Recent studies in steam ecology have indicated that stream sediments support a biologically active community. This community is connected to the surface stream by vertical currents that transport substances such as nutrients and organic matter between these two areas. Even when the stream appears "dried up", flow may continue beneath the sediment surface; thus, biological activity can continue in this "hyporheic zone" during drought. While it is know that the hyporheic zone is biologically active; the source of energy supporting these activities is unknown. The goal of this research is to determine how the hyporheic zone is "fueled" on a seasonal basis and between flood- disturbance events. A combination of field measurements and experiments will be conducted to test several hypotheses explaining the economy of this ecological system. Chief among these are that organic matter is derived from surface photosynthesis and transported either as dissolved or particulate material deep into the hyporheic zone. An alternative is that organisms of this depend on material derived from the terrestrial watershed (e.g. leaves, twigs, decomposed wood) and transported to the stream channel during flash floods. A better understanding of the hyporheic zone as part of the larger stream ecosystem will aid in managing this resource wisely and in extending environmental protection to all functional components of the ecosystem, including subsurface and groundwater elements.
