FISHERIES BULLETIN: VOL. 84, NO. 1 



females and stage V copepodites in triplicate aliquots 

 taken from the preserved catches of net 2. 



Sample Analyses 



All frozen samples were analyzed in the laboratory 

 within 6 wk of the time of collection. Plant pigments 

 were extracted from the filters in 90% acetone in 

 darkness at 4°C for 48 h. Chlorophyll a concentra- 

 tion was determined by the method of Strickland and 

 Parsons (1972) using a model 10-005 Turner Designs 

 fluorometer. The two chlorophyll a measurements 

 from each station were averaged. 



Groups of frozen animals (separate species and 

 sexes) were thawed in the laboratory, blotted lightly 

 to remove excess water, and weighed (±0.01 mg). 

 Animals were then freeze-dried for 24 h at -50°C 

 and reweighed. Groups were then immediately 

 ground in cold (4°C) succinic acid buffer (pH 5.0) 

 using a Polytron grinder (for euphausiids) or a hand 

 glass tissue grinder (for copepods). Homogenates 

 were analyzed for total proteins by the Lowry 

 method using Sigma protein standard (Merchant et 

 al. 1964). Laminarinase activity (LA) of the homo- 

 genates was determined by the methods described 

 by Cox (1981) and Willason (1983). LA was expressed 

 as a function of the animal's wet weight: yg glucose 

 produced per gram wet weight per minute of incu- 

 bation. Copepod homogenates were also analyzed for 

 total lipids using stearic acid as the standard (Bligh 

 and Dyer 1959; Marsh and Weinstein 1966). 



Data Analysis 



Willason and Cox (in press) found that E. pacifica 

 exhibits a diel rhythm in enzyme activity associated 

 with feeding activity at night. Thus, to compare LA 

 of E. pacifica collected at different times of the day 

 from different localities, enzyme levels had to be 

 standardized with respect to the time of capture. 

 Calibration factors, which convert the LA of E. 

 pacifica collected at different times to a standardized 

 maximum value (between 0200 and 0800 h), were 

 derived from the results of the 24-h time-series col- 

 lections in Willason and Cox (in press). These fac- 

 tors are based on the average relative increases and 

 decreases of enzyme activity over a 24-h period 

 (Table 1). LA of AT. difficilis and C. pacificus do not 

 show diel changes (Cox et al. 1983; Willason and Cox 

 in press) and, therefore, were not standardized. 



The data set for each station consists of surface 

 temperature, surface chlorophyll a, zooplankton 

 abundance, LA, individual wet and dry weights, pro- 

 tein content, and lipid content (copepods only). To 



permit parametric statistical comparisons between 

 the various biological and physical properties and 

 between regions, chlorophyll a, zooplankton abun- 

 dance, and zooplankton LA were normalized by log 

 transformation. The log transformed values were 

 used for all parametric statistical tests. Zooplankton 

 wet weight, dry weight, protein content, and lipid 

 content were found to be normally distributed by 

 probit analysis and were not log transformed. Non- 

 transformed values from all data sets were used to 

 construct contour maps. The contour maps are in- 

 tended to show general trends and patchiness within 

 the sampling grid. 



Table 1.— Correction factors for standard- 

 izing laminarinase activity (LA) of Euphausia 

 pacifica. These factors account for diel 

 changes in LA and are based on the time 

 of capture. They were derived from the 24-h 

 time-series collections of Willason and Cox'. 

 LA was standardized to the 0200-0800 time 

 period. LA of euphausiids captured during 

 other time periods was multiplied by the 

 corresponding factor. 



'Willason, S. W. and J. L. Cox. In press. Diel 

 feeding, laminarinase activity and phytoplankton 

 consumption by euphausiids. Biol. Oceanogr. 



RESULTS 



Surface Water Temperature and 

 Surface Chlorophyll a 



Surface water temperatures along the California 

 coast during April 1981 ranged from 9.6° to 16.0°C. 

 The coldest water was located in the northern near- 

 shore region and the warmest was found in the 

 southern offshore region (Table 2, Fig. 2). Two small 

 areas showed very low surface water temperatures: 

 close to the shore along the central coast of Califor- 

 nia and just off San Francisco Bay (Fig. 2). A cold 

 water plume extended from Point Conception south 

 into the Southern California Bight. 



Chlorophyll a concentrations showed greater than 

 100-fold variation between stations and were inverse- 

 ly correlated with surface water temperatures (r = 

 0.83, P < 0.001). Lowest values, 0.09 to 0.16 mg 

 chlorophyll a/m 3 , were found in the southern off- 

 shore region. Highest concentrations occurred in the 

 northern nearshore region (Table 2, Fig. 3). Within 



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