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Complex causes of amphibian population declines
J M Kiesecker1, A R Blaustein, L K Belden
1Department of Biology, The Pennsylvania State University, 208 Mueller Laboratory, University Park, Pennsylvania 16802-5301, USA. jmk23@psu.edu
Nature
|April 5, 2001
Summary
Global climate change is driving amphibian declines. Reduced water depth due to altered precipitation increases embryo exposure to harmful ultraviolet-B (UV-B) radiation, leading to increased disease susceptibility and mortality.
Area of Science:
- Ecology
- Environmental Science
- Amphibian Biology
Background:
- Amphibian populations worldwide face significant declines and extinctions.
- Climate change, UV-B radiation, and disease are suspected factors, but their global interplay is unclear.
Purpose of the Study:
- To investigate the link between climate-induced UV-B exposure and amphibian pathogen outbreaks in the western USA.
- To determine the role of precipitation variability and El Niño/Southern Oscillation (ENSO) cycles in amphibian mortality.
Main Methods:
- Analysis of long-term observational data on precipitation, UV-B exposure, and amphibian infection rates.
- Field experiments to assess the impact of water depth and UV-B on embryo survival and disease (Saprolegnia ferax).
Main Results:
- Reduced water depth at breeding sites, driven by precipitation changes, increases amphibian embryo exposure to UV-B radiation.
- Increased UV-B exposure elevates embryo vulnerability to infection by the oomycete pathogen Saprolegnia ferax, causing high mortality.
- Precipitation patterns are strongly linked to ENSO cycles, indicating a role for large-scale climate phenomena.
Conclusions:
- Climate-induced changes in UV-B exposure are a significant driver of amphibian declines via pathogen outbreaks.
- Elevated sea-surface temperatures in the tropical Pacific may be a precursor to widespread, climate-driven amphibian declines globally.
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