g 

 > 



a 



2 30000 







t 



N = 48 



r 2 =. 75 



SR = P-=.0l 



—i 1 1 1 1— 



2 3 4 5 6 



SETTLING VOLUME (ML) 



Figure 3. --Correlation of zooplankton settling volume with the number of 



individuals counted in the sample. Results are given for regression analysis 

 (r^) and Spearman Rank Correlation (S.R.). 



Caloric determinations were made on six freeze-dried (10.5-15.5 mg) samples 

 of zooplankton (all dominated by copepods) using a microbomb calorimeter (Tinkle 

 and Hadley, 1973). Samples of known volume were ashed at 450°C for 5 hr for 

 ash weight determination. Samples of known settling volume were freeze dried, 

 weighed, and the weight/individual calculated using the mean value of 1.6 x 10"^ 

 individuals/ml settling volume determined from a count of individuals from 30 

 samples of known settling volume. Samples consisting of 20-30 individuals were 

 removed and weighed on a Cahn Electro-balance for an independent estimate of 

 individual weight. 



In addition to volumetric determinations on all 392 samples, 56 of the 

 zooplankton samples from 7 nights at the 3 reef sites were enumerated. 



RESULTS 



Differences in the "packabil ity" of species may result in difficulties in 

 interpreting settling volume data. However, the dominance of a single species 

 and the general similarity in morphology, size, and composition of species in 

 these samples made volume determinations a relatively easy method by which to 

 compare sites. As illustrated in figure 3, the number of zooplankton is 

 positively correlated (Spearman Rank Correlation, p < 0.01) with the settling 

 volume of zooplankton. 



104 



