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 A novel synthetic antibody enables conditional “protein knockdown” in vertebrates
20.08.2018 | Technische Universität Dresden

nachricht Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: It’s All in the Mix: Jülich Researchers are Developing Fast-Charging Solid-State Batteries

There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.

The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Quantum bugs, meet your new swatter

20.08.2018 | Information Technology

A novel synthetic antibody enables conditional “protein knockdown” in vertebrates

20.08.2018 | Life Sciences

Metamolds: Molding a mold

20.08.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>