PVC Particles Make Marine Worms Lose Their Appetite
A study suggests plastic debris in the sea slows the rate at which lugworms can process sediment, which could affect marine diversity.A study published in the journal found that microscopic pieces of plastic litter prevalent in the ocean can slow digestion in an important species of marine worms.
Researchers exposed Arenicola marina worms, commonly known as lugworms, to microscopic unplasticized PVC (uPVC) at concentrations known to exist in oceanic contamination hotspots. Those that were exposed to sediment with 5% uPVC by weight took 1.5 times longer to expel waste, reduced their feeding activity by approximately 25%, and had up to 50% less energy reserves compared to a control group. The researchers assert that the prolonged digestion times “imply that microplastics, which are of low nutritional value, are being retained and subjected to extensive digestion, at an energetic cost.”
These aren’t just a group of constipated sea worms. At a density of 85 individuals per m2—typical of a tidal-flat habitat—lugworms are estimated to process 400 cm3 of sediment annually. In a place where lugworms are a keystone species, like Wadden Sea, an intertidal zone in the North Sea, reduced feeding activity to the degree observed in the study would result in 130 m3 less sediment reworked and oxygenated per year, a process crucial to maintaining marine diversity.
The researchers call for policymakers to reconsider how PVC, polystyrene, polyurethane, and polycarbonate debris is classified in terms of hazard.
Published December 30, 2013