Why is MPCA involved?
Dr. Helgen and Mark Gernes at MPCA are involved in the investigation of deformed frogs in Minnesota because they are developing a biological index for wetlands water quality using invertebrates and amphibians. Gernes and Helgen were involved in the investigation of deformed frogs reported in the area of Granite Falls in 1993 after the flood of 1993.
How did this get started?
Cindy Reinitz, a teacher at the Minnesota New Country School, and her students discovered the deformed frogs. They have greatly assisted the investigation by making collections of the frogs and by reporting their observations, e.g., on where frogs may go to overwinter.
Why are frogs biological indicators of environmental condition?
Their life cycle requires them to reproduce in shallow, small (Type I, II, or III) wetlands that dry down or winterkill so they are fishless. Frogs could be exposed to a toxicant as tadpoles in the small wetland, as adults feeding on the landscape, and in the deeper water of the overwintering lake or river. Frogs integrate the landscape over time and space.
Where have deformities been observed this year?
We have confirmed large numbers of deformed frogs in the area near Henderson Minnesota on both sides of the Minnesota River, and a site in Meeker County northeast of Litchfield. Unconfirmed reports have been made from just south of Litchfield and from near Brainerd. One or two deformed frogs have been reported from north Mankato, near Elk River, Silver Bay and Rainy River, but these reports have not been confirmed by collections.
Are they mutations?
It is more likely that these are developmental abnormalties than heritable mutations. It would be unlikely to have populations of frogs with heritable deformities suddenly appearing in such high numbers and in several locations.
What could be causing this?
There are many kinds of agents from certain heavy metals to older types of pesticides, maybe even a parasite that might cause such defects in young frogs. The agent could have been in the eggs at a very early stage or ingested by the tadpoles.
What is being done to figure this out?
Helgen and Gernes are working with several cooperating labs that are providing analysis on sediments and water and frogs. Dr. McKinnell at the U of MN is working closely with the MPCA. The frog tissues will be analyzed for several contaminants. This research will take three to four months to complete and analyze. The investigation should be continued next spring, to do this funding will need to be acquired.
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