LOXAHATCHEE WATERSHED CONCEPTUAL ECOLOGICAL MODEL

Historically, the Loxahatchee River watershed included an area of more than 560 km2. The drainage basin was comprised primarily of pine flatwoods interspersed with cypress sloughs, hardwood swamps, marshes, and wet prairies. Rain falling on the basin was directed through natural topography into wetlands, treated by natural biological and chemical action, and slowly released to the receiving water bodies, the Loxahatchee River and Estuary and the Indian River Lagoon. Today, approximately 434 km2 of the original watershed drain to the Atlantic Ocean through Jupiter Inlet. The watershed still includes substantial amounts of upland, freshwater wetland, riverine, and estuarine habitats, but large areas have been developed for urban and agricultural land uses. Development in the watershed, stabilization of the inlet, and dredging of the estuary and river have resulted in saltwater intrusion in the river, destruction of riverine cypress forest along the river, and upstream migration of seagrasses and mangroves. A conceptual ecological model, in the risk assessment framework, was developed for the Loxahatchee system to characterize the wetland, riverine, and estuarine components of this complex and diverse system. This model was developed as a means to build understanding and consensus among scientists and managers regarding the linkages between ecological stressors and attributes in the Loxahatchee river system. These relationships lead to development of a set of working hypotheses that explain how observed shifts in the distribution of riverine floodplain plant communities, oysters, seagrasses and other key species are related to increases in salinity in the river and estuary that have occurred during the past century in response to changing land use, climate change and water management practices. Basic and applied research is needed to address questions related to ecosystem structure and mechanisms that control the abundance and distribution of plants and animals in this system.