Marine Ecosystems Research Department - jamstec japan agency ...

Japan Marine Science and Technology Center
Frontier Observational Research System for Global Change
Sea Surface
Acoustic Transponder
McLANE Flotation Buoy
Bumper
CTD SBE-37
Current and CTD miter
Anderaa RCM-7
CTD SBE-16
McLANE CTD and current
profiler
Bumper
Sea Bottom
CTD SBE-37
Anderaa RCM-7
Double Release 8242SX
800 kilo Anchor weight
Fig.18 Sensor configuration of NABOS mooring system deployed in FY2002.
(II) Multi-Disciplinary Group
The Multi-Disciplinary Group mainly aims to clarify
the impact of bio-geochemical processes on climate and
environmental changes. In FY, seawater and bottom
sediment samples were collected taking advantages
of the cruises of the R/V Mirai, Hokkaido University's
training vessel Oshoromaru and UAF R/V Alpha Helix,
and biological and chemical analyses started. Analytical
items are concentrations of chlorophyll a (Chl a), nutrient
salts, lipid biomarkers and dissolved organic carbon/nitrogen,
their stable isotope ratios, and turbidity.
The analytical results obtained so far suggest that
ammonia-rich subsurface water, iron, organic phosphorus,
etc. are involved in the formation of coccoliths, but
the identification of the decisive factors will still
require further investigation. The intensity of coccolithophere
blooming is weakening in time and space.
Marine biological activity beneath ice is a unique
bio-geochemical process characterizing sea ice zones,
and its contribution to global warming is not yet wellknown.
Following polar dawn, regular observations of
bio-production (abundance of plankton), biomarkers,
dimethyl sulfide (DMS) and dimethylsulfoniopropionate
(DMSP) were made at Point Barrow. The measurement
of the opto-environmental condition including
solar radiation, observation of sea ice composition,
meteorological parameters, etc. were also carried out
in collaboration with other organizations. Although
the amount of chlorophyll, an indicator of bio-productivity
potential, dramatically increased by more than
times within about one month as observed last
year, it was followed by a rapid fall. A slight decrease
in sea ice thickness and presence of large-size zooplankton
were also observed this year. Since this phenomenon
seemed due to feeding pressure from zooplankton
and other organisms based on the
results, we tried to examine the zooplankton grazing
pressure. However, owing to the lack of professional
assistance, the zooplankton grazing pressure could not
be studied this year. This plan is to be executed in the
FY field activity. Throughout the observation
period, DMSP was observed at high levels, irrespective
of the abundance of chlorophyll. This fact indicates
that DMSP that has been generated beneath sea
ice is not easily transformed into DMS (Fig.).
To continue the observation of carbon exchange
169