Twenty-four fresh marsh-wet prairie wetland sites in southwestern Florida were studied with respect to vegetation zonation, substrate characteristics, and morphometry.Six major wetland zones were identified.The Hypericum zone occupied the shallowest position (closest to the upland edge) and was confined to ~andy substrates.The Panicum-Rhynchospora zone typically followed downslope and was also associated with sandy substrates.The Mixed Emergent, CLadium, Cephalanthus and Fraxinus-Salix zones all occurred on organic soils in wetland interiors.In addition to depth and substrate type, other important determinants of zone composition included fire and disturbance due to feral hog rooting and cattle grazing.

Two artifici~l marsh/pond systems with a combined area of 21 ha were studied during a one-year period.Since their construction in 1978, volunteer plant colonization has resulted in a shifting mosaic of cattails (Typha spp.), water pennywort (Hydrocotlye umbellata), frog's-bit (Limnobium spongia), duckweed (Lemna spp.}, and other less abundant species.At least 45 bird species were observed to use the wetlands during this study with very dense populations no£ed for several wetland-dependent species.Alligators, fish, turtles, and snakes were abundant in the ponds.The ponds operate a5 flow-through systems, receiving an average treated wastewater application of 4.8 cm per week. Mass balances indicated significant percent removals for biochemical oxygen demand [82 %), total suspended solids (80 %), and total nitrogen (93 %).Removal of total phosphorus was lower, averaging 31% over the one year study.

Carolina bays are oriented, elliptical land forms of uncertain origin, present over much of the Atlantic coastal plain, and most heavily concentrated in the Carolinas. Ten Carolina bays in Horry County, South Carolina, were studied in an effort to determine their suitability for municipal effluent advanced treatment and disposal.Field studies included vegetation mapping, inventories of threatened and endangered species, substrata cores, and water quality analyses. Reported treatment efflclencies and characteristics of othel natural effluent disposal sites were compared with the observed properties of the Carolina bays in order to predict effluent treatment potential and vegetational changes.

Approximately 2650 m~/day of secondarily-treated efflt~ent is currently discharged into a 206 ha mixed hardwood swamp located south of Jacksonville, Florida.In the early summer of 1981, a study was conducted to assess (i) whether the swamp was s~tisfactorlly assimilating the present discharge, and (2) whether the swamp ecosystem was suffering significant adverse impacts due to the discharge.Intensive field sampling coincided with a period of extended drought.The study plan included examination of water chemistry and vegetation at the receiving swamp and at four nearby control swamps not receiving scco:~dary effluent.The major outflow of the receiving swamp differed significantly from outflows of the control swamps in concentrations of total nitrogen, nitrate-nitrite nitrogen, total and dissolved phosphorus, and specific conductance.Based on flow measurements and mass balance c~lculations, the receiving swamp achieved nutrient "removal" rates of 87.0% (26.1 kq/day) for total nitrogen and 62.0% (8.8 kg/day] for total phosphorus.Data indicated that much of this removal occurred throuqh infiltration.Field investigations indicated that swamp vegetation stresses were present at the receiving swamp and at one of the control swamps.