A group of scientists from the U.K. found that tadpoles worldwide have a high risk of infection with a type of single-cell microscopic organisms that attack their livers and may further contribute to the reduction of their already dwindling numbers.
The newly found disease in tadpole population is highly infectious and may affect all frog populations across the globe. The research team was only able to measure the severity of the disease in tadpoles living on three continents, but scientists believe that the microbes affect the tiny creatures regardless of their habitat.
The disease is caused by microscopic organisms called “protists,” which enter the body of a tadpole and get transported by the blood stream to the animal’s liver. There the microorganisms act like parasites and sicken their host. The microorganisms were found in the blood samples of tadpoles from six countries located on three different continents. The highly infectious disease was common to species dwelling in both tropical and temperate sites, scientists said.
The study was published August 11 in the National Academy of Sciences Journal.
Researchers explained that the tadpole disease is very similar to a condition affecting oysters worldwide due to an infection with a species of parasites called Perkinsea. This parasite, which usually affects bivalve mollusks including clams, oysters, mussels, and scallops, enters their body via their gills and palps. Once inside, it reaches the digestive gland and starts reproducing. After reproduction, the gland is infected with spores and nearly suffocated. In the process, the mollusk cannot feed anymore and dies. It virtually starves to death.
Thomas Richards, lead author of the study and biologist at Exeter University, in Devon, U.K., explained that frogs already face massive die-offs worldwide. Mr. Richards believes that one of the major factors triggering the die-offs is the newly found infectious disease.
“We now need to figure out if this novel microbe causes significant disease and could be contributing to the frog population declines,”
Mr. Richards added.
Amphibians including frogs feature on top spots of the endangered species lists worldwide. Seven years ago, more than 30 percent of frog species were deemed threatened or on brink of extinction, while 42 percent were categorized as in decline.
Scientists believe that the dwindling populations of frogs and animals across our planet may be caused by a large-scale phenomenon called the sixth mass extinction event. Unlike other mass extinction events such as the disappearance of dinosaurs, the 6th mass extinction is human-made and happens really fast – most species went extinct in less than 250 years.
Image Source: Daily Mail