In contrast to many other sea creatures, jellyfish are among the winners of climate change. Because of the rising water temperatures of the world’s oceans, they could penetrate further and further into the Arctic Ocean in the future, as a study by the Bremerhaven Alfred Wegener Institute (AWI) shows. In a computer model, researchers exposed eight Arctic jellyfish species to rising water temperatures, as would be expected due to climate change.
The result: With one exception, all species examined could significantly expand their habitat towards the Arctic from the period 1950 to 2014 to the period 2050 to 2099. The study was published in the journal “Limnology and Oceanography”.
According to the results, the yellow hair jellyfish, known as the fire jellyfish and found in the Baltic Sea, is spreading particularly strongly towards the north. “It can even almost triple its habitat,” said AWI marine biologist Charlotte Havermans. Only one species examined (Sminthea arctica) recorded a decline of 15 percent because it retreats to colder depths when temperatures are high. According to the information, jellyfish also benefit from nutrient inputs and overfishing. If climate change puts stress on marine life, cnidarians, which include jellyfish, could often prevail against food competitors such as fish, said lead author Dmitrii Pantiukhin. In Spitsbergen, the crown jellyfish has already taken over an entire fjord, emphasized Havermans.
“Many jellyfish feed on fish larvae and eggs, delaying or preventing the recovery of fish populations that have come under pressure, which are also often heavily managed by humans,” said Pantiukhin. Scientists are already talking about an impending global “squalification” of the oceans. This is also reflected in the fact that over the last 15 years, people in the Mediterranean have been more frequently affected by jellyfish stings, said Havermans.
It is still unclear how the northward advance of cnidarians will affect Arctic fish stocks. “There is much to suggest that important Arctic fish species such as polar cod, whose larvae and eggs are often eaten by jellyfish, are coming under even greater pressure,” said Havermans.
