Irish scientists have found how plastics in the faeces of jellyfish-like animals could ultimately affect carbon dioxide levels in our atmosphere.
Researchers from NUI Galway looked at the impact of microplastics being ingested by marine animals and found it means that some faecal pellets don't sink as fast as before.
Greenhouse gas carbon dioxide (CO2) is released during the burning of fossil fuels. However, it is naturally absorbed by our oceans through biological, chemical, and physical processes.
Jellyfish-like animals called salps play a very important role in this uptake of carbon dioxide and its downward transport to the sea floor where it is stored.
The research team looked at the effect of microplastics on these salps.
At the sea surface, microscopic algae turn dissolved CO2 into fuel (organic carbon). These algae are consumed by many different animals and form the basis of the marine foodweb. As this organic carbon is passed up through the food chain much of it is respired and converted back into CO2, which is then released into the ocean and the atmosphere.
However, some of the captured carbon is transported to the sea floor in the form of sinking particles.
Salps ingest algae at the sea surface and produce dense faecal pellets, which rapidly sink to the deep sea, carrying with them some of this captured carbon.
However, during laboratory experiments, the researchers found that when salps ingest microplastics their faecal pellets did not sink as fast anymore.
Lead author of the study Alina Wieczorek, of the Ryan Institute, NUI Galway, said: "Our oceans are estimated to have captured one-quarter to one-half of all human-derived carbon dioxide from the atmosphere in the last two centuries and this downward transport of carbon by salps and other zooplankton animals accounts for a major portion of this.
"These findings show that microplastics have the potential to lower the efficiency of one of the most important natural processes occurring within our oceans, that is, the biologically driven transport of CO2 to the sea floor."
Dr Tom Doyle, senior author of the study from UCC, added: "Our study highlights that marine litter and microplastics may impact on animals and even ecosystems in ways we just haven't considered yet."
The research, published in 'Enviornmental Science and Technology', was led by marine scientists from the Ryan Institute at NUI Galway in collaboration with UCC and Villefranche sur Mer Laboratory, Nice, France.