the least amount of lignin influence in both the enriched and reference sites in the benthic

layer, which are accompanied by the greatest amount of apparent N limitation with the

exception of the ROS site. The reference open water site also exhibited the greatest N

and P limitation in relation to C mineralization in both layers. The distinct grouping in

the soil layer reflects primarily changes in P among the enriched habitats and changes in

N among the reference habitats (Figure 3-4). However, this relationship is not evident in

the benthic layer.

 Enzyme Index of Carbon Quality (EICQ) values did not vary in a significantly

consistent fashion along the gradient. However, open water habitat EICQ values were

significantly higher in the benthic layers at both the enriched and reference sites,

indicating greater perceived C quality. EICQ was only weakly correlated with the

benthic nutrient parameters TN and TP as well as soil TN.

 Discussion


 The use of enzyme comparisons, such as Ecell/Ep and Ecell/En, are based on the

premise that the use of energy to produce certain extracellular enzymes reduces the net

energy available for the expression of other enzymes. The relationships between certain

enzyme groups are unique and serve to convey information that is specifically related to

perceived environmental conditions. The MARCIE model components, originally

developed as a relationship to mass loss rates (Sinsabaugh and Moorhead, 1994 & 1996),

may be used as a tool for determining microbial productivity and perceived nutrient

limitations (Jackson et al., 1995; Sinsabaugh and Findlay, 1995; Sinsabaugh et al., 1997).

The use of these models as predictive components in this paper is due to the lack of

corresponding decomposition data provided by litter bags or other means. However,