Underwater Hydrilla Plant Not as Harmful as ThoughtWhen it was discovered in the Potomac River in the early 1980s, the exotic plant Hydrilla verticillata was seen as the ecological equivalent of suburban sprawl. Environmentalists feared that the fast-growing Asian import would crowd out less aggressive native plants that are important sources of food for waterfowl.
But a new study by the U.S. Geological Survey has found that hydrilla is not such a bad neighbor after all. The submerged plant, which can grow to the surface and form dense mats, did not impair the reemergence of native species at a time when officials were working to reduce nitrogen concentrations in the river from sewage-treatment facilities, the study found. Cutting nitrogen levels reduces algae blooms and allows more light to get to the bottom of the river, which in turn permits aquatic plants to grow.
Hydrologists Nancy B. Rybicki and Jurate M. Landwehr of the USGS examined data between 1985 and 2001 in aquatic plant beds in the Potomac.
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