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MARI/CCPO Seminar Series

Jellyfish May Not be Increasing Globally

Robert Condon, University of North Carolina Wilmington.

Jellyfish populations fluctuate across multiple temporal and spatial scales. Globally, they have been shown to exhibit multi-decadal cycles but individual populations within regions may fluctuate enormously from year to year. Consequently the magnitude, timing and location of bloom events are often very difficult to predict, making it challenging for ecosystem models to forecast future trends. Identifying the natural and anthropogenic biotic and abiotic environmental conditions that regulate bloom dynamics is, however, essential for understanding jellyfish population ecology, for capitalizing on the ecosystem services they provide and for developing strategies for predicting and managing problematic and unnatural bloom events. In this seminar, I will provide a status update of a recent linear mixed model meta-analysis (Condon et al. 2013) examining global trends in jellyfish on all available long-term data sets from the past three centuries. Spectral and wavelet analysis comparing long-term jellyfish indices with natural and anthropogenic environmental variables further suggest 'jelly cycles' are driven by natural astronomical cycles, which mediate global heat and solar fluxes to the ocean. The implications of recent experiments on the polyp and ephyrae stages of the cnidarian life cycle, some of which were performed by 6th grade students as part of my Toward Elementary Advancement in Marine Science Program (, will be discussed in the context of mechanisms driving the 'jelly cycles' and potential linkages to global climate change.