158
describe the general taxonomic composition of the phytoplankton in different oceanic regions.
By correcting for the system response, and reabsorption of fluoresced light we have extended this technique to studies
of primary production and photbadaptation.
II. MATERIAL AND METHODS
A.
Sample preparation
Samples from both the field and lab were filtered onto Whatman GF/C
filters with low vacuum pressure «5mm.Hg.). Field samples were collected with Niskin bottles on a rosette containing a CTD package. For laboratory analyses described here, cultures of Duna1ie11a tertio1ecta were
grown in f/2 enriched sterile se"awater under continuous illumination
from cool white fluorescent lamps.
Samples were kept dark and refrigerated before analysis of fluorescence spectra, which was done as soon as
possible after filtration.
Prior to absorption spectra analysis, the
filters were moistened with filtered seawater to ensure saturation, since
the optical density of the filter varied with the degree of saturation.
Storage of the samples at -20 C. prior to measurement of absorption can
be done with no apparent effect, however samples should not be frozen
prior to fluorescence analysis because a loss of energy transfer from
accessory pigments to chlorophyll ~ is apparent. Nevertheless, the
losses due to freezing are comparable for different samples so that qualitative comparisons of spectral shapes can still be used to obtain information about photoadaptation (Neori etal. 1982).
B.
Instrumentation
For measurements of particle absorption, a vertical light path sample
compartment (Butler,1962) , specifically described by Kiefer and SooHoo
(1982) is used. The components include a Bausch and Lomb high intensity
monochromator (33-86-76) coupled to a Bausch and Lomb 45 watt tungstenhalide light source. The optical density for the sample, ODS (A) , is calculated from measurements of the light intensities transmitted by a sample filter, ES(A), and a blank filter EB(A). Measurements are made with
a Gamma 20-20-10 photomultiplier and 2900 autophotometer. The photometer
is interfaced, after amplification, to a Digital Equipment Corporation
PDP 1103 with which the analog data is digitized, averaged, smoothed,
and processed.
For fluorescence excitation sp"ectra, the mirror which reflects the
monochromatic beam onto the sample is replaced with a long wavelength
transmitting dichroic fi1ter(OCLI CSF-A) that reflects the excitation
beam onto the sample while allowing the chlorophyll a fluorescence to
describe the general taxonomic composition of the phytoplankton in different oceanic regions.
By correcting for the system response, and reabsorption of fluoresced light we have extended this technique to studies
of primary production and photbadaptation.
II. MATERIAL AND METHODS
A.
Sample preparation
Samples from both the field and lab were filtered onto Whatman GF/C
filters with low vacuum pressure «5mm.Hg.). Field samples were collected with Niskin bottles on a rosette containing a CTD package. For laboratory analyses described here, cultures of Duna1ie11a tertio1ecta were
grown in f/2 enriched sterile se"awater under continuous illumination
from cool white fluorescent lamps.
Samples were kept dark and refrigerated before analysis of fluorescence spectra, which was done as soon as
possible after filtration.
Prior to absorption spectra analysis, the
filters were moistened with filtered seawater to ensure saturation, since
the optical density of the filter varied with the degree of saturation.
Storage of the samples at -20 C. prior to measurement of absorption can
be done with no apparent effect, however samples should not be frozen
prior to fluorescence analysis because a loss of energy transfer from
accessory pigments to chlorophyll ~ is apparent. Nevertheless, the
losses due to freezing are comparable for different samples so that qualitative comparisons of spectral shapes can still be used to obtain information about photoadaptation (Neori etal. 1982).
B.
Instrumentation
For measurements of particle absorption, a vertical light path sample
compartment (Butler,1962) , specifically described by Kiefer and SooHoo
(1982) is used. The components include a Bausch and Lomb high intensity
monochromator (33-86-76) coupled to a Bausch and Lomb 45 watt tungstenhalide light source. The optical density for the sample, ODS (A) , is calculated from measurements of the light intensities transmitted by a sample filter, ES(A), and a blank filter EB(A). Measurements are made with
a Gamma 20-20-10 photomultiplier and 2900 autophotometer. The photometer
is interfaced, after amplification, to a Digital Equipment Corporation
PDP 1103 with which the analog data is digitized, averaged, smoothed,
and processed.
For fluorescence excitation sp"ectra, the mirror which reflects the
monochromatic beam onto the sample is replaced with a long wavelength
transmitting dichroic fi1ter(OCLI CSF-A) that reflects the excitation
beam onto the sample while allowing the chlorophyll a fluorescence to