Barnacles may look nice and nautical on things like rocks, but they’re a major problem for watercraft of all sorts. On the hulls of ships, for example, they can drastically decrease the vessel’s hydrodynamics, causing it to burn more fuel and emit more emissions in order to maintain its cruising speed. The most common way of keeping barnacles off those hulls involves the use of environmentally-unfriendly paints. Now, however, a scientist from Sweden’s University of Gothenburg has developed what could be a less harmful alternative.

In regular “anti-fouling” hull paints, toxins such as copper oxide are mixed into the paint. That poison gradually leaches out of the paint, repelling would-be barnacle hitch hikers, but also entering the marine ecosystem. Various research institutes are looking at the use of more innocuous substances, such as a seed-inspired coating, electrified paint, and even a twitching polymer.

U Gothenburg post-grad student Emiliano Pinori has taken yet another approach. Instead of copper oxide, he’s mixed an antiparasitic agent known as ivermectin with regular hull paint. Unlike the copper, very little of the substance leaves the paint. Instead, barnacles come into contact with it only once they attempt to penetrate the paint’s surface. They’re then poisoned, and fall off the vessel.

According to Pinori’s research, a concentration of just 0.1 percent ivermectin is sufficient to render a paint barnacle-proof, with the anti-fouling effect lasting for “many years.” While small amounts of ivermectin still do leach into the water, he is hoping to get that amount down to zero.

Emiliano isn’t the only scientist at the university who’s investigating new methods of keeping barnacles off boats. Other Gothenburg researchers have recently explored the use of bacteria-produced macrocyclic lactones, and a veterinary medicine known as medetomidine.