The accelerated melting of the Antarctic ice sheet due to global warming profoundly influences adjacent marine ecosystems. The delivery of fresh water from the ice sheet potentially represents a new source of key nutrients, including iron (Fe), a micronutrient known to limit phytoplankton primary production and the biological pump of CO2 in the Southern Ocean. But the bioavailability of Fe, provided mainly in the form of colloids and particles by glacial ice, is poorly understood. The main objectives of PIANO are to elucidate the role of marine prokaryotes as key engineers in the transformation of Fe delivered by Antarctic ice sheet melting and its consequences on their interactions with phytoplankton. PIANO aims to elucidate 1- the processes by which prokaryotes transform and acquire glacial Fe 2- the response of phytoplankton to Fe processed by prokaryotes and 3- the nature and strength of the Fe-mediated prokaryote-phytoplankton interactions. To fill these knowledge gaps the multidisciplinary team of PIANO will combine experimental observations using model organisms of prokaryotes and phytoplankton, a mechanistic model, and in situ observations throughout one year at a coastal Antarctic site influenced by ice melting. This latter will be achieved by the deployment of two innovative autonomous samplers. The identification of the pathways involved in the acquisition of glacial Fe by prokaryotes and the resulting interactions with phytoplankton together with the seasonal in situ dynamics of the respective genes and transcripts will provide original insights to the metabolic routes and microbial taxa involved in this key process. PIANO will thereby provide a better understanding of a key mechanism likely to influence the Southern Ocean ecological trajectory under climate change conditions.

Marine mesozooplankton play a crucial role in the functioning of pelagic ecosystems and global biogeochemical cycles. It is very diverse from a taxonomic and phylogenetic point of view (e.g., giant protists, copepod, krill, small jellyfish, fish larvae), but also functionally (e.g., small vs. large organisms, herbivores who are filtering-courant feeders vs. carnivores who are ambush feeders, vertical migrations, lipid reserve production, etc.). Yet, the link between mesozooplankton diversity and ecosystem functioning remains poorly understood.? TRAITZOO aims to decipher this link using a trait-based approach and taking advantage of recent developments in high-throughput sequencing and imaging of marine plankton. Using already available data, that has been collected in various biogeographical provinces of the global ocean and covering wide environmental gradients, mostly collected by our consortium, we will use numerical ecology and machine learning tools to 1) provide new tools to study functional traits from imaging and transcriptomic data, 2) describe the biogeography of functional traits and identify the main drivers of mesozooplankton functional diversity, and 3) improve marine ecosystem models and develop new trait-based models to better quantify plankton-mediated carbon fluxes. Our consortium brings together experts in mesozooplankton ecology and physiology, marine biogeochemistry, and applied mathematics. Our skills cover plankton imaging, transcriptomics, metabarcoding, biogeochemical modelling, individual-based modelling, statistics, and machine learning.

ROME is a basic research project that will focus on Rare and Overlooked Microbial Eukaryotes, an unexplored reservoir of novel 'species', genes, and metabolic pathways. We will focus on the ecological functions and roles of “rare” (i.e., below 0.01 to 1% of the total number of pyrosequence reads) and “neglected abundant” (primarily zoosporic organisms) species in two contrasting, well-circumscribed and well-studied systems, Lake Pavin and the Eastern English Channel. Deep environmental sequencing, coupled with experimental manipulations and microscopic observations, will unveil the ecological potentials of rare and neglected “ microbial eukaryotes in aquatic ecosystems. Our central hypothesis is that abrupt environmental changes result in novel communities. Among the neglected abundant eukaryotes, zoosporic chytrid pathogens of phytoplankton likely play a key and hitherto unrecognised role in food web dynamics. To explore this possibility, the genomes of one host-pathogen system will be sequenced, annotated and used as a reference to explore gene function in the environment. This information will be combined with functional ecological measurements performed on field communities and mesocosm experiments, in order to model fluxes in the ecosystems under study. We will combine analytical, biochemical, microbiological, and molecular biological techniques in an integrative study of organisms with neglected ecological functions. ROME is a unique collaboration between researchers with complementary expertise in microbial food web interactions and trophic relations, purification/culture and microscope identification of protists and zoosporic organisms, molecular ecology, functional genomics, analysis of community structure, and food web modelling.

APERO proposes a mechanistic approach of the biological carbon pump (export of surface production of biogenic carbon and fate in the water column -200/2000m). APERO aims at reducing the gap between the quantity of organic carbon produced by photosynthesis transferred to the deep ocean and the carbon demand in the water column. The three major contributions of APERO are the study of the role of small-scale dynamics (~1-10km) using autonomous platforms, imaging and innovative instrumentation, the simultaneous observation of all the processes regulating the attenuation of carbon flux in the water column and the quantification of the fluxes associated with these processes. Based on a substantial international collaboration and an ambitious observation strategy, complemented by molecular biology and modeling approaches, the field study, planned for 2022, will contribute to a significant reduction in the uncertainties of carbon storage by the ocean.