The number of jellyfish sightings in the UK has increased significantly in the past year, according to the Marine Conservation Society.
The most commonly seen species are the large barrel jellyfish, but there have also been reports of crystal jellyfish, a warm-water species rarely seen in UK waters.
While jellyfish populations fluctuate naturally, experts suggest that climate change may be creating more favorable conditions for these gelatinous creatures, with potential impacts on the marine ecosystem.
A June heatwave in the UK caused water temperatures to increase by 3-4C, a significant jump for this region.
The world has been experiencing record-breaking temperatures in recent months, leading scientists to express alarm over the implications for marine life.
Ocean temperatures in August were the highest ever recorded, reinforcing concerns about the effects of climate change on the world's oceans.
According to BBC, From October 2022 to September 2023, jellyfish sightings increased by 32% compared with the previous year.
Most were on the UK's west coasts, particularly in Cornwall and Wales. And 11% were of large blooms of more than 100.
One of the most frequently seen jellyfish in UK waters is the barrel jellyfish, which can grow up to 3ft (1m) in diameter and is sometimes colloquially known as the "dustbin-lid" jellyfish.
These jellyfish have eight thick arms rather than long tentacles. Other notable species seen in UK waters include the lion's mane jellyfish, Portuguese man o' war, moon jellyfish, and compass jellyfish.
The Marine Conservation Society has been asking the public to report sightings of jellyfish for 20 years.
"These numbers could be part of a 20-year long boom-and-bust cycle but there are very few surveys out there which show what's happening," Dr Peter Richardson said.
"But this survey gives us an indication of what's happening in our seas with climate change."
Dr Abigail McQuatters-Gollop, a plankton expert at the University of Plymouth, agrees that there is an abundance of jellyfish this year.
She went diving every day in August and says she had never seen so many jellyfish, including the crystal jellyfish which she had never before seen in the UK.
This creature usually prefers warmer waters, but the hot weather experienced in June appears to have created conditions that allowed it to thrive in the UK.
According to scientists, many marine species are expected to migrate to colder, northern waters as ocean temperatures continue to rise. As a result, the appearance of tropical or subtropical species in areas that were previously too cold for them is likely to become more common.
"But we don't know if the high numbers this summer are a longer-term natural trend or linked to the marine heatwaves. There is a lack of research - we have to do more studies," she says.
The warming of UK waters over time is likely to have lasting effects on the country's fish populations. The food sources that support current fish species, such as cod, could be altered or even disappear, leading to changes in the overall balance of marine ecosystems. In addition, the survey reported an unusually high number of sea turtle sightings, including several leatherback sea turtles - a rare occurrence.
- If you see a jellyfish or sea turtle, avoid touching it, as some jellyfish can sting and sea turtles should not be disturbed.
- If you see a jellyfish, you can help by identifying it and reporting your sighting to the Marine Conservation Society.
- If you find a hard-shelled turtle on the beach, do not return it to the water. This could put the turtle in shock, as it is likely adapted to cold waters.
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