FISHERY BULLETIN: VOL. 83, NO. 2 



turnal, prestorm; three diurnal, poststorm 

 (excluding the 6 April profile); and three noctur- 

 nal, poststorm. In order to give each profile w^ithin 

 a set equal weight and to restrict attention to 

 vertical relations, we arranged data from each 

 profile in order of increasing concentration of 

 chlorophyll; next ranked the samples in order of 

 increasing abundance of the taxon of interest; 

 then calculated the Kendall's tau coefficient as a 

 measure of correlation between that taxon and 

 chlorophyll within each profile; and finally calcu- 

 lated the coefficient of concordance between the 

 rearranged ranks of the taxon in the three profiles 

 of a set as a measure of agreement on a common 

 tendency (see Mullin and Brooks 1972). We then 

 defined a persistent relation between a taxon and 

 chlorophyll in one full set of profiles as requiring a 

 significant {P ^ 0.05) concordance between the 

 individual profiles of the set, tau coefficients of all 

 profiles of the same sign (positive or negative), and 

 at least one of the tau coefficients significant (P ^ 

 0.05). 



No persistently negative relations were found 

 between any taxon and chlorophyll in any set of 

 profiles. In the diurnal, prestorm set, naupliar 

 Acartia, naupliar Calanus, copepodid and adult 

 Acartia, and appendicularians were all positively 

 related to chlorophyll, and CI-CIV Calanus 

 tended in this direction. These relations all van- 

 ished at night by our criteria, though naupliar 

 Calanus tended to retain a positive association. 

 After the storm, the strength of the diurnal, posi- 

 tive relations of naupliar Acartia, copepodid and 

 adult Acartia, CI-CIV Calanus, and appendicula- 

 rians increased, and naupliar "Paracalanus" also 

 had a positive relation. At night after the storm, 

 all taxa except naupliar "Paracalanus" , CV and 

 adult Calanus, Metridia, and Pleuromamma had 

 positive relations with chlorophyll. Thus, contrary 

 to expectations, after the storm there were more 

 positive relations between these particle-grazing 

 taxa and the concentration of their food, measured 

 as chlorophyll. 



We reached a similar conclusion for the ciliates, 

 Laboea and Lohmanniella; neither were persis- 

 tently related to the vertical distribution of 

 chlorophyll before the storm, but both were posi- 

 tively related after the storm by our criteria. Since 

 fewer profiles for these protozoans were counted, 

 we did not separate night from day in searching for 

 the correlations. 



Such correlations can also show seasonal vari- 

 ability; for example, Fiedler (1983) found strongly 

 positive correlations between the vertical dis- 



tributions of chlorophyll, Paracalanus, and 

 Penilia avirostris (a cladoceran) in October, but 

 strongly negative correlations between these zoo- 

 plankters and chlorophyll in May; Ctenocalanus 

 vanus showed a seasonal reversal of its relation to 

 chlorophyll in the opposite direction. 



In spite of the increased correlation after the 

 storm between particle-grazers and their food, 

 there is some evidence that the poststorm grazing 

 pressure on phytoplankton was less than that pre- 

 storm. The ratio of chlorophyll to phaeopigments 

 in the water column is an indicator of the ratio of 

 living phytoplankton to the fecal material of graz- 

 ers, and hence is inversely related to the grazing 

 pressure per unit phytoplanktonic crop (Lorenzen 

 1967). The chlorophyll/phaeopigment ratio was 

 significantly greater (P < 0.05 by rank sum test) 

 after the storm, indicating a reduction in grazing 

 relative to the available crop. 



We derived a second indicator of the effect of the 

 storm on relations between phytoplankton and 

 zooplankton from a study of egg production of the 

 copepod, Paracalanus parvus, and chlorophyll 

 and particulate nitrogen in the Southern Califor- 

 nia Bight (Checkley 1980b). Checkley found that 

 the nitrogen in phytoplankton was the best mea- 

 sure of fecundity-stimulating food, that about half 

 the chlorophyll retained on a fiberglass filter was 

 in particles >5 pim, and that the weight ratio of 

 nitrogen in phytoplankton to chlorophyll was 12. 

 From these relations, the egg production of 

 Paracalanus is food-limited where the concentra- 

 tion of total chlorophyll is below 1.3 /xg/1. By this 

 standard, only 18% of the upper 50 m contained 

 sufficient food for maximal egg production prior to 

 the storm, while 34% of the water column met this 

 criterion afterwards. 



This conclusion is likely to be qualitatively cor- 

 rect unless the size distribution of phytoplankton 

 was altered markedly by the storm, or the breadth 

 of the copepods' diet with respect to nonphyto- 

 plankton was changed. Neither of these sources 

 of error is particularly likely, since the ratio of >5 

 /i,m to total chlorophyll agrees with earlier results 

 in the Bight (Mullin and Brooks 1976) and since 

 the range of the data from which Checkley de- 

 duced the importance of chlorophyll in regulating 

 egg production included all but one of the concen- 

 trations of chlorophyll we measured. 



Further, the vertical distribution of adult and 

 copepodid "Paracalanus" was positively corre- 

 lated with that of chlorophyll after the storm and 

 at night (see above). If this finding applies to 

 female "Paracalanus" by themselves, a consider- 



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