Tiny bits of plastic trash could spell big trouble for some of the smallest and most crucial members of the marine ecosystem according to scientific findings released today.
Research conducted by Plymouth University and the University of Exeter has revealed the unpalatable situation confronting the lugworm when it is exposed to high levels of microplastic in ocean sediments.
A study by the University of Exeter has shown that elevated levels cause lugworms to eat less, and suffer from reduced energy levels. While a complementary study from Plymouth has shown that ingesting microplastics can give the marine animals a harmful diet of hydrocarbons, antimicrobials and flame retardants.
The two reports are published in the Cell Press journal Current Biology on December 2nd, and highlight the threats facing the worms, who play a key ecological role as an important source of food for other animals.
Professor Richard Thompson, of the School of Marine Science and Engineering at Plymouth, and project lead for the work, said: "These chemicals are persistent, meaning they could accumulate in the tissue of organisms and take a long time to break down. Our laboratory studies provide the first clear evidence that microplastics could cause harm and show that this could result from both physical presence of ingested plastic and chemical transfer. Our next steps will be to establish the full implications of these findings for organisms in natural habitats’’
The microplastic levels used in the two papers, one led by Stephanie Wright in Exeter and the other by Dr Mark Anthony Browne in Plymouth, approximate those found at highly contaminated sites such as…. There are many other organisms - including starfish, sea cucumbers and fiddler crabs - that may be similarly affected by the tiny bits of plastic.
Dr Stephanie Wright said: ”Lugworms also feed on and churn the organic content in sediments, much as earthworms in the soil do. If worms in contaminated environments were to reduce feeding levels by an amount comparable to that seen in that lab, it would mean significantly less turnover of sediment by the lugworms each year. In an area the size of the Wadden Sea, for instance, sediment turnover could drop by more than 130,000 litres each year.”
It is widely accepted that plastics have the potential to be chemically hazardous in two ways. Firstly, many plastics contain chemical additives, such as plasticizers, dyes and antimicrobials, which can leach out into sediments and seawater. Microplastics also concentrate water-borne chemicals on their surfaces, such as pesticides and detergents.
Dr Mark Browne said: ”Plastic debris degrades into ever smaller pieces which means that a wider size-range of organisms can ingest this material. Now particles of microplastic are the most abundant form of solid-waste pollution on our planet.’’
The bottom line, the researchers say, is that plastic waste should be kept out of marine environments in order to minimise potential impacts.
“We believe our study has highlighted the need to reduce the amount of plastic waste and therefore microplastics which enter our seas,” said Tamara Galloway of the University of Exeter. “Plastics are enormously beneficial materials. However, if marine plastic pollution continues to increase, impacts such as those demonstrated in our laboratory studies could occur in the natural environment. It is therefore important that we prevent the accumulation of plastic and microplastic debris in marine habitats through better waste handling practices and smarter choices in the materials we use.”