Statistical methods (principal component analysis)
Multivariate statistical analyses (R-mode factor analysis and
Q-mode cluster analysis) were applied to the statistically signif-
icant fractional abundance values. Statistically significant gen-
era were considered as those with abundance P5% even in one
sample or 2% in at least 2 samples, (Schmiedl et al., 1998). Q-
mode cluster analysis was performed by using Ward’s method
(Schubo¨ and U¨hlinger, 1986) using Euclidean distance as sim-
ilarity index. Factor analysis is a multivariate statistical tech-
nique that is used to compile applied data set to a few main
components (factors) that represent the relationship among
sets of many interrelated variables.
R-mode factor analysis was carried out on the benthic for-
aminiferal data set, using the program Statistica, V.5.1 (1996).