Stable composition of the nano- and picoplankton community during the ocean iron fertilization experiment LOHAFEX.
The iron fertilization experiment LOHAFEX was conducted in a cold-core eddy in the Southern Atlantic Ocean during austral summer. Within a few days after fertilization, a phytoplankton bloom developed dominated by nano- and picoplankton groups. Unlike previously reported for other iron fertilization experiments, a diatom bloom was prevented by iron and silicate co-limitation. We used 18S rRNA gene tag pyrosequencing to investigate the diversity of these morphologically similar cell types within the nano- and picoplankton and microscopically enumerated dominant clades after catalyzed reported deposition fluorescence in situ hybridization (CARD-FISH) with specific oligonucleotide probes. In addition to Phaeocystis, members of Syndiniales group II, clade 10-11, and the Micromonas clades ABC and E made up a major fraction of the tag sequences of the nano- and picoplankton community within the fertilized patch. However, the same clades were also dominant before the bloom and outside the fertilized patch. Furthermore, only little changes in diversity could be observed over the course of the experiment. These results were corroborated by CARD-FISH analysis which confirmed the presence of a stable nano- and picoplankton community dominated by Phaeocystis and Micromonas during the entire course of the experiment. Interestingly, although Syndiniales dominated the tag sequences, they could hardly be detected by CARD-FISH, possibly due to the intracellular parasitic life style of this clade. The remarkable stability of the nano- and picoplankton community points to a tight coupling of the different trophic levels within the microbial food web during LOHAFEX.
Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany.
Stefan
S
Thiele
Department of Polar Biological Oceanography, Division of Bioscience, Alfred Wegener Institute - Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany.
Christian
C
Wolf
Department of Polar Biological Oceanography, Division of Bioscience, Alfred Wegener Institute - Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany; Bremen International Graduate School for Marine Sciences (GLOMAR), MARUM - Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany.
Isabelle Katharina
IK
Schulz
Center for Ice, Climate and Ecosystems (ICE), Norwegian Polar Institute, Fram Centre, Tromsø, Norway.
Philipp
P
Assmy
Department of Polar Biological Oceanography, Division of Bioscience, Alfred Wegener Institute - Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany.
Katja
K
Metfies
Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany.
Bernhard M
BM
Fuchs
D044822:Biodiversity; D056890:Eukaryota / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D017404:In Situ Hybridization, Fluorescence; D007501:Iron / Q000378:metabolism*; D009792:Oceans and Seas; D010839:Phytoplankton / Q000145:classification / Q000254:growth & development*; D012335:RNA, Ribosomal / Q000235:genetics*
D012335:RNA, Ribosomal; D007501:Iron