CalCOFI
Cruise 0007 & 0010 Data Report
INTRODUCTION
The data in
this report were collected during cruises 0007* and 0010 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 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 the cruises
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. 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
At each station on these cruises a
Sea-Bird Electronics, Inc., Conductivity-Temperature-Depth (CTD)
instrument was
deployed with a 24-place 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. 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 which 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
_________________________________
* 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 (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). Estimates of precision of
the standard
techniques are given in SIO (1991).
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 0.505µm
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 which are not presented in this report. These programs
include:
1)
Underway Data.
Continuous near surface measurements of
temperature, salinity and chlorophyll fluorescence were recorded from
water
pumped through the ship’s uncontaminated seawater system. The data were logged at
one-minute
intervals.
2)
ADCP.
Continuous profiles of ocean currents and
acoustic backscatter between 20 and 400 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)
Atmospheric and Marine Optics.
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 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 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.