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Science Wednesday: Why are Frogs (and Other Amphibians) Declining?

2008 December 3

Each week we write about the science behind environmental protection. Previous Science Wednesdays.

About the author: Steven Whitfield is a Ph.D. candidate in the Department of Biological Sciences at Florida International University in Miami. His work is funded by a Greater Research Opportunities (GRO) Fellowship from the U. S. Environmental Protection Agency.

Investigating Patterns and processes implicated in enigmatic declines of amphibians and reptiles at La Selva Biological Station, Costa Rica

Photo of man holding a brown frogHere’s a picture of me and a Mexican tree frog, (I’m the one on the left).

Amphibians are the most threatened group of vertebrates, with approximately one-third of their species at risk of extinction.

Rapid declines of amphibian populations, even in apparently pristine, protected reserves, have generated much alarm. The causes associated with these “enigmatic declines” are poorly understood.

Through my dissertation research—supported by a GRO Fellowship from EPA’s National Center for Environmental Research—I am investigating a variety of factors associated with population declines, including chytridiomycosis (Amphibian Chytrid Fungus), habitat modification, and climate change, in amphibians and reptiles in the lowland forests of Central America.

That’s where my work at La Selva Biological Station in Costa Rica comes in.

Photo of man holding a brown frogThe strawberry poison frog (Oophaga pumilio) is one of the common species at my field site that is slowly becoming less common.

Amphibians are the most threatened group of vertebrates, with approximately one-third of their species at risk of extinction.

La Selva populations of terrestrial amphibians have declined by 75% since 1970, and similar declines have been noted in terrestrial lizards. It is currently unclear what factors have contributed to these declines, but potential stressors include fungal disease, shifting climate, pesticide drift from nearby agricultural areas, and habitat modification surrounding the La Selva Reserve.

I am using extensive field investigations and synthesis of long-term datasets collected at La Selva. I hope my research will provide important information necessary to protect biological diversity of this important group of animals.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

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2 Responses leave one →
  1. Lina-EPA permalink*
    December 5, 2008

    Interesting article. Have you focused on amphibians only in La Selva Reserve? Have you studied at all the issue of the varieties of coquis in Puerto Rico and those transplanted to the Hawaiian Islands?

  2. Tanner permalink
    March 12, 2009

    There’s extensive information about amphibian declines and chytrid fungus at the USGS NBII amphibian site,

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