Overview of the MOSAiC expedition: Ecosystem
Authors: Fong Allison A. , Hoppe Clara J. M. , Aberle Nicole , Ashjian Carin J. , Assmy Philipp , Bai Youcheng , Bakker Dorothee C. E. , Balmonte John P. , Barry Kevin R. , Bertilsson Stefan , Boulton William , Bowman Jeff , Bozzato Deborah , Bratbak Gunnar , Buck Moritz , Campbell Robert G. , Castellani Giulia , Chamberlain Emelia J. , Chen Jianfang , Chierici Melissa , Cornils Astrid , Creamean Jessie M. , Damm Ellen , Dethloff Klaus , Droste Elise S. , Ebenhöh Oliver , Eggers Sarah L. , Engel Anja , Flores Hauke , Fransson Agneta , Frickenhaus Stephan , Gardner Jessie , Gelfman Cecilia E. , Granskog Mats A. , Graeve Martin , Havermans Charlotte , Heuzé Céline , Hildebrandt Nicole , Hill Thomas C. J. , Hoppema Mario , Immerz Antonia , Jin Haiyan , Koch Boris P. , Kong Xianyu , Kraberg Alexandra , Lan Musheng , Lange Benjamin A. , Larsen Aud , Lebreton Benoit , Leu Eva , Loose Brice , Maslowski Wieslaw , Mavis Camille , Metfies Katja , Mock Thomas , Müller Oliver , Nicolaus Marcel , Niehoff Barbara , Nomura Daiki , Nöthig Eva-Maria , Oggier Marc , Oldenburg Ellen , Olsen Lasse Mork , Peeken Ilka , Perovich Donald K. , Popa Ovidiu , Rabe Benjamin , Ren Jian , Rex Markus , Rinke Annette , Rokitta Sebastian , Rost Björn , Sakinan Serdar , Salganik Evgenii , Schaafsma Fokje L. , Schäfer Hendrik , Schmidt Katrin , Shoemaker Katyanne M. , Shupe Matthew D. , Snoeijs-Leijonmalm Pauline , Stefels Jacqueline , Svenson Anders , Tao Ran , Torres-Valdés Sinhué , Torstensson Anders , Toseland Andrew , Ulfsbo Adam , Van Leeuwe Maria A. , Vortkamp Martina , Webb Alison L. , Zhuang Yanpei , Gradinger Rolf R. 
Published: August 2024

The international and interdisciplinary sea-ice drift expedition “The Multidisciplinary drifting Observatory for the Study of Arctic Climate” (MOSAiC) was conducted from October 2019 to September 2020. The aim of MOSAiC was to study the interconnected physical, chemical, and biological characteristics and processes from the atmosphere to the deep sea of the central Arctic system. The ecosystem team addressed current knowledge gaps and explored unknown biological properties over a complete seasonal cycle focusing on three major research areas: biodiversity, biogeochemical cycles, and linkages to the environment. In addition to the measurements of core properties along a complete seasonal cycle, dedicated projects covered specific processes and habitats, or organisms on higher taxonomic or temporal resolution in specific time windows. A wide range of sampling instruments and approaches, including sea-ice coring, lead sampling with pumps, rosette-based water sampling, plankton nets, remotely operated vehicles, and acoustic buoys, was applied to address the science objectives. Further, a broad range of process-related measurements to address, for example, productivity patterns, seasonal migrations, and diversity shifts, were made both in situ and onboard RV Polarstern. This article provides a detailed overview of the sampling approaches used to address the three main science objectives. It highlights the core sampling program and provides examples of habitat- or process-specific sampling. The initial results presented include high biological activities in wintertime and the discovery of biological hotspots in underexplored habitats. The unique interconnectivity of the coordinated sampling efforts also revealed insights into cross-disciplinary interactions like the impact of biota on Arctic cloud formation. This overview further presents both lessons learned from conducting such a demanding field campaign and an outlook on spin-off projects to be conducted over the next years.