Fast-sinking jellyfish could boost the oceans’ uptake of carbon dioxide

The Helmholtz Center for Ocean Research (Kiel):  How much more carbon dioxide (CO2) will the oceans be able to take up? To find out more about the efficiency of this service, scientists estimate the sinking velocities of organisms involved in the biological pump. Increasing numbers of gelatinous plankton might help in mitigating the CO2 problem. In field and laboratory experiments scientists from GEOMAR Helmholtz Centre for Ocean Research Kiel have shown that dead jellyfish and pelagic tunicates sink much faster than phytoplankton and marine snow remains. Jellies are especially important because they rapidly consume plankton and particles and quickly export biomass and carbon to the ocean interior.

...To assess the efficiency of the biological carbon pump, data on sinking velocities of the different species are necessary. Together with colleagues from Germany, Spain, the United Kingdom and the United States, Dr. Mario Lebrato, Biological Oceanographer in Prof. Andreas Oschlies’ group at GEOMAR Helmholtz Centre for Ocean Research Kiel, conducted field and laboratory experiments with gelatinous plankton remains. Their latest article in the international magazine “Limnology and Oceanography” describes for the first time the sinking speed of organic remains from jellyfish and pelagic tunicates. Together with a previous article in the same journal that calculated biomass export efficiency for these organisms for the first time, these new data allow robust estimates of global carbon export associated with gelatinous plankton.

...“Our dataset provides an initial overview and comparison for modelers and experimentalists to use in subsequent studies examining the role of jellies in carbon export and the efficiency of the biological pump”, Lebrato says. “We are continuously asked, how much organic carbon and CO2 do gelatinous plankton sink worldwide, whether their export capacities are similar to phytoplankton and marine snow. And if an increase of jellyfish in the future will enhance organic carbon export and CO2 sequestration. Until recently, few people believed that jelly organisms could play any major role in the carbon cycle, thus they have been excluded from large biogeochemical research programs. In consequence, the data available up to now are scarce and we are just starting to comprehend the fundamental properties that will allow us to better understand the role of jellyfish and pelagic tunicates in the global carbon cycle.”

Accumulation of pelagic jellies. New experiments indicates that fast-sinking jellyfish could boost the oceans’ uptake of carbon dioxide. Photo: Veronica Fuentes, found on the GEOMAR website