The first results from the HOPE buoy are in... and show us that carbon sequestration by the tropical ocean is a highly dynamic process!
Thanks to unprecedented hourly sampling, the HOPE buoy is revealing unsuspected variability within the marine ecosystem. In the space of just a few hours, the quantity of plankton at the surface - the micro-organisms that fix CO₂ - can be multiplied by 4, leading to major variations in the quality and quantity of marine snow (the carbon-rich particles that sink to the depths), modulating on a daily scale the quantity of carbon trapped in the depths...
The adventure is just beginning, and the HOPE buoy, elegantly operated by Jordan Duchêne-Candidopromises to provide us with invaluable knowledge to help us better understand the highly complex process of the biological carbon pump in these fine dynamics, which are still largely unknown.
Objective To better understand, model and predict the biological carbon pump, a key process in climate regulation.
In the tropical ocean, diazotrophs play a major role, particularly in the austral summer (November-April), when these organisms generate majestic blooms and act as a natural fertiliser, boosting the food chain and the carbon pump.
Latest surprise Spectacular blooms of Trichodesmium, a tropical diazotroph, observed in the middle of the austral winter, around the HOPE buoy... Rare events in winter, probably linked to a long-lasting marine heat wave in New Caledonia (see Mercator Ocean map)*. This phenomenon could have a major impact on the offshore marine ecosystem, which we are trying to determine in partnership with the PPR maHeWa projectco-piloted by Sophie Cravatte.
This efflorescence has enabled us to launch laboratory experiments with doctoral students. Ambroise Delisée, Matthieu Savarino and our microbiologist colleague Mercedes Camps to study how these organisms form marine snow, how quickly it sinks and how quickly it is recycled, in order to assess how much of the carbon from these organisms is stored permanently on the ocean floor.
A history of scienceof collaboration, and of oceans in transformation.
More in the next issue...
*Mercator Ocean, Copernicus Marine Service, in partnership with the maHeWa project, forecasts marine heat waves on a global scale and, as part of maHeWa, provides NC "zooms", analysing the current situation and making forecasts: https://lnkd.in/gFT-TvXM
