France The MicroCO2sm Project: Real-time experiment to assess the combined effects of plastic pollution, global warming and ocean acidification on the native flat oyster and raise citizen awareness

Co-leaders: Carole Di Poi (Ifremer – UMR LEMAR), Arnaud Huvet (Ifremer – UMR LEMAR), Emilien Pousse (postdoc Ifremer – UMR LEMAR), Ika Paul-Pont (CNRS – UMR LEMAR)

Collaborators: UMR LEMAR, Nicolas Desroy (Ifremer LER BN), Isabelle Arzul et Cyrielle Lecadet (Ifremer ASIM), Jean-Louis Gonzalez (Ifremer LER PAC), Camille Detrée et Gerardo Zardi (UMR BOREA), Massimo Milan (University of Padova, Italy)

Funders: Evertas, Région Bretagne, Ifremer

MicroCO2sm lies at the heart of the triple planetary crisis that is threatening the health of marine ecosystems and that of humankind: pollution, climate change and biodiversity loss. Until now, plastic pollution and climate change have been studied as two separate issues although they are fundamentally linked and may dangerously affect marine ecosystems over the next decades. In this project, we present an alternative view and study the vulnerability of the native flat oyster Ostrea edulis to plastic pollution combined with ocean warming and acidification over a whole life cycle. This species has been chosen because it is an emblem of the erosion of the native marine biodiversity in Europe. Although numerous research programmes in the NORA network are striving to restore, or reintroduce, this species into several ecosystems, we wonder whether the flat oyster will be able to cope with the global threats to our oceans.

Twelve oyster reefs, naturally parasited, were installed in re-circulated mesocosms (250 L) and exposed to an increase in seawater temperature (+2°C), a decrease in pH (-0.32 pH unit) and the addition of microplastics (concentration x 50) as a single or combined factor exposure and based on end-of-century scenarios (SSP3-7.0) using regional projections. For one year, high-throughput tools (e.g. -omics, live-cell imaging, ecophysiology) are used to assess the effects of the environmental stressors at individual and population levels, eventually through the next generation, while the evolution of the biodiversity functional traits, richness and abundance in each scenario will be analysed using multivariate and trajectory analyses.

The other original aspect of MicroCO2sm is that the experiment is taking place in Oceanolab, a new space designed by the Océanopolis Aquarium and science centre and the University of Western Brittany. Oceanolab is a new space where the citizens can see “science in the making”. Visits and communication tools inform visitors about the experiment in progress, and discussions take place with the scientists in residence to inform them about the challenges facing the oceans and raise awareness on the flat oyster decline, climate change and plastic pollution. This unique “win-win” initiative enables robust scientific knowledge to be produced and transferred directly to society.