The Tara Pacific expedition—A pan-ecosystemic approach of the “-omics” complexity of coral reef holobionts across the Pacific Ocean

Abstract

Coral reefs are the most diverse habitats in the marine realm. Their productivity, structural complexity, and biodiversity critically depend on ecosystem services provided by corals that are threatened because of climate change effects—in particular, ocean warming and acidification. The coral holobiont is composed of the coral animal host, endosymbiotic dinoflagellates, associated viruses, bacteria, and other microeukaryotes. In particular, the mandatory photosymbiosis with microalgae of the family Symbiodiniaceae and its consequences on the evolution, physiology, and stress resilience of the coral holobiont have yet to be fully elucidated. The functioning of the holobiont as a whole is largely unknown, although bacteria and viruses are presumed to play roles in metabolic interactions, immunity, and stress tolerance. In the context of climate change and anthropogenic threats on coral reef ecosystems, the Tara Pacific project aims to provide a baseline of the “-omics” complexity of the coral holobiont and its ecosystem across the Pacific Ocean and for various oceanographically distinct defined areas. Inspired by the previous Tara Oceans expeditions, the Tara Pacific expedition (2016–2018) has applied a pan-ecosystemic approach on coral reefs throughout the Pacific Ocean, drawing an east–west transect from Panama to Papua New Guinea and a south–north transect from Australia to Japan, sampling corals throughout 32 island systems with local replicates. Tara Pacific has developed and applied state-of-the-art technologies in very-high-throughput genetic sequencing and molecular analysis to reveal the entire microbial and chemical diversity as well as functional traits associated with coral holobionts, together with various measures on environmental forcing. This ambitious project aims at revealing a massive amount of novel biodiversity, shedding light on the complex links between genomes, transcriptomes, metabolomes, organisms, and ecosystem functions in coral reefs and providing a reference of the biological state of modern coral reefs in the Anthropocene.

Tara Pacific Expedition’s Atmospheric Measurements of Marine Aerosols across the Atlantic and Pacific Oceans: Overview and Preliminary Results

“…Marine aerosol measurements were collected during the Tara Pacific Expedition (Planes et al 2019;Gorsky et al 2019) along the approximately 110,000 km route in the Atlantic and Pacific Oceans (see the route in Fig. 1).…”

“…In May 2016, the Tara Ocean Foundation (see Appendix E) embarked in its eleventh expedition, the Tara Pacific Expedition, a 2.5-yr research project aimed to understand coral reef holobiont and its associated surface plankton ecosystem (Planes et al 2019), and to assess inter-island and open-ocean surface plankton community structures (Gorsky et al 2019). The Tara Pacific Expedition mainly took place in the Pacific Ocean, and while performing the coral reef studies, surface ocean measurements together with detailed aerosol measurements were performed all along Tara's route (Fig.…”

Interspecies Communication in Holobionts by Non-Coding RNA Exchange

“…Understanding the complexity of the coral holobiont would need coordinated efforts to apply advanced molecular techniques in the characterization of different corals from diverse environments [81]. In this context, the Tara Pacific consortium intends to provide a baseline for coral "omics" data worldwide with the aim of characterizing novel biodiversity and unraveling the molecular links between genomes, transcriptomes, metabolomes, microbiota, and holobiont functions in coral reefs [86]. Population dynamics within the coral holobiont in response to biotic or abiotic stress has been the subject of deep investigation in the past years due to the ecological importance of corals [72].…”

Expanding Tara Oceans Protocols for Underway, Ecosystemic Sampling of the Ocean-Atmosphere Interface During Tara Pacific Expedition (2016–2018)

“…Marine aerosols, defined as the aerosols present in the marine atmospheric boundary layer, consist of a mixture of natural and FIGURE 1 | Sailing track of the Tara Pacific expedition showing seawater temperature measured by the thermosalinograph, and the 32 coral islands studied as part of the expedition (Planes et al, 2019). Sections of the expedition where some of the instruments were not functioning are underlined as follows: continuous black line -hyperspectral absorption and attenuation sensor, discontinuous line -Equilibrator Inlet Mass Spectrometer and dotted line-CDOM fluorometer.…”

“…Here we present the sampling strategy adopted during the Tara Pacific expedition (Planes et al, 2019) to study open water ecosystems at the ocean-atmosphere interface across the North Atlantic and tropical Pacific Ocean, and in the wake of several tropical coral islands. A consistent set of protocols was used throughout the expedition to sample aerosols, neuston and plankton at the ocean surface, as well as essential environmental variables.…”