(35% of the community), dominated by Skeleto- 

 nema costatum. Cysts of Halosphaera sp. com- 

 posed about 20% of the community on both dates; 

 the motile form was not detected. Coccolithophor- 

 ids composed about 10% of the cells counted. 

 Mean chlorophyll a concentrations at the station 

 were 0.56 and 1.16 iig/\ on 12 and 26 September, 

 respectively. 



At stations N4 and N6 there were about 10 5 

 phytoplankton/1 on each occasion. About 60% of 

 the phytoplankton in the samples were diatoms 

 of the genus Chaetoceros. Other diatom species 

 composed about 25% of the community, and dino- 

 flagellates made up 10%. Halosphaera cysts, 

 small unidentifiable spherical cells (some of 

 which probably contained chlorophyll b) and 

 coccolithophorids made up about 5% of the com- 

 munity. Mean chlorophyll a concentrations were 

 1.54 and 1.92 yug/1 on 12 and 26 September, re- 

 spectively. 



Figure 2a, b summarizes gut fullness estimates 

 for 50 A. tonsa from stations N4 and 7B. At sta- 

 tion N4 (Fig. 2a), 70% of the animals exhibited 

 >40% gut fullness; mean gut fullness was 55.5%. 

 At station 7B (Fig. 2b), about 20% of the animals 

 exhibited >40% gut fullness; the mean was 31% 

 fullness. 



Gut chlorophyll a concentrations (corrected 

 for the absorbance of empty gut animals) are 

 shown in Table 2. Comparative water column 

 data are also provided. The concentration of 

 chlorophyll a in the gut contents of A. tonsa 

 increased with seaward distance. Animals col- 

 lected at station 7B had, on average, 40 times 

 more chlorophyll in their guts than the same spe- 

 cies at nearshore locations. 



The chlorophyll b and c content of the water 

 column diminished slightly with distance from 

 shore (Fig. 3a). In the guts of Acartia these pig- 

 ments increased sharply from nearshore to off- 

 shore stations (Fig. 3b). 



a) 



100r 



80 



H 



e 



TO 



14-1 



o 



o\° 



b) 



0) 



60 



40 



20 







100r 



80 



6 60 



to 



14-4 



o 40 



20 







A. tonsa N-4 



Mean Fullness = 55.5% 



— T 



A. tonsa 7-B 



Mean Fullness = 31.0% 



20 40 60 80 

 % Fullness 



100 



Figure 2.— Percent gut fullness of Acartia tonsa at stations a) 

 N4 and b) 7B on 26 September 1980. AT = 50. 



Table 2.— Chlorophyll a in two copepod species, Acartia tonsa and Calanus pacificus, 

 at stations of varying distances from shore, with comparative water column 1 values. 



'Water column chlorophyll a values are mean ± standard deviation (in parentheses) from water 

 column composite samples. On 12 September only one sample was analyzed; on 26 September. 5 sub- 

 samples of the water column composite were analyzed. 



a Data from cruise on 26 September 1980. 



3 Data from cruise on 12 September 1980 



"Numbers of C. pacificus at the nearshore stations were too low (<5 animals/tow) for the analysis to 

 be conducted. 



157 



