Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New study sheds light on frog malformations

19.06.2002


The emergence of mutant frogs with extra arms and legs may smack of a low-budget sci-fi script. But it is a reality, and a new study provides more evidence that ultraviolet radiation could be responsible. The findings are reported in three consecutive papers in the July 1 print issue of Environmental Science & Technology, a peer-reviewed journal of the American Chemical Society, the world’s largest scientific society.



Concern has been mounting for years over the depletion of the ozone layer — the atmospheric shield that helps block harmful ultraviolet (UV) radiation from reaching the Earth’s surface. At the same time amphibian populations have been declining, and many have been turning up with unusual malformations, such as missing or extra limbs.

A number of causes have been suggested to explain the malformations, including exposure to chemicals and parasites. Only recently have researchers been examining the potential connection to UV radiation to determine if it is coincidence or something more.


Until now, most of the research has focused on exposing frogs to UV radiation in the laboratory, providing little information about how these findings translate to natural habitats. "We really wanted to fill the gap between the findings of other laboratory research and what might happen in natural environments," said Steve Diamond, Ph.D., an environmental toxicologist at the United States Environmental Protection Agency in Duluth, Minn., and an author on all three papers.

In the first study, Diamond and his colleagues kept frog eggs in small outdoor containers while exposing them to varying degrees of UV radiation — from 25 to 100 percent of natural sunlight. As the eggs developed, the researchers observed hatching success, tadpole survival and the presence of malformations. They found that the frequency of malformations increased with increasing UV radiation, with half of the frogs experiencing malformations at 63.5 percent of the intensity of natural sunlight.

This supplements data from a previously published paper, which reported that 100 percent sunlight reduces survival by an average of 50 percent. In the course of these experiments, the researchers also determined that a specific region of the UV spectrum, known as UVB, appears to cause the malformations.

In the real world, however, frogs rarely experience 100 percent of natural sunlight. A variety of environmental factors conspire to reduce the levels of UV radiation entering wetlands, including ozone levels, cloud cover and UVB-absorbing dissolved organic carbon (DOC) in water. Accordingly, in the second study, the researchers measured DOC levels in wetlands in Wisconsin and Minnesota and found that the top five to 20 centimeters of wetlands absorb as much as 99 percent of UVB.

To complete the picture, the third study involved a survey of 26 wetlands in the same region to estimate the specific level of risk of frogs living in these environments. Using a combination of computer models, historical weather records and DOC measurements, they concluded that UVB posed a risk to amphibians living in three of the 26 wetlands.

While these findings suggest that most frogs are not currently at risk for UVB effects in this area of the country, the possibility of effects on amphibians in general should not be completely ignored, according to Diamond. Continued reduction of ozone and other global climate change effects may increase UV exposure in wetlands, suggesting that the potential risk to amphibians should continue to be studied.

Diamond’s team and a group of researchers from the National Parks are presently evaluating UVB levels across landscapes to compare them with the occurrence or absence of amphibians. "Those results," Diamond said, "combined with the risk assessment presented in these three manuscripts, will add significantly to our understanding of the relationship between UVB levels and amphibian declines or malformations.

Beverly Hassell | EurekAlert!

More articles from Life Sciences:

nachricht Colorectal cancer: Increased life expectancy thanks to individualised therapies
20.02.2020 | Christian-Albrechts-Universität zu Kiel

nachricht Sweet beaks: What Galapagos finches and marine bacteria have in common
20.02.2020 | Max-Planck-Institut für Marine Mikrobiologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A step towards controlling spin-dependent petahertz electronics by material defects

The operational speed of semiconductors in various electronic and optoelectronic devices is limited to several gigahertz (a billion oscillations per second). This constrains the upper limit of the operational speed of computing. Now researchers from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, and the Indian Institute of Technology in Bombay have explained how these processes can be sped up through the use of light waves and defected solid materials.

Light waves perform several hundred trillion oscillations per second. Hence, it is natural to envision employing light oscillations to drive the electronic...

Im Focus: Freiburg researcher investigate the origins of surface texture

Most natural and artificial surfaces are rough: metals and even glasses that appear smooth to the naked eye can look like jagged mountain ranges under the microscope. There is currently no uniform theory about the origin of this roughness despite it being observed on all scales, from the atomic to the tectonic. Scientists suspect that the rough surface is formed by irreversible plastic deformation that occurs in many processes of mechanical machining of components such as milling.

Prof. Dr. Lars Pastewka from the Simulation group at the Department of Microsystems Engineering at the University of Freiburg and his team have simulated such...

Im Focus: Skyrmions like it hot: Spin structures are controllable even at high temperatures

Investigation of the temperature dependence of the skyrmion Hall effect reveals further insights into possible new data storage devices

The joint research project of Johannes Gutenberg University Mainz (JGU) and the Massachusetts Institute of Technology (MIT) that had previously demonstrated...

Im Focus: Making the internet more energy efficient through systemic optimization

Researchers at Chalmers University of Technology, Sweden, recently completed a 5-year research project looking at how to make fibre optic communications systems more energy efficient. Among their proposals are smart, error-correcting data chip circuits, which they refined to be 10 times less energy consumptive. The project has yielded several scientific articles, in publications including Nature Communications.

Streaming films and music, scrolling through social media, and using cloud-based storage services are everyday activities now.

Im Focus: New synthesis methods enhance 3D chemical space for drug discovery

After helping develop a new approach for organic synthesis -- carbon-hydrogen functionalization -- scientists at Emory University are now showing how this approach may apply to drug discovery. Nature Catalysis published their most recent work -- a streamlined process for making a three-dimensional scaffold of keen interest to the pharmaceutical industry.

"Our tools open up whole new chemical space for potential drug targets," says Huw Davies, Emory professor of organic chemistry and senior author of the paper.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

70th Lindau Nobel Laureate Meeting: Around 70 Laureates set to meet with young scientists from approx. 100 countries

12.02.2020 | Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

 
Latest News

Active droplets

21.02.2020 | Medical Engineering

Finding new clues to brain cancer treatment

21.02.2020 | Health and Medicine

Beyond the brim, Sombrero Galaxy's halo suggests turbulent past

21.02.2020 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>