"Long before it's in the papers"
January 27, 2015


Are jellyfish really taking over? Global database to shed light

May 15, 2014
Courtesy of the University of Southampton
and World Science staff

An in­terna­t­ional study has led to the crea­t­ion of the world’s first glob­al database of jel­ly­fish records to map jel­ly­fish popula­t­ions in the oceans.

The “database of ge­lat­i­nous pres­ence,” as sci­en­tists are call­ing it, has im­plica­t­ions for our en­vi­ron­ment.

Chrysaora plo­camia jel­ly­fish stranded on a beach in Pat­a­go­nia, Ar­gen­ti­na. (Cred­it: Dr. Her­mes Mi­an­zan )

Sci­en­tists and con­serva­t­ion­ists have ex­pressed wor­ries about wheth­er human-caused env­iron­ment­al des­truct­ion has creat­ed new oppor­tu­ni­ties for well-adapted, ag­gres­sively spread­ing “nui­sance” species. In the water, these may include jel­ly­fish; on land, rats and others.

On the oth­er hand, early re­ports of a glob­al jel­ly­fish ex­plo­sion were con­tra­dicted by a lat­er, 2012 study sug­gest­ing that the num­bers were just ris­ing and fall­ing per­i­od­ic­ally.

Yet the au­thors of that stu­dy, from the Uni­vers­ity of South­amp­ton in the U.K., have ac­knowl­edged that in­forma­t­ion on jel­ly­fish popula­t­ions re­mains in­ad­e­quate.

They have there­fore spear­headed the new database proj­ect, known as Jel­ly­fish Database In­i­ti­a­tive, or JeDI. Us­ing the database they mapped jel­ly­fish “biomass,” or to­tal weight, in the up­per 200 me­ters (a­bout 220 yards) of the world’s oceans and ex­plored causes be­hind the pat­terns of dis­tri­bu­tion.

“Any­one can use JeDI to ad­dress ques­tions” about the ex­tent of “jel­ly­fish popula­t­ions at lo­cal, re­gion­al and glob­al scales,” and their po­ten­tial im­plica­t­ions, said Rob Con­don of the Uni­vers­ity of North Car­o­li­na Wil­ming­ton, who par­ti­ci­pated in the proj­ect.

No word yet on wheth­er “ge­lat­i­nous pres­ence” is tak­ing over the world, but the au­thors did find that jel­ly­fish and oth­er “ge­lat­i­nous zoo­plank­ton” are pre­s­ent through­out the oceans, with the great­est con­centra­t­ions in mid-Northern wa­ters. In the North At­lantic, dis­solved ox­y­gen and sea sur­face tem­per­a­ture were found to be the main drivers of jel­ly­fish dis­tri­bu­tion.

A re­port on the find­ings, with South­amp­ton ma­rine bi­ol­o­gist Cathy Lu­cas as lead au­thor, ap­pears in the lat­est is­sue of the jour­nal Glob­al Ecol­o­gy and Bi­o­ge­og­raphy.

* * *

Send us a comment on this story, or send it to a friend

Sign up for

On Home Page         


  • St­ar found to have lit­tle plan­ets over twice as old as our own

  • “Kind­ness curricu­lum” may bo­ost suc­cess in pre­schoolers


  • Smart­er mice with a “hum­anized” gene?

  • Was black­mail essen­tial for marr­iage to evolve?

  • Plu­to has even cold­er “twin” of sim­ilar size, studies find

  • Could simple an­ger have taught people to coop­erate?


  • F­rog said to de­scribe its home through song

  • Even r­ats will lend a help­ing paw: study

  • D­rug may undo aging-assoc­iated brain changes in ani­mals

An international study has led to the creation of the world’s first global database of jellyfish records to map jellyfish populations in the oceans. The “database of gelatinous presence,” as scientists are calling it, has implications for our environment. Scientists and conservationists have expressed worries about whether aggressively spreading jellyfish species—and other “nuisance” breeds such as rats—are taking over the world, ironically, by exploiting opportunies created when humans ruin the environment. On the other hand, early reports of a global jellyfish explosion were contradicted by a later, 2012 study suggesting that the numbers were just rising and falling periodically. Yet the authors of that study, from the University of Southampton in the U.K., have acknowledged that information on jellyfish populations remains inadequate. They have therefore spearheaded the new database project, known as Jellyfish Database Initiative, or JeDI. Using the database they mapped jellyfish “biomass,” or total weight, in the upper 200 meters (about 220 yards) of the world’s oceans and explore the environmental causes behind the patterns of distribution. “Anyone can use JeDI to address questions” about the extent of “jellyfish populations at local, regional and global scales,” and their potential implications, said Rob Condon of the University of North Carolina Wilmington, who participated in the project. No word yet on whether “gelatinous presence” is taking over the world, but the authors did find that jellyfish and other “gelatinous zooplankton” are present throughout the oceans, with the greatest concentrations in mid-Northern waters. In the North Atlantic, dissolved oxygen and sea surface temperature were found to be the main drivers of jellyfish distribution. A report on the findings, with Southampton marine biologist Cathy Lucas as lead author, appears in the latest issue of the journal Global Ecology and Biogeography.