SS3.16 Lentic-Lotic Linkages in Freshwaters: Comparisons from Different Ecosystems
Date: Monday, June 10, 2002
Time: 2:00:00 PM
Location: Colwood
MelackJM, University of California, Santa Barbara, USA,
Floodplains are important components of the biogeochemistry, ecology and hydrology of large river systems because they modify riverine discharge and chemical composition, and are significant sources of organic matter to neighboring waters, greenhouse gases to the atmosphere and fish to humans. Multiple interfaces with differing exchanges occur in these systems: river-floodplain, upland stream-floodplain, inter-floodplain units, intra-floodplain habitats, sediment-overlying water, groundwater-floodplain, epilimnion-hypolimnion, atmosphere-floodplain. Examples illustrating these interfaces and exchanges will be provided from floodplains of South America. Characterizing the temporal changes in areal extent of these ecosystems is critical to regionalization of their biogeochemical processes. Recent advances in active and passive microwave remote sensing provides much of the needed information on inundation and aquatic vegetation. For example, combination of such remote sensing data with extensive measurements of dissolved carbon dioxide for the central Amazon indicates that evasion to the atmosphere of carbon dioxide is about ten times the fluvial export of organic carbon by the Amazon River. The organic carbon fueling the evasion is largely derived from riparian and floodplain vegetation, illustrating the importance of terrestrial-aquatic-atmospheric exchanges in floodplain systems.