British scientists have found that tadpoles are coming down with a highly infectious new disease that could be threatening frog populations worldwide. Tadpoles from six countries across three continents were tested for single celled microbes called ‘protists’, complex cells which store their DNA in a nucleus, like human cells.
The previously unknown infectious agent was present in tadpole livers in both tropical and temperate sites, as well as across all continents tested. The parasite was identified as a distant relative of Perkinsea sp., a marine parasite found in animals and algae.
Amphibians are one of the most threatened of all animal groups. 32% of frog species were categorised as threatened or extinct and 42% were listed as in decline, in 2008.
Professor Thomas Richards from the University of Exeter says:
“Global frog populations are suffering serious declines and infectious disease has been shown to be a significant factor. Our work has revealed a previously unidentified microbial group that infects tadpole livers in frog populations across the globe.
We now need to figure out if this novel microbe – a distant relative of oyster parasites – causes significant disease and could be contributing to the frog population declines.”
The decline of amphibian populations, in particular frogs, is thought by some scientists to suggest that Earth is now undergoing a sixth mass extinction event.
Thomas A. Richards, et al.
Cryptic infection of a broad taxonomic and geographic diversity of tadpoles by Perkinsea protists
PNAS August 10, 2015 doi: 10.1073/pnas.1500163112