Blooms of jellyfish have had a palpable impact on coastal populations and recent media reports have pointed to increases in jellyfish due to factors including global warming and overfishing. But a new global and collaborative study conducted at UC Santa Barbara’s National Centre for Ecological Analysis and Synthesis (NCEAS) is challenging these claims by noting that they are not supported with any hard evidence or scientific analyses.

“There’s no support as yet to make any assertion that jellyfish are rising globally”, told co-principal investigator Carlos Duarte of the University of Western Australia’s Oceans Institute and the Instituto Mediterráneo de Estudios Avanzados in Spain, ABC reports.

The results of the study, led by Rob Condon, marine scientist at the Dauphin Island Sea Lab (DISL) in Alabama, US, were published in the latest issue of the journal BioScience.

“Clearly, there are areas where jellyfish have increased –– the situation with the Giant Jellyfish in Japan is a classic example”, Condon acknowledged. “But there are also areas where jellyfish have decreased, or fluctuate over the decadal periods.”

He said understanding the long-term rather than short-term data is necessary to solve the question about jellyfish blooms.

“The important aspect about our synthesis is that we will be able to support the current paradigm with hard scientific data rather than speculation”, noted Duarte.

The study underscores the focus of the team’s research collaboration with NCEAS — the development of a global database called the Jellyfish Database Initiative (JEDI) being used in the global analysis and to test the worth of the current paradigm. The database contains more than 500,000 data points about global jellyfish populations collected since 1790, and will serve as a future repository for datasets to allow for ongoing monitoring of jellyfish blooms.

Analysing JEDI will let the group assess key aspects behind the paradigm, including whether jellyfish blooms are currently caused by human-made actions or whether their effect has merely become more noticeable due to their impact on human activities.

“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”, said Condon. “The more we know, the better we can manage oceanic ecosystems or respond accurately to future effects of climate change.

The global analyses using JEDI have an anticipated finish date of spring 2012.

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