Multivariate statistical analysis of the factors controlling the distribution of scaled chrysophytes

A total of 332 collections from 62 water bodies was analyzed for scaled chrysophytes with electron microscopy and correlated with limnological characteristics. The pH and specific conductance were the most important factors controlling the distribution of scaled chrysophytes; temperature and total phosphorus were of lesser importance. A mean of nine and seven taxa per collection were recorded at a pH of 5.5-6.0 and a specific conductance ~40 $S, respectively. Significantly fewer taxa per collection were found as the pH lowered below 5.5 or raised above 6.0 or as the specific conductance increased above 40 $S. Similar distributional patterns were found for the genera Mallomonas, Synura, and Spiniferomonas. A two-factor principal component model explained 70% of the total variance within the data set (n = 1,355). The first principal component explained 80 and 83% of the total variance within the pH and specific conductance variables. The pH and specific conductance also dominated the first principal component for each genus and for 23 of the 25 species tested. A cluster analysis, using within-group linkages, produced five groups of organisms that differed primarily with respect to their distribution along a pH gradient.