MESO: Microbial Ecogenomics of the Southern Ocean – Analysis of the functional diversity, evolution and ecology of the Southern Ocean plankton, from genes and metabolites to Earth System Models

1. Methodological and coordination objectives

The MESO workgroup aims at delivering contextualized high-quality omics and microimaging data resulting from the diverse inSync operations that can be shared and re-used by the Southern Ocean research community

1. Establish Standard Operating Procedures for seawater, sea-ice and sediment sampling, across InSync expeditions and platforms, for high-quality omics data collection.
2. Establish appropriate wet-lab procedures and bioinformatics workflows to deliver high-quality and intercomparable biological objects observation tables (genes, transcript, proteins, metabolites and Mobile Genetic Elements interactions) from raw omics data, that can be shared effectively with the polar research community (polar microbiology, biogeochemistry, modeling, climate research, etc.).
3. Establish a data management plan for omics data, from raw data to final biological observation tables, adhering to the FAIR principles. Ensure tight synchronization with other InSync datasets, in particular biogeochemical, physical and remote sensing parameters acquired during InSync operations.
4. Adapt protocols for platform-specific capabilities and specificities, enabling additional measurements and sampling (in-situ incubations and activity measurements, sampling of deep water-masses, deployment and recovery of autonomous samplers and vehicle, ice-breaking and ice sampling capacity, sediment coring capacity).
5. Build an integrated, season-stratified operations schedule with deliberate overlap between stations and/or habitat foci and ensure hand-offs among research platforms or expedition legs, enabling direct cross-cutting process studies on autumn decline, overwintering, spring bloom onset and summer productivity.
6. Conceptual and computational framework for heterogenous data integration and annotation (omics, micro- and satellite imagery, and geochemical data).
7. Develop computational models and tools to gain predictive and mechanistic understandings of microbial (metabolic) interactions, community function, and ecosystem functioning in the Southern Ocean.
8. Develop computational models and methods to infer ecological traits and metabolic phenotypes directly from omics data with the goal to reveal ecosystem responses by implementing evolutionary processes within trait-based ecosystem models, bridging molecular observations and knowledge into Earth System dynamics for improving mechanistic predictions.

2. Scientific objectives

The overarching scientific objective of the MESO workgroup is to advance fundamental knowledge on the SO microbial compartment, its activity, diversity, ecology and evolution as well as its sensitivity to predicted environmental changes and its integration to realistic regional ocean models.

1. Establish a SO biome and water-mass resolved reference atlas of viral, prokaryotic and eukaryotic plankton genes and genomes through omics approaches.
2. Understand and model seasonal biological variations associated with SO functioning (open-water, sea ice, polynya formation, sub-antarctic island weathering, continental coastal systems, glacier fronts, etc.).
3. Identify SO specific genomic features and adaptations to polar environments, including metabolic interactions in the phycosphere sustaining carbon fixation and export.
4. Identify SO genomic and metabolic responses to seasonal transitional periods from high to low productivity and vice versa¹.
5. Identify biological markers that can be used to assess and monitor biological and ecological shifts in climate changes scenarios.
6. Document under-represented ecosystems with key contributions and microbial communities (coastal systems, glacier fronts, sympagic communities, etc.).
7. Identify biological, metabolic and ecological features relevant for their integration in SO-specific Earth System Models.
8. Predict, identify and analyze symbiotic and parasitic cross-kingdom interactions within microbial communities, especially during phases with low primary production.
9. Assess ecological and biogeochemical contributions of sea and sea-ice microbial communities in SO seasonal cycles.
10. Highlight the contribution of viral infection in plankton population dynamics and primary production and export.
11. Highlight the role of viruses and mobile genetic elements in rapid polar plankton evolution through horizontal transmission of auxiliary metabolic genes using HiC contact maps.
12. Reconstruct past biological variations from marine sedimentary records using paleogenomics.

3. Societal relevance : interface with policy and ecosystem management objectives

Owing to their richness, complexity and sensitivity to environmental changes at different time scales, omics data are particularly well suited to delineate spatial and temporal marine ecoregions. A central objective to the MESO workgroup will be to evaluate how new knowledge on plankton diversity and dynamics can contribute to redefine ecosystem management and protection concepts and vocabularies adapted to the unique Southern Ocean ecological and political environment.

1. Define omics-informed diagnosis and steering policy indicators.
2. Rethinking marine ecosystems time, space and boundaries with omics data: conceptual contribution of marine microbial diversity to ocean ontologies and geo-philosophies of the Southern Ocean.