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Combined effects of increased UV-B and temperature on the pigment-determined marine phytoplankton community of the St. Lawrence Estuary

2011; Inter-Research; Volume: 445; Linguagem: Inglês

10.3354/meps09484

1616-1599

Marie Lionard, Shovonlal Roy, M Tremblay-Létourneau, Gustavo Ferreyra,

Microbial Community Ecology and Physiology

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 445:219-234 (2012) - DOI: https://doi.org/10.3354/meps09484 Combined effects of increased UV-B and temperature on the pigment-determined marine phytoplankton community of the St. Lawrence Estuary M. Lionard1,2,*, S. Roy1, M. Tremblay-Létourneau1, G. A. Ferreyra1 1Institut des Sciences de la Mer de Rimouski (ISMER), Université du Québec à Rimouski, Rimouski, Québec G5L 3A1, Canada 2Present address: Département de Biologie, Pavillon Alexandre-Vachon, Université Laval, Québec, Québec G1V 0A6, Canada *Email: marie.lionard@bio.ulaval.ca ABSTRACT: The combined effects of increased UV-B and temperature on natural marine phytoplankton from the St. Lawrence Estuary (Canada) were examined in an 8 d mesocosm experiment carried out in Rimouski (Québec, Canada) in August 2008. We tested the hypothesis that increased temperature (+3°C) will offset algal growth suppression by UV-B (78% UV-B increase) using duplicate mesocosm experiments containing natural phytoplankton assemblages. The response of the entire phytoplankton community, in terms of HPLC pigment-based phytoplankton biomass, community composition (CHEMTAX), xanthophyll cycles photoprotection and quantum yield of photosystem II (the ratio of variable to maximum fluorescence: Fv/Fm), showed a significant influence of temperature (negative on small phytoplanktonic cells, <5 µm, and positive on larger diatoms) but only after the peak of the diatom bloom, when nutrients became limited. Interactions between temperature and UV-B treatments were significant only for small cells during post-bloom; UV-B induced an increase in phytoplankton biomass at the normal temperature but had no effect at warmer temperatures. Enhancing UV-B delayed the bloom slightly under the normal temperature and spread it over a longer period of time, with no sign of major cellular damage. Our results do not support the tested hypothesis, and they suggest that temperature plays a greater role than UV-B radiation in structuring phytoplankton communities, possibly favouring diatoms rather than small cells in a warmer climate scenario. Other effects such as grazing or coastal eutrophication should be considered in future studies. KEY WORDS: Mesocosm experiment · Ultraviolet-B radiation · Temperature · Phytoplankton · Global warming Full text in pdf format PreviousNextCite this article as: Lionard M, Roy S, Tremblay-Létourneau M, Ferreyra GA (2012) Combined effects of increased UV-B and temperature on the pigment-determined marine phytoplankton community of the St. Lawrence Estuary. Mar Ecol Prog Ser 445:219-234. https://doi.org/10.3354/meps09484 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 445. Online publication date: January 20, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.