The airport serving Norway’s northern city of Tromsø has to deal with an unusual problem because of its location right next to a large marsh that extends into the sea around the Arctic island. Every day the runway is littered with prickly, stone-hard shells that housed sea urchins thriving in the nearby marsh.
“We’re talking about hundreds of sea urchins (called kråkeboller in Norwegian), every morning,” Svein-Idar Henriksen, operating chief at the Tromsø airport, told local newspaper Nordlys. He explained that “massive numbers” of seabirds, particularly gulls, hunt out the sea urchins during the night, eat them and then drop the empty shells on the runways. The birds, he complained, “don’t clean up after themselves.”
That leaves Henriksen’s crews having to clear the runways, to avoid the sea urchins’ housing from being sucked into aircraft engines. Cleaning crews don’t just hose away the sea urchins but also the shells of mussels and other “seafood that’s been on the birds’ menu during the night,” Nordlys wrote.