FISHERY BULLETIN: VOL. 70, NO. 2 



Table 1. — Results of sampling study at Subarctic Pacific Station 23. 



Species 



\. 10-m depth 



Nitzickia 



turgiduloides^ 

 Denticula 



seminae^ 



Chaetoceros 

 atlanticus^ 



DactyliosoUn 

 mediterraneus^ 



Coscinodiscus 

 marginatus 

 Rhizosolenia 



Thalassiothrix 



longissima 

 Rhizosolenia 



hebetata hiemalis 



Corethron 

 criophilum 



II. 35-m depth 



Nitzschia 



turgiduloides'^ 

 Denticula 



seminae^ 

 DactyliosoUn 



meditcrraneus'^ 

 Chaetoceros 



attanticus^ 

 Thalassiothrix 



longissima 

 Rhizosolenia 



hebetata hiemalis 



Rhizosolenia 



alatd^ 

 Corethron 



criophilum 



Coscinodiscus 

 marginatus 



III. 50-m depth 



Nitzschia 



turgiduloides^ 

 Denticula 



seminae^ 

 DactyliosoUn 



mediterraneus^ 

 Corethron 



criophilum 



Coscinodiscus 



marginatus 

 Chaetoceros 



atlanticus^ 

 Rhizosolenia 



hebetata hiemalis 



al 



^Vo-2 



513.5 

 53.8 

 8.A 

 4.4 

 2.1 

 1.6 

 1.5 

 1.3 

 1.1 



801.0 

 119.3 

 23.1 

 3.0 

 1.5 

 1.4 

 0.9 

 0.9 

 0.8 



330.6 

 39.0 

 7.7 

 0.7 

 0.6 

 0.2 

 0.1 



17,981.23 

 61.44 

 9.59 

 5.02 

 2.40 

 1.83 

 1.71 

 1.48 

 1.26 



28,048.62 

 136.24 

 26.38 

 3.43 

 1.71 

 1.60 

 1.03 

 1.03 

 0.91 



11,581.91 

 50.04 

 9.88 

 0.90 

 0.77 

 0.26 

 0.13 



20,764.30 

 271.28 

 8.26 

 9.30 

 0.76 

 2.26 

 1.16 

 1.56 

 0.98 



122,374.22 



1,966.23 



367. 1 1 



17.55 



3.16 



2.04 



0.76 



0.98 



1.28 



291,104.04 

 279.33 

 65.30 

 1.13 

 0.93 

 0.40 

 0.10 



1.15 

 4.42 

 0.86 

 1.85 

 0.32 

 1.23 

 0.68 

 1.05 

 0.78 



4.36 

 14.43 

 13.92 

 5.12 

 1.85 

 1.28 

 0.74 

 0.95 

 1.41 



25.13 

 5.58 

 6.61 

 1.26 

 1.21 

 1.54 

 0.77 



<0.00I 



<0.10 



<0.001 

 <0.001 

 <0.001 

 <0.001 

 <0.10 



<0.00I 

 <0.001 

 <0.001 



• Statistics based on numbers of chains per aliquot. 



The expression which was ultimately chosen 

 to estimate the precision of single observations 

 was derived empirically from the 5th and 95th 

 percentiles of the frequency distributions. For 

 any single count, x, of a nonrandomly distrib- 

 uted species at a single depth, it was found that 

 the expression 



0.3x ^ X < 3.2a: 



included the observed population mean X 90% 

 of the time. The expression was conservative 



for species with nonaggregated distributions. 

 When all species were considered, the expression 

 included the population mean 95% of the time. 

 The expression gave satisfactory results for es- 

 timates of mean numbers of cells of chain-form- 

 ing species (F -^ 0.13) and for mean total diatom 

 abundances (P — 0.14). 



The use of this expression is demonstrated 

 in Table 3, where it has been applied to two 

 samples from 35-m depth at Subarctic Station 23, 



366 



