A new study, published in Royal Society Open Science, reveals that around four billion microscopic plastic fibres could be littering each square kilometre of deep sea sediment around the world. Experts Anna Sànchez, Miquel Canals and Antoni Calafat, from the Department of Stratigraphy, Paleontology and Marine Geoscience of the University of Barcelona (UB), participated in the study.
The mystery of marine plastics
Marine plastic debris is a global environmental problem, affecting worldwide coastal and oceanic ecosystems from pole to pole. Researcher Anna Sànchez, leader of the Consolidated Research Group on Marine Geosciences of the UB, explains that “the number of fibres (rayon, polyester, etc.) recorded in the deep seas is up to four times more abundant in the deep seas than in shallow and coastal waters”. Monitoring over the past decades has not seen its concentration increase at the sea surface or along shorelines, despite experts know that more is being created. “In fact —she adds—, the study solves the mystery of the missing plastic: where is all the plastic?”.
“The study —says Anna Sàchez— proves that deep-sea sediments are a likely sink for microplastics which, in the form of fibres, have accumulated on sea floors, from the Antarctica to the Arctic, all over the planet”.
Results are relevant within the context of the Marine Strategy Framework Directive of the European Union and other similar global initiatives. The presence, composition and impact of debris —particularly, plastics— on marine habitats is an indicator of good environmental status of oceans, an issue to which the European Union is strongly committed by means of the programme Horizon 2020. According to Miquel Canals, head of the Consolidated Research Group on Marine Geosciences of the UB, “to be exact, the study contributes to the PERSEUS project, which is founded by the European Commission and centred on the establishment of management policies for the conservation of southern European seas”.
A threat to deep sea ecosystems
Besides the UB research team, scientists from Plymouth University and the Natural History Museum in London also participated in the study. They analysed deep-sea sediment and coral samples collected from 16 sites in the Mediterranean Sea, Atlantic and Indian Oceans. Dr Lucy Woodall, zoologist at the Natural History Museum in London and first author of the study, affirms: “It is alarming to find such high levels of contamination, especially when the full effect of these plastics on the delicate balance of deep sea ecosystems is unknown”.
Rayon, polyester and polyamides on seabeds
Rayon, polyester, polyamides, acetate and acrylic are the commonest compounds in samples. Richard Thompson, professor of Marine Biology at Plymouth University and coordinator of the study, says: “The deep sea habitat extends to more than 300 million km² globally, so the discovery of previously under-reported microplastics suggests there may be even greater accumulation than was previously suspected”.
The Consolidated Research Group on Marine Geosciences of the UB, headed by Miquel Canals, participated also in a recent study warning about the impact of human marine litter (bottles, plastic bags, fishing gear, etc.) on deep seas.
Images: Consolidated Research Group on Marine Geosciences of UB