Abstract of Dissertation Presented to the Graduate School 



of the University of Florida in Partial Fulfillment of the 



Requirements for the Degree of Doctor of Philosophy 



DIATOMS AS INDICATORS OF HISTORICAL 

 MACROPHYTE BIOMASS IN FLORIDA LAKES 



By 



Thomas James Whitmore 

 May 1991 



Chairman: Frank G. Nordlie 

 Major Department : Zoology 



Macrophytes represent an important component of primary 

 production in lakes that is usually ignored in trophic state 

 classification. Trophic classifications traditionally emphasize water- 

 column nutrient concentrations and phytoplankton biomass. 

 Predictive models have been developed from diatom assemblages to 

 assess historical changes in lake trophic state, but these models 

 usually infer water-column total P or chlorophyll a values and thus 

 also ignore macrophyte production. Lake-sediment core samples 

 often indicate former periods of low trophic state, although these 

 periods may instead represent low water-level events that 

 periodically occur in Florida lakes. Because macrophyte biomass is 

 negatively correlated with water-column nutrients, macrophyte 

 biomass may have been high at times when nutrient inferences 

 suggest that lakes were unproductive. 



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