NEWS FROM THE STROUD WATER RESEARCH CENTER
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Summer 1999
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Six "blends" of Watershed Tea:
White Clay Creek in the Pennsylvania Piedmont; the Hillsboro River in Florida's Coastal Plain; Rio Tempisquito in the Cordillera de Guanacaste of Costa Rica; Boulder Creek in the Southern Rocky Mountains; White River in the Interior Low Plateaus; and Hyalite Reservoir in the Northern Rocky Mountains.
These provide a broad range of watersheds in which to perform this interdisciplinary study.
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As rain water passes through a forest’s canopy and floor, it picks up an enormous variety of molecules which have been produced by plants, animals and microorganisms. These molecules blend together into a mix of natural organic matter that enters the forest's streams in much the same way that tea flows out of its tea bag into a cup of boiling water.
Just as different spices create different flavors of tea, so individual watersheds produce their own special blends of organic matter. In fact, so specific is each "watershed tea," that migrating fish use the memory of their watershed's particular blend as a beacon to find their way home at spawning time.
The tea also provides a supply of food for bacteria living in the stream. Recent studies at the Stroud Center indicate that each watershed supports a unique community of bacterial species which develop as a result of their ability to use the local food resource. These findings suggest that by studying the activity of microscopic organisms in our watersheds, we may gain important insights into issues ranging from the quality of our drinking water to the processes of global warming.
With more and more water utilities turning to biological filtration in the purification process, the role played by bacteria in the watershed has become increasingly critical to both monitoring and protecting drinking water. The more we know about how bacteria consume organic matter in a watershed, the better we can evaluate biological filtering systems. If those systems are able to impede the growth of bacteria, then water utilities should be able to reduce their dependence on chemical disinfectants.
On a broader level, despite the best efforts of watershed bacteria, a great deal of the organic matter that flows through our streams and rivers ends up in the ocean, where it has a significant aggregate impact on global carbon cycles. Consequently, as we improve our knowledge of how microbes process the matter in their particular watersheds, we should simultaneously enhance our understanding of the factors influencing global warming.
Because of the implications of our findings, the American Water Works Association Research Foundation awarded Lou Kaplan of the Stroud Center and his colleagues, David Stahl of Northwestern University and Patrick Hatcher of Ohio State, a grant to test several hypotheses aimed at understanding the precise components of watershed teas, the species composition of bacterial communities and the critical information on water quality they may provide.
By bridging three distinct disciplines -- biogeochemistry, microbial ecology, and analytical organic chemistry -- within a single experimental framework, this project can address fundamental questions about what happens to organic matter in stream ecosystems and what role specific bacteria play in purifying water. The answers to these questions have important implications for expanding our knowledge of the biological treatment of drinking water. They should also provide fresh insights into the fate of organic matter as it is carried by streams from its terrestrial origin to its oceanic destination. That knowledge, in turn, may tell us much about the future of our planet.
