Table 1 — Regression relationships between displacement volume (DV; ^lL m"^) 

 and ash-free dry mass (AFDM: mg m ^). F-ratio designates the ratio of regression 

 mean square: residuals mean square. Regression P-value indicates the significance of 

 a linear regression, and the residuals P-value indicates the significance of the first order 

 serial correlation of regression residuals. /V = 160 for both size fractions. 



Size fraction 



Equation 



Regression Residuals 



F-ratio P-value r^ P-value 



<505M.m DV = 17. 86(AFDM) + 3.86 2,869.1 <0.001 0.938 

 1594.7(AFDM) 



>505 |jLm DV 



105.5 + AFDM 



2,725.6 — 



■0.10 

 — >0.10 



ASH - FREE DRY MASS 



20 



15 



>- 

 o 



LlI 



3 10 



O 



LlI 



tr 



I I I I I I r" 



■T — I — I — I — I — I — I — I — I — I — I — I — I — r 



m 



W W''" 



D Day 

 W Night _ 



^ 



n 



8 16 24 32 40 48 56 64 72 80 88 96 

 AFDM (% < 505 /im) 



Figure 4. — Frequency distribution of the percentage of ash-free dry mass in the 

 fraction <505 [xm, from 4 CalCOFI cruises (TV = 111). 



the total standing stock was 30.2%. Partitioned 

 by time of sampling, the day mesozooplankton 

 averaged 35.0% and the night mesozooplankton 

 28.1% of total standing stock. Day and night 

 medians differed significantly (P < 0.05, Mann- 

 Whitney U test). The higher proportion of 

 macrozooplankton (>505 jj-m) in nighttime sam- 

 ples probably reflects nocturnal vertical migra- 

 tion of larger zooplankton into the upper 200 m of 

 the water column or, perhaps, diurnal net avoid- 

 ance. At individual stations, the mesozooplank- 

 ton contribution ranged up to 82% of the total. 



Despite considerable variance in the relation- 

 ship, zooplankton standing stocks were posi- 

 tively correlated with the Chla concentration 

 (Fig. 5). This relation, apparently curvilinear, is 

 illustrated as log AFDM plotted against the log 

 ma.ximum Chla concentration in vertical profile 



at each station for the fraction <505 ixm (Fig. 

 5A: r = 0.73, P < 0.001, Spearman's rank 

 correlation, N = 110) and that >505 ixm (Fig. 

 5B: r = 0.70, P < 0.001, iV = 110). When plotted 

 against the log chlorophyll integi'ated to 150 m 

 the correlation coefficients were slightly smaller 

 «505 ixm: r = 0.71; >505 |xm: r = 0.64). 



The relative contribution of mesozooplankton 

 to total standing stocks varied independently of 

 Chla concentration. Neither in the day samples 

 (r, = -0.117, P > 0.10, iV = 49) nor in the night 

 samples (r, = 0.060, P > 0.10, A^ = 61) was the 

 fraction of standing stock <505 |j.m associated 

 with Chla (Fig. 6). 



Sufficient samples to analyze cross-shore 

 gradients in total standing stock and in the 

 percentage of standing stock contributed by the 

 mesozooplankton were obtained only along lines 



971 



