Decline in amphibian populations

The Golden toad of Monteverde, Costa Rica, was among the first casualties of amphibian declines. Formerly abundant, it was last seen in 1989.

Since the 1980s, decreases in amphibian populations, including population decline and localized mass extinctions, have been observed in locations all over the world. These declines are known as one of the most critical threats to global biodiversity.

Recent (2007) research[1][2] indicates the reemergence of varieties of chytrid fungi may account for a substantial fraction of the overall decline. A more recent (2018) paper[3] published in Science confirms this.

Several secondary causes may be involved, including other diseases, habitat destruction and modification, exploitation, pollution, pesticide use, introduced species, and ultraviolet-B radiation (UV-B). However, many of the causes of amphibian declines are still poorly understood, and the topic is currently a subject of much ongoing research. Calculations based on extinction rates suggest that the current extinction rate of amphibians could be 211 times greater than the background extinction rate and the estimate goes up to 25,000–45,000 times if endangered species are also included in the computation.[4]

Although scientists began observing reduced populations of several European amphibian species already in the 1950s, awareness of the phenomenon as a global problem and its subsequent classification as a modern-day mass extinction only dates from the 1980s. By 1993, more than 500 species of frogs and salamanders present on all five continents were in decline.

  1. ^ Kriger, Kerry M.; Hero, Jean‐Marc (26 July 2007). "The chytrid fungus Batrachochytrium dendrobatidis is non‐randomly distributed across amphibian breeding habitats". Diversity and Distributions. 13 (6): 781–788. doi:10.1111/j.1472-4642.2007.00394.x. S2CID 85857635. Batrachochytrium dendrobatidis has been implicated as the causative agent of mass moralities, population declines, and the extinctions of stream‐breeding amphibian species worldwide.
  2. ^ Retallick, Richard W. R.; Miera, Verma (2007). "Strain differences in the amphibian chytrid Batrachochytrium dendrobatidis and non-permanent, sub-lethal effects of infection" (PDF). Diseases of Aquatic Organisms. 75 (3): 201–207. doi:10.3354/dao075201. PMID 17629114. The chytrid fungus Batrachochytrium dendrobatidis (Bd) is likely the cause of numerous recent amphibian population declines worldwide.
  3. ^ O’Hanlon, Simon J; et al. (2018). "Recent Asian origin of chytrid fungi causing global amphibian declines". Science. 360 (6389): 621–627. Bibcode:2018Sci...360..621O. doi:10.1126/science.aar1965. PMC 6311102. PMID 29748278.
  4. ^ McCallum, M. L. (2007). "Amphibian Decline or Extinction? Current Declines Dwarf Background Extinction Rate" (PDF). Journal of Herpetology. 41 (3): 483–491. doi:10.1670/0022-1511(2007)41[483:ADOECD]2.0.CO;2. S2CID 30162903. Archived from the original (PDF) on 2008-12-17.

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