Managing the productivity of the oceans

Through satel­lite obser­va­tions of the light released by micro­scop­ic marine plants through nat­ur­al flu­o­res­cence, the Ocean Glow project aims to bet­ter under­stand what con­trols marine pri­ma­ry pro­duc­tiv­i­ty. It also aims to improve glob­al mon­i­tor­ing and mod­el­ing of their cli­mate-dri­ven changes. For this inno­v­a­tive research idea, Dr. Thomas Brown­ing, marine biol­o­gist and chemist at GEOMAR Helmholtz Cen­tre for Ocean Research Kiel, receives one of the cov­et­ed Start­ing Grants of the Euro­pean Research Coun­cil (ERC).

The small­est organ­isms in the ocean form the basis for all life in the sea: sin­gle-celled marine plants, the phy­to­plank­ton, pro­duce organ­ic mat­ter. They sup­ply the entire marine food web, on which humans ulti­mate­ly depend. The immense abun­dance can even be viewed and mapped from space. But as clear­ly vis­i­ble as the pro­lif­er­a­tion of phy­to­plank­ton is, it is still unclear what fac­tors reg­u­late growth and how they are affect­ed by cli­mate change. Dr. Thomas Brown­ing, a marine biol­o­gist and chemist at GEOMAR Helmholtz Cen­tre for Ocean Research Kiel (Ger­many), plans to devel­op a new approach to deter­mine which nutri­ents lim­it phy­to­plank­ton growth using satel­lite obser­va­tions, with sup­port from a €1.5 mil­lion Start­ing Grant from the Euro­pean Research Coun­cil (ERC).

“Of the mod­els cur­rent­ly used to pre­dict future cli­mate change impacts on phy­to­plank­ton pro­duc­tiv­i­ty, some show increas­es and oth­ers show decreas­es. As long as this dis­agree­ment exists, it is dif­fi­cult to assess how life-sus­tain­ing func­tions of the ocean, such as food sup­ply or cli­mate reg­u­la­tion, will evolve in the future.” — Dr. Thomas Browning

Results from field research show that ocean pro­duc­tiv­i­ty is high­ly depen­dent on the avail­abil­i­ty of nutri­ents, par­tic­u­lar­ly nitro­gen and iron. Until now, cap­tur­ing how nutri­ent avail­abil­i­ty lim­its phy­to­plank­ton has required mea­sure­ments tak­en on research cruis­es at sea. This has lim­it­ed insights to sin­gle points in time and very small parts of the ocean. Brown­ing’s Ocean Glow project aims to devel­op an approach to scale up these obser­va­tions to glob­al scales using the nat­ur­al flu­o­res­cent light emit­ted by phytoplankton.

“The flu­o­res­cence sig­nals could tell us which nutri­ents reg­u­late phy­to­plank­ton growth. But at present, they are not well enough under­stood to do so. Ulti­mate­ly, it may be pos­si­ble to use satel­lite obser­va­tions of flu­o­res­cence to con­duct glob­al mon­i­tor­ing to observe the effects of cli­mate change and assess the accu­ra­cy of cli­mate mod­els,” says Dr. Brown­ing. “Thanks to ERC fund­ing, and build­ing on pre­vi­ous work at GEOMAR, we hope to lit­er­al­ly shed new light on cru­cial ques­tions relat­ed to cli­mate change impacts on the ocean.”

The ERC-fund­ed project will run for five years, start­ing in mid-2022, and includes three new posi­tions for post­doc­tor­al researchers*. At GEOMAR, a nov­el facil­i­ty for pre­cise­ly con­trolled exper­i­ments will be devel­oped to test the flu­o­res­cence of four glob­al­ly rel­e­vant phy­to­plank­ton species under dif­fer­ent nutri­ent con­di­tions. The mea­sure­ments from the lab­o­ra­to­ry will then be com­pared with data from more com­plex plank­ton com­mu­ni­ties on research expe­di­tions. The final step is to inte­grate the new infor­ma­tion into mod­els and ana­lyze exist­ing satel­lite data to exam­ine dis­tri­b­u­tion, sea­son­al­i­ty and changes in nutri­ent limitation.

“If we are tru­ly suc­cess­ful in deci­pher­ing nutri­ent lim­i­ta­tion from satel­lite-cap­tured flu­o­res­cence, ‘Ocean Glow’ will be suc­cess­ful in three ways,” Dr. Brown­ing points out. “First, the project will help make exist­ing Earth sys­tem mod­els more real­is­tic. Sec­ond, satel­lite data from the past 20 years can be rean­a­lyzed to doc­u­ment how cli­mate change has affect­ed ocean pro­duc­tiv­i­ty to date. And third, we will be able to assess how wide­spread var­i­ous nutri­ent lim­i­ta­tions already are in the ocean. This will be key to under­stand­ing the future impacts of cli­mate change on the ocean and its var­i­ous func­tions for humanity.”

A total of 397 young sci­en­tists received ERC Start­ing Grants total­ing 619 mil­lion euros in the cur­rent fund­ing round. More than 4,000 pro­pos­als were received in response to the call for pro­pos­als under the Euro­pean Union’s Hori­zon Europe research and inno­va­tion pro­gram, which were reviewed by renowned researchers from around the world. The select­ed pro­pos­als cov­er all research dis­ci­plines, from med­ical appli­ca­tions of arti­fi­cial intel­li­gence to design­ing a legal regime for fair influ­encer mar­ket­ing. The projects are being car­ried out at uni­ver­si­ties and research cen­ters in 22 Euro­pean coun­tries, 72 of which are in Germany.