conclusions. Collins et al. (1987), for instance, compared macrophyte 

 biomass density with 13 different chemical, physical and biological 

 variables at various sites in Lake George, NY. They concluded that 

 water depth was the most important factor affecting macrophyte 

 biomass, and that substrate type and eutrophication status were of 

 secondary importance. Canfield and Hoyer (1988) studied the 

 influence of light and nutrient availability on macrophytes in Florida 

 streams, and they concluded that nutrients do not regulate the 

 abundance of macrophytes. Shading of macrophytes was the most 

 important factor regulating macrophytes in that study, while 

 substrate type, water depth and current velocity had a secondary 

 influence. Jackson and Charles (1988) studied macrophyte species 

 composition in 31 small, unproductive lakes in New York that were 

 low in specific conductance. They concluded that pH was the 

 regulating factor, that area, slope and substrate composition were of 

 secondary importance, and that macrophyte distribution bore no 

 relation to trophic state indicators. Crowder et al. (1977) concluded 

 that specific conductance was as important a macrophyte 

 determinant as pH in their study on circumneutral to hardwater 

 lakes. Duarte and Kalff (1990) determined that alkalinity and slope 

 were the most important factors in their study, but they explained 

 the discrepant conclusions between studies as the result of 

 differences in scale of analysis. When macrophytes are compared 

 between lakes in hardwater areas, water chemistry, including 

 specific conductance and trophic state are bound to be important 

 determinants of macrophyte disribution (Duarte and Kalff 1990, 

 Jackson and Charles 1988). Surveys of unproductive, dilute lakes 



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