Nanoflagellate diversity during the iron fertilization experiment LOHAFEX
S. Thiele
1, C. Wolf
2, I. Schulz
2, B. Fuchs
1, K. Metfies
2, P. Assmy
3, R. Amann
11
Department of Molecular Ecology, Max Planck Institut für Marine Mikrobiologie, Bremen, Germany
2
Research Group Bioscience, Alfred Wegener Institut, Bremerhaven, Germany
3
Department of Biological Oceanography, Norwegian Polar Institute, Tromsø, Norway
Results
Background
• Iron fertilization in iron limited but nutrient rich areas leads to phytoplankton blooms.
• During LOHAFEX, an iron fertilization experimtent in the Southern Atlantik, a phytoplankton bloom of mainly nanoflagellates (NF) was induced.
• The bacterial community within the bloom was top-down controlled by heterotrophic nanoflagellates.
• Autotrophic nanoflagellates play a role as primary producer in marine systems, whereas heterotrophic nanoflagellates (HNF) graze upon Bacteria and Archaea of a size range between 1 µm and 3 µm. Mixotrophic organisms are phototrophic and ingest bacterial prey at the same time.
Diversity using 454 Pyrosequencing
Acknowledgement: Prof. Dr. V. Smetacek Prof., Dr. W. Naqui References: Simon et al., 2000; Massana et al., 2002, 2006; Pernthaler et al., 2002; Not et al., 2004; Eller et al., 2007,
Conclusions
•Higher nanoflagellate abundances at 40 m depth compared to 20 m depth.
• Increase of Micromonas, an autotrophic prasinophyte, after the second iron fertilization (day 18) at day 22, followed by a decrease in abundance due to predation.
•Remarkably stable community, pointing towards overall top-down control by heterotrohphic predators, e.g. dinoflagellates.
t [days]
0 10 20 30 40
cells ml-1
0,0 5,0e+3 1,0e+4 1,5e+4
2,0e+4 IN 20m OUT 20m IN 40m OUT 40m
t [days]
0 10 20 30 40
cells ml-1
0,0 2,0e+3 4,0e+3 6,0e+3 8,0e+3
1,0e+4 IN 20m OUT 20m IN 40m OUT 40m
Nanoflagellate abundances using CARD FISH
Total cellnumbers Prasinophyceae
Eukaryota Pelagophyceae
t [days]
0 10 20 30 40
cells ml-1
0,0 1,0e+3 2,0e+3 3,0e+3 4,0e+3
5,0e+3 IN 20m OUT 20m IN 40m OUT 40m
t [days]
0 10 20 30 40
cells ml-1
0,0 1,0e+3 2,0e+3 3,0e+3 4,0e+3
5,0e+3 IN 20m OUT 20m IN 40m OUT 40m
t [days]
0 10 20 30 40
cells ml-1
0,0 1,0e+3 2,0e+3 3,0e+3 4,0e+3
5,0e+3 IN 20mOUT 20m IN 40m OUT 40m
Prymnesiophyceae MicromonasPhaeocystis
t [days]
0 10 20 30 40
cells ml-1
0,0 1,0e+3 2,0e+3 3,0e+3 4,0e+3
5,0e+3 IN 20m OUT 20m IN 40m OUT 40m
t [days]
0 10 20 30 40
cells ml-1
0,0 1,0e+3 2,0e+3 3,0e+3 4,0e+3
5,0e+3 IN 20m OUT 20m IN 40m OUT 40m
T o t a l c e l l n u m b e r s a n d a b u n d a n c e s o f nanoflagellate clades inside (IN) and out of the fertilized patch (OUT). Shown are Prasinophytes w i t h t h e s u b g r o u p M i c r o m o n a s ( g r e e e n ) , Prymnesiophytes with the subgroup Phaeocystis (blue) and the different Straminopiles Pelagophytes (red) and members of the Marine Straminopiles (MAST) clades 1, 3 and 4. For later ones the sum of the clades MAST 1A, 1B, 1C, 3 and 4 is shown since single values are at the detection limit. Please note the different scales for Total cell numbers, Eukaryotes, different groups and the MAST clades.
MAST clades1, 3 & 4
t [days]
0 10 20 30 40
cells ml-1
0,0 1,0e+2 2,0e+2 3,0e+2 4,0e+2
5,0e+2 IN 20m OUT 20m IN 40m OUT 40m DAPI + EUK516
EUK516
MAST 1C MICRO1
PELA02
PHAE03 PRAS04
PRYM02
