Acid rain and other atmospheric contaminants in rainfall or concentrated in spring snowmelt. Heavy metals, such as mercury, which bio-accumulate in aquatic food webs Widely used toxic chemical contaminants, including pesticides and synthetic fertilizers. Much new scientific research is pointing to toxic chemical contaminants, such as pesticides, as the major culprits. The unique physiology of the frog makes it highly vulnerable to synthetic chemicals in the frog s aquatic environment. Most of a frog s complex life cycle in spent in or near water.
Frogs have permeable skin that both breathes and takes in water.
Whatever chemicals frogs encounter are readily absorbed through their skin, at all life stages. Frog eggs laid in water absorb many times their weight in water as they puff into gelatinous blobs. Newly hatched larvae pump water through internal gills, absorbing oxygen and whatever natural and synthetic chemicals are present. In addition, water passes through the skin of tadpoles. Organic pollutants including pesticides can cause deformities Over the past fifty years persistent organic pollutants have become distributed globally.