The role of periphyton in nitrogen and phosphorus cycling in the Amazon floodplain will be investigated. Lowland floodplains of large rivers like the Amazon are sites of the highest biological productivity within the river system. A key characteristic of floodplains that leads to their high productivity is nutrient retention. Periphyton is conjectured to be important in nutrient trapping and recycling in the floodplain. Periphyton is also thought to be an important source of labile carbon and nutrients to the open waters of the Amazon. The carbon and nutrients derived from periphyton in turn are thought to be important in the support of the large secondary production of open waters, including fish production. The importance of periphyton in the Amazon floodplain will be studied using state.of.the.art techniques. For example, tritiated thymidine will be used to determine microbial activity. The importance of periphyton as an energy source for open.water food chains will be determined using stable isotopes. And the results from site.specific studies will in extrapolated to larger scales with the aid of remote sensing technologies. A variety of these technologies will be used including LANDSAT TM (30X30 m resolution) and synthetic aperture radar (SAR). The remote sensing technologies will help to establish the extent of floodplain habitat. The significance of this research is that it will help us to understand what role the floodplains play in the operation of large river basins in the tropics. These areas are under increasing development pressure from the expanding human population. The importance of floodplains in these systems is often ignored. This research should provide documentation of this importance and provide a scientific basis for wise management of this resource. Drs. Fisher and Melack have good records of productivity working in this very difficult field environment. The institutional support available to them is superior.
