Shipping also promotes the triumph of the jellyfish. When they are transported into new bodies of water in the ballast water of ships, they often settle successfully and displace local species. They are not picky eaters, consuming whatever enters their mouth opening. And if they can't find sufficient food, they simply shrink their bodies temporarily.
What is more, jellyfish apparently benefit from climate change. Many species grow more quickly at higher temperatures. And tropical species like the sea wasp, whose venom can kill people within two minutes, are spreading in subtropical waters.
Does this mean that jellyfish are the beneficiaries of man's over-exploitation of the environment? A toxic reminder that, in the end, everything has its price?
Convincing the Skeptics
Jellyfish researcher Gili says that he isn't worried about tourism in his country, because there are currently no deadly jellyfish in the Mediterranean, unlike Australia and Asia. But the biologist does find it troubling that jellyfish are changing the ecological balance. What can be done about it? Can we put an end to overfishing of the oceans? Pollution of the environment? Climate change? Gili's colleague Verónica Fuentes is beginning to have success convincing Catalan fishermen of the importance of her research project. It's no small task. What fisherman wants to be told not to fish as much, for the sake of the environment?
Fuentes has invited Mario Vizcarro, the fishermen's attorney and secretary of Catalonia's official federation of fishermen, to the institute. Vizcarro represents the interest of 1,200 fishermen from the region. They sit in a conference room where the lights are dimmed, the petite scientist and the bull-necked lawyer. Fuentes begins the conversation diplomatically, saying: "There are many reasons why the jellyfish are spreading. Fishery is one reason, but there is also water pollution and warmer temperatures." Vizcarro looks skeptical.
The scientist projects a photo onto a screen: a jellyfish with small, silver-colored fish hanging from its tentacles. Some jellyfish eat fish, Fuentes explains in a soft voice. Vizcarro bends forward and stares at the photo. "That sort of thing exists here?" he asks, sounding disgusted. "Not here, not yet," says Fuentes, "but they're already in the North Sea."
Vizcarro examines the photo. His fishermen also have a problem, he says: They are hardly catching any sardines anymore. Could it be that the jellyfish are eating the little sardines? He finds the idea unsettling. He scrutinizes Fuentes with newly awakened interest.
Then she shows him a short film from Japan, which depicts massive numbers of giant jellyfish in bursting fishing nets. "Ah!" Vizcarro exclaims, turning away. Fuentes has been working up to this moment. "We need your help," she says. "We monitor the coast, but we also need information on how many jellyfish there are out there in the ocean. Only fisherman can give us this information." Her idea is to use a smartphone app specially developed for fishermen.
Vizcarro nods. "We're interested," he says. His fishermen, he adds, are also reporting that they are seeing more jellyfish than in the past, and that there are fewer fish in areas where there are lots of jellyfish. Vizcarro sits up and says: "We too want to know what's going on."
Translated from the German by Christopher Sultan