We are entering a new dimension of the Anthropocene age affecting the Earth and its vital biogeochemical cycles in an unprecedented way. The anthropogenically-produced mass (including plastics, titanium dioxide (TiO2), and ultrafine-soot particles) had surpassed all global living biomass with annual fluxes entering the environment estimated at millions of tons. These anthropogenic particles integrate oceans and interact with the biogeochemical cycles, from microscale to nanoscale (or colloidal scale). The main goal of NANO-GATE is to characterize the presence and the biogeochemical cycling of anthropogenic nanoparticles in the Arctic Ocean. Nanoplastics, TiO2, and nano-soots are targeted due to their extensive use in anthropogenic activities, high reactivity against other contaminants in the environment, and expected ubiquity in the AO. Despite its relatively small size and lower direct contact with human activities, the Arctic Ocean (AO) is one of the most exposed oceans to anthropogenic impacts. While the presence of microscale anthropogenic particles starts to be partially documented there is absolutely no data concerning nanoparticles. And yet, even at (ultra)-trace concentration, and due to their high surface specificity, diffusivity and reactivity, nanoparticles are more likely to interact with biota, especially primary producers, and to impact the main biogeochemical cycles. In light of these properties and the increase in anthropogenic material mass entering the global ocean, there is an urgent need to address the pervasiveness of ANP dispersal, particularly in the AO. NANO-GATE will pioneer ANP research in the AO by providing a unique dataset of their distribution and cycling, with the determination of their behavior with key variables specific to the AO. NANO-GATE will provide unprecedented data to support the various Arctic monitoring program agencies and policymakers and list ANPs as an emerging threat.

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.

In the Arctic Ocean, microalgae experience extreme seasonal variations in available light, from the polar night under the ice pack to the midnight sun in ice-free waters. We have recently discovered that they could grow under the extreme low-light regime typical of the polar night exit. The objective of the Dim project is to quantify growth of Arctic microalgae under extreme low light, and identify the regulation mechanism of cellular metabolism that make it possible. The project includes i) a series of laboratory experiments to characterize the growth of an Arctic diatom at low light, ii) a field campaign in Baffin Bay during winter 2023-2024 to document in situ growth of the various taxonomic groups present between January and April, and iii) modelling experiments to determine the possible role of low-light winter growth on inoculating the spring bloom of micro-algae in the Arctic Ocean. In the first two laboratory experiments the polar diatom Fragilariopsis cylindrus will be grown under continuous light and sine light-dark cycles closely reproducing natural ones, at 7 light levels from ~0.01 to 10 mmol photons m-2 s-1. In a third experiment, various forms of organic carbon will be added to study the possible role of heterotrophy, and in a fourth experiment, we will compare F. cylindrus growth at very low light with that of 3 other Arctic diatoms and a typical prasinophyte, Micromonas polaris. In these experiments, we will try to determine the possible contribution of the following strategies that may allow growth at extremely low light: maximization of light capture and efficient photosynthesis, minimization of respiration, optimization of the use of reserves, notably lipids, and possible use of heterotrophy to complement energy provided by photosynthesis. A detailed characterization of photophysiology, together with proteomics, lipidomics, and transcriptomics analyses will allow deciphering the role of each of these possible strategies. During the field campaign, growth of microalgae in sea ice and in the water column under sea ice will be monitored from December 2023 to April 2024 in the vicinity of Qikiqtarjuaq (Nunavut, Canada) under landfast ice. Every four days, we will document: the light field at the bottom of sea ice and in the water column with ultra-sensitive radiometers, micro-algae pigments, light-absorption properties and photosynthetic parameters, abundance and taxonomy of phytoplankton and zooplankton, carbon and nitrogen assimilation by microalgae, zooplankton grazing rate, nutrients, hydrological properties and vertical fluxes of particles. Additionally, phytoplankton communities and species will be identified using high throughput amplicon sequencing targeting the V4 and V9 regions of the 18S rRNA and the 16S rRNA from chloroplasts. Finally, we will use a numerical framework allowing for the simulation of various plankton functional types to test our hypotheses regarding the ecological impacts of the physiological responses of the Arctic diatom community to the polar-night light conditions (trait-based model coupled to the MIT general circulation model). We plan the following numerical experiments: (i) a series of local sensitivity analyses in a 1-D water column implementation to quantify the range of physiological and biological parameter values required to simulate a positive net growth of numerical diatom types in extreme low light regimes, (ii) test of the role of the simulated predation pressure (top-down control) on the biomass of the phytoplankton community at the onset of the light conditions sought to initiate positive net growth, and (iii) use of a 3-D configuration of Baffin Bay in order to quantify the role of diatom adaptations to extreme low light conditions on the spatio-temporal patterns in the phenology and amplitude of the phytoplankton bloom.

The community was recently warned about the notion of microplastic and a fortiori nanoplastics (NPs) concentrate pollutants acquired from the surrounding environment and potentially released them into organism as bioavailable contaminants. Nevertheless, the knowledge of the factors influencing the sorption/desorption/speciation of chemicals associated to NPs is still unknown. The protocols applied so far for microplastic study cannot be simply cloned off to NPs and a sensor approach should respond to several challenges: collection, NP physico-chemical behavior and toxicant uptake. PLASTI-SCARE aims to give a comprehensive study of the NP impact as pollutant carrier for a better evaluation of the water quality. The project will enlighten the fate of NPs and will offer a better understanding of the interaction of NPs with pollutant and organic matter. New environmental sensor will be developed to access to the pollution level (risk and hazard level) via a multidisciplinary approach..

Originating from either natural sources (such as hydrothermal, eruptive or weathering processes) or a range of anthropogenic activities, metallic elements flow in the Earth water and biota. This phenomenon is subject to investigations across a wide range of settings including the most remote parts of the Arctic and Antarctic. The strong interest in the assay of metal element is driven by various applications: monitoring in the context of the Water Framework Directive (Directive 2000/60/EC) and the Marine Strategy Framework Directive (2008/56/EC), bio-geo-chemical studies for the investigation of the contribution of hydrothermal vent to the global ocean or impact studies of the potential exploitation of the Seafloor Massive Sulphide by the mining industry. In this context, metallic element assays have been developed and are routinely carried out. However, most of these analyses are currently performed in laboratories after collection, transportation and storage of the samples. While providing accurate data, this methodology suffers from poor temporal and spatial resolution. Thus, there is a crucial need for the development of robust and sensitive field sensors. The aim of the SURIMI project is to develop multi-detection metallic element sensors capable of performing robust and sensitive analyses in settings ranging from a laboratory environment to the harshest conditions (e.g. deep ocean and/or polar seas). Two applications are concerned: 1. Pollution monitoring of Cd, Hg, Pb and Ni: one laboratory and one on-field system will be developed and industrially valorized by the SME Klearia. 2. Oceanographic studies on Ni, Cu, Zn, and Hg: one submarine system allowing for a rapid screening of these elements in the seawater will be developed and tested. The instruments will be capable of assaying four different metallic elements at the same time at concentration as low as nM every 5 min. To achieve these objectives, the consortium will be composed of seven partners: two industrial and commercial public establishments (Ifremer and BRGM), one SME (Klearia), four academic laboratories including two international CNRS joint units (Laboratory of Analytical and Bioanalytical Sciences and Miniaturization at ESCPI Paris and Laboratoire Charles Fabry at Institut d’Optique Graduate School, Laboratoire Nanotechnologies et Nanosystèmes and Takuvik respectively). The instruments will combine advanced robust and reliable technologies. They will consist in an Surface Plasmon Resonance Imaging (SPRI) transducer functionalized by new ion imprinted polymers (IIPs) specific to the target elements and integrate a microfluidic circuit. SPRI system is capable of detecting several target molecules and determining their concentration at the same time. Its specificity and sensitivity depend on the functionalization layer, whose aim is to specifically concentrate the target molecules on the surface of the chip. As molecularly imprinted polymers (MIPs), IIPs possess recognitions sites able to bind selectively a target. They are very stable to acids, bases and organic solvents and can withstand high temperature and high pressure, which makes them well adapted for harsh environment sensors. The instrument will integrate microfluidics for a high sensitivity and a low consumption of reagents. The circuit will be made in glass for a high chemical and thermal resists. When all these technologies will have been optimized and combined, the sensor characteristic will be rigorously established in laboratory and mesocosm facilities using natural samples collected in freshwater, deep ocean and the Artic environment. Finally, the systems will be deployed during technological and opportunity scientific campaigns. At the end of the project, the industrial valorization will be investigated by the SME Klearia, supported by the BRGM and Ifremer. A new product is expected to be commercialized at the end of the project.