Walk across a mudflat at low tide and you might notice small, neat mounds of sediment scattered across the surface.

These so-called “chimneys” are the calling card of the humble bamboo worm (Macroclymenella stewartensis) which inhabits sandy sediments within New Zealand’s sheltered bays and estuaries.

Despite their hidden lives and small size – most measure just a few centimetres long – these worms have an outsized influence on the health of our marine environment.

But now there are troubling signs that microplastics – tiny but pervasive fragments of broken-down plastic – are disrupting the vital role the worms play, with potentially wider effects we are only just beginning to understand.

Hidden heroes of the seafloor

Over time, scientists have come to recognise the role bamboo worms and other tiny creatures have in bioturbation: a process essential to the functioning of coastal ecosystems.

When healthy, the worms burrow in the seafloor, enabling oxygenated water to enter deeper into the sediment. This, in turn, breathes life into the seabed.

The worms........

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