title: Short-term responses of unicellular planktonic eukaryotes to increases in temperature and UVB radiation.
abstract: BACKGROUND
  Small size eukaryotes play a fundamental role in the functioning of coastal ecosystems, however, the way in which these micro-organisms respond to combined effects of water temperature, UVB radiations (UVBR) and nutrient availability is still poorly investigated.
  
  
  RESULTS
  We coupled molecular tools (18S rRNA gene sequencing and fingerprinting) with microscope-based identification and counting to experimentally investigate the short-term responses of small eukaryotes (<6 μm; from a coastal Mediterranean lagoon) to a warming treatment (+3°C) and UVB radiation increases (+20%) at two different nutrient levels. Interestingly, the increase in temperature resulted in higher pigmented eukaryotes abundances and in community structure changes clearly illustrated by molecular analyses. For most of the phylogenetic groups, some rearrangements occurred at the OTUs level even when their relative proportion (microscope counting) did not change significantly. Temperature explained almost 20% of the total variance of the small eukaryote community structure (while UVB explained only 8.4%). However, complex cumulative effects were detected. Some antagonistic or non additive effects were detected between temperature and nutrients, especially for Dinophyceae and Cryptophyceae.
  
  
  CONCLUSIONS
  This multifactorial experiment highlights the potential impacts, over short time scales, of changing environmental factors on the structure of various functional groups like small primary producers, parasites and saprotrophs which, in response, can modify energy flow in the planktonic food webs.
authors.affiliation: INRA, UMR 42 CARRTEL, Thonon-les-bains, France. isabelle.domaizon@thonon.inra.fr
authors.forename: Isabelle
authors.initials: I
authors.lastname: Domaizon
authors.forename: Cécile
authors.initials: C
authors.lastname: Lepère
authors.forename: Didier
authors.initials: D
authors.lastname: Debroas
authors.forename: Marc
authors.initials: M
authors.lastname: Bouvy
authors.forename: Jean Francois
authors.initials: JF
authors.lastname: Ghiglione
authors.forename: Stephan
authors.initials: S
authors.lastname: Jacquet
authors.forename: Yvan
authors.initials: Y
authors.lastname: Bettarel
authors.forename: Corinne
authors.initials: C
authors.lastname: Bouvier
authors.forename: Jean Pascal
authors.initials: JP
authors.lastname: Torréton
authors.forename: Francesca
authors.initials: F
authors.lastname: Vidussi
authors.forename: Behzad
authors.initials: B
authors.lastname: Mostajir
authors.forename: Amy
authors.initials: A
authors.lastname: Kirkham
authors.forename: Emilie
authors.initials: E
authors.lastname: Lefloc'h
authors.forename: Eric
authors.initials: E
authors.lastname: Fouilland
authors.forename: Helene
authors.initials: H
authors.lastname: Montanié
authors.forename: Thierry
authors.initials: T
authors.lastname: Bouvier
mesh_terms: D044822:Biodiversity; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D056890:Eukaryota / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000528:radiation effects*; D019083:Mediterranean Region; D008853:Microscopy; D008969:Molecular Sequence Data; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012623:Seawater / Q000382:microbiology; D017422:Sequence Analysis, DNA; D013696:Temperature; D014466:Ultraviolet Rays
chemical_list: D004275:DNA, Ribosomal; D012337:RNA, Ribosomal, 18S