SEEDS II Workshop

Second Iron Enrichment Experiment in the Western Subarctic Pacific

Background And Objectives
Main Themes
Provisional Agenda
Program (Oral, Posters)
Participants by Affiliations
Contact Person
October 17-18, 2005
Ocean Research Institute, The University of Tokyo, Tokyo, Japan
A. Tsuda, S. Takeda, M. Uematsu (Univ. of Tokyo) and M. Wells (Univ. of Maine)
Organized by:
Ocean Research Institute, The University of Tokyo
Sponsored by:
Ocean Research Institute
The University of Tokyo
North Pacific Marine Science Organization (PICES)

The subarctic North Pacific is one of the major High-Nitrate, Low-Chlorophyll open ocean regions. Three mesoscale iron-enrichment experiments have been performed in the western and the Alaska gyres (SEEDS, SEEDS II and SERIES) to test the iron-limitation hypothesis at ecosystem scales as part of the PICES-IFEP and SOLAS activities. SEEDS II was conduced in the same western subarctic Pacific region as the initial SEEDS experiment, and was an international collaborative study utilizing two research vessels (R.V. Hakuho Maru and R.V. Kilo Moana). This experiment was designed to characterize the evolution of the fertilized patch over a longer time scale (1 month) and with a greater range of parameters than measured during SEEDS.
The preliminary results from SEEDS II showed both the iron-induced increase and subsequent decline in phytoplankton biomass. However, the iron-initiated bloom was much less intense than observed in SEEDS. Chlorophyll-a concentrations increased only 2 to 3 times over initial values, and the drawdown of nutrients and pCO2 were small. The aim of the SEEDS-II Workshop is to provide a forum for exchanging scientific information and expertise to better understand the underlying cause for the dramatically different chemical and biological responses observed in these two mesoscale experiments.

MAIN THEMES (back to the top)
1. To synthesize the key biological findings of the SEEDS II
2. To elucidate the changes in iron biogeochemistry
3. To determine the effect of iron addition on the production of trace gases
4. To compare the biogeochemical changes associated with SEEDS I and SEEDS II


PROVISIONAL AGENDA (back to the top)

Monday, October 17th
  • Invited oral presentations summarizing key observations from SEEDS II and SEEDS I (30 min. each) followed by an afternoon poster session.

  • Establish the charges for breakout groups, select a Chair and rapporteur for each group, and begin discussions of the key aspects of the findings.
Tuesday, October 18th
  • Continue breakout group discussions in the morning followed with oral presentations by group Chairs and synthesis discussion by all participants.


PROGRAM (back to the top)
October 17th
9:30-9:50 A. Tsuda
Background and introduction of SEEDS II
  Session 1: Chair - K. Johnson
9:50-10:20 D. Tsumune, Y. Watanabe, A. Shimamoto
Physical behavior of the iron-fertilized patch by SF6 tracer release
10:20-10:50 J. Nishioka, H. Obata, S. Takeda, K. Johnson, M. Wells, S. Nakatsuka, Y. Kondo, S. Takada, Y. Sorin
Iron and trace metal chemistry
10:50-11:10 Coffee Break
  Session 2: Chair - S. Takeda
11:10-11:40 H. Saito, K. Suzuki, H. Kiyosawa, A. Tsuda
Biological responses
11:40-12:10 I. Kudo, T. Aramaki, W. Cochlan, Y. Noiri, T. Ono, and Y. Nojiri
Primary production, bacterial production and nitrogen assimilation dynamics during SEEDS II
12:10-12:40 W. Cochlan, M. Wells, C. Trick
Complexity of grow-out experiments: further iron stimuration of communities from an iron fertilized patch
12:40-14:00 Lunch
  Session 3: Chair - C. Trick
14:00-14:30 I. Nagao, S. Hashimoto, M. Uematsu
DMS in the seawater and atmosphere measured during the iron fertilization experiment (SEEDS-II) in the sub-arctic North Pacific
  M. Levasseur, M. Lizotte and G. Caron
The role of bacteria in modulating the impact of Fe on DMS production in HNLC waters
14:30-15:00 M. Uematsu, Y. Narita, Y. Iwamoto, M. Kondo, K. Yoshida, I. Nagao, S. Hashimoto, S. Toda, S. Kato, K. Kajii
Distribution of marine biogases and their fates between surface seawater and marine atmospheric boundary layer during the SEEDS II cruise in the northern North Pacific
15:00-15:30 J. Hall
The SAGE Experiment: Why was there no bloom?
15:30-16:30 Poster session
  Session 4: Chair - A. Tsuda

Establish the charges for breakout groups, select a Chair and rapporteur for each group, and begin discussions of the key aspects of the findings.

Groups and Chairs
1. Trace metal chemistry (S. Takeda)
2. Biological responses (H. Saito)
3. Gasses (M. Uematsu)

October 18th
9:30-11:30 Continue the group discussion
11:30-12:15 M. Fujii (M. Wells), N. Yoshie
Suggestions from modelers
12:15-13:45 Lunch
13:45-15:00 Report from each breakout group
15:00-15:20 Coffee break
15:20-17:00 Synthesis and future plans
Contribution to IFEP/PICES
Listing of planed manuscripts
International meetings

POSTERS (back to the top)
1 Meso- and microzooplankton dynamics in SEEDS II.
A. Tsuda, H. Saito and R. Machida
2 Dynamics of mass flux and particulate matter flux during SEEDS II
T. Aramaki, Y. Nojiri, and K. Imai
3 Release of organic iron-binding ligands during grazing on phytoplankton and its effect on phytoplankton community structure.
M. Sato, S. Takeda and K. Furuya
4 Complexation of iron (III) by natural organic ligands during SEEDS II.
Y. Kondo, S. Takeda, J. Nishioka and K. Furuya
5 Iron oxidation status during the SEEDS II mesoscale experiment and its potential biological implications.
E. Roy, M. Wells, C. Trick and W. Cochlan
6 Trace gasses in the water.
U. Tsunogai
7 Geochemistry of bioactive trace metals during an in-situ iron enrichement in the subarctic western North Pacific Gyre (SEEDS II).
S. Nakatsuka, J. Nishioka, M. Kinugasa, Y. Sorin
8 Phytoplankton dynamics.
K. Suzuki, H. Kiyosawa (cancelled)
9 Ammonium inhibition of nitrate uptake during mesoscale iron-enrichment experiments: A comparison of the planktonic response during SOFEX and SEEDS II.
W. Cochlan, J. Herndon, J. Betts, D. Costello, C. Trick and M. Wells
10 Behavior of rare earth elements and 210Po-210Pb during the iron fertilization experiment
Y. Hara, H. Obata, T. Doi, Y. Hongo, T. Gamo
11 Behavior of thorium and particles obtained by the multiple-unit large-volume in situ filtration system in SEEDS II.
T. Aono, T. Nakanishi, J. Zheng, M. Yamada and M. Kusakabe
12 Temporal variability of cosmogenic radionuclides 32P, 33P and 7Be in SEEDS II
T. Nakanishi, T. Aono, M. Yamada and M. Kusakabe
13 Phosphorus dynamics during the SEEDS II
T. Yoshimura
14 Effects of iron fertilization on the distribution of volatile organic compounds in seawater.
S. Toda, Y. Narita, H. Oda, Y. Akatsuka, T. Nagai, M. Kurihara, M. Uematsu,
S. Hashimoto

University of Tokyo Tsuda, A., Uematsu, M., Obata, H., Hara, Y., Doi, T., Hongo, Y., Gamo, T., Takeda, S., Sato, M., Kondo, Y., Furuya, K., Machida, R.
Institute of Ocean Sciences, Canada Johnson, K., Ianson, D.
CRIEPI Tsumune, D., Yoshimura, T.
Hokkaido Univ. Watanabe, Y., Suzuki, K., Kudo, I., Yoshie, N., Tsunogai, U., Nishioka, J.
KANSO Shimamoto, A.
University of Maine Wells, M., Fujii, M.
Kyoto University Nakatsuka, S., Sorin, Y., Kinugasa, M.
Tohoku National Fisheries Research Inst. Saito, H.
Marine Biological Research Institute of Japan Kiyosawa, H.
National Institute of Environmental Research Aramaki, T., Nojiri, Y.
Hokkaido National Fisheries Research Inst. Ono, T.
San Francisco State Univ. Cochlan, W., Henderson, J., Betts, J., Costello, D.
Univ. of West Ontario Trick, C.
Université Laval Lavasseur, M., Lizotte, M., Caron, G.
Nagoya Univ. Nagao, I.
Univ. of Shizuoka Hashimoto, S., Toda, S.
Tokyo Metropolitan Univ. Kato, S., Kajii, K.
NIWA New Zealand Hall, J.
National Institute of Radiological Sciences Aono, T., Nakanishi, T., Zheng, J., Yamada, M., Kusakabe, M.

CONTACT PERSON (back to the top)

For questions regarding the scientific program, abstract submission, registration and accommodation, please contact:

Dr. Atsushi Tsuda
Ocean Research Institute, The University of Tokyo
1-15-1 Minamidai, Nakano, Tokyo, Japan
Fax: +81-3-5351-6481
E-mail: tsuda@ori.u-tokyo.ac.jp

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