Posidonia helps clean up plastics in the Mediterranean Sea
Posidonia oceanica is a marine plant endemic to the Mediterranean with great benefits for the marine ecosystems in which it resides. Among its qualities are the regulation of water quality, its great capacity to absorb carbon dioxide and its coastal protection.
Posidonia oceanica a great ally in the fight against the plastics problem
In addition, a recent study by the University of Barcelona, published on 14 January 2021, recognises Posidonia for its fight against plastics and microplastics found in the Mediterranean Sea.
The study led by Anna Sànchez-Vidal, professor of Marine Geosciences at the University of Barcelona, reveals the importance of Posidonia oceanica for its ability to retain plastics and remove them from the Mediterranean meadows.
What mechanism does Posidonia use to remove plastics from the sea?
The results of the study, published in the journal Nature Scienctific Reports, reveal how Posidonia oceanica acts as a trap, especially for microplastics, filaments and fragments of polymers denser than seawater.
Plastic waste is trapped in the dense posidonia seagrass me adows and this prevents it from ending up in the deep sea, keeping all plastic waste close to the shore.
Marine erosion, the result of waves, causes the posidonia to release fibres. These fibres intertwine to create balls called pellets, also known as "Neptune's balls". The plastics that had been trapped in the posidonia are retained by these fibrous balls.
And now you may be wondering... but how is Posidonia able to remove plastics from the water? During storms, the posidonia pellets are detached from the meadows by the strong waves and a large part of them end up deposited on the coast. In this way, the plastics that are entangled in Neptune's balls are expelled from the sea.
How much plastic is capable of cleaning posidonia?
There is not yet enough data to be able to give firm figures. But after the recent study we can get first estimates:
- Posidonia is capable of extracting approximately 1,470 plastics per kilogram of plant fibre.
- Posidonia balls would be contributing to the removal of up to 867 million plastics annually.
Reference article:
Sànchez-Vidal, A.; Canals, M.; De Haan, W. P.; Romero, J.; Veny, M. "Seagrasses provide a novel ecosystem service by trapping marine plastics". Scientific Reports, January 2021. Doi: 10.1038/s41598-020-79370-3
