Jellyfish blooms, consisting of thousands of swarming individuals, can result in major changes to the marine food chain, an international team of researchers reports in the journal PNAS

There’s evidence the blooms are on the increase worldwide. Robert Cordon from Dauphin Island Sea Lab in Alabama, US, and his colleagues wondered what impact this surge in numbers might have on fish and other marine organisms – whether these creatures were being denied food energy by the preponderance of jellyfish

To investigate, the researchers measured the amount of carbon-rich dissolved organic matter released by two jellyfish - Mnemiopsis leidyi (pictured above) and Chrysaora quinquecirrha – after they had eaten

By feeding this matter - mucus and faeces – to bacteria that live in the water, the team showed that the microbes could increase their respiration rate by 80% in summer

The bacteria convert the carbon released by the jellyfish blooms, like the one pictured above, to carbon dioxide. As a consequence, food energy that is typically available for fish and other organisms is instead largely removed or lost from the marine food web