A disease fatal to common frogs will become increasingly widespread as the planet warms. A study published on 9 May in Global Change Biology found that higher temperatures led to more severe ranavirus epidemics in the lab and in wild frog populations in the United Kingdom.
Common frogs, or Rana temporaria, have habitats across much of Europe and northern Asia. An infectious disease called ranavirus is thought to be contributing to the decline of amphibian populations around the world.
To test what makes ranavirus deadlier, the researchers gathered historical data on weather and ranavirus epidemics in U.K. wild frog populations going back to the 1990s. They found that when the average daily maximum temperature for a month rose above 16°C, the rate of ranavirus infections rose sharply and became much more severe. Those times correlated with historical mass mortality events for common frogs.
The scientists also tested the spread of ranavirus in cell cultures and live frogs in controlled laboratory conditions. They found a similar trend connecting temperature with the spread, severity, and deadliness of ranavirus. This result helps explain why the disease is more widespread and deadlier during the U.K. summer than during its winter.
With global temperatures on the rise, days hotter than 16°C are becoming more common.
“This is one of the first studies that provides strong evidence of the impact of climate change on wildlife disease, and helps to explain how it may facilitate the spread of ranavirus across the UK,” lead author and biologist Stephen Price of University College London said in a statement.
If left unchecked, climate change will shift the warmest months to earlier in the year, infringing on tadpole season. It’s possible that this change could lead to very low survival rates for common frog tadpoles and endanger the species, the team says.
“Climate change isn’t something that’s just happening in faraway places,” Price said. “It’s something real and present that’s already had hard-to-predict impacts on wildlife in our own back gardens here in the UK.”
—Kimberly M. S. Cartier (@AstroKimCartier), Staff Writer