(Beyond Pesticides, April 29, 2016) Traces of pesticides, including the long-banned organochlorine chemical DDT, have been found in Western pond turtles, insects, and soil sediment at Sequoia National Park, according to a study.Â The study, entitled Organic contaminants in western pond turtles in remote habitat in CaliforniaÂ and published in the journal Chemosphere, surveys a suite of 57 current- and historic-use pesticides, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) in the western pond turtle, along with their potential prey items and habitat. California study sites include Sequoia National Park, Whiskeytown National Recreation Area, and Six Rivers National Forest, all of which are downstream of undeveloped watersheds and varied in distance from agricultural and urban pollution sources.
Researchers found that organic pollutants are widespread in the western pond turtle, which has conservation status; that pesticides are prominent in Sequoia National Park, which is downwind of heavy agriculture; and that the legacyÂ pesticides and PCB concentrations indicate that bioaccumulation is occurring.
Brian Todd, Ph.D., an associate professor of wildlife, fish, and conservation biology at University of California Davis, co-authored the study. Dr. Todd said controlling the flow of pesticides into national parks is pretty much impossible. âSequoia National Park is very interesting, because it begins in the foothills, just downwind of very heavy agricultural land in the southern part of the Central Valley,â Dr. Todd told KCBS. âIt tends to accumulate from drift and runoff, a lot of the pesticides that have been used over the last several decades.â Dr. Todd says the study focused heavily on turtles because they are whatâs known as an âindicator species,â whose reaction to changes in the environment serves as a kind of barometer of those changes.
The impacts of pesticides on wildlife are extensive, and expose animals in urban, suburban and rural areas to unnecessary risks. According to a recent assessment by EPA, two commonly used pesticides (chlorpyrifos and malathion) are âlikely to adversely affectâ 97% of species listed under the Endangered Species Act (ESA).
Wildlife can be affectedÂ by pesticides through direct or indirect applications, such as pesticide drift, secondary poisoning, runoff into local water bodies, and groundwater contamination. It is possible that some animals could be sprayed directly, while others consume plants or prey that have been exposed to pesticides. To learn more, read about pesticide impacts on wildlife.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.