INTRODUCTION

The data in this report were collected during cruises 9608* and 9610 of the California Cooperative Oceanic Fisheries Investigations (CalCOFI) program aboard the RV New Horizon and the RV Roger Revelle of Scripps Institution of Oceanography, University of California, San Diego. Cruise 9610 was the maiden scientific voyage of RV Roger Revelle. This expedition size ship accommodated a larger than usual scientific party and numerous extra projects. 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 9608 and 9610 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

At each station on cruises 9608 and 9610 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 20-24 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. 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).

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 cruise 9610 standard CalCOFI CTD/rosette casts were modified and additional casts taken to investigate the detailed distribution of nutrients in the mixed layer above the nutricline. At all stations four extra depths in the upper 30 meters were sampled. On five stations of Line 93 and all stations of Line 90 except 90.30 and 90.28, a second nutrient sample was drawn from rosette bottle

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* The first two digits represent the year and the last digits the month of the cruise.

sampling depths less than about 130 m; these samples were analyzed on a second Autoanalyzer set up for increased sensitivity at low nutrient levels. This Autoanalyzer was also used on samples from CTD/rosette casts taken every 4 hours in the upper 125 m at two 24-hour stations, 93.50 and 90.120, and special CTD/rosette casts to 125 m at three Line 90 stations.

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

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).

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).

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.

2) ADCP. Acoustic Doppler Current Profiler data were recorded continuously along the ship’s cruise track.

3) Bio-optics. On cruise 9608 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 detrital and soluble material, and HPLC determination of

plant pigments. On cruise 9610 samples were collected and analyzed for particulate organic carbon and particulate size distribution. Also on cruise 9610 measurements were made of water leaving radiance and aerosol optical

thickness for calibration of current satellite ocean color sensors, namely the Japanese Ocean Color and Temperature Sensor (OCTS) and the French Polarization and Directionality of the Earth Reflectance (POLDER) instrument. In addition measurements were made of atmospheric optics and ocean spectral reflectance by deploying radiosondes and coordinating overflights of the NASA/JPL AVIRIS hyperspectral radiometer on the ER2 aircraft.

4) Carbon Monoxide Cycling. On cruise 9610 the rate of microbial oxidation of CO was measured in a variety of samples from the mixed layer at 18 stations. Measurements were also made of the relative rate of photogeneration of CO upon irradiation of filtered (0.2µm) and unfiltered mixed-layer water samples by a solar simulator at 12 stations. At 8 stations an ‘optical buoy’ was used to measure depth integrated CO production in situ.

5) Benthic Sampling. Bottom samples were collected from the same two sites on each cruise using a multicoring sampler as part of a series of samples for the study of the temporal variation in living benthic foraminiferal assemblages in the California Current system. These sediment cores were subsampled in 1 cm and 0.5 cm sections and either preserved in formalin or frozen for subsequent faunal and geochemical analyses.

6) Pigment studies. These studies on each cruise included measurement of ¹⁴C incorporation into pigments in incubated samples, phytoplankton pigment analyses of euphotic zone samples using high performance liquid chromatography, phytoplankton fluorescence measurements before and after DCMU addition, and nutrient enrichment experiments to assess changes in phytoplankton fluorescence, source-specific nitrogen uptake rates, and phytoplankton population changes as indicated by pigment concentrations.

7) Mesoscale Zooplankton Structure. On cruise 9610 a suite of techniques including molecular genetics, enzyme biochemistry, and bio-acoustics were used to examine the mechanisms that define the boundaries of zooplankton species distributions in the California Current. Particular interest was focused on how neritic zooplankton species maintain persistent population concentrations in coastal regions, despite the highly advective field.

8) Diversity and Distributions of Cyanobacterial Populations. On cruise 9610 marine Synechococcus, Prochlorococcus, and eukaryotic algae populations were studied in water samples from the upper 120 meters at selected stations using the FACSort Flow Cytometer. Gluteraldehyde fixed samples were also prepared to compare the effects of fixation on the fluorescence signatures of the cell types. 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.

TABULATED 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.

Except for the special nutrient enrichment casts, 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 cruise 9608 a contamination problem occurred with the Autoanalyzer which erroneously elevated some of the deep nitrite concentrations. The elevated values have not been included in this report.

Nutrient samples drawn on cruise 9610 from four stations on Line 93 and all stations on Line 90, except 90.30 and 90.28, are reported in the table entitled High Resolution Nutrients. The usual nutrient samples collected from the CTD/rosette casts on these stations are also reported in this table for direct comparison to the high resolution measurements.

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.

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.

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.