The quality of organic matter, or nutrient-containing compounds derived from living things, is variable across the Everglades landscape due to differences in vegetation, geomorphology, and seasonality of hydrology and primary productivity, or the amount of living material produced when nutrients and energy from sunlight are used to create plant tissues. Ecosystem energetics, including the structures of food webs, is influenced by floc (large clumps of organic matter), particulate organic matter (organic matter that is suspended in the water column, and dissolved organic matter (organic matter that is so fine that it floats, nearly invisible, in the water column).
In Phase I of the FCE-LTER project, researchers devoted considerable resources to understanding the sources, fate, and transport of dissolved organic matter (DOM). The scientists developed methods for characterizing DOM and are now able to identify major sources of DOM from key ecosystem components. These methods are being used in Phase II to study DOM. In particular, they are being used to examine the contribution of soil-derived DOM and groundwater-derived DOM to the overall pools of DOM in the estuarine ecotones.