Carbon flows through the microbial food web of first-year ice in Resolute Passage (Canadian High Arctic)

• Main Authors: Vezina, A. F., Demers, S., Laurion, I., Sime-Ngando, Télesphore, Juniper, S.K., Devine, L.
• Other Authors: Department of Fisheries and Oceans Canada, Maurice Lamontagne Institute, GREC and INRS-Océanologie, Université du Québec à Rimouski (UQAR), Département de biologie, Université Laval Québec (ULaval), Laboratoire Microorganismes : Génome et Environnement (LMGE), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université d'Auvergne - Clermont-Ferrand I (UdA)-Centre National de la Recherche Scientifique (CNRS), Département des Sciences Biologiques Montréal, Université du Québec à Montréal = University of Québec in Montréal (UQAM)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 1997
• Subjects: Carbon cycle; Trophic chain; Microbial activity; Sea ice; Trophic level; Modeling; Bloom; Organic carbon; Primary productivity; Algae; Zooflagellata; Ciliata; Northwest Territories; Arctic Region; Thallophyta; Protozoa; Canada; North America; America; Marine environment; Microorganism; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; Arctic; Resolute Passage; ice algae; Zooplankton
• Online Access: https://hal.science/hal-00528645

International audience Copyright (c) 1996 Elsevier Science B.V. All rights reserved. Ice algal communities are host to thriving populations of microheterotrophs whose trophic role remains poorly understood. We report here an inverse modelling analysis of the microbial food web associated with the spring bloom of ice algae at Resolute Passage in the High Arctic. Carbon flows among microbial components (ice algae, autotrophic and heterotrophic nanoflagellates, microflagellates and ciliates) and their exchanges with particulate and dissolved organic carbon (POC and DOC) were inferred from the observed changes in standing stocks of these compartments between 13 April and 22 May 1992. Calculations were made for three phases of the blooms development and for two sites under thin and thick snow cover. Observed DOC accumulations within the bottom ice originated largely from the ice algae. However, calculated production rates were too high to result strictly from normal physiological exudation. Mechanical or physiological stresses that disrupt the integrity of the cells and grazing by zooplankton at the ice−water interface may well be involved in this process. Inverse modelling confirmed field and experimental evidence that nanoflagellates may directly assimilate DOC to support their growth. Patterns in trophic flows between sites with thin and thick snow cover were similar. In contrast, trophic interactions changed as the bloom progressed: production of DOC and detritus from the ice algae were the only significant carbon flows during the early phase; bacterivory developed and peaked during the middle phase and was superseded by DOC utilization and herbivory by flagellates and ciliates during the late phase. Only ca. 20% of the DOC produced was utilized by the microheterotrophs. Direct links from DOC and ice algae to protists potentially increase the efficiency of C transfers within the ice-associated microbial food web; on the other hand, low recovery efficiency limits the role of the microbial loop in recycling DOC.