Herbicides & Amphibians

Amphibians are impacted by herbicides.

Chemical herbicides are essentially poisons used to control unwanted plant life. They are highly toxic to plants, which is why they are so effective at eliminating weeds. In humans, herbicide chemicals have been found to produce a range of harmful effects, including mild irritations, acute poisoning symptoms and long-term health problems. Further research is needed to fully assess the impact of these chemicals on the environment, but there is concern that runoff from these chemicals can enter local water sources and damage wildlife. Amphibians are one group of organisms that appear to be especially affected by environmental contaminants.

Amphibians

Amphibians react to changes in the water they live in.

Common amphibians include frogs, toads and salamanders. Some amphibians, like frogs and toads, are born with gills and begin life in the water, inhabiting streams and ponds. As they mature, these animals shed their gills and develop legs, allowing them to live the remainder of their life on land. Other amphibians spend their whole lives in the water. Because water is an essential element in the growth and development of these creatures, they are among the first to respond to changes in their aquatic environments.

Amphibian Declines and Malformations

Since the 1990s, there have been a disproportionate number of extinctions of amphibian species and it is estimated that 43 percent of the remaining species are experiencing population decline. Since the 1990s, many amphibian populations have been found to exhibit a variety of malformations, including missing limbs, missing eyes, extra limbs, under-formed limbs and hermaphroditism. Environmental contamination is speculated to be one cause of these deformities, according to the National Biological Information Infrastructure website.

Contaminants, Malformation and Herbicide

Many associations have been made between amphibian malformations and pesticides, because the prevalence of malformations seems to increase when the amphibians' environment is near an agricultural site. According to the Pesticide Action Network, studies found chemical compounds used in herbicides and fungicides to be more prevalent in California groundwater than other agricultural chemicals. Because these chemicals can be absorbed by groundwater, they are more likely to become present in the ponds and streams where amphibians live.

Effects of Herbicide Chemicals

Extensive research has been conducted on the effects of specific chemicals on various organism groups, including amphibians. Several chemicals found in herbicides have been labeled as known or potential groundwater contaminants. These chemicals have been found to affect the behavior, development, physiology, reproduction, biochemistry and immune systems of amphibians. These findings appear to support the theory that herbicide run-off has contributed to the changes in amphibian populations.

Other Factors

Groundwater contaminants are probably only one in a series of environmental factors affecting amphibian populations world wide. Climate change, radiation, habitat destruction and/or alteration and disease have all been proposed as causes for amphibian malformations and declining populations. A fungal disease called chytridiomycosis is thought to be an especially serious threat to amphibian populations.

Helping Out

Report any malformations you find in amphibians.

While frogs and salamanders may not seem like a particularly important part of your life, they act as an ecological barometer and their reactions to environmental changes could have far-reaching implications. You can provide researchers with valuable data by reporting any amphibian mutations you observe to the North American Reporting Center for Amphibian Malformations (see Resources). Whenever possible, avoid the use of chemical pesticides and/or fertilizers on your lawn and garden.

References

• UCMP: Life, History and Ecology of Amphibia
• AmphibiaWeb: Worldwide Amphibian Declines
• National Biological Information Infrastructure: Amphibian Malformations
• PAN Chemical Database

Resources

• Report a Malformation