WHY ARE ZEBRA MUSSELS SO STICKY?

A water tank full of coin-sized invertebrates may not be the first thing you’d expect to see in a materials science and engineering research lab.

But Eli Sone, a professor in the department of materials science and engineering in the University of Toronto’s Faculty of Applied Science & Engineering and the Institute of Biomedical Engineering, and his team have been studying both zebra and quagga mussels for years in the hope that they can help solve a diverse range of challenges.

“There’s a materials science angle, but there’s also a biomedical angle,” says Sone. “On the one hand, these mussels are a problem in terms of what we call biofouling, so we’re looking to design materials or coatings to keep them from clogging water intake pipes, for example.”

“But on the other hand, if we understand why they stick so well, that could help us design things like non-toxic biodegradable glues, which could offer an alternative to internal stitches for surgery or localized drug delivery applications.”

Zebra and quagga mussels are native to the lakes and rivers of southern Russia and Ukraine. They arrived in the Great Lakes of North America in the 1980s—likely by hitching a ride in the ballast water of ships that departed from Europe.

They have since become invasive in many North American waterways, displacing native mussel species and fouling boats, water intake pipes and other infrastructure.

The team’s latest study, recently published in Scientific Reports, outlines new techniques for measuring the adhesion of zebra and quagga mussels to various surfaces.

“One of the challenges is how small these mussels are compared to other species,” says U of T Engineering alumnus Bryan James, who worked on the project as part of his undergraduate thesis and is now a post-doctoral scholar at the Woods Hole Oceanographic Institution in Woods Hole, Mass.

“The threads they use to attach themselves to surfaces are only a few millimeters long and as thin as a human hair. You can’t put them in a traditional apparatus for testing tensile strength.”

The team’s improvised solution involved a pair of fine-tipped, self-closing tweezers, a digital camera and a force gauge. With these, they were able to measure just how much force was required to break the protein-based glue that the mussels secrete.