A new study suggests that increases in water temperature and copper pollution may increase mortality and abnormalities in frogs. This research, conducted by the U.S. Fish and Wildlife Service, Alaska Pacific University, and the University of California at Davis, and recently published in the journal Ecosphere, follows previous studies of amphibian abnormalities and shows how pollution and climate change climate change
Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.
Learn more about climate change may contribute to amphibian decline.
In laboratory tests, wood frog tadpoles were attacked by dragonfly larvae 30 minutes sooner and three times more often in warmer water with a slight increase in copper pollution, than in cooler, copper-free treatments. The attacks either killed the tadpoles directly, left them with injuries that could become abnormalities in later life, or increased levels of stress measured by the behavior of other tadpoles in the tanks.
Amphibians are important indicators of environmental health, and their populations are in global decline. “It’s estimated that at least one third of amphibian species are threatened with extinction worldwide,” said Mari Reeves, an ecologist with the U.S. Fish and Wildlife Service and co-author of the study. “Climate change and pollution are thought to be two of the main causes of the declines, in addition to habitat loss, invasive species invasive species
An invasive species is any plant or animal that has spread or been introduced into a new area where they are, or could, cause harm to the environment, economy, or human, animal, or plant health. Their unwelcome presence can destroy ecosystems and cost millions of dollars.
Learn more about invasive species and disease.”
In 2000, the U.S. Congress asked agencies in the Department of the Interior, including the Service and the U.S. Geological Survey, to address growing concerns among the public about the health of amphibians. This study is one result of these efforts to understand why amphibians are disappearing at alarming rates.
The research follows previous studies that indicate pollutants, such as copper, can affect amphibian behaviors, including foraging and predator-prey interactions in their breeding habitat. Copper at very low concentrations has also been found to be toxic to the olfactory system in salmon and diminishes salmon’s ability to avoid predators.
Copper is present in vehicle exhaust and brake-pad dust, and its concentrations are often elevated in waters adjacent to roadways due to runoff. Both California and Washington have enacted legislation to lower the amount of copper in brake pads to reduce this pollution source to rivers and other aquatic ecosystems. Other sources of copper pollution include mining and agricultural activities.
The amount of copper used in this study, was less than half of the average level found in ponds used to treat runoff from roads and parking lots in Anchorage, Alaska.
“The amount of copper we used was so small,” said Tess Hayden, graduate student at Alaska Pacific University and lead author on the study. “I was surprised that we saw an effect on behavior.”
As global air temperatures rise, the temperatures of aquatic habitats on which amphibians depend are predicted to increase. These changes mixed with pollution and continued habitat loss are expected to have a detrimental effect on amphibian populations.
The Service works with partners both nationally and internationally to conserve amphibians and the clean water and habitats on which they depend. To learn more about this study visit: http://www.esajournals.org/doi/abs/10.1890/ES14-00461.1.
To watch a video of segments of the study visit: https://youtu.be/IMoKIL_FkJA.
To learn more about our work and what you can do to help visit: http://www.fws.gov/endangered/.
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