The Tara Oceans expedition was a global scientific undertaking to explore the diversity and function of microscopic life across the world’s oceans. This ambitious project, spanning multiple years, aimed to provide a comprehensive view of planktonic organisms and their interactions within marine ecosystems. It gathered a snapshot of their distribution, offering a baseline understanding of their presence and activity on a global scale.
Understanding the Ocean’s Microscopic Life
Ocean microbes, including plankton, viruses, bacteria, and protists, form the base of marine food webs and exert a profound influence on global biogeochemical cycles. Photosynthetic phytoplankton, for example, are responsible for nearly half of the planet’s net primary production, converting inorganic carbon dioxide into organic matter. This process significantly impacts the carbon cycle, regulating Earth’s climate by absorbing a substantial portion of the CO2 produced daily.
Beyond carbon, marine microbes are involved in the cycling of other elements like nitrogen, sulfur, and oxygen. Diazotrophic bacteria and cyanobacteria convert atmospheric nitrogen into usable forms, fundamental for marine ecosystem productivity. Sulfur-metabolizing microbes also contribute to climate regulation through the production of compounds like dimethylsulfide (DMS), which can influence cloud formation. Studying these organisms globally addressed knowledge gaps concerning their ecological roles and contributions to planetary processes.
The Global Expedition and Its Approach
The Tara Oceans expedition used the schooner Tara, a research vessel, to traverse the world’s oceans. The expedition spanned from September 2009 to March 2012, covering approximately 57,000 miles across 37 countries. This route allowed for systematic sample collection from diverse oceanic regions, including the North Atlantic, Southern, Indian, and Pacific Oceans.
Methodologies were employed to analyze the collected samples, which included around 40,000 plankton samples. The project integrated multi-omics technologies, such as genomics, metagenomics, transcriptomics, and proteomics, to study the genetic and functional diversity of marine microbes. An imaging platform also allowed for the observation of these organisms, providing a comprehensive view of their morphological and genetic characteristics. This standardized approach ensured consistency in data collection across various environments.
Key Revelations from the Data
The data collected by Tara Oceans yielded scientific discoveries, changing our understanding of marine microbial diversity. Researchers identified over 100 million genes, with more than half previously unknown, establishing a gene catalog for marine plankton. This work revealed an immense diversity, particularly among protists.
The expedition also uncovered new species and metabolic pathways, providing insights into specialized functions within plankton communities. Findings indicated that environmental factors like temperature and nutrient concentrations influence the distribution patterns and community compositions of marine microbes. The project also explored the ocean virome, defining viral community gene sets and suggesting that viral communities act as a reservoir of dormant individuals, contributing to high local diversity.
The Project’s Lasting Influence
The Tara Oceans project has advanced our understanding of ocean ecosystems and marine biodiversity. It has reshaped scientific perspectives on the role of microscopic life in global processes, including carbon sequestration and oxygen production. Its contributions extend to climate change research, offering insights into how marine microbes respond to environmental shifts.
The datasets and methodologies developed by Tara Oceans have laid groundwork for future oceanographic research. Its open-access protocols and data promote further scientific inquiry and collaboration worldwide. This initiative also fostered international cooperation, with over 22 laboratories and numerous partners involved.