Gelatinous zooplankton biomass in the global oceans: Geographic variation and environmental drivers

Aim: Scientific debate regarding the future trends, and subsequent ecological, biogeochemical and societal impacts, of gelatinous zooplankton (GZ) in a changing ocean is hampered by lack of a global baseline and an understanding of the causes of biogeographic patterns. We address this by using a new global database of GZ records to test hypotheses relating to environmental drivers of biogeographic variation in the multidecadal baseline of epipelagic GZ biomass in the world's oceans. Location: Global oceans. Methods: Over 476,000 global GZ data and metadata items were assembled from a variety of published and unpublished sources. From this, a total of 91,765 quantitative abundance data items from 1934 to 2011 were converted to carbon biomass using published biometric equations and species-specific average sizes. Total GZ, Cnidaria, Ctenophora and Chordata (Thaliacea) biomass was mapped into 5° grid cells and environmental drivers of geographic variation were tested using spatial linear models. Results: We present JeDI (the Jellyfish Database Initiative), a publically accessible database available at http://jedi.nceas.ucsb.edu. We show that: (1) GZ are present throughout the world's oceans; (2) the global geometric mean and standard deviation of total gelatinous biomass is 0.53±16.16mg C m-3, corresponding to a global biomass of 38.3 Tg C in the mixed layer of the ocean; (3) biomass of all gelatinous phyla is greatest in the subtropical and boreal Northern Hemisphere; and (4) within the North Atlantic, dissolved oxygen, apparent oxygen utilization and sea surface temperature are the principal drivers of biomass distribution. Main conclusions: JeDI is a unique global dataset of GZ taxa which will provide a benchmark against which future observations can be compared and shifting baselines assessed. The presence of GZ throughout the world's oceans and across the complete global spectrum of environmental variables indicates that evolution has delivered a range of species able to adapt to all available ecological niches. Copyright © 2014 John Wiley.This research was carried out as part of the Global Jellyfish Project sponsored by the National Center for Ecological Analysis and Synthesis (NCEAS). Funding for NCEAS comes from National Science Foundation (NSF) Grant no. DEB-94-21535, from the University of California at Santa Barbara, and from the State of California. R.H.C. was also supported by NSF Grant no. NSF-OCE 1030149. C.J.H. carried out the data analysis as part of her Master of Research (Ocean Science) project and was supported by the award of a Richard Newitt prize by the University of Southampton. D.O.B.J. was funded for this work as part of the NERC Marine Environmental Mapping Programme (MAREMAP)Peer Reviewe