[Animals] Indicator species: animals that offer crucial clues about environmental change

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What is an indicator species?
An indicator species is an organism (bacteria, plant or animal) that reflects the state of the environment around it. They are often the first in their ecosystem to be affected by a specific environmental change, such as climate warming, pollution, human development and other types of environmental degradation. By tracking changes in the behavior, physiology, or numbers of an indicator species, scientists can monitor the health of their entire environment.

Crayfish, for example, can indicate freshwater quality, as changes in water acidity are stressful for them. The health of corals can indicate trends such as rising sea levels and fluctuating temperatures, which in turn are signs of climate change. Peregrine falcons are an indicator of the presence of pesticides; DDT, for example, causes the shells of their eggs to thin. Many native plants are indicators of the presence and impact of invasive species. For example, US ash trees were the first to be decimated by the invasive emerald ash borer beetle.

To be an effective indicator species, also called a bioindicator, a species must have some key characteristics. Their health should be an indicator of the health of other species in the same ecosystem; a species that is especially vulnerable or struggling is a poor bioindicator. And any changes it undergoes must be clear and measurable, acting as an early warning system for broader changes. Finally, you must respond to change in predictable ways.

Featured indicator species
Amphibians, such as frogs and toads, are good indicators of pollution. They have permeable skin through which they absorb oxygen and toxins. Therefore, they are extremely sensitive to changes in air and water quality.

 

 

For example, they are often the first animals affected by the use of pesticides in or near their ecosystems. Many amphibian po[CENSORED]tions have plummeted around the world, while others have developed deformities, such as extra legs, due to pesticides.

Conversely, certain species of bacteria thrive where toxins are present, making them bioindicators as well. An overabundance of bacteria can indicate the presence of a toxin in the same way as the absence of frogs.

Spotted Owls are a well-studied indicator species in the United States. Scientists look to them to get an idea of the overall health of ancient forest ecosystems and to monitor the effects of human-caused habitat changes. Native to the Pacific Northwest, these owls nest in old tree cavities, broken treetops, and abandoned raptor nests, all in old-growth forests in the region. But with logging, agriculture and urban development, owls have lost their nests and their po[CENSORED]tions have plummeted. They continue to decline by an average of almost 4% each year.

Its decline indicates that other species in the forest are likely also declining and that the forest (and the web of life that supports it) has been degraded. Likewise, a thriving spotted owl po[CENSORED]tion indicates that an ecosystem is healthy and capable of supporting a range of other plants and animals.

Pikas (small furry, short-eared rabbit-like mammals) are perfectly adapted to living in harsh high mountain habitats, meaning that even the smallest changes in their environment affect them. That is why they are good indicators of global warming.

Instead of hibernating for the winter, pikas take shelter under rocky debris and rely on the insulation of dense winter snow cover to keep their burrows warm. In the 2000s, researchers began to notice a decline in pika po[CENSORED]tions at low elevations, especially in the drier areas of the western US.

 

https://www.nationalgeographic.es/animales/especies-indicadoras-que-son-utilidiad