Seagrasses provide a novel ecosystem service by trapping marine plastics

Abstract

There is strong evidence that the seafloor constitutes a final sink for plastics from land sources. There is also evidence that part of the plastics lying on the shallow seafloor are washed up back to the shoreline. However, little is known on the natural trapping processes leading to such landwards return. Here we investigate microplastics and larger plastic debris within beached seagrass remains including balls (aegagropilae) made of natural aggregates of vegetal fibers intertwined by seawater motion. We found up to 1470 plastic items per kg of plant material, which were mainly composed of negatively buoyant polymer filaments and fibers. Our findings show that seagrass meadows promote plastic debris trapping and aggregation with natural lignocellulosic fibers, which are then ejected and escape the coastal ocean. Our results show how seagrasses, one of the key ecosystems on Earth in terms of provision of goods and services, also counteract marine plastic pollution. In view of our findings, the regression of seagrass meadows in some marine regions acquires a new dimension.

Canopy Accumulation: Are Seagrass Meadows a Sink of Microplastics?

“…These mechanisms all related to the seagrass blades "trapping" microplastics in the water columnfor example, microplastics sticking to blades via adhesive biofilms. Recent high profile evidence from the Mediterranean has also found that the creation of so called as 'Seaballs or Neptune balls' leads to the trapping of microplastics [47]. Such seaballs of fibrous seagrass material tend to be much more common in the Mediterranean than in other localities.…”

Plastics in blue carbon ecosystems: a call for global cooperation on climate change goals

“…5 The current stocks of plastic-carbon in the global coastal systems are about 3-10 million metric tonnes, 5 with growing reports of plastic-carbon within BCEs. [6][7][8] If the present cubic growth trend for plastic accumulation and uncertain socioeconomic factors continue, amounts of plasticcarbon stock within the Earth system are projected to rise to 14 000 million metric tonnes by 2035, meaning that the amount of plastic-carbon will be equivalent to global blue carbon stock. 5 The probable effects of plastics on chemical, physical, and biological processes within BCEs puts us in unchartered territory, raising questions about how plastic-carbon accumulation in BCEs might affect global blue carbon storage and sequestration capacity in future.…”

<em> </em>Current Research on Microbe-Plastic Interactions in the Marine Environment

“…Moreover, recent research indicates that ecologically and economically important seagrass meadows [287][288][289][290][291] and other habitat-forming taxa, such as hard corals 290 , can trap and accumulate microplastics, while potential seagrass 150 and coral 69 pathogens have been found on plastics and plastic debris has been associated with an increased likelihood of disease on coral reefs 292 . Other taxa that are not generally regarded as invasive, toxic or pathogenic as such, but that can cause nuisance via mucilage events, such as the diatom species Ceratoneis closterium 83 have also been reported as plastisphere members.…”