A new study conducted by researchers at Washington State University shows that even antifreeze frogs are affected by stress.
The research was published recently in "Proceedings of The Royal Society B". Studies have found that tree frogs raised in high-salinity ponds on road de-icers are more susceptible to deadly ranavirus infections. These findings provide more support for the stress-induced susceptibility hypothesis, which may help explain the sharp decline in wildlife numbers in recent years.
"We saw that large-scale deaths of these wild animals are usually caused by infectious diseases; at the same time, we noticed that this is related to some kind of environmental change," said the study's first author Emily Hall. The research is part of her doctoral thesis at Washington State University.
Researchers have studied tree frog larvae in ponds in the northeastern United States, where salt is commonly used as a road deicing agent. At first, Hall was interested in the effect of road salt in the pond on the development of frogs, but at some of her research sites, all tadpoles died.
"When you come to a pond, suddenly all the little tadpoles float on the water, which is really dramatic," Hall said. She found that they died of ranavirus (a common viral pathogen), and healthy tree frogs usually survive.
Hall collaborated with her consultant, stress physiology expert Professor Erica Crespi and disease ecologist Jesse Brunner to start a new study that combines field work and laboratory research to study the relationship between salinity stress and infection susceptibility Potential connections.
The researchers found that animals exposed to salt had an infection intensity 10 times higher when exposed to ranavirus. Saltwater tadpoles are also more infectious, and they release five times more virus into the water than infected animals that grew up in fresh water without salt.
The researchers did not find that just because of the increase in salinity, the frog's corticosteroids, that is, stress hormones, also increased. Only in the case of viral infections will they see elevated hormone levels, thereby suppressing the immune response.
Crespi said: "The significance of this discovery is beyond the scope of small ponds in the Northeast. We may be studying amphibious pathogen systems, but the phenomenon we are seeing now may play a role in the COVID-19 outbreak. Chronic non-fatal stress can cause Health outcomes that we did not realize before the crisis. People who are under constant socioeconomic pressure or have metabolic diseases or asthma are experiencing more severe infections and higher mortality. This is also what we see in the saltwater pool Case."
Washington State University ’s research also has an impact on how scientists protect wildlife and mass extinction. Unlike other types of amphibians, the number of tree frogs has not decreased significantly. This is a common, usually flexible, frog that extends from Alabama to the Arctic. Large-scale deaths caused by this virus have been observed in many parts of the world, but why one population will die and another will not die is an open question. The researchers hypothesized that potentially severe conditions will increase stress, which may play a role in these deaths.
"Since tree frog is not a species to watch, people may not think it is a conservation story, but I think it is," Crespi said. "No one can predict the demise of a species. This is not a linear decline process. It is always the result of a combination of factors that leads to a more serious result than expected. We should consider looking for preventive medicine in conservation."
Crespi said that taking preventive protection measures requires monitoring population numbers, assessing the complex relationship between stressors and health threats, and finding ways to reduce threats. In this case, the researchers suggested that road workers look for opportunities to reduce the use of salt in winter road treatment, while also considering safety issues, such as the use of gravel, as done in the Pacific Northwest.
Source: Gade Chemical Network
