News Excerpt:

According to conservationists, the snow leopard is an “indicator species”.

Indicator species:

• These living organisms indicate changes in their environment and can be easily observed.
• They are also known as bioindicators and are monitored for patterns over time, which can show stress on the species's size, age structure, density, growth, and reproduction rate of populations from factors like pollution, habitat loss, or climate change.
• Animals are the most commonly used indicator species. Other species can include plants and microorganisms.

Characteristics of indicator species:

• A good indicator species should also respond to changes relatively quickly and be easy to observe.
• Their response should be representative of the entire population or ecosystem. 
• They should be relatively common and have a population big enough to study easily.
• Species that have been studied extensively are good candidates for bioindicators.
• Species that reproduce quickly and in high numbers and have a specialized habitat or diet would make ideal indicators.

Significance of indicator species:

• Scientists use indicator species to determine a change in an ecosystem based on what they observe in the indicator species.
• Indicator species are used to show both good and bad environmental changes.
• These changes can include the presence of pollutants, changes in biodiversity and biotic interactions, and changes in the physical environment.

Bioindicator vs. Biomonitor

• A bioindicator is an organism used to assess an environmental change qualitatively.
• For example, E. coli is a type of bacteria commonly found in the faecal matter of warm-blooded animals. The U.S. Environmental Protection Agency uses it to indicate the presence of faecal matter in freshwater.
• A biomonitor is used to measure environmental responses and changes that indicate pollution quantitatively.
• For example, Lichens, a combination of fungus and algae, are used as biomonitors because of their sensitivity to air pollution.
• Scientists know that air pollution is present if the amount of chlorophyll in a lichen decreases.  

Keystone species:

• It is a species that plays a critical role in maintaining the structure of an ecological community and whose impact on the community is greater than would be expected based on its relative abundance or total biomass.
• Without the keystone species, the ecological community to which it belongs would be greatly altered, and many other species would be negatively impacted.
• In many cases, a keystone species is a predator. This is because a small population of predators is able to influence the distribution and numbers of many prey species.
• Predators not only affect prey populations by reducing their numbers but also alter the behaviour of prey species—where they forage, when they are active, and how they select habitats such as burrows and breeding grounds.

Umbrella species:

• These are species that protect many other species in some way.
• For example, an umbrella species might require a large amount of habitat. If the umbrella species remains healthy and protected, then that protection also protects a host of smaller species.