[Animals] The specimens of the Ordesa y Monte Perdido National Park are in critical condition infected by a virus that is multiplied by the effect of climate change

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These are bad times for the Pyrenean frog (Rana pyrenaica), a small brown amphibian emblematic of the Ordesa y Monte Perdido National Park, where it was discovered in 1990. Its condition is critical, trapped between a ranavirus, which multiplies with the increase in temperature due to climate change, and a fungus that weakens it even more. Mortality is massive and many dead specimens have been found in the park, especially larvae, but also adults, juveniles and recently metamorphosed ones. The PCR tests that were carried out pointed to the culprit: ranavirus, a very cruel disease that causes tissue to necrose, parts of the body fall out and internal organs fall apart, describes CSIC scientist Jaime Bosch. 90% of the Pyrenean frog po[CENSORED]tion, endemic to the Pyrenees and classified as endangered by the International Union for Conservation of Nature (IUCN), lives in Alto Aragon, at altitudes between 1,000 and 1,700 meters. The rest is distributed in a small nucleus in Navarra and France.

"It is a problem of climate change, because we have sequenced the viruses and they are autochthonous, so the species could fight by having always lived with them, but with rising temperatures the ranovirus soars", clarifies Bosch. The Pyrenean Observatory of Climate Change (OPCC) indicates that the Pyrenees face a temperature increase of 1.2 degrees Celsius since 1950, 30% higher than the world average, which is 0.85 degrees.

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Bosch came across the first ranaviruses in 1994, when he was studying a large mortality of the common midwife toad (Alytes obstetricans) in the Piedrafita lake, near Sallent de Gállego (Huesca). "We did not know what it was, we called it red leg syndrome because they had hemorrhages in that part of the body," he recalls. Then they learned that it was a ranavirus and that the hemorrhages were caused by opportunistic bacteria that took advantage of the weakness of the sick specimens.

Since then, the ranavirus has progressed unstoppably and no treatment has been found that works. "We cannot even treat them in the laboratory, something that we have achieved with the fungus that causes chytridiomycosis [another emerging disease that is killing amphibians] by applying fungicides," he says. "How do you stop climate change?" Asks this researcher, who considers that the only solution that can be adopted with the Ordesa frog is to find places where they can live with a cooler temperature, and create po[CENSORED]tions there.

Francisco Villaespesa, head of conservation of the national park, explains that they are trying to manage the variables that are within their reach, because they can do little in the face of the unstoppable increase in temperature. The decline of the species is such that they are going to launch an ex situ conservation program "with the collection of spawns in the field to get subadults in captivity and introduce them into the environment." In addition, breeding individuals will be kept in captivity to release their young. The Spanish Herpetological Association will develop this plan that already has an approved budget. Ponds have also been recovered in the national park and trout introduced in the headwaters of the Arazas river have been removed to prevent fish from eating the larvae of the few frogs.

Bosch is concerned about the rest of the towns in Aragon, which are not monitored like those in the Ordesa y Monte Perdido National Park. "We don't know how they are," he points out. In the world there are five variants of ranavirus and in Spain an autochthonous branch and other introduced ones have been detected, "which have reached the amphibians through fish with which the rivers have been repo[CENSORED]ted for fishing for decades". "As fish are asymptomatic, it is not known that they are carriers and spread the virus," adds the CSIC scientist. Reptiles are also contagious and "we have observed mortalities of aquatic snakes and water terrapins."

 

https://elpais.com/clima-y-medio-ambiente/2021-09-27/la-agonia-de-la-rana-pirenaica.html