Structure and Functioning of Plankton Communities of Phototrophic and Mixotrophic Protists in the Coastal Lagoon “Lake Kislo-Sladkoe” (White Sea, Karelian Coast)

• Main Authors: A. O. Plotnikov, E. A. Selivanova, Yu. A. Khlopko, D. A. Voronov, D. N. Matorin, D. A. Todorenko, E. D. Krasnova, А. О. Плотников, Е. А. Селиванова, Ю. А. Хлопко, Д. А. Воронов, Д. Н. Маторин, Д. А. Тодоренко, Е. Д. Краснова
• Other Authors: The work was carried out under the state budget theme “Diversity, structure and functioning of marine and coastal ecosystems” (CITIS no. 121032500077-8) and Development program of Moscow State University “The future of the planet and global environmental changes.”, Исследование выполнено в рамках государственной темы “Разнообразие, структура и функционирование морских и прибрежных экосистем” (номер ЦИТИС: 121032500077-8), Программы развития МГУ имени М.В. Ломоносова “Будущее планеты и глобальные изменения окружающей среды”.
• Format: Article in Journal/Newspaper
• Language: Russian
• Published: Izvestiya Rossiiskoi Akademii Nauk. Seriya Geograficheskaya 2023
• Subjects: высокопроизводительное секвенирование; coastal meromictic lakes; separating water bodies; phototrophic protists; phytoplankton; chlorophyll fluorescence; DNA metabarcoding; high-throughput sequencing; прибрежные меромиктические водоемы; отделяющиеся водоемы; фототрофные протисты; фитопланктон; флуоресценция хлорофилла; ДНК метабаркодинг; Arctic; Lagoon Lake; White Sea; karelian; Phytoplankton; Белое море
• Online Access: https://izvestia.igras.ru/jour/article/view/1672; https://doi.org/10.31857/S2587556622060127

For the first time the taxonomic composition and vertical structure of phototrophic protist (PhP) communities were determined in a meromictic water body of the Russian coast of the Arctic, namely a lagoon Lake Kislo-Sladkoe, using DNA metabarcoding. Temperature, salinity, oxygen concentration, pH, Eh, illumination, and functional parameters of chlorophyll fluorescence were measured at different depths. 140 operational taxonomic units of PhP belonging to major taxa Dinoflagellata, Chlorophyta, Cryptophyta, Haptophyta, Ochrophyta, Cercozoa were identified. PP predominated over heterotrophic protists at depths of 0– 1.0 and 2.5–3.5 m reaching a maximum in the chemocline, especially in the 3.0 m horizon, above the redox transition. The taxonomic composition of the PhP in different layers differed according to the hydrological and hydrochemical stratification. In addition to abiotic factors, the composition and distribution of PP was influenced by predatory protists such as the cercozoan flagellate Ebria tripartita and the dinoflagellate Oxyrrhis marina, which significantly reduced the abundance of PhP while their mass distribution. Five layers were identified with different sets of dominant PhP. The surface 0−0.5 m layer of freshened water was featured the dominance of cryptophytes Teleaulax sp. and Hemiselmis cryptochromatica. The photosynthesis activity here was lower compared to the underlying layers that may be determined by photoinhibition. In the 1.0–2.0 m layer of seawater below the pycnocline Chlorophyta dominated, which are typical for picoplankton of the northern seas, as well as representatives of Cryptophyta, Haptophyta, Pedinellida, and diatoms. The PhP community at the lower boundary of the oxycline (2.5 m) had a specific structure with the mass development of the mixotrophic dinoflagellate Heterocapsa rotundata, for which the most favorable conditions were formed here facilitating the transition from photosynthesis to phagotrophic consumption of bacteria. In the chemocline, a maximum of chlorophyll ...