Amphibians / Reptiles
Impacts of Pesticides on Amphibians
Amphibians can be indirectly exposed to pesticides through runoff from land that has been treated with pesticides, and even through skin contact with contaminated soil. A 2013 study published in PloS ONE found that amphibians are vanishing at a rate of about 3.7 percent each year, which means that they will be absent from half of the habitats they currently occupy in about 20 years.
African Clawed Frog. Photo by Brian Gratwicke.
- The hermaphroditic changes range from males turning fully into females, to still being biologically male but having a loss of interest in reproduction and a lack of sperm, and sometimes even to mating with other males instead of females.
- Exposure to atrazine essentially “chemically castrates” amphibians – impeding their ability to mate and reproduce.
- A 2014 study published in Environmental Pollution demonstrated that frogs accumulate measurable body burdens when exposed to soil that has been treated with pesticides such as imidacloprid, atrazine and fipronil.
- In 2013, biologist Jason Rohr, PhD, studied the effects of atrazine on the immune system of amphibians and found that exposure to atrazine lowers immune functioning, leaving frogs susceptible to death from a certain fungal disease, Batrachochytrium dendrobatidis. This fungal disease, commonly known as chytrid fungus, is devastating amphibian populations across the world. Research has shown that the fungus has been in existence for a long time, but our changing world has created an environment that leaves amphibians vulnerable to the disease. As stated above, pesticides can play a large role in creating this vulnerability.
- Researchers in Germanystudied two chemicals commonly used in orchards and on grains, and found a 100% mortality rate when frogs were exposed to doses recommended on the label.
- In 2012, University of Pittsburgh researchers have found that the use of the weed killer Roundup, which contains the active ingredient glyphosate, in sub-lethal and environmentally relevant concentrations causes two species of amphibians to change their physiological shape by interfering with the hormones of tadpoles.
|Quinbi Village, Island of Matzu. Photo by Prince Roy.|
Amphibians provide essential services for human society. They provide food provisioning services to humans and other wildlife, and have shown promise for medical use – secretions from frog skin have been shown to inhibit the transfer and spread of HIV. Some amphibians can inhibit the spread of mosquito-borne diseases through predation. They are prominent in some religions and mythology, providing cultural services. Finally, they are essential to regulating ecosystem structures, through nutrient cycling and the alteration of physical habitats. Unfortunately, it can be difficult to quantify how to put a number value onto ecological services, as there is not enough research to place a definitive economic value on all of these services that amphibians provide.
Litigation & Lawsuits
A federal district court approved a settlement in November 2013 requiring the U.S. Fish and Wildlife Service to better protect California red-legged frogs from seven common pesticides known to be highly toxic to amphibians. The settlement gave the agency two years to prepare biological opinions under the Endangered Species Act (ESA), to analyze pesticide use in and near the frog’s aquatic and upland habitats.
What Can You Do?
- Learn about the Hazards and Alternatives to using lawn pesticides.
- Go Organic – Visit our Eating with a Conscience page to learn why eating organic foods is the right choice.
- Visit our Tools for Change page to learn how to organize your community against pesticide use.
- Sign up for Beyond Pesticides’ Action Alerts to stay up-to-date on the latest petitions and news.
The diamondback terrapin's (Malaclemys terrapin) wide geographic distribution, long life span, occurrence in a variety of habitats within the saltmarsh ecosystem, predatory foraging behavior, and high site fidelity make it a useful indicator species for contaminant monitoring in estuarine ecosystems. In this study fat biopsies and plasma samples were collected from males and females from two sites within Barnegat Bay, New Jersey, as well as tissues from a gravid female and blue mussels (Mytilus edulis), which are terrapin prey. Samples were analyzed for persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), chlorinated pesticides, and methyl-triclosan. Terrapins from the northern site, Spizzle Creek, closest to influences from industrial areas, had higher POP concentrations for both tissues than terrapins from the less impacted Forsythe National Wildlife Refuge. Sex differences were observed with males having higher contaminant concentrations in fat and females in plasma. PCB patterns in terrapin fat and plasma were comparable to other wildlife. Plasma contaminant concentrations significantly and positively correlated with those in fat. This study addresses several aspects of using the terrapin as an indicator species for POP monitoring: site and sex differences, tissue sampling choices, maternal transfer, and biomagnification.
[Basile ER, Avery HW, Bien WF, Keller JM. 2011. Chemosphere. 82(1):137-44]