December 4, 2013

Manitoulin Island turtle deaths worry researchers and more wildlife disease news stories


The Good and Bad News about Frog Abnormalities
 On average, amphibian deformities at U.S. national wildlife refuges are lower than expected. But in abnormality “hotspots,” rates can approach 40 percent.

... Malformed frogs like these started turning up regularly in 1995, when children playing around a pond in Minnesota famously found deformed frog after deformed frog. Some of the frogs had missing limbs or digits. Others had an extra leg or two. More discoveries soon happened around the country. In 2000 the U.S. Congress asked the U.S. Fish and Wildlife Service (FWS) and the U.S. Geological Survey to look into the health of the country's amphibians.

This week the FWS released the results of their 10-year study, which examined the rate of amphibian abnormalities on national wildlife refuges. Their paper, published November 18 in PLoS One, examines more than 68,000 frogs found at 497 wetland sites on 152 refuges. It reveals that frog deformities at these locations are actually much lower than expected, averaging fewer than 2 percent across the entire country over the period of 2000 to 2009. Previous smaller-scale, regional studies had anticipated a rate closer to 5 percent. Cases of extra limbs (polymelia) were almost nonexistent, with just 22 cases over the 10 years. "Our study shows that abnormal amphibians are not the norm across the landscape," says Reeves, the study's lead author and an ecologist with the FWS field office in Anchorage.

But the study did find high percentages of abnormal frogs—those with absent or shortened limbs, missing eyes, shortened digits or other injuries—at several "hotspots" around the country, including the Mississippi Valley, California's Central Valley, and south-central and eastern Alaska. At some of these sites the abnormality rate approached 40 percent in certain years. "This phenomenon of abnormal amphibians appears to be really variable," Reeves says. Some years they might have found 10 abnormal frogs out of 100. The next year they might not have found any. "We've long suspected that abnormalities are localized to hotspots," says co-author Pieter Johnson, associate professor of ecology and evolutionary biology at the University of Colorado at Boulder. He says this paper, by virtue of its scope and time span, is the first attempt to confirm and quantify the existence of the hotspots.

Scientific American
21 Nov 2013
JR Platt

Cited Journal Article
Reeves MK, Medley KA, Pinkney AE, Holyoak M, Johnson PTJ, et al. (2013) Localized Hotspots Drive Continental Geography of Abnormal Amphibians on U.S. Wildlife Refuges. PLoS ONE 8(11): e77467. doi:10.1371/journal.pone.0077467

Other Amphibian News

Great Lakes Waterfowl Die-Offs: Finding the Source

A deadly menace stalks the loons, gulls, and other water birds of the Great Lakes region: Type E botulism, a neuromuscular disease caused when birds eat fish infected with toxin-producing bacteria. Cases of the disease are on the rise, killing approximately 10,000 more waterfowl in 2007 than when it was first reported in 1963.

To understand die-off origin and distribution, ocean engineers from the Florida Atlantic University (FAU) Institute for Ocean Systems Engineering in Dania Beach, Florida are using their expertise in experimental hydrodynamics. They have teamed with the U.S. Geological Survey to help develop a novel way of tracking waterfowl carcasses to determine the source of lethal outbreaks that infect fish eaten by waterbirds....

The team performed towing tank experiments on submerging bird carcasses to determine the relevant drag coefficients. Together with wind and current data, these coefficients can be used in probabilistic source tracking simulations to calculate waterbird drift velocity and direction in order to reconstruct the likely routes that bird bodies may have traveled after a die-off.
Ultimately, this information will be compared to waterbird distribution and abundance revealed through aerial surveys to identify locations where waterbirds are likely exposed to botulinum toxin, explained Karl von Ellenrieder of FAU.

Science Daily
24 Nov 2013

Invasive Sparrows Immune Cells Sharpen as They Spread

When invasive species move into new areas, they often lose their natural enemies, including the microbes that make them sick. But new research from evolutionary biologists at the University of South Florida has found that adjustments in the immune system may help house sparrows, one of the world's most common bird species, thrive in new areas.

In research published this week in Proceedings of the Royal Society B, Biological Sciences, Associate Professor Lynn Martin and Assistant Professor Aaron Schrey from Armstrong Atlantic State University found that on the molecular level, the immune systems of house sparrows at the edge of the species' range in Kenya were more attuned to finding dangerous parasites than birds from older sites in the same country. These differences may help keep invading birds from becoming sick in new areas where pathogens are more likely novel.

Science Daily
20 Nov 2013

Cited Journal Article
L. B. Martin, C. A. C. Coon, A. L. Liebl, A. W. Schrey. Surveillance for microbes and range expansion in house sparrows. Proceedings of the Royal Society B: Biological Sciences, 2013; 281 (1774): 20132690 DOI: 10.1098/rspb.2013.2690

Manitoulin Island turtle deaths worry researchers

More than 50 dead turtles found on northern Ontario island this summer

Researchers at Laurentian University in Sudbury say they are stumped in the case of more than 50 dead turtles found on Manitoulin Island. The turtles were found by a Ministry of Natural Resources scientist earlier this year and, so far, the cause of death is unknown.

... “At least in Canada, as far as I know, nobody has ever seen such a large number of turtles killed without an obvious reason,” Jacqueline Litzgus said. She said two full boxes of carcasses have been catalogued and the remains are in plastic bags. The only thing left of the turtles are their shells.

... Litzgus said the mysterious cause of the turtles’ demise could be there are new predators or a rare type of disease. Whatever the cause, Litzgus said she’s worried. “When you find a couple of dead turtles, it’s really disturbing,” she explained. “But when you find this many dead ones, it becomes hard to comprehend.”

CBC News
18 Nov 2013
Manitoulin Island, Canada - Map It   

Marine Mammal Health News
Deer Health News 
One Health News Corner
It Ain't All Bad News

No comments: