Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Dying frogs sign of a biodiversity crisis

14.08.2008
Devastating declines of amphibian species around the world are a sign of a biodiversity disaster larger than just frogs, salamanders and their ilk, according to researchers from the University of California, Berkeley.

Carcasses of Southern Yellow-legged Frogs in Sixty Lake Basin in Sierra Nevada, California. The frogs died of chytridiomycosis, an amphibian disease caused by a particularly virulent fungus. (Vance Vredenburg)

In an article published online this week in the journal Proceedings of the National Academy of Sciences, the researchers argue that substantial die-offs of amphibians and other plant and animal species add up to a new mass extinction facing the planet.

"There's no question that we are in a mass extinction spasm right now," said David Wake, professor of integrative biology at UC Berkeley. "Amphibians have been around for about 250 million years. They made it through when the dinosaurs didn't. The fact that they're cutting out now should be a lesson for us."

The study, co-authored by Wake and Vance Vredenburg, research associate at the Museum of Vertebrate Zoology at UC Berkeley and assistant professor of biology at San Francisco State University, will appear in a special supplement to the journal featuring papers based on presentations from the December 2007 Arthur M. Sackler Colloquium of the National Academy of Sciences, "In the Light of Evolution II: Biodiversity and Extinction."

New species arise and old species die off all the time, but sometimes the extinction numbers far outweigh the emergence of new species. Extreme cases of this are called mass extinction events, and there have been only five in our planet's history, until now.

The sixth mass extinction event, which Wake and others argue is happening currently, is different from the past events. "My feeling is that behind all this lies the heavy hand of Homo sapiens," Wake said.

There is no consensus among the scientific community about when the current mass extinction started, Wake said. It may have been 10,000 years ago, when humans first came from Asia to the Americas and hunted many of the large mammals to extinction. It may have started after the Industrial Revolution, when the human population exploded. Or, we might be seeing the start of it right now, Wake said.

But no matter what the start date, empirical data clearly show that extinction rates have dramatically increased over the last few decades, Wake said.

The global amphibian extinction is a particularly bleak example of this drastic decline. In 2004, researchers found that nearly one-third of amphibian species are threatened, and many of the non-threatened species are on the wane.

Our own backyard provides a striking example, Wake said. He and his colleagues study amphibians in the Sierra Nevada, and the picture is grim there, as well.

"We have these great national parks here that are about as close as you can get to absolute preserves, and there have been really startling drops in amphibian populations there, too," Wake said.

Of the seven amphibian species that inhabit the peaks of the Sierra Nevada, five are threatened. Wake and his colleagues observed that, for two of these species, the Sierra Nevada Yellow-legged Frog and the Southern Yellow-legged Frog, populations over the last few years declined by 95 to 98 percent, even in highly protected areas such as Yosemite National Park. This means that each local frog population has dwindled to 2 to 5 percent of its former size. Originally, frogs living atop the highest, most remote peaks seemed to thrive, but recently, they also succumbed.

There are several frog killers in the Sierra Nevada, Wake said. The first hint of frog decline in this area came in the 1990s, and researchers originally thought that rainbow trout introduced to this area were the culprits - they like to snack on tadpoles and frog eggs. The UC Berkeley team did experiments in which it physically removed trout from some areas, and the result was that frog populations started to recover.

"But then they disappeared again, and this time there were carcasses," Wake said.

The culprit is a nasty pathogenic fungus that causes the disease chytridiomycosis. Researchers discovered the fungus in Sierra Nevada frogs in 2001. Scientists have documented over the last five years mass die-offs and population collapses due to the fungus in the mountain range.

But the fungus is not unique to California. It has been wiping out amphibians around the world, including in the tropics, where amphibian biodiversity is particularly high.

"It's been called the most devastating wildlife disease ever recorded," Wake said.

Global warming and habitat constriction are two other major killers of frogs around the world, Wake said. And the Sierra Nevada amphibians are also susceptible to poisonous winds carrying pesticides from Central Valley croplands. "The frogs have really been hit by a one-two punch," Wake said, "although it's more like a one-two-three-four punch."

The frogs are not the only victims in this mass extinction, Wake emphasized. Scientists studying other organisms have seen similarly dramatic effects.

"Our work needs to be seen in the context of all this other work, and the news is very, very grim," Wake said.

The National Science Foundation and National Institutes of Health helped support this study.

Rachel Tompa | EurekAlert!
Further information:
http://www.berkeley.edu

More articles from Life Sciences:

nachricht Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

Im Focus: Newly proposed reference datasets improve weather satellite data quality

UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration

"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...

Im Focus: Repairing defects in fiber-reinforced plastics more efficiently

Fiber-reinforced plastics (FRP) are frequently used in the aeronautic and automobile industry. However, the repair of workpieces made of these composite materials is often less profitable than exchanging the part. In order to increase the lifetime of FRP parts and to make them more eco-efficient, the Laser Zentrum Hannover e.V. (LZH) and the Apodius GmbH want to combine a new measuring device for fiber layer orientation with an innovative laser-based repair process.

Defects in FRP pieces may be production or operation-related. Whether or not repair is cost-effective depends on the geometry of the defective area, the tools...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Multiregional brain on a chip

16.01.2017 | Power and Electrical Engineering

New technology enables 5-D imaging in live animals, humans

16.01.2017 | Information Technology

Researchers develop environmentally friendly soy air filter

16.01.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>