Linking extreme seasonality and gene expression in arctic marine protists

• Main Authors: Wutkowska, Magdalena, Vader, Anna, Logares, Ramiro, Pelletier, Eric, Gabrielsen, Tove
• Other Authors: The University Centre in Svalbard (UNIS), The Arctic University of Norway Tromsø, Norway (UiT), Institute of Marine Sciences / Institut de Ciències del Mar Barcelona (ICM), Consejo Superior de Investigaciones Cientificas España = Spanish National Research Council Spain (CSIC), Genoscope - Centre national de séquençage Evry (GENOSCOPE), Université Paris-Saclay-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Global Oceans Systems Ecology & Evolution - Tara Oceans (GOSEE), Université de Perpignan Via Domitia (UPVD)-École Pratique des Hautes Études (EPHE), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Aix Marseille Université (AMU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université d'Évry-Val-d'Essonne (UEVE)-Université de Toulon (UTLN)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 )-Institut de Recherche pour le Développement (IRD France-Nord )-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay)-European Molecular Biology Laboratory (EMBL)-NANTES UNIVERSITÉ - École Centrale de Nantes (Nantes Univ - ECN), Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Université australe du Chili, University of Agder (UIA)
• Format: Report
• Language: English
• Published: HAL CCSD 2021
• Subjects: metatranscriptomics; polar night; polar day; microbial eukaryotes; unicellular eukaryotes; time series; [SDV.EE]Life Sciences [q-bio]/Ecology; environment; [SDV.BIBS]Life Sciences [q-bio]/Quantitative Methods [q-bio.QM]; Arctic; Climate change; Svalbard
• Online Access: https://cea.hal.science/cea-03480606; https://doi.org/10.1101/2021.11.11.467955

At high latitudes, strong seasonal differences in light availability affect marine organisms and restrict the timing of ecosystem processes. Marine protists are key players in Arctic aquatic ecosystems, yet little is known about their ecological roles over yearly cycles. This is especially true for the dark polar night period, which up until recently was assumed to be devoid of biological activity. A 12 million transcripts catalogue was built from 0.45-10 μm protist assemblages sampled over 13 months in a time series station in an arctic fjord in Svalbard. Community gene expression was correlated with seasonality, with light as the main driving factor. Transcript diversity and evenness were higher during polar night compared to polar day. Light-dependent functions had higher relative expression during polar day, except phototransduction. 64% of the most expressed genes could not be functionally annotated, yet up to 78% were identified in arctic samples from Tara Oceans, suggesting that arctic marine assemblages are distinct from those from other oceans. Our study increases understanding of the links between extreme seasonality and biological processes in pico- and nanoplanktonic protists. Our results set the ground for future monitoring studies investigating the seasonal impact of climate change on the communities of microbial eukaryotes in the High Arctic.