standardization of environmental data and information - International ...

Presumably oxygen, CO2, salinity and nutrient samples will be obtained from
all or most of these depths. Samples for particulate organic carbon (POC)
and particulate organic nitrogen (PON) are obtained from each bottle
following JGOFS protocols, based on filtration of water samples onto GF/F
(glass-fibre) filters and analysis with the CEC (Control Equipment
Corporation) 240-XA elemental analyser 11 .
2.4. Microbiology
Bacterial abundance, biomass and productivity should be measured
at all standard depths. The standard method for assessment of microbial
biomass and abundance is based on counts of bacterial numbers from
samples fixed in glutaraldehyde, stored in the dark at 4 degrees Celsius,
filtered onto a 0.2-micron Irgalan Black stained Nuclepore polycarbonate
filter, stained with acridine orange or DAPI and examined under an
epifluorescence microscope 12 . Counts must be made within several days of
fixation. The estimated volume of randomly selected bacteria and use of
carbon/volume estimates provides an estimate of bacterial biomass 13 .
Microbial productivity is assessed from measurements of the incorporation
of tritiated methyl thymidine 14 .
2.5. Phytoplankton
Phytoplankton biomass is assessed based on measurement of
chlorophyll a and phaeopigments by fluorometric analysis. 15 Community
composition is assessed both from high-performance liquid chromatography
(HPLC) analysis of algal pigments and cell counts, using the samples and
procedures as per bacterial cell counts based on epifluorescent
microscopy 16 . Biovolumes are based on measurements of a sub-sample of
different phytoplankton cell types and estimates of the third dimension 17 .
Sampling is carried out at standard depths within the pelagic zone: 0, 25,
50, 75, 100 m, chlorophyll maximum, 150, 200 m. Phytoplankton
productivity is assessed based on the incorporation into organic matter of
inorganic radioactive C-14, following 12-hour incubations under as realistic
light conditions as possible 18 . New production, relative to primary
production based on recycled nitrogen, should be measured based on the
incorporation of NO3 labelled with N-15 into phytoplankton during
incubation experiments, similar to the incorporation of C-14 19 . New
production may prove an important parameter, if there is significant flux of
deepwater into the euphotic zone.
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