Because amphibians are good indicators of environmental health, scientists suspect their sudden disappearance is a sign of a larger global problem that could threaten all of biodiversity, humans included. If frogs begin showing signs of distress, it could be only a matter of time before other species are affected, including humans. The causes for amphibian declines seem to be working at both local levels and global levels. Amphibians are often eliminated when game and baitfish are introduced into wetlands, ponds, and lakes. Many of these introductions are propagated by fishery departments, fishing enthusiasts, and citizens who buy fish for stocking.
Habitat loss is another contributing factor in amphibian population declines.
Frogs are dependent on wetlands for breeding, and throughout their lives. When wetlands are developed and destroyed, amphibians suffer.herbicides has been shown to harm amphibian eggs and juvenile amphibians. Many of the sites in which deformed amphibians have been found are close to agricultural fields. These chemicals can interfere with embryonic development and thyroid functions in amphibians and their eggs. The northern leopard frog is one species that has been adversely affected by agricultural pollution and runoff.