Unprecedented Jellyfish Numbers Reported in UK Seas Amid Warming Waters

Unprecedented Jellyfish Numbers Reported in UK Seas Amid Warming Waters
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An unusually high number of jellyfish have been observed in UK seas this summer, a phenomenon scientists are attributing to elevated sea surface temperatures exacerbated by global heating, The Guardian reported. These warmer conditions create an ideal environment for jellyfish reproduction, leading to population blooms and extended presence along the British coast. The Met Office had reported record-high sea surface temperatures in April and May, contributing to the anticipated increase in jellyfish blooms.

Jellyfish play a vital role at the base of aquatic food webs. Several species have been identified in UK waters this season. Among them are the large barrel jellyfish, which can reach up to a meter in diameter and possess a mild sting, and the compass jellyfish, known for its painful sting and as a preferred food source for turtles. Moon, lion’s mane, blue, and mauve stinger jellyfish have also been sighted.

The Marine Conservation Society recorded 1,432 jellyfish sightings in 2024, representing a 32% increase from the previous year. This data supports the hypothesis that climate change and warming waters are contributing to more frequent jellyfish blooms. Despite their increased numbers, jellyfish typically have short lifespans, with some completing their entire life cycle within a single summer. As the season progresses, some may follow currents back to sea, while others will perish due to old age, lack of food, or severe weather conditions, which are also linked to climate breakdown.