A tiny parasite disrupts an entire ecosystem in the high Andes • Earth.com


A new study published in the journal Ecology Letters examined the cascading effects of a scabies outbreak on the high Andean ecosystem of Argentina’s San Guillermo National Park. Prior to the 2015 mange epidemic, vicunas, pumas, and condors were intrinsically linked, with vicunas browsing on grass, pumas feeding on it, and condors feeding on the remains of pumas. However, after mange nearly wiped out the entire vicuña population, these relationships quickly unraveled, profoundly destabilizing the ecosystem.

Sarcoptic mange is caused by parasitic mites that burrow under the skin of animals, causing excruciating pain that prevents animals from moving or feeding. The San Guillermo outbreak is likely caused by domesticated llamas that were introduced to private land outside the park in 2015.

“This reserve is about as remote as it gets, with very little human interaction, and yet it still isn’t safe from human activities happening hundreds of miles away,” said Justine Smith, co -lead author of the study, as an assistant professor at the University. of California, Davis. “Pathogens can take hold quickly, giving animals little time to react or adapt. We could see unintended consequences that we should prepare for when managing wildlife populations at risk.

Before this outbreak, cougars were the biggest threat to vicuñas. However, this tiny mite proved far more dangerous than the larger predators, decimating the park’s vicuña populations within a few years. When their primary food source disappeared, the condors eventually left the park altogether, while the cougars had to switch to other food sources, such as small rodents, to avoid starvation.

These changes among the animals also caused massive changes in the landscape. Bare ground has become covered with grass over huge swaths visible from space, and vegetation has increased by 900% in areas where vicuñas used to graze.

“We don’t really know how or if these systems will recover,” Smith said. “Will they return to the system we knew or will a new balance emerge from these dynamics? It’s hard to predict. »

“Continuing to support our Argentinian colleagues who have worked for decades to understand and protect this unique system will be vital in tracing the ongoing effects of the disease and promoting ecosystem recovery,” the co-author concluded. study, Julia Monk.

By Andrei Ionescu, Terre.com Personal editor


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