Research show seagrass retains microplastics
The increasing amount of microplastics in the oceans is alarming, the plastic's small size affects a wide range of organisms, possibly threatening the wildlife. Research at Kristineberg shows that seagrass meadows can retain microplastics, this helps the understanding of where in the ocean they eventually end up.
“Our results show that marine canopies might act as potential barriers or sinks for microplastics,“ says Eduardo Infantes, researcher at the Department of Marine Sciences at the University of Gothenburg, and the Norwegian Institute for Water Research.
Plastic has become common in the oceans, with microplastics being one of the most abundant plastic debris. Microplastics are of significant environmental concern because their small size makes them accessible to a wide range of organisms through filtration or ingestion.
This is the first time researchers investigated if marine canopies are able to retain microplastic. The research is conducted at Kristineberg Marine Research Station, led by guest researcher Carmen B. de los Santos from the University of Algarve in Portugal, in cooperation with Eduardo Infantes, and Anna-Sara Krång at the IVL Swedish Environmental Research Institute.
Simulation using flumes at Kristineberg
The experiment was designed using the flume facilities at Kristineberg Marine Research Station. “We picked eelgrass from the sea near the station and planted them one by one in the flume tank. Then we could drop microplastic particles of different polymers and see how the currents and the eelgrass affected the amount of microplastics retained,” Eduardo Infantes explains.
Overall, microplastics particles transported with the flow were retained in the seagrass canopies. “Our simulations revealed that less dense particles might escape from the canopy at high velocities, while denser sinking particles can be trapped in scouring areas created by erosive processes around the eelgrass shoots.”
The importance of seagrass meadows
The research shows that it’s possible to predict where the microplastics in the ocean will end up. This could help when determining the effects of the plastics on the environment.
“Seagrass meadows, and other aquatic canopy-forming ecosystems, should be prioritized habitats in assessment of microplastic exposure and impact on coastal areas since they may accumulate high concentration of microplastic particles that could affect associated fauna.”
Eduardo doesn’t believe there is a way to extract or remove the microplastics trapped in the sediment from the meadows. “It might be trapped there in the sediment for a long time. However, if we lose the seagrass the plastic will be released back into the ocean. So it’s very important to keep these plants.”
The research received funding from the European Union’s Horizon 2020 research and innovation programme under the ASSEMBLE Plus project.
Text: Simon Ungman Hain
The scientific article in Environmental Pollution
C.B. de los Santos, A.-S. Krång and E. Infantes (2020) Microplastic retention by marine vegetated canopies: Simulations with seagrass meadows in a hydraulic flume, Environmental Pollution