"The overarching hypothesis of CAP-ICE is that in the present warming climate, UIBs are more prevalent and productive than open water blooms across the AO due to high pre-bloom nutrient concentrations beneath the sea-ice and increased light transmission through thin sea-ice and melt ponds. To test this hypothesis, the main objectives of the CAP-ICE project was to examine three specific objectives:
• Characterize the optimal environmental conditions controlling the initiation and magnitude of UIBs;
• Design a coupled satellite-derived sea-ice/biogeochemical model adapted to under-ice Arctic waters;
• Integrate the carbon contribution of UIBs to the marine Arctic carbon cycle.
Environmental conditions controlling UIBs. The researcher has proposed to write a review on the recent main changes in phytoplankton dynamics in the Arctic Ocean for Nature Climate Change. Such review is currently lacking for the Arctic scientific community and more broadly for scientists actively involved in the science of climate change. Based on our Arctic expertise and knowledge (with the host researcher, i.e. Kevin Arrigo), we gathered the latest breakthroughs in our field and our understanding of Arctic marine ecosystems in the context of rapid environmental change. This review brings together updated satellite-derived trends in Arctic primary production, new discoveries based on ""traditional"" expeditions and novel ""autonomous"" platforms. More importantly, by achieving this prospective, we attempt to outline the main scientific challenges that the community will have to tackle in the short- and long-term.
In a second paper (in Elementa), based on an international consortium, the fellow compiled a comprehensive dataset from a large number of Arctic Ocean expeditions to identify the environmental drivers responsible for initiating and shaping the magnitude and assemblage structure of UIBs. The main finding was that two main types of UIBs bloom were identified, dominated by either diatoms or the prymnesiophyte, Phaeocystis pouchetii. The implications of such dichotomy in UIBs could have important ramifications for Arctic biogeochemical cycles, and ultimately impact carbon flow to higher trophic levels and the deep ocean.
Satellite-derived sea-ice/biogeochemical model. Designing a coupled satellite-derived sea-ice/biogeochemical model adapted to under-ice Arctic waters is a complex task. This second objective was addressed in an article summarizing everything we know about UIBs and highlighting their impact on marine Arctic carbon cycle for a special issue of Frontiers in Marine Science. By running a unique simulation, we were able to determine the magnitude and extent of the UIBs in the past and present. During the period (1850-1900), UIBs were restricted at low latitude in the Arctic Ocean and only for one month. But today, during the period (2010-2014), UIBs occur for at least 3 months in summer and throughout the Arctic Ocean. Such findings suggest the relevance of these UIBs on Arctic biogeochemical cycles (and in particular the carbon cycle) and marine ecosystems (temporal asynchrony, species diversity, migrations) in the context of climate change.
New autonomous technologies in the Arctic Ocean. In the same article in Frontiers in Marine Science, the novelty of this work and its scope of application, also in line with the objective 3, is to gather all the information obtained by autonomous platforms. Not only BGC-Argo floats were discussed, but also other autonomous platforms (e.g. ITPs ""Ice-tethered profilers"", ROVs ""Remotely Operated Vehicle""). This initiative will be useful for the Arctic scientific community by showing the potential and the progress we can make in understanding under sea-ice phytoplankton dynamics using these new technologies.
At this end of the fellowship, the direct and indirect outcomes of the MSCA Fellowship are, four peer reviewed articles as first author (in Nature Climate Change, Nature Communications, Frontiers in Marine Science and Elementa: Science of the Anthropocene), 7 peer reviewed articles as co-authors (in Cell, Nature Communications, Frontiers in Marine Science, Global Biogeochemical Cycles, Journal of Geophysical Research: Oceans, Scientific Report and Deep-Sea Research Pt. II), and finally 1 peer reviewed article on disseminating data (in Earth System Science Data)."
