Make Our Planet Great Again Post doc to uncover ocean deoxygenation impacts on zooplankton and...

The Laboratoire d'Océanographie de Villefranche (LOV ; http://lov.obs-vlfr.fr/ ) is located close to Nice, on the French Riviera. It belongs to one of the three marine stations of Sorbonne Université. With about 90 permanent staff, the LOV generates and analyses a large quantity of marine data, including imaging, genomic, and satellite data to study the ocean.

The COMPLEx (COMPutational PLAnkton Ecology) team gathers ~30 members studying marine plankton by collecting data with quantitative imaging instruments and high throughput genomics that informs advanced numerical analysis methods (modeling, statistics, machine learning). Plankton encompasses all organisms roaming with marine currents. Those organisms are responsible for producing some of the oxygen we breathe, storing the carbon we emit, feeding the fish we eat; plankton is therefore a major building block of Earth’s ecosystem. COMPLEx strongly interacts with the Quantitative Imaging Platform of Villefranche (PIQv; https://sites.google.com/view/piqv ), which oversees the operation of the tools that the team develops. Those tools include imaging sensors, such as the Underwater Vision Profiler or the ZooScan, and software packages, such as ZooProcess or the EcoTaxa web application (https://ecotaxa.obs-vlfr.fr/ ) that uses machine learning to assist taxonomists into sorting plankton images. We also have a long experience in interacting with private companies for instruments development and computer scientists, in academia (e.g. LS2N in Nantes, I3S in Nice, ENSTA in Paris, MIP in Kiel) and the private sector (e.g. Google Brain lab in Paris).

Mission : The post-doc will be recruited by SU at the LOV to participate in the Make Our Planet Great Again project “Tropical Atlantic Deoxygenation: Gateway dynamics, ecosystem impacts and feedback mechanisms” (MOPGA-TAD) led by Dr. Rainer Kiko. This project has started in December 2019 and will continue until end of November 2024.

Activités principales : Ocean “deoxygenation disrupts marine ecosystems, affects fish stocks and aquaculture and leads to loss of habitat and biodiversity.” (Kiel Declaration; Oschlies et al. 2019). Ocean deoxygenation in the recent past was to a large extent caused by global warming, but residual effects might be linked to enhanced oxygen demand in deeper water layers. Ocean deoxygenation affects the highly dynamic upwelling ecosystems of the Eastern Tropical Atlantic (ETA). These ecosystems are regions of intense oceanic productivity and critical for food supply to millions of people. Ocean deoxygenation in these regions might continue due to increased stratification, feedbacks in plankton dynamics, increased respiratory demand and a slowing-down of oxygen supply via the equatorial current system. A sustained observation system for plankton and particle dynamics in the ETA and particularly at the equatorial gateway to the ETA was set up via the MOPGA-TAD project, activities of the TRIATLAS project and international partners. In particular, Underwater Vision Profiler data, but also Multinet sample data analyzed using the Zooscan-approach were obtained at high spatial and temporal resolution and this particle and zooplankton data are now available via the EcoTaxa (https://ecotaxa.obs-vlfr.fr ) and Ecopart (https://ecopart.obs-vlfr.fr/ ) platforms. These data collection efforts now enable us to elucidate how equatorial current dynamics and biological oxygen demand impact atmospheric carbon uptake, oxygen distribution and available habitat for fish in the ETA.

The post-doc will now have the chance to conduct a synoptic analysis of all gathered data using classic biological oceanographic techniques (transect analysis, lagrangian statistics), but also machine learning and/or biogeochemical model-data comparison approaches to assess plankton and particle impacts on the oxygen distribution in the tropical Atlantic. He/She will analyze how oxygen content and demand in the tropical Atlantic are driven by primary productivity, particle and plankton abundance and particle flux. The spatial and temporal analysis of all data will aim to elucidate feedback mechanisms between wind forcing, current dynamics, upwelling activity, plankton and particle dynamics on the oxygen content of the tropical Atlantic. To this end, machine learning approaches to generate gridded plankton and particle distribution data will be co-developed in our team. The resulting products will be used to estimate biogeochemical rates, also under future ocean conditions and to assess current biogeochemical models to better understand expected global change impacts on the carbon cycle and oxygen distribution of the tropical Atlantic upwelling systems.

The post-doc will work in close interaction with the marine ecologists and biogeochemists of the LOV in Villefranche-sur-mer, as well as with biological and physical oceanographers and biogeochemical model developers at the GEOMAR Helmholtz Center for Ocean Research Kiel. Further international collaborations will also be supported and the post-doc will benefit from our large network of collaborators in Europe and beyond.