generally higher at the reference habitats in the soil layer and were within the ranges of

reported activities in the Everglades (Wright and Reddy, 2001b) and other systems

(Sinsabaugh and Linkins, 1990; Sinsabaugh et al., 1992b). Another study found no

significant changes in phenol oxidase activity along the gradient in WCA2A in the

Everglades (Wright and Reddy, 2001). The positive correlation of soil PHE with LEU

suggests that a greater proportion of N may be in recalcitrant form. Soil PHE was also

negatively correlated with TOC. There was not a significant trend of decreasing phenol

oxidase activity with depth.

 Overall normalized hydrolytic (EThyd) and hydrolytic plus oxidative (EThyd+ox)

enzyme activities in the benthic layer exhibited mixed relationships with the gradient and

among habitats (Table 3-5). EThyd values were within the range reported in a previous

study of a riverine system (Sinsabaugh et al., 1997). EThyd and EThyd+ox in both the cattail

and open water habitats were significantly greater at the enriched sites. However, there

were no consistently significant differences between habitats. The differences between

the EThyd and EThyd+ox values demonstrate the contribution of apparent lignin degradation

to the overall enzyme activity. The reference open water benthic layer (ROB) exhibited

the smallest contribution of oxidases to the overall enzyme activity (7%) while the

reference sawgrass habitat soil layer (RSS) showed the greatest (37%). The contribution

of normalized enzyme activities are illustrated in radar plots for the benthic and soil

layers (Figure 3-1) for visualizing the relationships presented for the calculated MARCIE

model components. It is interesting to note that the shapes of the radar plots for each

layer are similar in both the enriched and reference sites. However, energy allocation

does appear to be different in the soil versus benthic layers.