CEODOS: baseline exploration of ocean microbiomes along the Chilean coast leading to nature-based ecosystemic solutions

In December 2020 an international consortium of universities and research centers, together with the TARA Oceans Foundation, launched the three-year ‘Mission Microbiomes’ expedition. A series of back-to-back cruises dedicated to the macroscale investigation of marine microbiomes across coastal biogeochemical gradients, linking the Atlantic and Pacific oceans. The first part of the expedition, called CEODOS (www.ceodoschile.cl), occurred between February and May 2021, and covered the entire Chilean coast, sampling consistently and with unprecedented biological resolution pristine areas in Chilean Patagonia, high productivity zones in the upwellings of south-central Chile, and the most extended zones of minimum oxygen in the South Pacific. Chilean coastlines are an open laboratory for studying planetary biology (i.e., stable water temperature with high fertilization effects), CEODOS mapped microbial and morphological diversity along with biogeochemical variability along the Chilean coast, identifying species, genes (genomes), and interactomes that can contribute to climate change mitigation, prediction and adaptation. This will help to identify areas where natural carbon fixation through the biological carbon pump and other essential climate and biogeochemical services must be preserved. These critical areas, which we named KOPAS - Key Ocean Planktonic Areas - have the specificity to be highly dynamical in both space and time and should be protected. In terms of resources CEODOS is about to release the sequencing of 160 bacterial meta-genomes and meta-transcriptomes, which represents a critical genetic database for studying the unique mosaic of environmental conditions characterizing Chilean coastal waters. Functional and taxonomic studies of this data have revealed high variability at the level of genes and metabolic regulators compared to previous knowledge of the open ocean, which may translate into functional gains and losses in the ecological functions and services performed by the marine ecosystem in these regions, rich in fish production activities. These data represent a baseline for validating KOPAS identified from previous Tara Ocean campaigns, with the overarching goal of their prediction at a planetary scale.