multivariate techniques, some interpretations may be explored even when the 
assumptions are not met. Generalized distances are determined in discriminant 
analysis and the maximum distances for the microcosms and the bay for the 
first axis in Figure 24-8 and Table 24-6 are shown in Table 24-7. These distances 
are much smaller among the replicated microcosms than among bay stations. It 
seems feasible to consider that standard generalized distances exist for natural 
systems, for specific variable sets, which might be compared to generalized 
distances which result during experiments on perturbation and subsequent 
recovery in microcosms. 
Table 24-7. Maximum Generalized Distances and 
Normalized Distances Among the Microcosms and Among 
Bay Stations from August to December 1976 and 1972 
Respectively, from the Discriminant Analysis Shown in 
Figure 24-7 and Table 24-6. 
max 
Normalized 
D-j max 
Microcosms: 
2 vs 3 
0.9 
3 
2 vs 5 
0.7 
2 
2 vs 9 
0.3 
1 
3 vs 9 
0.6 
2 
Bay Stations: 
Prov. River vs mouth E. Passage 
4.4 
14 
Ohio Ledge vs mouth E. Passage 
3.0 
9 
Ohio Ledge vs mouth W. Passage 
1.9 
6 
CONCLUSIONS 
The nine MERL microcosms operated during the 4-month replicability 
study were generally as similar to each other as they were to adjacent areas of 
Narragansett Bay using nutrient and phytoplankton data sets for comparison. 
Zooplankton abundance in the MERL microcosms was somewhat low but 
this was probably caused by an artifact that can be removed. 
Multivariate statistical techniques seem essential to the comparison of the 
large and heterogeneous data sets generated in such studies as this. 
379 
