Tidal Freshwater Wetlands: The Fresh Dimension of the Estuary

Abstract

In the upper reaches of estuaries where rivers end, the constant input from the river creates permanent fresh water conditions even though tidal energy is still present. The physical, chemical and biological conditions differ from the brackish part of the tidal area due to the interaction of the tidal wave with the river ecosystem. Just like in the brackish estuary, tidal freshwater wetlands exhibit gradient variation from tidal flats to higher elevated forests. Chemical processes and accretion are prominent, creating wetlands with high turnover. Many tidal freshwater wetlands have been historically reclaimed for human use as cities, ports, and for agriculture. A diverse flora and fauna is represented and biomass in tidal freshwater wetlands is mostly very high. Because this system is at the interface of salt – fresh conditions, tidal freshwater wetlands are particularly susceptible to sea level rise and global warming.