Marine
organisms can shred a
plastic bag into 1.75 million pieces, study shows
University of Plymouth
A single plastic
carrier bag could be shredded by marine organisms into around 1.75 million
microscopic fragments, according to new research.
Marine scientists at
the University of Plymouth examined the rate at which bags were broken down by
the amphipod Orchestia gammarellus, which inhabits coastal areas in
northern and western Europe.
They believe the
results are an example of marine wildlife actually contributing to the spread
of microplastics within the marine environment, rather than them simply being
emitted from the water supply or forming through the physical and chemical
break down of larger items.
The study was
conducted by BSc (Hons) Marine Biology and Coastal Ecology students Daniella
Hodgson and Amanda Bréchon, and Professor of Marine Biology Richard Thompson.
It is published in Marine Pollution Bulletin.
Its main aim was to
discover whether different types of plastic and the presence of a biofilm -- a
layer of organic material which accumulates over time -- altered the rate at
which such organisms broke down plastic debris.
Through monitoring in the laboratory and on the shoreline, researchers demonstrated the bags were torn and stretched by Orchestia gammarellus, with microplastics subsequently being found in and around their faecal matter.
The type of plastic
(conventional, degradable and biodegradable) had no effect on the rate of
ingestion, however the presence of a biofilm meant the shredding took place
around four times as quickly.
This, the researchers
say, is consistent with recent studies into the feeding behaviour of seabirds
and suggests marine life might be increasingly attracted to marine debris as a
source of food regardless of the potential harm caused.
Previous studies led
by the University have shown that more than 700 species of marine life have
been found to have encountered plastic debris, with clear evidence that
ingestion and entanglement causes direct harm to many individuals.
Professor Thompson,
Head of the University's International Marine Litter Research Unit, said:
"An estimated 120 million tonnes of single use plastic items -- such as
carrier bags -- are produced each year and they are one of the main sources of
plastic pollution.
"They already represent a potential hazard to marine life, but this research shows species might also be contributing to the spread of such debris. It further demonstrates that marine litter is not only an aesthetic problem but has the potential to cause more serious and persistent environmental damage."
"They already represent a potential hazard to marine life, but this research shows species might also be contributing to the spread of such debris. It further demonstrates that marine litter is not only an aesthetic problem but has the potential to cause more serious and persistent environmental damage."
