A unique warm-water oasis in the Siberian Arctic's Chaun Bay sustained by hydrothermal groundwater discharge

Chaun Bay on the East Siberian Sea shelf hosts a unique warm-water, high-productivity ecosystem atypical for the Siberian Arctic. Using shipboard physical, biogeochemical and geological measurements (October 2020) and under-ice hydrological observations (April 2023), the study shows that warm-water biological communities are sustained by hydrothermal submarine groundwater discharge (SGD) supplying heat, salinity, nutrients, and trace elements. A cyclonic eddy mixes warm, nutrient-rich groundwater with oxygenated surface waters, creating a water mass resembling highly productive North Pacific and Southern Chukchi waters. Elevated chlorophyll-a and zooplankton were observed, with epibenthic abundance and diversity exceeding values elsewhere on the East Siberian Sea shelf. Benthic communities included boreal species uncommon for the Arctic Ocean, and persistent Thysanoessa krill populations were observed.

Alexander N. Charkin, Ksenia N. Kosobokova, Elizaveta A. Ershova, Vitaly L. Syomin, Glafira D. Kolbasova, Pavel Yu. Semkin, Andrey E. Leusov, Oleg V. Dudarev, Timofey A. Gulenko, Elena I. Yaroshchuk, Anatoly M. Startsev, Pavel A. Fayman, Vladislav A. Krasikov, Sergey A. Zverev, Elena A. Bessonova, Alexander S. Ulyantsev, Evgeny V. Elovsky, Daria A. Yurikova, Kirill A. Kobyakov, Olga L. Zimina, Alexandra V. Gerasimova, Peter P. Tishchenko, Alexander A. Didov