61 



Results of Cluster Analyses 

 Cluster analysis based on the percentage data for 47 taxonomic 

 groups produced 16 clusters of taxa. Nine of these clusters 

 ^K demonstrated significant correlation coefficients with TSI(AVG), and 



i^ ' six clusters showed significant correlations with pH (Table 6). Four 



clusters that were correlated with TSI(AVG) and pH also showed 

 significant correlations with specific conductance. Three clusters 

 were correlated with both lake surface area and shoreline length. 

 Mean depth and shoreline development were each correlated with 

 single separate clusters. Of the 80 correlation coefficients between 

 diatom clusters and macrophyte variables, only two were significant, 

 one with percent-volume infestation, and one with emergent 

 biomass. Navicula papula vars. (S-NAVPU) and Stauroneis spp. (S- 

 STAU) were the taxonomic groups in the cluster correlated with 

 percent-volume infestation, and these were included among the pool 

 of independent variables (Appendix 3.1) in a stepwise procedure to 

 construct a model that predicts percent-volume infestation. Caloneis 

 sp. A and Navicula seminulum vars. (S-NAVSEM) were the taxonomic 

 groups correlated with emergent biomass, but this correlation was 

 driven by a single datum because both species showed anamalously 

 high percentages in Crooked Lake. 



Due to the overwhelming influence TSl(AVG) and pH had on 

 composition of taxonomic clusters, cluster analysis using taxonomic 

 percentages was repeated while partialling out the effects of pH and 

 TSI(AVG). Fourteen diatom clusters resulted from this procedure. 

 Seven of the clusters still demonstrated a significant correlation with 

 TSI(AVG), and six of these had significant correlations with pH. Two 



