Tara Oceans: towards global ocean ecosystems biology
Abstract A planetary-scale understanding of the ocean ecosystem, particularly in light of climate change, is crucial. Here, we review the work of Tara Oceans, an international, multidisciplinary project to assess the complexity of ocean life across comprehensive taxonomic and spatial scales. Using a modified sailing boat, the team sampled plankton at 210 globally distributed sites at depths down to 1,000 m. We describe publicly available resources of molecular, morphological and environmental data, and discuss how an ecosystems biology approach has expanded our understanding of plankton diversity and ecology in the ocean as a planetary, interconnected ecosystem. These efforts illustrate how global-scale concepts and data can help to integrate biological complexity into models and serve as a baseline for assessing ecosystem changes and the future habitability of our planet in the Anthropocene epoch.
The Tara Oceans project
The ocean ecosystem covers ~70% of Earth’s surface and contains 97% of all water on our planet. Plankton are the dominant life forms in the ocean and comprise highly dynamic and interacting populations of viruses, bacteria, archaea, single-celled eukaryotes (protists) and animals that drift with the currents. Together, these mostly microscopic organisms play a major role in maintaining the Earth system by, for example, carrying out almost half of the net primary production on our planet1 and by exporting photosynthetically fixed carbon to the deep oceans2,3,4. Plankton also form the base of food webs that sustain the complexity of life in the oceans and beyond5.
With the goal to gain a holistic understanding of this complexity, ocean ecosystems biology investigates how biotic and abiotic processes determine emergent properties of the ocean ecosystem as a whole6. Analogously to systems biology studies that require well-characterized cell lines or model organisms for a mechanistic, molecular understanding of their phenotypes, achieving this goal will require to establish an inventory of the ocean’s plankton, to collect data on the interactions of organisms with each other and the environment, and to integrate this information in the context of physicochemical boundaries in the ocean ecosystem across space and time7. Global-scale efforts, although challenging, are poised to offer new insights into each of these directions and should make possible better predictions of the impact of climate change on this crucial component of the biosphere.
Planetary-scale studies of open-ocean organisms have long been the stuff of dreams — from the Challenger Expedition (1872–1876), which led to the discovery and description of countless eukaryotic organisms, to the Global Ocean Sampling Expedition (2004–2008), which pioneered the genomic exploration of ocean microbial communities8,9,10. Following this dream, Tara Oceans was conceived in 2008: a multidisciplinary project and team, including researchers with expertise in biological and physical oceanography, marine ecology, cell and systems biology, genomics, imaging as well as (bio)informatics, with a common goal to study epipelagic and mesopelagic plankton on a global scale (Fig. 1a) from the gene level to the community level7. At its beginning (Box 1), this project, which would use the 36-m schooner Tara (Fig. 1b) for the expedition, required trade-offs and innovations in sampling needs and capabilities. Enormous planning was required to identify oceanic areas of scientific interest; to negotiate international waters, ports and sampling authorizations; and to resolve intense debates across disciplines to establish baseline sampling protocols. Finally, in September 2009, Tara set sail from Lorient, France, partially navigating through stormy weather and around pirates, to collect samples for analysis by state-of-the-art molecular and imaging technologies (Supplementary Box 1).
Sunagawa S., Acinas S.G., Bork P., Bowler C., Tara Oceans Coordinators, Eveillard D., Gorsky G., Guidi L., Iudicone D., Karsenti E., Lombard F., Ogata H., Pesant S., Sullivan M.B., Wincker P., de Vargas C. Tara Oceans: towards global ocean ecosystems biology. Nature Reviews Microbiology 18: 428–445.
doi: 10.1038/s41579-020-0364-5, PMID: 32398798.