Plastic pollution extends to all corners of the planet and negatively affects a long list of habitats and species. Researchers from the British Antarctic Survey (BAS, a British scientific entity attached to the Natural Environment Research Council) have now verified that krill and salps that inhabit the Antarctic or Southern Ocean can also ingest microplastics and, therefore, incorporate synthetic polluting elements into the trophic chain this staple food for whales. The results of this research have been published in the Royal Society Open Science journal.
A new study led by BAS researchers discovered microplastics in Antarctic krill (Euphausia superba), a small shrimp-like crustacean, and salps (Salpa thompsoni), a gelatinous marine invertebrate. The results show in laboratory tests how this ingestion occurs and “provide important evidence that these animals, as well as other zooplankton, ingest plastic in their natural environment,” indicates this British scientific institution.
Microplastics are present in the Southern Ocean from the sea surface to the seabed. Due to the small size of these particles (<5 mm), it is likely that Antarctic zooplankton mistake the plastics for their natural food source. The team focused on two of the most abundant species of zooplankton in the Southern Ocean: Antarctic krill and salps.
“These two species are critical to the diet of much of the marine wildlife of the Southern Ocean,” recalls the BAS. Krill are the main food source for whales, penguins and seals, while some larger fish and seabirds eat salps.
Samples of krill and salpa were collected aboard the RRS research vessel James Clark Ross on two research missions off the northern tip of the Antarctic Peninsula in 2016 and near the island of South Georgia in 2018. Microplastics were collected from both species , with plastic microfibers being the most common. One of the largest sources of these fibers is released from clothing during washing and drying. About 60% of the krill and salps contained nylon, a microplastic with significant commercial applications in clothing, fishing tackle, rope, and reinforced car tires.
The lead author of the study, Laura Wilkie Johnston, a marine biologist at BAS, outlines the worrying situation revealed in her study: “The evidence of the consumption of microplastics in two very abundant species in the Southern Ocean is worrying. Both species are an integral part of the Southern Ocean ecosystem, and we do not yet fully understand the impact microplastics will have on this environment.”
Emily Rowlands, co-author of the study and BAS marine biologist, explained that in their research they have verified harmful effects that plastic ingestion can have on Antarctic zooplankton in the laboratory.
“In this study we show how vulnerable these animals are to plastic in their natural habitat. The research is particularly important as it supports laboratory experiments and provides new insights into the amounts and types of plastics krill and krill are exposed to. salps in the Southern Ocean”, Rowlands details in statements released by the BAS.
The findings underscore how sensitive the Antarctic marine ecosystem is to plastic pollution. Due to short food chains in Antarctica, these microplastics are most likely transferred from krill to larger predators such as whales, penguins, and seals. Plastic in krill and salps could also negatively affect the Southern Ocean as one of the largest carbon sinks on the planet.
The pelagic marine ecologist at BAS Clara Manno, and principal scientist of the CUPIDO project and co-author of the study, explains her results with these words:
“In addition to being important sources of food in the Antarctic marine ecosystem, krill and salps play an important role in slowing down climate change. The Southern Ocean is a very important carbon sink and these animals play an integral role in transferring atmospheric CO2 to the deep oceans. Interactions with microplastics have the potential to interfere with the amount of carbon these organisms can capture and trap in the deep ocean.”
