The 24-hour series of oblique hauls mads on Manning cruise 

 9 affords a further test of the sine method of adjustmente As previous- 

 ly statedj, the series consisted of paired oblique hauls -co th^rge depths 

 — SOOj, 300, and 500 meters--all taken within a relatively small areao 

 The results of the adjustment for the th_ree depths are shown in table 

 10 o As evidenced by the coefficient of determination (r^)^ for the 200- 

 meter hauls 92 percent of the variation in the zooplankton volumes is 

 associated with correlated changes in the sine function o The degree of 

 correlation is less, however^ for the 300-meter hauls and still less for 

 the 500-meter hauls » This is accompanied by a parallel decrease in the 

 significance of th^ regression of Y (zooplankton volumes) on X (sine 

 function) o 



Data from all seven cruises in local waters v;ere adjusted by 

 the sine method » The adjusted values for cruises employing 200-meter 

 oblique hauls are given in tables 18, 19^ 20, 21;, and 22 1 adjusted val- 

 ues for cruises employing horizontal hauls are given in table 6. Table 

 7 provides a comparison of the results of the adjustment for the various 

 cruises o Among the 200-meter oblique hauls the night/day ratio for un- 

 adjusted volumes ranged from lo30 to lo70^ while for the adjusted 

 volumes the ratio varied from 0<,97 to lo05o For the horizontal hauls j, 

 after adjustment, the ratio ranged from 0o69 to IdS^ indicating the 

 presence of considerable variation in the horizontal hauls v/hich is 

 possibly not associated vdth the day-night differences » 



The high significance shown, by the "t" tests for the re- 

 gression of zooplankton volumes on the sine curve and the relatively 

 high value of r^ (table 7) are general evidence in favor of the methods 

 It is conceivable^ however^ that both "t" and '"r^** might vary inversely 

 with the amount of variation — other than diurnal— present in the data^ 

 even though the diurnal effect were constanto Therefore these two 

 statistics possibly do not provide a crucial test of the adjustment 

 methodo Since this transformation appeared to correct— to a large ex- 

 tent at least--for the day-night differences among the 200'=meter oblique 

 hauls, the adjusted volumes were used for examining geographical and 

 short-term variations and for correlations v/ith environmental factors o 



GEOGRAPHICAL AM) TET.'IPORAL VARIATION 



In figure 10 we have attempted to shcv: lines of equal zoo- 

 plankton concentration or "isoplankts" for the three cruises of the 

 Hugh Mo Smith v/hich were based on 200-meter oblique hauls and provided 

 general coverage of the area. From an examination of these charts we 

 conclude that although the abundance of zooplankton was remarkably uni- 

 form throughout the Island vt'aters, there were certain areas v;hichwere 

 consistently richer or poorer than other areas o For example, stations 

 southwest of Oahu, in all three cruises, produced volumes somewhat higher 

 than average o Also, an area north of Kauai showed an unusually high 

 concentration on two cruises » The southeast comer of the survey area 

 produced consistently low catches o 



25 



