FN Archimer Export Format PT J TI Effects of experimental warming on small phytoplankton, bacteria and viruses in autumn in the Mediterranean coastal Thau Lagoon BT AF Courboulès, Justine Vidussi, Francesca Soulié, Tanguy Mas, Sébastien Pecqueur, David Mostajir, Behzad AS 1:1;2:1;3:1;4:2;5:3;6:1; FF 1:;2:;3:;4:;5:;6:; C1 MARBEC (Marine Biodiversity, Exploitation and Conservation), Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France MEDIMEER (Mediterranean Platform for Marine Ecosystems Experimental Research), OSU OREME, CNRS, Univ Montpellier, IRD, IRSTEA, Sète, France BioPIC Platform (Biology Platform of Imaging and Flow Cytometry) FR3724, Observatoire Océanologique de Banyuls-Sur-Mer Laboratoire Arago - SU/CNRS, Banyuls-sur-mer, France C2 UNIV MONTPELLIER, FRANCE CNRS, FRANCE CNRS, FRANCE UM MARBEC IN WOS Cotutelle UMR copubli-france IF 2.218 TC 16 UR https://archimer.ifremer.fr/doc/00688/79979/82933.pdf LA English DT Article DE ;Pico;and nanophytoplankton;Bacterioplankton;Virus;Warming;In situ mesocosm;Thau lagoon AB To investigate the responses of a natural microbial plankton community of coastal Mediterranean waters to warming, which are still poorly known, an in situ mesocosm experiment was carried out in Thau Lagoon during autumn 2018. Several microorganisms, including virio-, bacterio-, and phytoplankton < 10 µm in size, were monitored daily and analysed using flow cytometry for 19 consecutive days in six mesocosms. Three mesocosms (control) had the same natural water temperature as the lagoon, and the other three were warmed by + 3 °C in relation to the control temperature. The cytometric analyses revealed an unexpected community dominated by picophytoplanktonic cells, including Prochlorococcus-like and Picochlorum-like cells, which had not previously been found in Thau Lagoon. The experimental warming treatment increased the abundances of nanophytoplankton, cyanobacteria, bacteria and viruses during the experiment and triggered earlier blooms of cyanobacteria and picoeukaryotes. Only the abundance of Picochlorum-like cells was significantly reduced under warmer conditions. The growth and grazing rates of phytoplankton and bacterioplankton estimated on days 2 and 8 showed that warming enhanced the growth rates of most phytoplankton groups, while it reduced those of bacteria. Surprisingly, warming decreased grazing on phytoplankton and bacteria at the beginning of the experiment, while during the middle of the experiment it decreased the grazing on prokaryote only but increased it for eukaryotes. These results reveal that warming affected the Thau Lagoon plankton community from viruses to nanophytoplankton in fall, inducing changes in both dynamics and metabolic rates. PY 2021 PD JUL SO Aquatic Ecology SN 1386-2588 PU Springer Science and Business Media LLC VL 55 IS 2 UT 000633749000001 BP 647 EP 666 DI 10.1007/s10452-021-09852-7 ID 79979 ER EF