Third of animal parasites may be extinct by 2070: Study

Washington: Climate change could cause the extinction of up to a third of Earth's animal parasite species by 2070, which may dramatically disrupt ecosystems, according to a global analysis.

The study suggests that parasites are one of the most threatened groups of life on Earth.

The diverse group of organisms includes tapeworms, roundworms, ticks, lice, fleas and other pests - most of which are best known for causing disease in humans, livestock and other animals.

However, parasites play important roles in ecosystems. They help control wildlife populations and keep energy flowing through food chains.

Because many parasites have complex life cycles that involve passing through different host species, parasite diversity can be considered a sign of a healthy ecosystem, said Anna Phillips, from the Smithsonian Institution's National Museum of Natural History in the US.

"Having parasites is a good indicator that the ecosystem has been stable. It means the system has a diversity of animals in it and that conditions have been consistent long enough for these complex associations to develop," said Phillips.

To find out how climate change is likely to affect the survival of a wide range of parasite species, Colin Carlson, from the University of California, Berkeley in the US and colleagues turned to museum collections.

Records from the US National Parasite Collection were combined with additional information from specialised databases cataloguing ticks, fleas, feather mites and bee mites to enable a comprehensive global analysis.

"Climate change has the capacity to alter nearly every dimension of biodiversity," said Nyeema Harris, an assistant professor at University of Michigan in the US.

"Given our concerns about parasites devastating animal populations and the transmission risks to humans, it is been surprising to discover their patterns of diversity and to understand their sensitivities to such a major environmental concern," said Harris.

Using climate forecasts, the researchers compared how 457 parasite species will be impacted by changes in climate under various scenarios.

The analysis determined that parasites are even more threatened than the animal hosts they rely on.

The most catastrophic model predicted that more than a third of parasite species worldwide could be lost by 2070. The most optimistic models predicted a loss of about 10 per cent, researchers said.

"(Slowing climate change) has a really profound impact on extinction rates, but even in the best-case scenario, we are still looking at fairly major global changes," Carlson said.

"Parasites are definitely going to face major extinction risk in the next 50 years. They are certainly as threatened as any other animal group," Carlson added.