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Global Experts Question Claims About Jellyfish Populations – Are Jellyfish Increasing in the World’s Oceans?

Feb 1, 2012

Blooms, or proliferation, of jellyfish have shown a substantial, visible impact on coastal populations – clogged nets for fishermen, stinging waters for tourists, even choked intake lines for power plants – and recent media reports have created a perception that the world's oceans are experiencing increases in jellyfish due to human activities such as global warming and overharvesting of fish.  Now, a new global and collaborative study questions claims that jellyfish are increasing worldwide and suggests claims are not supported with any hard evidence or scientific analyses to date.

The results of the study, led by Dr. Rob Condon, marine scientist at the Dauphin Island Sea Lab (DISL) in Alabama, appear in the latest issue of BioScience (BioScience manuscript # 11-0051.R1). His co-authors are comprised of experts from the Global Jellyfish Group, a consortium of approximately 30 experts on gelatinous organisms, climatology, oceanography and socioeconomics from around the globe, and include co-principal investigators Dr. Carlos Duarte of the University of Western Australia’s Oceans Institute and the Instituto Mediterráneo de Estudios Avanzados (IMEDEA) in Spain, and Dr. Monty Graham of the University of Southern Mississippi.

The Global Jellyfish Group conducted their work at the National Center for Ecological Analysis and Synthesis (NCEAS), a cross-discipline ecological and data synthesis research center affiliated with the University of California, Santa Barbara.

“Clearly, there are areas where jellyfish have increased, the situation with the Giant Jellyfish in Japan is a classic example,” says Condon.  “But there are also areas where jellyfish have decreased, or fluctuate over the decadal periods.”  Condon says understanding the long-term rather than short-term data is the key to solving the question about jellyfish blooms.

Increased speculation and discrepancies about current and future jellyfish blooms by the media and in climate and science reports formed the motivation for the study. “There are major consequences for getting the answer correct for tourism, fisheries and management decisions as they relate to climate change and changing ocean environments,” says Carlos Duarte.  “The important aspect about our synthesis is that we will be able to support the current paradigm with hard scientific data rather than speculation.”

The study highlights the centerpiece 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 analyzing 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 Condon.  “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,” says Condon.  The global analyses using JEDI are currently underway with an anticipated finish date of spring 2012. 


BioScience Article #11-0051.R1: “Questioning the Rise of Gelatinous Zooplankton in the World’s Oceans" by Robert Condon et al.


Media enquiries should be directed to the contacts listed below. For media- or embargo-related questions, please contact the BioScience News Office.

National Center for Ecological Analysis and Synthesis, UCSB
Dr. Stephanie Hampton, NCEAS Deputy Director, Santa Barbara, CA; tel: 805-892-2505, e-mail: Hampton@nceas.ucsb.edu

Mrs. Lori Angelo, Administrative Assistant to the Director, DISL, Dauphin Island, Alabama; tel: 251-861-2141 extension 2312; e-mail: langelo@disl.org

University of Western Australia
Mrs. Lauren White, Executive Assistant to the Director, UWA Oceans Institute, Australia; tel: +61 6488 8116; e-mail: lauren.white@uwa.edu.au

Global Jellyfish Group participants
Dr. Rob Condon, DISL, AL; e-mail: rcondon@disl.org
Dr. Carlos Duarte, UWA, Aust., IMEDEA, Spain; e-mail: carlos.duarte@uwa.edu.au
Dr. Monty Graham, USM, MS
Kr. Kylie Pitt, Griffith University, Australia
Dr. Cathy Lucas, National Oceanography Centre, Southampton, UK
Dr. Steve Haddock, Monterey Bay Aquarium Research Institute, CA
Dr. Kelly Sutherland, University of Oregon, OR
Ms. Kelly Robinson, DISL & University of South Alabama, AL
Dr. Michael Dawson, UC Merced, CA
Dr. Mary Beth Decker, Yale University, CT
Dr. Claudia Mills, Friday Harbor Laboratories, WA
Dr. Jennifer Purcell, Shannon Point Marine Lab, WA
Dr. Alenka Malej, National Institute of Biology, Slovenia
Dr. Hermes Mianzan, INIDEP, Argentina
Dr. Shin-ichi Yue, Hiroshima University, Japan
Dr. Stefan Gelcich, Catholic University of Santiago, Chile
Dr. Larry Madin, Woods Hole Oceanographic Institute, MA


Individual files depicting examples of jellyfish blooms available as part of press packet. Media should acknowledge the appropriate people when using files.

Figure showing examples of historical and modern jellyfish blooms from around the world.
Top row: (left) Moon jellyfish (Aurelia) in Chesapeake Bay (Photo credit: Scott Kupiec); (center) Giant Jellyfish (Nemopilema nomurai) clogging fishing nets in Japan (Photo credit: Dr. Shin-ichi Uye); and (right) salp bloom off the coast of New Zealand (Photo credit: seacology.co.nz).
Bottom row: (left) fossil jellyfish bloom (Photo credit: Dr. JW Hagadorn); and (right) moon jellyfish beach stranding at San Francisco in Nov 2010 (Photo credit: Ocean Beach Bulletin).


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