Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Turtle shell disease fungus (Emydomyces testavorans): first documented occurrence in California and prevalence in free-living turtles.

Abstract

Pond Turtle Shell Disease is an emerging infectious disease associated with the fungus Emydomyces testavorans (Emte). Here, we report the first documented case of Emte in free-ranging Californian turtles. We assayed Emte in nine Western Pond Turtles (Emys = Actinemys marmorata; WPT) and three non-native Red-eared Slider turtles (Trachemys scripta elegans; RES) from the same pond in Santa Cruz County, California. Despite several WPT exhibiting significant shell lesions, scute defects, and pliable scutes, all tested negative for Emte. However, all three RES were Emte-positive, although two of these showed no shell defects. Given all tested RES were Emte-positive, it is possible that some WPT results are false negatives, either due to assay performance or insufficient shell tissue sampling. However, our Emte results in WPT are likely true negatives, and thus our observations contrast the high prevalence of Emte and shell disease in WPT from Washington. The emergence of Emte in California poses a previously unaccounted conservation concern for imperiled WPT. Emte's presence in California is also an important opportunity to study the epidemiology and ecology of this pathogen in a contrasting environmental context to Washington state where shell disease has had pronounced conservation consequences. Given the recent discovery of Snake Fungal Disease in California and the substantial impact the amphibian chytrid fungus has had on California's amphibians, there is an urgent need to understand the spread, prevalence, and impacts of Emte and other emerging wildlife diseases in California and elsewhere.