May 26, 2009

Chytridiomycosis in Asia

Of the Earth's amphibian-harboring continents (all but Antarctica), Asia was until recently unique in not yet having been invaded by the amphibian chytrid fungus (Bd). That now seems to be changing quickly. During the last few years ago Bd was reported from Japan, South Korea, and Indonesia, all countries around the periphery of this amphibian-rich continent. In the last few weeks Bd was reported from the Philippines, another country on Asia's edge. For a description of the amphibian fauna of the Philippines, check out Herpwatch Philippines.

Given that elsewhere in the world, including Australia, Central America, and California's Sierra Nevada, Bd spread as a distinct wave it seems likely that these initial occurrences of Bd in Asia represent the first outbreaks in what will become a wave of infections. Given the high amphibian species diversity in Asia and high levels of endemism, the spread of Bd across this continent will almost certainly result in hundreds of species extinctions.

Will we find a way to stop the spread of this disease or will our only role be to describe Asia's amphibian extinctions

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May 18, 2009

Good News and Bad News About Amphibian Diversity

The number of known amphibian species worldwide has risen by approximately 20% during the the past decade thanks to intense research on this group of vertebrates. A total of 6487 amphibian species have been described to date ( That is the good news.

Now here comes the bad news. Based on a study published in 2004 in the journal Science, more than 40% of the world's amphibians are threatened with extinction. Given the current number of amphibian species (6487), that means that more than 2500 amphibian species are in serious decline. However, a study by Vieites and colleagues just published in the Proceedings of the National Academy of Sciences suggests that the number of described amphibian species vastly underestimates the actual number of amphibian species on Earth. That means that far more species are in danger of extinction than previously believed.

Vieites and colleauges used DNA sequences from 2850 amphibian specimens sampled from over 170 localities in Madagascar to show that the current number of described amphibian species
(244) in this biodiversity hotspot represents only about one-half of the actual number of species present (estimated actual number of species is 373-465). Therefore, hundreds of species remain undescribed. Habitats on Madagascar have been badly degraded by deforestation, and the results of the new study suggest that this has caused the extinction of far more species than have so far been documented. Furthermore, to date Madagascar is still free of the amphibian chytrid fungus. When the fungus does invade, it won't be 244 species that are impacted. It will be 373 to 465.

The more we learn the bleaker the prospects seem for conserving even a fraction of the Earth's amphibian biodiversity.

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May 4, 2009

Trout Impacts and Stocking Controversies - Beyond California

Much of the recent research on impacts of trout stocking has focused on aquatic ecosystems in California. However, a research program in Maine is now showing just how pervasive these impacts are. Most of Maine's naturally fishless lakes (and there were thousands of them historically) have now been stocked with numerous fish species, including brook trout, and all indications are that these introductions have had similar effects as those documented in California's Sierra Nevada and elsewhere - the disappearance of amphibians and conspicuous invertebrate taxa. The New York Times ran a story last week that provides an interesting overview of what the Maine research is turning up.

On the opposite coast, the practice of trout stocking continues to cause controversy in North Cascades National Park. This is the only national park in the country in which fish stocking is still allowed, but after many years of debate about the practice and detailed scientific study it appears that trout stocking may be on its way out. A recent Associated Press story provides the details.

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