Posidonia oceanica, a seaweed that plays an important ecological role in the marine environment, can remove plastic left in the sea, according to a study published in Scientific Reports.
The study describes for the first time the prominent role of Posidonia as a filter and traps for plastics in coastal areas. The study describes the natural mechanisms for the capture and removal of these materials from the sea.
This algae grows very densely, forming a “prairie.” Posidonia also has great ecological value (food, housing, reproduction, etc.) for marine biodiversity. A team of scientists analyzed the capture and recovery of plastic in the large sea meadows of Posidonia on the Mallorcan coast.
“All indications are that plastic is stuck in Posidonia algae. The plastic is converted into agglomerates of Posidonia Neptune spherical natural fibers in the meadows, which are ejected from the marine environment during storms. According to the analysis, captured microplastics in the Posidonia oceanica prairie are mainly fibers, fibers, and fragments of polymers denser than seawater, such as polyethylene terephthalate (PET).”
Anna Sanchez Vidal, Member of the Department of Ocean and Earth Dynamics, Biodiversity Research Institute.
These balls have a vegetative structure, consisting of a modified stem with a rhizome shape, from which roots and leaves emerge. When the leaves fall off, their bases (pods) are added to the rhizomes and give them the appearance of feathers. As a result of mechanical erosion in the marine environment, these pods gradually release lignocellulosic fibers under the seabed, which are slowly added and intertwined until they form agglomerates in the shape of a ball known as egagropyl. They are expelled from the prairie during periods of strong waves and often end up on beaches.
While there are no studies that quantify the amount of egagropil expelled from the marine environment, it is estimated that there are about 1,470 plastics per kilogram of plant fiber, far more than the amount captured by leaves or sand. First estimates show that Posidonia balls can trap up to 867 million plastic annually.