Jellyfish increase along Sweden's coast, new species arrive

Jellyfish are becoming more numerous along Sweden's west coast, with both red and blue varieties increasing in recent years. Marine biologist Christin Appelqvist notes a significant rise in these stinging creatures. "The jellyfish have clearly become more numerous," she stated.

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The jellyfish have clearly become more numerous.

Appelqvist initiated a citizen science project last year, which has been highly successful, collecting over 2,000 public reports of jellyfish sightings. This data helps researchers understand various marine phenomena, including the concerning decline of moon jellyfish along the west coast. "I have long been worried that the moon jellyfish is not doing well and what consequences that could have," Appelqvist said.

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It has been very successful. I am very grateful for all the reports, I think there are over 2,000 so far.

While the exact reasons for the moon jellyfish's decline are unclear, their decrease appears to benefit the stinging jellyfish. "We are already seeing that both blue and red jellyfish are increasing," Appelqvist observed. She also noted that rising water temperatures might favor jellyfish, but the correlation with the moon jellyfish's decline is a key observation.

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I have long been worried that the moon jellyfish is not doing well and what consequences that could have.

Adding to the concern, new jellyfish species are appearing in Swedish waters. The compass jellyfish, with stinging capabilities similar to common jellyfish, is becoming more prevalent. Appelqvist explained that new species arrive partly through human activity, such as in ship ballast water. "With global warming, we also get warmer water, so we get some other species from the south," she said, citing the luminous jellyfish, which stings even more intensely than local varieties, as a recent example.

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But what we are already seeing is that both blue and red jellyfish are increasing.