May 19, 2013
USGS Initiative Studying Impact Of Climate Change On Amphibians
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redOrbit Staff & Wire Reports - Your Universe Online
A US Geological Survey (USGS) effort to monitor the impact of climate change on amphibians living in the ponds and swamps of the southeastern United States has discovered that changes in rainfall patterns can cause short-term declines in mole salamanders, the agency reported on Friday.
As part of their research, the USGS´s Amphibian Research and Monitoring Initiative (ARMI) — established in 2000 by lawmakers as a response to concerns over declines in amphibian populations — set out to determine how droughts and deluges affected larvae living in small isolated ponds in St. Mark´s National Wildlife Refuge in Florida.
According to the researchers, larval mole salamanders were chosen because of their similarity to the flatwoods salamander, a threatened species that is difficult for experts to study. The similarities between the two species means that whatever affects one type of salamander will likely also affect the other, they explained.
“In the four years of the study, drought consistently decreased salamander occupancy in ponds,” the USGS said. “To support young salamanders, rain has to fill a pond during the breeding season and then the pond has to stay filled long enough for larvae to transform into the next life stage. Therefore, scientists confirmed that drought did indeed cause short-term declines in mole salamanders.”
Their results, which appear in the April 2013 edition of the journal Wetlands, suggest that the flatwoods salamander may experience a similar phenomenon due to climate change, the agency said. The April study is just one of several published recently by ARMI scientists, who are attempting to monitor the status of amphibians while also studying the reasons for their decline throughout the US.
In one study, agency researchers investigated how a range of different amphibian species would respond to changes in rainfall patterns. They took pattern changes predicted by many current climate models — patterns which suggest an increase in deluges alternating with droughts — and reported on each species´ reactions to those changes in a paper published in the March 2013 edition of the journal Biology.
“When USGS scientists reviewed what was known about amphibian responses to rainfall, it turned out that both extremes in rainfall — drought and heavy rainfall events — can decrease the number of amphibians,” the agency explained. “If ponds dry up while aquatic juveniles are developing, survival of the next generation is lowered. However, if a deluge occurs at that time, nearby pools that often contain fish will be physically connected with the pools containing juvenile amphibians, and the fish will eat the juveniles.”
Also in March, ARMI researchers published a paper in the journal Restoration Ecology examining whether or not habitat conservation could have a positive impact on frog and toad populations. Specifically, they examined whether or not the USDA Conservation Service Wetlands Reserve Program (WRP) — a voluntary initiative that allows landowners to protect and restore wetlands on their property — was beneficial to these amphibians.
“To assess the potential benefit of WRP restoration to amphibians, in this case, frogs and toads, USGS scientists surveyed 30 randomly selected WRP sites and 20 nearby agricultural sites in the Mississippi Delta in northwest Mississippi,” the researchers explained. “The scientists found that WRP sites had more kinds of species and was home to more numbers of amphibians than the agricultural sites studied. The restoration of wetland hydrology appeared to provide the most immediate benefit to the animals.”
ARMI´s efforts will continue in the months ahead, the organization noted.
“With multiple studies pointing to the synergistic role of climate change, disease, habitat change, and other factors in amphibian declines, USGS and its partners are continuing their research to provide information which resource managers can use in making decisions that can help arrest or reverse declines,” they said. “Additionally, a new study that provides the first-ever broad assessment of amphibian populations in the United States, and the first quantitative estimate of trends for amphibian populations at a continental scale, will be published later in May.”