Trouble in the aquatic world: How wildlife professionals are battling amphibian declines

Abstract

A parasitic fungus, similar to the one that caused the extinction of numerous tropical frog and toad species, is killing salamanders in Europe. Scientists first identified the fungus, Batrachochytrium salamandrivorans, in 2013 as the culprit behind the death of fire salamanders ( Salamandr a salamandra ) in the Netherlands ( Martel et al. 2013 ) and are now exploring its potential impact to other species. Although the fungus, which kills the amphibians by infecting their skin, has not yet spread to the United States, researchers believe it’s only a matter of time before it does and, when that happens, the impact on salamander populations could be devastating ( Martel et al. 2014 ). Reports of worldwide declines of amphibians began a quarter of a century ago ( Blaustein & Wake 1990 ). Globally, some amphibian population declines occurred in the late 1950s and early 1960s, and declining trends continued in North America ( Houlahan et al. 2000 ). In the earlier years, population declines were attributed primarily to overharvest due to unregulated supply of species such as the northern leopard frog ( Lithobate s pipiens ) for educational use ( Dodd 2013 ). In later years, however, causes of declines were less evident. In 1989, herpetologists at the First World Congress of Herpetology traded alarming stories of losses across continents and in seemingly protected landscapes, making it clear that amphibian population declines were a “global phenomenon.” In response to these reports, in 1991, the International Union for Conservation of Nature (IUCN) established the Declining Amphibian Populations Task Force to better understand the scale and scope of global amphibian declines. Unfortunately, the absence of long-term monitoring data and targeted studies made it difficult for the task force to compile information. Today, according to AmphibiaWeb.org, there are 7,342 amphibian species in the world — double the number since the first alerts of declines — making the situation appear deceptively less dire. In fact, our understanding of genetic diversity significantly raises the stakes, and we are at risk of losing far more species than we believed only a few years ago. According to the IUCN, amphibians now lead the list of vertebrate taxa affected by the larger “biodiversity crisis” and sixth major mass- extinction event on Earth ( Keith et al. 2014 , Wake and Vredenburg 2008 ).