Spring jellyfish blooms bring turtles to UK shores

Marine Conservation Society’s wildlife sightings project asks beachgoers to share their discoveries and contribute to research

The Marine Conservation Society’s long-running wildlife sightings project focuses on two key species which arrive on UK shores: jellyfish and, as a result, turtles. Both species are vital in supporting ocean biodiversity and are indicators of climate change while being at risk from its impacts.

The charity is asking beach and seagoers to share when they spot either of these marine animals to support ongoing research.

During spring and summer, jellyfish arrive in the UK’s warming waters to feed on plankton blooms or, in fact, anything small enough to get caught. To that extent, jellyfish feed not only on plankton, but also the array of eggs and larvae of fish, crustaceans, starfish and molluscs which rely on plankton as a stage of reproduction.

With healthy fish stocks and rich biodiversity, jellyfish quickly become part of an effective food chain. Everything from tuna to turtles will feed on jellyfish of various sizes, so the population is well controlled. Supported by a rich and diverse ocean ecosystem, jellyfish link the microscopic world of plankton to larger marine animals and the ocean around them.

Jellyfish are especially appealing for marine turtles. Six of the world’s seven marine turtle species have been spotted in UK seas as a result of jellyfish blooms in spring and summer.

The largest sea turtle, and the most common in UK seas, is the leatherback which has a ‘vulnerable’ conservation status. Reporting sightings of these incredible creatures will support the Marine Conservation Society and others in understanding their movements, potential threats and how to better protect them.

Amy Pilsbury, Citizen Science Project Lead at the Marine Conservation Society, said:“For more than 17 years, beachgoers across the UK have been contributing to scientific research by sharing their wildlife sightings with us. It’s a key part of our work and plays a vital role in better understanding and protecting our ocean.”

In 2014, with partners from the University of Exeter, the Marine Conservation Society published the first paper from the survey data, confirming key information about UK jellyfish and including the first distribution maps of the surveyed species.

Since the 2014 paper, the wildlife sightings project has recorded notable events such as massive and extensive annual blooms of barrel jellyfish and several summers of Portuguese Man o’ War mass strandings.

The charity continues to run its wildlife sightings project to see what happens to the distribution and frequency of mass jellyfish blooms over time. The data will help to explore any links jellyfish blooms have with big-picture factors such as climate change.

Jellyfish can be spotted year-round in UK seas, but larger blooms are more likely to appear in spring, lasting through until autumn. Jellyfish sighting records from 2021 suggest that compass jellyfish are the most common around UK shores, making up 36% of reported sightings.

For more information on how to identify jellyfish and turtles, and to report a sighting, please visit the Marine Conservation Society’s website.