We humans are perilously ignorant of the sad fate of lugworms (Arenicola marina) and our role in their demise. We may not see lugworms because they spend their lives burrowing in the intertidal mud of Northern Europe. We don’t see the tiny pieces of plastic that blend seamlessly, to our human eyes, with that mud. How much harm can be done if we can’t even see it? A lot, according to a paper in the journal Current Biology.
Scientists studied the big, fleshy marine worms in the laboratory. Lugworms were put in sediment with varying concentrations of PVC plastic. Some plastic floats; these are the types of plastic found far out at sea. Other plastic, including PVC, sinks. Both plastics photo-degrade and break down into smaller and smaller pieces. The sinking types of plastic, which are turned into products like water bottles, plastic cups and plastic pipes, end up in the sediments near shore. In some hotspots, plastic concentrations in the mud reach over 3% by weight.
Lugworms live in this sediment. They also eat it. They swallow sediments loaded with organic material, then the sediment minus the organic food, makes its way out the other end. It is not a glamorous way to earn a living, but it works. Or rather, it worked until plastics were added to their diet. Researchers found that when lugworms ate PVC with their sediment at concentrations similar to those found in some wild lugworm habitats, they became significantly less fleshy. Their energy reserves were depleted by up to 50%. In healthy lugworms, sediment continually enters and then exits their bodies. Study lugworms exposed to PVC ate more slowly, sediment remained in guts longer and their immune systems responded to the PVC with inflammation. PVC affects lugworm growth, reproduction and survival.
Perhaps you’re not moved by the plight of the lugworm. You should care about their role in the environment. Lugworms keep silt from burying nearshore bottoms so they remain pleasant places to visit. This silt is turned into lugworm, and many of these worms get converted into beautiful shorebirds and tasty fish. Lugworms tunnel through sediments and bring oxygen into an environment that would be too harsh for the crabs, shrimps, clams and other delicious animals that live in it to survive. If we want to continue to enjoy lugworm benefits, we must stop the indiscriminate disposal of plastic. Save the lugworms! Keep intertidal mud plastic-free! Use the BlueTube at your beach!
Wright, Stephanie L., Darren Rowe, Richard C. Thompson, and Tamara S. Galloway. “Microplastc Ingestion Decreases Energy Reserves in Marine Worms.” Current Biology 23.23 (2013): 1031-033.