrement, also called feces. All of them were dominated by a type of particle smaller than 5 millimeters (mm) called microplastics. The composition? Polystyrene, polyesters – including polyethylene terephthalate or PET –, polyamide, polypropylene and polyurethane, all polymers widely used in various industries such as food, textiles, packaging, construction, and others. “We received the samples and analyzed them using two techniques to determine the chemical composition: RAMAN and infrared microspectroscopy,” said Lucas Rodríguez Pirani and Lorena Picone, CONICET specialists at the Center for Inorganic Chemistry (CEQUINOR, CONICET-UNLP-associated with CICPBA) and participants in the research.

While the first of the technologies is available at CEQUINOR, the second was carried out at the National Synchrotron Light Laboratory (LNLS) located in Campinas, in the Brazilian state of São Paulo. “The power and resolution that these tools provide us is key to determining the composition of the fibers and fragments found. Based on some morphological characteristics such as color and shape, it is possible to establish whether it is a plastic or not, but at this level we are determining which molecules make up the materials,” describes Picone. In addition to the polymers mentioned, it was also possible to determine the presence of pigments widely used in the textile and plastic industry: indigo, reactive blue 238, and blue and green copper phthalocyanine. The uses of the materials observed allow us to conclude that they are of anthropic origin, that is, produced or modified by human action. The discovery is completed with another polluting agent, called carbon black, a product of the incomplete burning of fuel that could come from ships or soot suspended in the air.

The sampling was carried out by Julieta Cebuhar, an Argentine biologist and PhD student at the Federal University of Rio Grande, Brazil, and lead author of the research. As she describes it, it is an opportunistic task in which the priority is the speed to detect fresh fecal matter associated with a particular individual, collect it from ice floes and drifting icebergs using clean procedures, and preserve it in airtight containers at 20 degrees below zero until it reaches the laboratory. “Plastic residues were found in all the samples analysed and there were only differences in size: the leopard seals had ingested larger remains than the others,” explains the scientist, and continues: “In general, this type of ingestion has negative effects for many species, and there are numerous studies on the subject, but this is the first time it has been carried out on seals. At the moment, we are not in a position to say that it makes them sick or affects their health, and the concentrations found are low compared to those present in other animals. The important thing is to first report it and then continue monitoring in order to develop effective conservation and management strategies for the Antarctic ecosystem.”

Leopard seal. (Photo: Javier Negrete, researcher at CONICET and the Argentine Antarctic Institute (IAA))

The diet of crabeater seals is usually represented by more than 80 percent of Antarctic krill, a crustacean also consumed by leopard seals but to a lesser extent, since the latter feed mainly on fish and cephalopods (squid and octopus) like Weddell seals, although the former also eat penguins and even pups of other species of seals or sea lions. “These species are usually considered top predators and mesopredators, since they occupy high and middle levels of the food chains. They are long-lived animals capable of traveling extensive areas in search of food and at certain times they group together in relatively accessible sites,” comments the CONICET researcher in charge of the Marine Mammal Program of the Argentine Antarctic Institute (IAA) and also author of the study, Javier Negrete. Because of these characteristics, he explains, they are considered sentinels or bioindicators of ecosystems, since by studying them, changes can be detected in the environment they occupy and in the populations they feed on at different time and space scales.

“Therefore, the detection of microplastics and other contaminating substances in the feces of these three species that feed on a wide range of animals and in a large part of the Argentine Antarctic territory could indicate that the concentration of these substances in the ecosystem may be greater than is believed,” concludes Negrete. “The anthropogenic impact in the region is measured by the various human activities, mainly tourism and fishing and, to a lesser extent, by the scientific bases themselves that, although they have protocols for the care of the environment, their mere presence inevitably generates an impact in terms of contamination. We must also consider what can arrive from other continents through marine and atmospheric currents of the so-called secondary microplastics,” says Rodríguez Pirani in reference to the microscopic-sized particles resulting from the degradation of waste over decades due to the effect of light and the abrasion of the climate, among other factors. It is worth mentioning that these pieces have the capacity to absorb persistent organic pollutants, which, when they enter the organism of the animals that ingest them, could multiply the dangers to which they are exposed.

According to data provided by the United Nations Environment Programme (UNEP), humanity produces more than 430 million tons of plastic per year, two-thirds of which are single-use or short-lived and quickly become garbage, most of which ends up in the oceans. Since they are not biodegradable materials but decompose in an estimated time of between one hundred and one thousand years, they spend that overwhelming amount of time floating on the surface or stranded on the seabed while they slowly degrade, if not before they end up in the stomach of some animal that accidentally ingests them. “Plastic production is projected to increase, so its disposal will also continue to grow exponentially until it reaches truly immeasurable quantities. We are talking about an industry that dates back to the 1950s, so in this case we can easily be analyzing fragments from that time,” the specialists conclude.

For more than three decades, the Marine Mammal Program of the Argentine Antarctic Institute (IAA) has been carrying out various research projects that contribute to understanding the population and health status of Antarctic seals. This research arises from the doctoral thesis of Julieta D. Cebuhar.

The study is titled “Anthropogenic debris in three sympatric seal species of the Western Antarctic Peninsula.” It has been published in the academic journal Science of the Total Environment. (Source: Mercedes Benialgo / CONICET. CC BY 2.5 AR)