The most commonly spotted were the large barrel jellyfish, but rarer warm-water crystal jellyfish were also seen. Jellyfish populations naturally vary over time, but climate change is warming the UK seas, creating favorable conditions for these creatures.
A marine heatwave in June raised UK water temperatures by about 3-4°C. This increase in jellyfish sightings could be part of a long-term trend linked to climate change, indicating the "tropicalisation" of oceans due to rising temperatures.