The data in this report were collected during cruises
9501* and 9504 of the California Cooperative Oceanic Fisheries
Investigations (CalCOFI) program aboard the NOAA ship RV David
Starr Jordan and RV New Horizon of Scripps Institution
of Oceanography, University of California, San Diego. The CalCOFI
program was organized in the late 1940's to study the causes of
variations in population size of fishes of importance to the State
of California. It is carried out by NOAA's National Marine Fisheries
Service Southwest Fisheries Science Center, the California Department
of Fish and Game, and the Marine Life Research Group (MLRG) at
Scripps Institution of Oceanography (SIO). MLRG contributes to
this program by investigations of the physical, chemical and biological
structure of the California Current. Data from CalCOFI cruises
9501 and 9504 were collected and processed by personnel of the
Marine Life Research Group and the Southwest Fisheries Science
Center. Volunteers and other SIO staff members also assisted in
the collection of data and chemical analyses at sea.
Rosette Cast Data
At each station on cruises 9501 and 9504 a Sea-Bird
Electronics, Inc., Conductivity-Temperature-Depth (CTD) instrument
was deployed with a 24-place General Oceanics rosette. The rosette
was equipped with 24 ten-liter plastic (PVC) bottles. The CTD/rosette
cast usually sampled 20 depths to a maximum sampling depth of
525 meters, bottom depth permitting. Pressures and temperatures
assigned to the water sample data were derived from the CTD signals
recorded just prior to the bottle trip. Pressures have been converted
to depths by the Saunders (1981) pressure-to-depth conversion
technique. CTD temperatures reported with the bottle data have
been rounded to the nearest hundredth of a degree Celsius. Salinity,
oxygen and nutrients were determined at sea for all depths sampled.
Chlorophyll-a and phaeopigments were determined at sea
within the top 200 meters, bottom depth permitting.
Salinity samples were collected from all rosette
bottles and analyzed at sea using a Guildline model 8400A Autosal
salinometer. The results were compared with the CTD salinity in
order to verify that the rosette bottle did not mis-trip or leak.
The salinometer was standardized before and after each group of
samples with substandard seawater. Periodic checks on the conductivity
of the substandard were made by comparison with IAPSO Standard
Seawater batch P122 on cruise 9501 and batch P127 on cruise 9504.
Salinity values have been calculated from the algorithms for the
Practical Salinity Scale, 1978 (UNESCO, 1981a) and were reported
to three decimal places, provided that accepted standards were
met. If only one determination per sample was obtained, or there
was doubt concerning the accuracy of the analytical results, the
salinities were reported to two decimal places.
Dissolved oxygen was determined by the Winkler method,
as modified by Carpenter (1965), using the equipment and procedure
outlined by Anderson (1971). Percent oxygen saturation was calculated
from the equations of Weiss (1970).
Silicate, phosphate, nitrate and nitrite nutrients
were determined at sea using an automated analyzer. The procedures
used are similar to those described in Atlas et al. (1971).
Samples for chlorophyll-a and phaeopigments
were filtered onto GF/F filters. The pigments were extracted with
a cold extraction technique in 90% acetone (Venrick and Hayward,
1984), and the fluorescence determined before and after acidification
with a Turner Designs fluorometer (Yentsch and Menzel, 1963; Holm-Hansen
et al. 1965).
Evaluation of the data involved comparisons with
the CTD cast profiles, adjacent stations and consideration of
the variation of a property as a function of density or depth
and the relationships with other properties (Klein, 1973). Estimates
of precision of the standard techniques are given in SIO, 1991.
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* The first two digits represent the year and the
last digits the month of the cruise.
Primary Productivity Sampling
Primary productivity samples were taken each day
shortly before local apparent noon (LAN), from the standard rosette
cast. Primary production was estimated from 14C
uptake using a simulated in situ technique. Light penetration
was estimated from the Secchi depth (assuming that the 1% light
level is three times the Secchi depth). The depths with ambient
light intensities corresponding to light levels simulated by the
on-deck incubators were identified and sampled on the up rosette
cast. Occasionally an extra bottle or two were tripped in addition
to the usual 20 levels sampled in the combined rosette-productivity
cast in order to maintain the normal sampling depth resolution.
The ten-liter bottles were equipped with epoxy-coated springs
and Viton O-rings. Triplicate samples (two light and one dark
control) were drawn from each productivity sample depth into 250
ml polycarbonate incubation bottles. Samples were inoculated with
10 µCi of 14C as
NaHCO3 (200 µl of
50 µCi/ml stock) prepared in a 0.3 g/liter solution of sodium
carbonate (Fitzwater et al. 1982). Samples were incubated
from LAN to civil twilight in seawater-cooled incubators with
neutral-density screens which simulate in situ light levels.
At the end of the incubation, the samples were filtered onto Millipore
HA filters and placed in scintillation vials. One half ml of 10%
HCl was added to each sample. The sample was then allowed to sit,
without a cap, at room temperature for 12 hours (after Lean and
Burnison, 1979). Following this, 10 ml of scintillation fluor
were added to each sample and the samples were returned to SIO
where the radioactivity was determined with a scintillation counter.
Salinity, oxygen, nutrients, chlorophyll-a and phaeopigments
were determined from all rosette productivity bottles.
Macrozooplankton Net Tows
Macrozooplankton was sampled with a 71 cm mouth diameter
paired net (bongo net) equipped with 0.505 mm plankton mesh. Bottom
depth permitting, the nets were towed obliquely from 210 meters
to the surface. The tow time for a standard tow was 21.5 minutes.
Volumes filtered were determined from flowmeter readings and the
mouth area of the net. Only one sample of each pair was retained
and preserved. The biomass, as wet displacement volume, after
removal of large (>5 ml) organisms, was determined in the laboratory
ashore. These procedures are summarized in greater detail in Kramer
et al. (1972).
Avifauna Observations
On cruises 9501 and 9504 seabirds were counted within
a 300 meter wide strip off to one side of the ship. Counts were
made while underway between stations during periods of daylight.
These counts were summed over 20 nautical mile (nm) intervals,
or the distance between consecutive stations, whichever was less.
Included at the end of this report are individual maps of the
most numerous bird species (individuals/nm).
Rosette Cast Data
The time reported is the Coordinated Universal Time
(UTC) of the first rosette bottle trip on the up cast. The rosette
bottles tripped on the up cast are reported as cast 2, where cast
1 is considered to be the down CTD cast. The sample number reported
is the cast number followed by a two digit rosette bottle number.
Bottom depths, determined acoustically, have been corrected using
British Admiralty Tables (Carter, 1980) and are reported in meters.
Weather conditions have been coded using WMO code 4501. Secchi
depths and Forel water color scales are also reported for most
daylight stations.
Observed data from individual CTD/rosette trip levels
are interpolated and reported for standard depths. Interpolated
or extrapolated standard level data are noted by the footnote
"ISL" printed after the depth. Density-related parameters
have been calculated from the International Equation of State
of Seawater 1980 (UNESCO, 1981, b). Computed values of potential
temperature, sigma-theta, specific volume anomaly (SVA), and dynamic
height or geopotential anomaly are included with both observed
and interpolated standard depth levels.
On stations where primary productivity samples were
drawn from six of the rosette bottles, a footnote appears after
each productivity depth sampled. The corresponding primary productivity
data are reported in a separate section following the tabulated
rosette cast data.
Primary Productivity Data
In addition to the normal hydrographic data also
reported in the rosette cast data section, the tabulated data
include: the in situ light levels at which the samples
were collected, the uptake from each of the replicate light bottles,
uptake 1 and uptake 2, (which have been corrected for dark uptake
by subtracting the dark value), the mean of the two uptake values
and the dark uptake. The uptake values are totals for the incubation
period. Also shown are the times of LAN, civil twilight, and the
value of the mean uptake integrated from the surface to the deepest
sample, assuming the shallowest value continues to the surface
and that negative values (when dark uptake exceeds light uptake)
are zero. The uptake data have been presented to two significant
digits (values <1.00) or one decimal (values >1.00). Precision
of the higher production values may not warrant all of the digits
presented. Incubation time, LAN, and civil twilight are given
in local Pacific Standard Time (PST); to convert to UTC, add eight
hours to the PST time. Incubation light intensities are listed
in a footnote at the bottom of each page.
Macrozooplankton Data
Macrozooplankton biomass volumes are tabulated as
total biomass volume (cm3/1000m3
strained) and as the total volume minus the
volume of larger organisms under the heading "Small."
Tow times are given in local PST (+8) time.
In addition to footnotes, special notations are used
without footnotes because the meaning is always the same.
D: CTD salinity value listed in place of normal ship-board salinity analysis.
ISL: After a depth value indicates that this is an interpolated or extrapolated standard level.
U: Uncertain value. Values which are not used in interpolation because they seem to be in error without
apparent reason.
At the present time the physical and chemical data
presented in this report are available over the internet via the
Nemo Oceanographic Server. The historical CalCOFI data from 1949
to present resides at the Nemo location. To access these data
telnet to nemo.ucsd.edu and login with username "info".
CalCOFI data reports from 1990 to the present are also currently
available on the World Wide Web at http://www-mlrg.ucsd.edu/calcofi/.
The physical and chemical data in this report will be submitted
to the National Oceanographic Data Center (NODC) and will eventually
be available through that service.