|Session II: Environmental Management
||Abstract #: 97205
THE L-31E FRESHWATER REDIVERSION PILOT PROJECT
Jack Meeder, Mike Ross, Pablo Ruiz and Guy Telesnicki
Southeast Environmental Research Program, Florida International University, University Park, Miami, FL 33199
Freshwater from South Dade presently is discharged directly into Biscayne Bay via theMowry Canal. In addition to the adverse impacts of this historic change in quantity, quality, andtiming of water delivery to the Bay, nearly all of the sheet flow and transverse glades flow to theBay has been curtailed by the construction of the storm tide levee (L-31E). Loss of the historicsheet flow to the Bay has resulted in westward expansion of salt marshes to the foot of the L-31Estructure and has reduced productivity and natural organic carbon export to the Bay.
The major objective of this study is to document the effects of the freshwaterrediversion on both the coastal wetlands and adjacent Biscayne Bay benthic communities. Nutrient loading to both the wetlands and nearshore bay ecosystems is the major concern.
The study employs a BACI design, employing two blocks of 20 ha. Our approach isbased upon an ecosystem process model in which we attempt to quantify the major pathways ofnutrient movement in the system and changes in storage of the different ecosystem components. Vegetation, soils, interstitial soil waters, surface and groundwater, benthic communities andmicrobial processes are all addressed. In addition, hydrologic parameters, climatic factorsincluding evapotranspiration, and flux from natural tidal channels are also being quantified.
Two major complications have occurred. The project was funded prior to HurricaneAndrew and therefore the litter load and extreme mortality of trees in the fringing environmentwas not anticipated. Therefore, litter decomposition studies have been initiated to address the nutrient release from mangrove wood, as well as other aspects of perturbation and recovery. Inaddition, a January 1996 freeze selectively killed most of the trees in the control scrub site, furthercomplicating the eventual analysis of the control versus treatment results.