|Mangroves and periphyton in the Taylor Slough ecotone
FCE-LTER scientists are studying the interaction of increased fresh water flow resulting from restoration and increasing pressure from sea level rise on the productivity of plants, such as sawgrass and mangrove trees, in the estuarine ecotone. Primary production has been shown to be higher in the estuarine ecotones than in the nutrient-poor upstream marshes of the Everglades. In the Shark River Slough ecotone, this was found to be due to mixing with phosphorus-rich marine waters, while in the Taylor Slough ecotone, the source appears to be phosphorus-rich groundwater. In Phase III of the FCE-LTER project, researchers are examining how the balance of fresh and marine water supplies regulates primary producer composition and productivity through interacting effects on P availability, salinity, and inundation (flooding). They believe that fresh water will enhance oligotrophy by pushing the relatively phosphorus-rich marine water away. On the other hand, sea level rise may increase productivity by bringing more phosphorus-rich surface and groundwater to Shark and Taylor Rivers, respectively. Increased salinity may also reduce the production of sensitive freshwater species like sawgrass in the estuarine ecotone.
Photo by Evelyn Gaiser
How do these factors affect people in south Florida?
Primary producers form the structure that can help buffer coastal areas during extreme events, like hurricanes, remove excess nutrients and contaminants from water, regulate air quality and provide a mosaic of food and habitat for a diversity of other organisms. They also provide an indication of the status of the ecosystem - their distribution and production are affected by water use and management. By measuring their productivity along with important water quality and quantity parameters along the freshwater-to-marine gradients, researchers can determine causes for changes in productivity that can be used to guide human activities in a way that preserves the important ecosystem services delivered by this feature.