Researchers on board a research cruise currently in the South Atlantic Ocean have been shocked by the amounts of what appear to be visible microplastic material found repeatedly in seawater samples.
Whilst it is known that coastal waters are contaminated with microplastics including beads, fragments and fibres, the distribution of these microscopic particles in the open ocean has until now remained relatively unknown.
The collaborative annual Atlantic Meridional Transect (AMT) programme research cruise is the first of its kind to follow such a long transect (in excess of 8000 miles) sampling for microplastics from the North to the South Atlantic.
The sampling and analysis on board is being completed by Madeleine Steer, working within the microplastic research group at Plymouth Marine Laboratory. Madie, currently on the RRS James Clark Ross 2500km east of Buenos Aires, commented:
“I've been surprised at the variety of microplastics found in the net samples; multiple colours and forms, found in consecutive trawls over the last few days. It is therefore concerning when we think about the possible impact on marine life, especially those organisms who feed on microplastic- sized prey items.”
Confirmation about exactly what type of synthetic material is being found will only be available once the samples are back at the laboratory, however from Madie’s experience there is ‘little doubt’ that the findings are not only man-made, but also that their abundance could have a harmful effect on marine life:
“Until we know the concentrations of microplastics in the water sampled on this expedition, it’s hard to assess the possible effect. However owing to the fact that zooplankton can ingest microplastics in laboratory experiments and suffer adverse health effects as a result, I find it hard to believe they wouldn't cause harm to these organisms at the base of the food chain if initial findings from this expedition prove correct, that’s what we are also investigating.”
Much of the microplastic Madie has found is buoyant and caught alongside high numbers of zooplankton which migrate to the surface at night time to feed under the safety of darkness. “It's this kind of overlap between animals and microplastic distribution that is of concern, and is the focus of the research for this expedition” she said.