ISOtopes of Metal Elements for Tracing marine METabolism – ISO2MET

SO2MET focuses on three trace metals particularly used in industrial applications and with high potential in marine ecotoxicology: zinc, copper and lithium. At the biochemical and cellular level, we quantify and model the biological isotopic fractionations induced by the key transporters of these metals. At the level of the organism, we measure with high precision the isotopes of these metals in samples of plankton and marine trophic chains evolving in contrasting environments or in aquacultures. Finally, we explore the potential of marine carbonates as a new isotopic proxy in ecotoxicology.

Beyond the developments made, the first significant results of the ISO2MET project are the first detailed description of the behavior of lithium and its isotopes at the cellular level, in plankton and marine trophic chains. By combining laboratory cultures and analyzes of organisms taken from the natural environment, ISO2MET highlights the strong bioaccumulation of lithium in bivalves such as mussels and oysters, with potential impacts on human health in contaminated coastal areas where their consumption is significant.
These results are reported into several scientific publications, two of which are effective, and one is currently being revised. They have also been shown at science festivals and international conferences, and lead to the establishment of new collaborations with oceanographers, teams working on water quality, and a college (SVT class).

The project continues to advance on the impact of these metals on marine organisms, with new cultures of bivalves, and special attention to how shells register contaminations. ISO2MET also aims to establish a comparative monitoring of plankton in areas that differ greatly in terms of anthropogenic inputs.

An article was published in the journal Science of the Total Environment, and we recently submitted another to the journal Environmental Science & Techonology. With our Korean collaborators, an article was published in the journal Nature Communications. Various oral and written communications were made, in particular at the Goldschmidt Conference (USA), and at the days of Sustainable Development in Nice-Sophia.

Trace metals play key roles in the metabolic cycles of marine organisms. Metal enrichment in polluted areas may also be responsible for reproductive anomalies and ecological disturbance since the onset of the industrial era. Despite recent advances in ecotoxicology and in molecular biology, the relationships between the concentrations of trace metals and marine biomass or biodiversity remain uncertain.
Members of ISO2MET consortium have evidenced that trace metals are isotopically fractionated in biological organisms. They recently discovered that this is due in a large part to the action of specific ion transporters that can be measured with a great accuracy. This offers a novel and unique approach to trace the mechanisms of accumulation, elimination and/or toxicity of trace metals in marine organisms.
ISO2MET will target three trace metals with intensive industrial application and high potential in marine ecotoxicology: zinc, copper, lithium. At the biochemical and cellular levels, we will quantify and model biological isotope fractionation performed by the major transporters of these metals, using state-of-the-art ion transport and electrophysiology techniques. At the organism level, we will perform high sensitivity isotopic measurements both on natural samples of plankton, plankton eaters and sediments collected in contrasted environments, and on laboratory aquacultures in controlled conditions. We will also explore bivalve shells and coral skeletons as new proxies in isotopic ecotoxicology.
To achieve this work, several internationally recognized laboratories decided to merge their resources and their competences. Thus, ISO2MET consortium is composed of physiologists and ecotoxicologists (LIENSs, IAEA-REL), experts in trace metal regulation by marine species, biochemists (LP2M), specialists of metal transfer in animal cells, geochemists (LOV, LGLTPE), specialized in non-conventional isotopes in the environment, and ecologists of marine plankton and trophic transfer (LOV, LIENSs). Owing to this innovative combination, the expectation is to provide a quantum leap improvement in our understanding of the link between metal levels and marine life evolution.