CalCOFI Cruise 9308 & 9310
INTRODUCTION
The data in this report were collected during Cruises 9308* and 9310 of the California Cooperative Oceanic
Fisheries Investigations (CalCOFI) program aboard the RV New Horizon of the 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 9308 and 9310 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.
STANDARD PROCEDURES
Rosette Cast Data
At each station on cruises 9308 and 9310 a Sea-Bird Electronics, Inc., Conductivity-Temperature-Depth (CTD)
instrument was deployed with a 24-place General Oceanics rosette. The rosette was equipped with 20 to 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 collected just prior to the bottle trip. Pressures have been converted to depth 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 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. 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 for all depths.
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 m 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
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).
TABULATED DATA
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.
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 and interpolated standard depth data from CTD/rosette casts have been interspersed and are presented
together sequentially by depth. 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), dynamic height or geopotential anomaly, and pressure 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.
Hydrographic data presented in the primary productivity data tables has been extended into the nutricline for
stations where the nutricline depth was deeper than the deepest productivity sample. 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.
FOOtnOTES
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.