48 



found to be highly correlated with specific conductance and pH 

 (Table 3, Fig. 1). Macrophyte variables were not significantly 

 correlated with water chemistry or morphometric variables, except 

 for percent-area coverage, that had a significant negative correlation 

 with TSI(AVG) (Fig. 2) and log-transformed total P (Table 3). 



Two hundred twenty-three diatom taxa were found in the recent 

 sediments of the survey lakes (Appendix 1). Initially, 125 taxa had 

 life-form preferences described in the literature (Lowe 1974, Patrick 

 and Reimer 1966-1975), but the average percentage of valves with 

 unknown life-form preference was 15.04%. Life-form preferences 

 were assumed for 28 additional taxa (Appendix 1) based on valve 

 morphology. Taxa with a raphe that belonged to genera known to be 

 largely periphytic were assumed to have a periphytic life-form 

 preference. Two small species of Cyclotella and the long, lineate 

 Nitzschia romana and Synedra filiformis var. exilis were assumed to 

 be tychoplanktonic. These assumptions were discussed with Rex L. 

 Lowe (pers. comm.), who believed them to be correct. The new life- 

 form assignments reduced the mean percentage of valves with 

 unknown life-form preference in survey samples to 2.03%. 



TSI(AVG) and pH were negatively correlated with the proportion 

 of periphytic diatoms (Fig. 3) and positively correlated with the 

 proportion of planktonic diatoms (Fig. 4) in surficial samples (Table 

 4). Diatom concentrations and accumulation rates were found to 

 vary as much as 4 orders of magnitude within the study lakes. Log- 

 transformed accumulation rates produced more significant 

 correlation coefficients with environmental variables than 



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