Scientists Have Questions Concerning Jellyfish Blooms
February 2, 2012

Scientists Have Questions Concerning Jellyfish Blooms

Scientists are questioning whether jellyfish blooms are real or just perceived by media hype. The report, which appears in the journal BioScience, questions the validity of increased jellyfish populations being reported around the world.

The report was issued by the Global Jellyfish Group, which is a consortium of around 30 experts on gelatinous organisms, climatology, oceanography, and socioeconomics from around the globe.

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

The apparent jellyfish blooms have a noticeable impact on coastal communities. In large numbers jellyfish will clog up fishing nets, sting tourists, or even choke the intake lines for power plants.

In order to study the fluctuations of jellyfish populations, scientists needed to develop a baseline. The group developed the Jellyfish Database Initiative (JEDI) to meet their needs. This database will consist of over 500,000 data points about global jellyfish populations dating back to 1790.

Studying the JEDI data will help the scientists determine whether the blooms are caused by human actions or whether we are just more aware due to human activities.

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

The report notes that the scarcity of long-term data on jellyfish populations helps to skew the perception of what is normal and abnormal for the populations. Contemporary observers either ignored or were ignorant of reported increases in populations decades ago.

The media sensationalizes notable events, such as population increases, in order to increase readers or viewers, whereas during years when populations are normal the animals are ignored.

According to the report, “Although media and scientific reports of massive numbers of jellyfish may be newsworthy, they should not be misinterpreted as an indication that gelatinous zooplankton abundance has deviated from their typical ranges.”


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