Tropical Atlantic Deoxygenation: gateway dynamics, feedback mechanisms and ecosystem impacts

The “Make Our Planet Great Again Project” “Tropical Atlantic Deoxygenation: gateway dynamics, feedback mechanisms and ecosystem impacts (TAD) started in 2019 to establish a sustained observation and modelling system for plankton and particle dynamics in the Eastern Tropical Atlantic. Also, in the last year of the project, many observational activities took place. MOPGA-TAD PostDoc Dr. Joelle Habib participated in the RV Meteor cruise M203, during which she could collect 81 plankton and particle profiles with an Underwater Vision Profiler 6. Another large UVP6 dataset (59 Profiles) was collected during the PIRATA FR34 cruise with RV Thalassa. Furthermore, replacements of the UVP6 LPs on the 23W, 0N and on the Cape Verde Ocean Observatory were prepared. These replacements were conducted during RV Meteor cruise M207 in early 2025. Focus in 2024 was again on the analyses of data from the very successful first four project years. In 2021, three BGC-Argo floats equipped with UVPs were deployed and later recovered again. Each float did collect about a year of data, one from a region south-west off South Africa, one from the upwelling region off Angola and one from the equator between 23°W and 7 °W. Dr. Joelle Habib finalized the analysis of the equatorial float and submitted the respective paper, (Habib et al. preprint, doi: 10.5194/egusphere-2024-3365), Dr. Dodji Soviadan (MOPGA fellowship holder) submitted the paper on the analysis of the Angola float (Soviadan et al. accepted, doi: 10.5194/egusphere-2024-3302) and Alexandre Accardio (MSc student stage 2) on the South African float (Accardo et al. 2025, doi: 10.5194/bg-22-1183-2025). Dr. Habib furthermore worked on the combined analyses of the TRATLEQ1 & 2 cruises and submitted an application to the Marie Sklodowska-Curie Action. The application was not successful, but she was invited to hand in a revised version. Dr. Kiko co-led the efforts to further homogenize UVP, Zooscan and Imaging Flow Cytobot data as part of the “Pelagic Size Structure database” project (www.pssdb.net). Further datasets were made publicly available in 2024, and two articles analyzing the data were submitted, with accompanying preprints already publicly available (Dugenne et al preprint, doi: 10.1101/2024.03.08.584097, Corrales-Dugalde et al. preprint, doi: 10.22541/essoar.173282346.66940641/v1). Finally, the closing seminar for theMOPGA-TAD project was held on the 1. Oct. 2024 with in total 12 presentations by MOPGA-TAD participants and collaborators. The seminar motivated efforts to finalize the publication of the MOPGA-TAD results and also highlighted the need for a better understanding of particle and plankton dynamics in the tropical Atlantic.