The missing majority: understanding global ocean ecology by revealing the unknown biology of the most abundant marine microbial eukaryotes

Project Information

GROWCEAN

Grant agreement ID: 949745

DOI

10.3030/949745

EC signature date 26 November 2020

Start date 1 September 2021

End date 31 August 2026

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 500 000,00

EU contribution

€ 1 500 000,00

Coordinated by

AGENCIA ESTATAL CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICAS
Spain

Periodic Reporting for period 3 - GROWCEAN (The missing majority: understanding global ocean ecology by revealing the unknown biology of the most abundant marine microbial eukaryotes)

Reporting period: 2024-09-01 to 2026-02-28

Summary of the context and overall objectives of the project

Oceans cover two thirds of the surface of the earth, and host half of earth’s primary production via photosynthesis. Within the ocean, the largest single group of organisms by biomass are the protists, while simultaneously being the least understood. Protists are unicellular and colonial eukaryotes that are not animals, plants or fungi. Because of their primary abundance, it is necessary to characterize protist biology and ecology in order to understand the oceanic food web and how energy from primary production is transferred to higher trophic levels, both on current time scales (as a food source for ecologically and economically important animals such as fish and whales) and on geological time scales (through the formation of crude oil deposits and calcareous rock such as limestone).

Global DNA sequencing surveys of protists in the sunlit ocean have revealed that only 500 species comprise roughly 75% of total protist abundance, yet the vast majority of these species are unknown to science (and are currently only identified by their unique DNA barcodes). This project seeks to isolate, culture in the lab, and characterize the biology of these globally abundant, unknown protists as a key to understand global ocean ecology.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

This project is divided roughly into two phases: in the first phase, the objectives are to isolate and culture globally abundant but previously unknown protist species, followed by a characterization of their biology via multiple microscopy methods and transcriptome sequencing. In the second phase, knowledge of their biology obtained in the first phase is used to interrogate global-scale gene expression data sets in order to formulate and then test specific hypotheses about their influence in ocean ecology.

After two and a half years of this project, we are nearing the successful completion of the first phase. We have isolated globally abundant, previously unknown protist species, and we have characterized their cell biology and life histories via superresolution confocal fluorescence microscopy and by time-lapse light microscopy. We have produced high-quality transcriptome assemblies representing catalogs of their gene expression. We continue to develop a specialized method to interrogate how their gene catalogs are deployed in changing ocean conditions, and are applying early versions of the method in order to transition into the second phase of the project, to be carried out over the final two and a half years.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

So far, we have identified and produced robust laboratory cultures for previously unknown, globally abundant protist species, and generated initial glimpses of their cell biology and gene expression. In the coming years, we will apply this knowledge to produce testable hypotheses on their ecology in varying ocean conditions, and then test these hypotheses in controlled laboratory conditions in order to understand the influence of these previously unknown, abundant species on global ocean ecology.