Two fur seals, one with symptoms of alopecia, in the San Benito Archipelago, in a file photo. Picasa (Courtesy)
Sea lions in Mexico suffer from alopecia. A group of scientists who had been studying them for a decade, specifically a subspecies called fur seals that live on the island of Guadalupe and the San Benito Archipelago in the Pacific, found that these animals, which normally have two layers of hair, turned out one of them. The shocking image they saw prompted them to take 13 samples to conduct medical studies to find out the reason for their baldness. Years later, they turned the theory on its head that rising sea surface temperatures were linked to the suffering of these fur seals. The researchers are analyzing whether warming in this part of the ocean has affected the food chain and thereby their diet, leading to hair loss.
The Guadalupe fur seal is named for the island these animals live on and the San Benito Archipelago, both off the coast of the state of Baja California. Because it was critically endangered a century ago, the Mexican government considers it a “priority species for protection.” Threats it still faces, according to the executive, include human activities, “such as fuel contamination of the marine environment” or “introduction of exotic species and associated pathogens to the islands”; in addition to the increase in sea surface temperature during the phenomenon known as El Niño and “its impact on prey availability.”
This species almost went extinct 100 years ago, but it began to be observed again in this region of Mexico at the end of the 1990s, explains one of the researchers, Fernando Elorriaga from the Interdisciplinary Center for Marine Sciences of the National Polytechnic Institute. Since then, they have been investigating how this population recovery came about. To understand their return, they monitored the animals’ health and diet. It was then that the problem of alopecia arose. “One of the aspects that we started to discover, especially since 2013 and 2014, is that some of these animals had spots. We could spot any spots or anomalies in their fur from afar.”
Given the difficulties involved in capturing a wild animal, in 2018 the team managed to capture about 13 specimens to study. They wiped them, took blood and hair samples. The team looked for the cause of alopecia by examining the factors that usually cause it in animals, such as fungi, mites or bacteria. But they found no trace of it. Some studies of similar alopecia in other pinnipeds from other parts of the world have suggested causes such as heat stress or dietary issues. This served as a trigger for the continuation of the studies that showed the possibility of climate change affecting what was happening.
A fur seal with symptoms of alopecia in the San Benito Archipelago, in a file photo. Picasa (Courtesy)
Looking at the temperature fluctuations in the area, the blob stood out as a warm mass of water that crossed the Pacific Ocean from Alaska to Mexico in 2013, destroying marine ecosystems along the way. The heat wave then reached a water temperature of about 2.5 degrees above normal. “These types of environmental changes can affect their thermoregulation, but they can also lead to enormous cellular stress,” says researcher Karina Acevedo from the Department of Microbiology at the Autonomous University of Querétaro. “It’s not an immediate aspect, there are aspects that are delayed because it also affects the entire food chain,” adds the researcher, another member of the working team. “It wouldn’t be direct damage to the fur. Rather, it is a change at the trophic chain level.”
Between 2015 and 2021, the rise in sea surface temperature caused by the blob, which also coincided with an El Niño phenomenon, triggered an unusual mortality event for Guadalupe fur seals, explains Elorriaga, who was involved in a previous study on the impact of this heatwave on the birth rate of fur seals. “They were animals in a very deteriorated physical condition where resources were insufficient and they eventually fell.”
This species feeds primarily on a species of squid, which researchers believe may have migrated to a deeper or more distant location in the heat. This caused the fur seals to switch their diet to a type of squid that has fewer nutritional properties. “If they can control what they eat, if they feed on less valuable prey, that obviously has implications for the formation of the entire biochemical pathway of keratin.” [el componente principal del pelo]says Acevedo.
A fur seal with symptoms of alopecia in the San Benito Archipelago, in a file photo. HIRAM RN (Courtesy)
These species of pinnipeds have two coats, one on top of the other. The bottom one looks like it’s made out of fluff. The top layer is a hard layer of hair that protects the animals from external influences such as pollution or sun exposure, explains Ariadna Guzmán Solís, one of the students who worked on the study, which is about to be published in an international scientific journal. The main function of the double coat of hair is to keep animals warm. The system works like a type of neoprene, keeping air between the two layers and helping the fur seal maintain body temperature when submerged in the water. Because of their damaged fur, these animals are less able to maintain their temperature and have to expend more energy to stay warm. The end result is more wasted energy to get food.
Researchers aren’t convinced that temperature rise is the sole cause. They admit that there could be factors that contributed to the alopecia of these animals, such as pollution of the marine environment. However, the team warns that this could only be the tip of the iceberg. The visible effects on the wolf’s coat are actually “a sign of something much broader at an environmental level that can affect the entire marine ecosystem,” concludes Acevedo.
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