INTRODUCTION
The data in this report were collected during cruises 9707*, 9709 and 9712 of the California Cooperative Oceanic Fisheries Investigations (CalCOFI) program aboard the NOAA ship RV David Starr Jordan, the RV New Horizon and the RV Robert Gordon Sproul 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. Cruise 9712 was the first of a series of shorter cruises designed to monitor the response of the California Current to the present El Niño Southern Oscillation (ENSO) event. Data from CalCOFI cruises 9707, 9709 and 9712 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
CTD/Rosette Cast Data
At each station on cruises 9707, 9709 and 9712 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. 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 and oxygen were determined at sea for all depths sampled. On cruises 9707 and 9709 nutrients were determined at sea for all depths sampled. On cruise 9712 nutrients were determined for stations 90.28 and 90.30. 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. 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 P127. 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. 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 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).
On cruises 9707 and 9709 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). On stations 90.28 and 90.30 of cruise 9712 samples were filtered through Whatman GF/F filters and frozen for later analysis ashore. Silicate, phosphate, nitrate and nitrite nutrients were determined on these samples using manual methods similar to those described in Parsons et al. (1984).
_________________________________
* The first two digits represent the year and the last digits the month of the cruise.
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
On cruises 9707 and 9709 primary productivity samples were taken each day shortly before local apparent noon (LAN). Primary productivity samples were not collected on cruise 9712. 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 µm 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
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 made from water pumped through the ship, and the data were logged at one-minute intervals. Pelagic fish eggs were collected underway with a separate large volume pump throughout the entire CalCOFI pattern on cruise 9707 and up to line 80 during 9709. Due to inclement weather, only a partial sample of line 80 and 77 were obtained during 9709. This pump drew a continuous sample of approximately 640 liters per minute, which was concentrated
and then collected by a 505 µm sieve. Samples were taken at intervals ranging from 10 to 30 minutes, depending on the sample concentration, for enumeration of all retained fish eggs.
2) ADCP. Acoustic Doppler Current Profiler data were recorded continuously along the ship’s cruise track.
3) Bio-optics. On cruises 9707 and 9709 apparent and inherent optical properties of the top 300 meters of the water column were measured daily with a bio-optical profiling package. Water samples obtained from the CTD/rosette cast were analyzed for determination of absorption by particulate and soluble material, and HPLC determination of phytoplankton pigments. On cruise 9707 samples were also collected and analyzed for detrital absorption. On cruise 9709 samples were collected for cyanobacteria counts, phycoerythrin filtration, particulate organic carbon and nitrogen, and measurements of polarized sky radiances and above-water ocean surface reflectance. Bio-optical profiles from 0 to 50 meters were also completed in coordination with SeaWiFS satellite orbital overpass times.
4) Diversity and Distributions of Cyanobacterial Populations. On Cruise 9709 marine Synechococcus and Prochlorococcus populations were sampled to 120 m at both near shore and open ocean sites. Genetic analyses of cyanobacterial populations were performed on total DNA extracted from cells retained on 0.45µm filters. Phytoplankton samples corresponding to those used for the genetic population survey were collected on glass fiber filters for pigment extraction and analysis by HPLC. In addition, FACSort Flow Cytometer analyses of these same samples were conducted to evaluate the number of different phytoplankton cell types, namely Synechococcus, Prochlorococcus and eukaryotic algae, present in the samples. Gluteraldehyde fixed samples were also prepared to compare the effects of fixation on the fluorescence signatures of the cell types. Samples for antibody analysis were also collected. To study some of the physiological properties of the marine cyanobacteria, culture enrichments were prepared at sea using the same water samples mentioned above. Isolated cultures will be maintained and evaluated in the laboratory.
5) Tests with an electronic particle counter. Test deployments of an electronic Optical Plankton Counter (OPC) were conducted on 9707 to determine the towing characteristics of the standard bongo net frame with the counter mounted on it, and to test for avoidance of the device by various kinds of zooplankters. The ultimate purpose 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.
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 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. 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 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 (cm
3/1000m3 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.