INTRODUCTION
The data in
this report were collected during cruises 0107* and 0110 of the California Cooperative Oceanic
Fisheries Investigations (CalCOFI) program aboard the 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 Integrative
Oceanography Division (IOD) at Scripps Institution of Oceanography (SIO). IOD contributes to this program by
investigations of the physical, chemical and biological structure of the
California Current. Data from the cruises were collected and processed by
personnel of the Integrative Oceanography Division and the Southwest Fisheries
Science Center. Volunteers and other
SIO staff members also assisted in the collection of data and chemical analyses
at sea. CalCOFI data presented in this report and collected on previous cruises
can be accessed via the World Wide Web (http://www.calcofi.org).
STANDARD PROCEDURES
CTD/Rosette Cast Data
A Sea-Bird Electronics, Inc., Conductivity-Temperature-Depth
(CTD) instrument with a rosette was deployed at each station on these
cruises. 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. Occasional
stations have multiple bottles tripped at the same depth to provide more water
for ancillary programs. The sample spacing was designed to sample depth
intervals as close as 10 meters around the sharp upper thermocline features
such as the chlorophyll, oxygen, nitrite maxima and the shallow salinity
minimum. 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.
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 samples were collected from all
rosette bottles and analyzed at sea using a Guildline model 8410 Portasal
salinometer. Salinity samples were
drawn in to 200 ml Kimax high-alumina borosilicate bottles that were rinsed
three times with sample prior to filling.
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 P134.
Salinity values have been calculated using the algorithms for the
Practical Salinity Scale, 1978 (UNESCO, 1981a) and were reported to three
decimal places, provided that accepted standards were met.
Dissolved oxygen samples were collected
in calibrated 100 ml iodine flasks, allowing at least 200% overflow. The dissolved oxygen samples were analyzed
at sea 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).
Nutrient samples were analyzed at sea for dissolved silicate, phosphate, nitrate and nitrite using procedures similar to those described in Gordon et al., 1993. Samples were collected in 45 ml high-density polypropylene screw-capped tubes which were rinsed three times prior to filling. Standardizations were done at the beginning and end of each group of samples with a set of mid-concentration range standards prepared fresh for each run. Samples
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* The first two digits represent the year and the
last digits the month of the cruise.
not analyzed immediately after collection were refrigerated and run the following day. Sets of six different concentration standards were analyzed periodically to determine the deviation from linearity as a function of concentration, primarily for the silicate and nitrate analyses. Final sample concentrations were corrected for deviations from linearity.
Samples for chlorophyll-a and phaeopigments were collected in
calibrated 138 ml polyethylene bottles and filtered onto Whatman 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 Model 10-AU-005-CE (Yentsch and Menzel, 1963; Holm-Hansen et al., 1965).
Evaluation of the water sample 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). Precision estimates for the routine analyses
were made on CalCOFI cruise 9003 and are reported in SIO Ref. 91-4.
Primary Productivity Sampling
Primary productivity samples were taken each day shortly before local
apparent noon (LAN). 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 0.505mm 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). An Optical Plankton Counter
(OPC) was routinely used in one side of the paired bongo net frame. The purpose of the OPC is to obtain
information on the vertical distributions of size categories of zooplankton,
using data from the counter, without affecting the ongoing time series of data
obtained from the catches of the integrative bongo net.
Avifauna Observations
Sea birds 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).
Ancillary Programs
Several ancillary programs produced data
on these cruises that are not presented in this report. These programs
include:
1) Underway
Data. Continuous near surface
measurements of temperature, salinity and in vivo chlorophyll
fluorescence were recorded from seawater pumped through the ship’s
uncontaminated seawater system from a depth of approximately 3 meters. The data were logged in one-minute averages
using a Sea-Bird Electronics, Inc., SBE 45 MicroTSG Thermosalinograph and a
Turner Designs SCUFAâII fluorometer.
2) ADCP.
Continuous profiles of ocean currents and acoustic backscatter between
20 and 500 meters deep were measured along the shiptrack from a hull-mounted
150 kHz Acoustic Doppler Current Profiler (ADCP). The ADCP data were averaged
over 3-minute intervals. Sixty 8-meter depth bins were recorded.
3) Bio-optics.
On cruise 0107 In-situ measurements
of apparent and inherent optical properties of seawater were obtained daily
using a bio-optical package consisting of a MER-2040 (Multi-channel
Environmental Radiometer), a Sea-Bird CTD, and two transmissometers. Also
integrated into the profiling system was a Hydroscat-6 that measured spectral
backscattering at six wavelengths.
Measurements were obtained daily at the primary productivity station in
the upper 300 meters of the water column.
Phytoplankton pigment concentrations were made using HPLC in addition to
determination of particulate organic carbon, nitrogen, phycoerythrin
concentrations and particle size distribution using flow-cytometry and Coulter
Counter techniques
4) Atmospheric and Marine Optics. On cruises 0107 and 0110 datasets of spectral water leaving radiance and aerosol optical thickness were acquired during daylight hours en route and on stations using hand held SIMBAD radiometers. The SIMBAD radiometer measures both variables in typical spectral bands of satellite ocean color sensors, namely bands centered at 443, 490, 560, 670 and 870 nm. The instrument was designed for evaluation of satellite derived ocean color. In sun viewing mode the instrument operates like a classic sun photometer. In sea viewing mode a vertical polarizer reduces sky light reflection in the instrument's field of view. Water samples were collected from the CTD/Rosette casts to determine particulate, detrital, and soluble absorption as well as phytoplankton pigment concentrations.
TABULATED DATA
CTD/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 profile. 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 are 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. Multiple bottles tripped at the same depth to provide water for ancillary programs are not used in the calculation of standard depth data. Density-related parameters have been calculated from the International Equation of State of Seawater 1980 (UNESCO, 1981b). 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 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.
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 shipboard 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.