It is well known that amphibian populations across the globe are currently facing unprecedented declines. The declines are largely attributed to a fungal disease sweeping across areas of the globe. The fungus, Batrachochytrium dendrobatidis, is responsible for the disease chytridiomycosis. Approximately forty percent of all amphibian species are in decline.
The fungal disease devastating amphibian populations was not discovered until the 1970s when it began impacting populations in Mexico. Some amphibian species are immune to the fungal disease, however the species in the Americas are not. It has been hypothesized by some scientists that the fungus reached the Americas through African claw-toed frogs, frogs which are carriers of the fungus but are immune themselves. These frogs were imported as live pregnancy tests for humans.
The spread of the disease has been significant, putting a large percentage of amphibians at risk. It is thought that from Mexico the disease has spread outwards, devastating species in both North and South America. A number of species extinctions have been attributed to the fungal disease, a disease scientists currently have no cure for. Currently more than 200 amphibian species are known to be suffering severe declines or extinction from the fungal disease.
A number of species have been targeted as sources for the disease, including the Pacific chorus frog in a recent study. Scientists determined that the frogs are able to survive with high levels of the fungus on its skin despite other species becoming extremely ill and populations decimated. American bullfrogs and African clawed frogs have also been potential sources as they are also able to survive the fungus and often even infections.
Now a recent study analyzing frogs for sale across the United States indicates that the trade of live amphibians is contributing significantly to the spread of the fungal disease. The findings were recently published in the journal Molecular Ecology and the study analyzed North American bullfrogs found at Asian food markets in the U.S. in seven different cities. Overall, the researchers determined that forty-one percent of the frogs tested positive for the fungal disease.
The sale of these frogs is most often for creating a dish of frog legs and the individuals are generally attained live via a number of countries, but largely from major frog farms in Brazil, Taiwan and Ecuador. The researchers believe that the frog farms are spreading the disease via live transport across the globe. The researchers hypothesize that the disease first cropped up in native Brazilian frogs and then spread to the live frog farms.
Efforts have been made to save amphibian populations from the fungal disease, however, they have been largely unsuccessful.