Ecosystem found in Stockholm subway

4:29 min

There may be an absence of people at the Kungsträdgården subway station now that it’s closed for rail work, but it’s still teeming with life. In fact, researchers have discovered an entire ecosystem in Stockholms’s deepest station.

When he’s not digitizing one of the largest plant collections in the world at the Swedish Museum of Natural History, Johannes Lundberg likes to explore caves. Now he doesn’t have to go far because in the depths of one of Stockholm’s subway stations, he and fellow researchers have discovered an entire ecosystem, with organisms more commonly found in grottos than subterranean urban transport systems.

At 30 meters below sea level, the Kungsträdgården station is Stockholm’s deepest. It’s also one of the city’s most beautiful, adorned with sculpture from a nearby 17th Century palace that burned down in 1825.

Lundberg and his colleagues took samples from the station’s naked granite wall a week before it closed for four months of rail work at the end of June.

So far they have found a rare cave dwarf spider, a crane fly, a rare moss and very small insects and worm-like animals.

“We also have at least one bacteria. It’s small but it’s a self-sufficient ecosystem,” Lundberg said.

Without the chalk from the manmade ceiling dripping down on the granite wall and the artificial light, this ecosystem would not be possible, says Lundberg.

“There’s a lot of moisture seeping down the walls feeding the life. As it percolates through the rock it picks up organic molecules and debris,” he says.

Lundberg adds that the passengers walking past also contribute energy rich molecules, like pieces of hair, that are nourishing the ecosystem.

Asked how an ecosystem like this develops, Lundberg says you need lime, granite, light and water, but also a source for these organisms. “It’s very interesting because the spider was found in the early 1980s, just a few years after the station was opened. So it must have gotten there from somewhere,” Lundberg says.

One thought is that they arrived with construction machines used in central Europe, the only other place this three millimeter cave dwarf spider has been spotted.

But there are other mysteries they hope the discovery of this ecosystem will help solve, says Lundberg, such as how fungi can erode walls.

“When we are watching the world we see the birds and we see the plants and the squirrels and the fishes. Everything that’s about the same size as we are. But there’s so much around us that we never see that’s important. And we are just starting to scratch on that surface. We are just starting to look into that world now,” says Lundberg.

“For example, the micro-organisms that have been living in this subway station here for so long without us knowing it. If we can find this in a subway station in Stockholm. What can’t we find in a cave in a remote area?”