Boulder, Colo.-A new study by the University of Colorado at Boulder ties increased levels of nitrogen and phosphates to deformed frogs. The study says that increased nutrients lead to more snails, which host microscopic parasites known as trematodes. These form cysts on developing tadpoles, thereby causing deformed frogs. Later, water birds eat the frogs, and as a result the trematodes cycle back to the ecosystem via defecation. TFI Vice President of Scientific Programs William Herz told Green Markets that the study is puzzling in light of the timeline. The deformed frogs were not identified until the mid-1990s. He noted that fertilizer use was nothing new in 1990s, but had been a constant for 25 years or more beforehand. He said there is not a strong effect relationship. As a result, he suggested that some other intervening factor must be involved in the complicated cycle in which the parasite must use three hosts ?Çô snails, frogs, and water birds. He noted that frog deformities can be replicated in the lab using pesticides, UV light, and parasitic infection. Regardless, the UC-Boulder study may not soon go away, as the authors see conclusions beyond the frogs. “The research has implications for both worldwide amphibian declines and a wide array of diseases potentially linked to nutrient pollution, including cholera, malaria, West Nile virus and diseases affecting coral reefs,” said Pieter Johnson, assistant professor, CU-Boulder ecology and evolutionary biology department.
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