Enigmatic Faunal Declines at La Selva Biological Station, Costa Rica: Pattern and Process in a Collapsing Tropical Herpetofauna

EPA Grant Number: F07F71130
Title: Enigmatic Faunal Declines at La Selva Biological Station, Costa Rica: Pattern and Process in a Collapsing Tropical Herpetofauna
Investigators: Whitfield, Steven M.
Institution: Florida International University
EPA Project Officer: Zambrana, Jose
Project Period: August 1, 2007 through August 1, 2010
RFA: GRO Fellowships for Graduate Environmental Study (2007) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Ecological Assessment , Fellowship - Terrestrial Systems Ecology


In the past three decades, dramatic amphibian declines and extinctions have been noted across the globe. For example, population trends for terrestrial frogs over 35 years from La Selva Biological Station in northeastern Costa Rica show unidirectional declines of nearly an order of magnitude. These declines are not consistent with current phenomena emphasized in global amphibian declines because they occur at a pristine lowland site and populations of syntopic reptiles also decline. This project aims to identify the spatial extent of and proximate drivers of these declines by investigating three potential mechanisms implicated in these declines: habitat fragmentation, chytridiomycosis, and changing climate.


Amphibians and reptiles will be sampled at a number of large, pristine reserves in the Atlantic Lowlands of Central America to determine whether habitat fragmentation is implicated in these declines, and to determine whether these declines are spatially widespread beyond the La Selva reserve. The rates of infection of the pathogenic chytrid fungus will be assessed by taking superficial swabs of epidermis of a wide range of amphibian species and analyzed using polymerase chain-reaction. Manipulations of leaf-litter depth on the forest floor will experimentally and empirically test a link between link amphibian and reptile populations to litter dynamics, the leading mechanistic tie to changing climate. Finally, populations of amphibians and reptiles will be monitored over a period of two years to better understand the response of amphibian and reptile populations to climate variability.

Expected Results:

It is expected that chytridiomycosis will be widespread at this site, and will adversely affect amphibian populations. It is expected that climate will adversely affect both amphibian and reptile populations. It is also expected that fragmentation will have little effect on amphibian and reptile density, and that declines seen at La Selva are spatially widespread. Results from this study will help to guide conservation plans for this and similar tropical herpetofaunas.

Supplemental Keywords:

mphibian decline, Batrachochytrium dendrobatidis, biodiversity conservation, Central America, conservation ecology, chytridiomycosis, climate change, climate variability, Costa Rica, enigmatic decline, frog, litter dynamics, lizard, neotropics, tropical ecology, tropical wet forest, zoology,, RFA, Air, climate change, Air Pollution Effects, Atmosphere

Progress and Final Reports:

  • 2008
  • 2009
  • Final