Increasing jellyfish populations: trends in Large Marine Ecosystems

  • Lucas BrotzEmail author
  • William W. L. Cheung
  • Kristin Kleisner
  • Evgeny Pakhomov
  • Daniel Pauly
Part of the Developments in Hydrobiology book series (DIHY, volume 220)


Although there are various indications and claims that jellyfish (i.e., scyphozoans, cubozoans, most hydrozoans, ctenophores, and salps) have been increasing at a global scale in recent decades, a rigorous demonstration of this has never been presented. Because this is mainly due to scarcity of quantitative time series of jellyfish abundance from scientific surveys, we attempt to complement such data with non-conventional information from other sources. This was accomplished using the analytical framework of fuzzy logic, which allows the combination of information with variable degrees of cardinality, reliability, and temporal and spatial coverage. Data were aggregated and analyzed at the scale of Large Marine Ecosystem (LME). Of the 66 LMEs defined thus far that cover the world’s coastal waters and seas, trends of jellyfish abundance after 1950 (increasing, decreasing, or stable/variable) were identified for 45, with variable degrees of confidence. Of those 45 LMEs, the majority (28 or 62%) showed increasing trends. These changes are discussed in the context of possible sources of bias and uncertainty, along with previously proposed hypotheses to explain increases in jellyfish.


Jellyfishes Gelatinous zooplankton Blooms Pelagic cnidarians Ctenophores Fuzzy logic 


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We thank the numerous scientists and marine professionals around the globe who kindly donated their knowledge and opinions of jellyfish populations. We also thank two anonymous reviewers and the guest editors of this volume whose comments improved the manuscript. This is a contribution from the Sea Around Us Project, a collaboration between the University of British Columbia’s Fisheries Centre and the Pew Environment Group.

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Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • Lucas Brotz
    • 1
    • 2
    Email author
  • William W. L. Cheung
    • 3
    • 4
  • Kristin Kleisner
    • 1
  • Evgeny Pakhomov
    • 2
  • Daniel Pauly
    • 1
  1. 1.Sea Around Us Project, Fisheries CentreUniversity of British ColumbiaVancouverCanada
  2. 2.Department of Earth and Ocean SciencesUniversity of British ColumbiaVancouverCanada
  3. 3.School of Environmental SciencesUniversity of East AngliaNorwichUK
  4. 4.Fisheries CentreUniversity of British ColumbiaVancouverCanada

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