By Roberta Attanasio, IEAM Blog Editor
Lugworms (Arenicola marina) live in muddy sand – they’re a component of the food chain and fishermen look for them because they make great bait. Their presence is given away by the piles of sand (casts) deposited above the burrows in which they live. Each burrow has two openings at the surface. The worm draws sand into the burrow through one of the openings and, following digestion, expels the sand through the other opening, thus carrying out its ecosystem engineering duty – sediment turnover – across beaches on both sides of the North Atlantic.
Now, lugworms are threatened by microplastics, one of the world’s major pollutants. Microplastics are very small particles – microparticles and nanoparticles – which include pre-production plastic pellets and polyethylene beads from personal care products, or derive from the breakdown of larger plastic pieces through mechanical and biological processes.
Because microplastics can not only enter the food web with ease but can also adsorb toxic chemicals in amounts a hundred times greater than those present in sediments, a team of scientists recently performed a study to test the ability of microplastics to transfer toxic chemicals (hydrocarbons, antimicrobials, flame retardants) to lugworm tissues. Tissue bioaccumulation can affect the health status of lugworms and, consequently, their important eco-physiological functions.
The scientists exposed the lugworms to polyvinyl chloride (PVC) previously prepared by separate adsorption of nonylphenol, phenanthrene, triclosan and PBDE-47. The results of the study (Microplastic Moves Pollutants and Additives to Worms, Reducing Functions Linked to Health and Biodiversity), published in Current Biology (December 2, 2013), show that – once ingested – the four chemicals desorbed from PVC and transferred into tissues, some at concentrations that compromised functions pivotal for sustaining health and biodiversity. Specifically, triclosan reduced survival, triclosan and PBDE reduced feeding, nonylphenol reduced immunity and therefore the ability to remove pathogenic bacteria, and PVC by itself reduced the antioxidant capacity.
Mark Anthony Browne, lead author of the study, said: “The work is important because current policy in the United States and abroad considers microplastic as non-hazardous, yet our work shows that large accumulations of microplastic have the potential to impact the structure and functioning of marine ecosystems.”
Chelsea Rochman and colleagues state “If current plastic consumption rates continue, the planet will hold another 33 billion tonnes of plastics by 2050. This would fill 2.75 bil¬lion refuse-collection trucks, which would wrap around the planet roughly 800 times if placed end to end.”
One of the possible solutions is to classify the most problematic plastics as hazardous. Rochman and colleagues estimate that by adopting this classification and replacing hazardous plastic with safer and reusable materials in the next decade, worldwide plastic waste could be reduced to just 4 billion tonnes.