Tiny mite triggers domino effect in the high Andes

The idea of food chains and food webs in the animal kingdom is simple: remove a link or thread and the system is broken. It is not always clear how the absence of one species may affect others.

Sometimes the connection is clear.

Argentina's wild vicuñas are related to llamas and alpacas. For decades, pumas and condors have been linked, sustaining the high Andes environment of Argentina's San Guillermo National Park.

After a mange outbreak decimated the park's population in less than five years, each of these relationships fell apart.

cascading consequences are felt by nearly all wildlife and plants when a disease is disrupted in a protected environment.

A study published in the journal Ecology Letters examines how the mange outbreak among vicuñas restructured tightly linked food-chain interactions that were previously driven by pumas, also called mountain lions.

There are remote chances.

It shows how even remote parks are not completely safe. Domestic llamas were introduced to private lands outside of the park, which led to the mange outbreak.

This preserve is about as remote as you can get, with very little human interaction, and yet it is still not safe from human activities occurring hundreds of miles away, said co-leading author Justine Smith, as assistant professor with the UC Davis Department of Wildlife, Fish. When managing at-risk populations of wildlife, we might see consequences that we should be prepared for.

There are chain reactions.

The disease of sarcoptic mange is a highly contagious disease in which parasites burrow under the skin, making it too painful to move. Many animals are easy prey.

The authors of the study were already studying pumas and vicu when mange began to spread through the park. They were studying the chain reaction of the disease outbreak.

They used a combination of on-the-ground vegetation surveys and remote sensor data from satellites to analyze landscape changes. Field technicians and researchers collected data on densities, mange prevalence and puma hunting behavior.

They found that introduced disease can cause rapid and catastrophic changes to wildlife populations.

The changes to the landscape were obvious even as we were collecting the data to confirm the patterns, according to co-leading author Julia Monk.

Big changes with a tiny mite.

Before the outbreak, pumas had been the biggest threat to vicuñas. The tiny mite was the bigger threat.

The study found that the number of people per square kilometer fell from 17 to 1 by 2020. The primary scavengers left the park when their food source disappeared.

The impact on pumas, the park's top carnivore, is less clear as tracking collars were only operational through the year. The authors know that at least one puma they monitored was starving to death. The authors observed that animals would switch prey to smaller items, such as a instance where a puma was hunting a tuco-tuco.

Range anxiety.

Massive change to the landscape was brought about by the changes among the animals. Grasses covered bare ground that was visible from space. In areas where vicuñas preferentially foraged to avoid becoming puma prey, vegetation increased up to 900%. There is some concern that this growth could cause a population explosion of European hares.

Smith said they don't know how or if the systems will recover. It is hard to predict.

The scientists say the study shows the importance of baseline monitoring, basic research and supporting the capacity of scientists outside the United States.

Monk said that continuing to support our colleagues in Argentina who have worked for decades to understand and protect this unique system will be vital for tracing the continuing effects of the disease.

More information: Julia D. Monk et al, Cascading effects of a disease outbreak in a remote protected area, Ecology Letters (2022). DOI: 10.1111/ele.13983 Journal information: Ecology Letters Citation: Tiny mite triggers domino effect in the high Andes (2022, March 7) retrieved 7 March 2022 from https://phys.org/news/2022-03-tiny-mite-triggers-domino-effect.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.