Frog Deformities
Frogs can develop deformities such as missing or extra limbs from increased nutrient levels in their water, according to a recent University of Colorado at Boulder study. High levels of nitrogen and phosphorous stimulate populations of snails, which host parasites called trematodes. Tadpoles develop cysts from these parasites that result in severe limb deformities. The problem first gained attention in the mid-1990s when Minnesota schoolchildren discovered that more than half of the leopard frogs in a nearby pond had missing or extra limbs.
More Resources
A recent EPA article on frog deformities and nutrient pollution
Pictures from the scientific study
Effects of Stormwater Pollution
This frog grew an extra hind leg because of parasites from excess nutrients in the water.