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.
1. To synthesize the key biological findings of the SEEDS
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
D. Tsumune, Y. Watanabe, A. Shimamoto
Physical behavior of the iron-fertilized patch by SF6 tracer release
J. Nishioka, H. Obata, S. Takeda, K. Johnson, M. Wells, S. Nakatsuka,
Y. Kondo, S. Takada, Y. Sorin
Iron and trace metal chemistry
Session 2: Chair - S. Takeda
H. Saito, K. Suzuki, H. Kiyosawa, A. Tsuda
I. Kudo, T. Aramaki, W. Cochlan, Y. Noiri, T. Ono, and Y. Nojiri
Primary production, bacterial production and nitrogen assimilation
dynamics during SEEDS II
W. Cochlan, M. Wells, C. Trick
Complexity of grow-out experiments: further iron stimuration of communities
from an iron fertilized patch
Session 3: Chair - C. Trick
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
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
The SAGE Experiment: Why was there no bloom?
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)
Continue the group discussion
M. Fujii (M. Wells), N. Yoshie
Suggestions from modelers
Report from each breakout group
Synthesis and future plans
Contribution to IFEP/PICES
Listing of planed manuscripts
Meso- and microzooplankton dynamics in SEEDS II.
A. Tsuda, H. Saito and R. Machida
Dynamics of mass flux and particulate matter flux during SEEDS
T. Aramaki, Y. Nojiri, and K. Imai
Release of organic iron-binding ligands during grazing on phytoplankton
and its effect on phytoplankton community structure.
M. Sato, S. Takeda and K. Furuya
Complexation of iron (III) by natural organic ligands during SEEDS
Y. Kondo, S. Takeda, J. Nishioka and K. Furuya
Iron oxidation status during the SEEDS II mesoscale experiment
and its potential biological implications.
E. Roy, M. Wells, C. Trick and W. Cochlan
Trace gasses in the water.
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
K. Suzuki, H. Kiyosawa (cancelled)
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
Behavior of rare earth elements and 210Po-210Pb during the iron
Y. Hara, H. Obata, T. Doi, Y. Hongo, T. Gamo
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
Temporal variability of cosmogenic radionuclides 32P, 33P and 7Be
in SEEDS II
T. Nakanishi, T. Aono, M. Yamada and M. Kusakabe
Phosphorus dynamics during the SEEDS II
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.