Are Jellyfish Taking Over the World's Oceans? Scientists Cast Doubt

The uptake in jellyfish numbers has been in the news a lot the last few years. Indeed just last year massive jellyfish blooms were the reason nuclear power plants in the UK had to shut down, as the little buggers clogged up water intakes used for cooling. Overfishing and climate change have been blamed, as predators of jellyfish are taken from the sea and changes in ocean temperatures and pH balance provide great environments for jellyfish to flourish. But a group of scientists say the drama revolving around "jellyfish taking over the ocean" could be a bunch of bunk.

PhysOrg reports that a study by experts from the Global Jellyfish Group, including Dr. Cathy Lucas, a marine biologist at the University of Southampton, say that the surges in jellyfish numbers are a completely normal part of the species' history. Yes, we're experiencing some significant blooms, but the notion that they're going to take over the oceans in the future is not based on hard evidence, and it sparked interest in the group conducting a thorough study.

The study highlights the centrepiece of their research collaboration with NCEAS – the formation of a global database called the Jellyfish Database Initiative (JEDI) – a community-based database project that is being used in the global analysis and to test the worthiness of the current paradigm. The database consists of over 500,000 data points about global jellyfish populations collected from as early as 1750, and will be made as a future repository for datasets so that the issue of jellyfish blooms can be continually monitored in the future.

By analysing JEDI, the group will be able to assess key aspects behind the paradigm including whether current jellyfish blooms are caused by human-made actions or whether we are simply more aware of them due to their impact on human activities, such as over-harvesting of fish and increased tourism.

"This is the first time an undertaking of this size on the global scale has been attempted but it is important to know whether jellyfish blooms are human-induced or arise from natural circumstances," says Dr. Robert H. Condon of Dauphin Island Sea Lab. "The more we know, the better we can manage oceanic ecosystems or respond accurately to future effects of climate change. The scientific data exists to answer this question, but it is fragmented in analysis".

Science Daily reports that Dr. Condon and his colleagues think that the perception is based on a lack of information about past blooms, more attention being paid to current blooms, and of course "media fascination" with an uptake in blooms. However, they still acknowledge that changes in jellyfish populations do have serious impacts on other sealife and could indeed be impacted by human activity. But they want to gather significant scientific evidence before drawing hard conclusions about the future of our ocean.

Are Jellyfish Taking Over the World's Oceans? Scientists Cast Doubt
There's no doubt we've seen an uptake in jellyfish numbers over the last few years, but does that mean they'll dominate the seas for year's to come? A group of scientists aren't so sure about that, and are taking a closer look.

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