Tidal wetlands are known to have a significant capacity to alter dissolved ions and gases as water floods and ebbs from these systems. At present we do not have a good understanding if what wetland attributes may be particularly important as predictors of the magnitude of change in water quality. We have examined the change in carbon, oxygen and nutrients for a set of tidal freshwater wetlands of the Hudson River and are relating these changes with vegetation attributes of individual sites.
All sites showed significant differences in water quality for flood versus ebb-tide waters for at least some of the response variables. Typically there was substantial removal of oxygen and nitrogen and generation of dissolved organic carbon. The magnitude of these changes however differed among sites and some variables were more strongly related to vegetation patterns than others. Generation of DOC was related to the extent of cover by a cattail-dominated vegetation cover class which is understandable given the known capability of litter from this cover class to release significant quantities of DOC. In contrast, nitrate removal was not readily predictable by any of the current vegetation attributes despite a large range in magnitude of removal among sites. A trade-off between plant-mediated and microbially-mediated nitrate removal may well explain the lack of a simple predictive relationship. Some fo the vegetation classes are known to be particularly sensitive to anticipated climate change and so we can forecast how some of these wetland functions may change in the future.