Posidonia marine seagrass can catch and remove plastics from the sea
A trap for plastics in coastal areas

Date:
January 14, 2021
Source:
University of Barcelona
Summary:
Posidonia oceanica seagrass can take and remove plastic materials
that have been left at the sea, according to a new study.



FULL STORY ========================================================================== Posidonia oceanica seagrass -- an endemic marine phanerogam with an
important ecological role in the marine environment -- can take and
remove plastic materials that have been left at the sea, according to a
study published in the journal Scientific Reports. The article's first
author is the tenure-track 2 lecturer Anna Sa`nchez-Vidal, from the
Research Group on Marine Geosciences of the Faculty of Earth Sciences
of the University of Barcelona (UB).


==========================================================================
The study describes for the first time the outstanding role of the
Posidonia as a filter and trap for plastics in the coastal areas, and it
is pioneer in the description of a natural mechanism to take and remove
these materials from the sea. Other authors of the study are the experts
Miquel Canals, William P. de Haan and Marta Veny, from the Research Group
on Marine Geosciences of the UB, and Javier Romero, from the Faculty of
Biology and the Biodiversity Research Institute (IRBio) of the UB.

A trap for plastics in coastal areas The Posidonia oceanica makes dense prairies that make a habitat with a great ecological value (nutrition,
shelter, reproduction, etc.) for marine biodiversity. As part of the
study, the team analysed the trapping and extraction of plastic in great seagrasses of the Posidonia in the coasts of Majorca. "Everything suggests
that plastics are trapped in the Posidonia seagrass. In the grasslands,
the plastics are incorporated to agglomerates of natural fiber with a ball shape -- aegagropila or Posidonia Neptune balls - - which are expulsed
from the marine environment during storms," notes Anna Sa`nchez-Vidal,
member of the Department of Ocean and Earth Dynamics of the UB.

According to the analyses, she continues, the trapped microplastics
in the prairies of the Posidonia oceanica are mainly filaments, fibers
and fragments of polymers which are denser than the sea water such as polyethylene terephthalate (PET).

How are Posidonia Neptune balls made? This marine phanerogam has a
vegetative structure made by a modified stem with a rhizome shape from
which the roots and leaves appear. When the leaves fall, its bases (pods)
are added to rhizomes and give them a feather-like appearance.

"As a result of the mechanical erosion in the marine environment, those
pods under the seafloors are progressively releasing lignocellulosic
fibres which are slowly added and intertwined until they make agglomerates
in a ball-shape, known as aegagropilae. Aegagropilae are expulsed
from prairies during periods of strong waves and a certain part ends
up in the beaches," says Professor Javier Romero, from the Department
of Evolutionary Biology, Ecology and Environmental Sciences and the Biodiversity Research Institute (IRBio) of the UB.

Posidonia aegagropilae are expelled from the prairies during periods of
strong waves and a part ends up piled in the beaches. Although there are
no studies that quantify the amount of aegagropilae expelled from the
marine environment, it is estimated that about 1,470 plastics are taken
per kilogram of plant fibre, amounts which are significantly higher than
those captured through leaves or sand. As researcher Anna Sa`nchez-Vidal
says, "we cannot completely know the magnitude of this plastic export
to the land. However, first estimations reveal that Posidonia balls
could catch up to 867 million plastics per year." Plastic-free oceans: everyone's responsibility The polluting footprint of plastics that
come from human activity is a serious environmental problem affecting
coastal and ocean ecosystems worldwide. Since plastics were created
massively in the 20th century fifties, these materials have been left and accumulated at the sea -- seafloors act as a sink for microplastics --
and are transported by ocean currents, wind and waves. "The plastics we
find floating in the sea are only a small percentage of everything we
have thrown onto the marine environment," warns Anna Sa`nchez-Vidal.

The paper published in the journal Scientific Reports has been carried
out within the frame of the subject of the EHEA bachelor's degree final
project of the degree in Marine Sciences of the Faculty of Earth Sciences,
and counted on the support from the Scientific and Technological Centers
of the UB (CCiTUB).

The new ecosystemic service of the Posidonia described in the article
has a significant value in a marine area such as the Mediterranean --
with high quantities of floating plastic and in the seafloors -- and with Posidonia seagrass that can occupy large areas up to forty meters deep.

"This is why we need to protect and preserve these vulnerable ecosystems.

However, the best environmental protection strategy to keep oceans free
of plastic is to reduce landfills, an action that requires to limit its
use by the population," conclude the experts.


========================================================================== Story Source: Materials provided by University_of_Barcelona. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Anna Sanchez-Vidal, Miquel Canals, William P. de Haan, Javier
Romero,
Marta Veny. Seagrasses provide a novel ecosystem service by
trapping marine plastics. Scientific Reports, 2021; 11 (1) DOI:
10.1038/s41598- 020-79370-3 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/01/210114130151.htm

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