These animals offer key clues for environmental change

Indicator species are often the first to be affected by change in an ecosystem. Studying these sensitive animals helps scientists detect the effects of climate change and pollution early.

Variable harlequin frogs are critically endangered, decimated by the chrytid fungus. Amphibians are considered indicator species because they’re highly sensitive to change in their environments. By monitoring them, scientists can learn about changes in the health of entire ecosystems.
Photograph by ROBIN MOORE, Nat Geo Image Collection

An indicator species is an organism—bacteria, plant, or animal—that reflects the condition of the environment around it. They’re often the first in their ecosystem to be affected by a particular environmental change, such as a warming climate, pollution, human development, and other environmental degradation. By monitoring changes in the behavior, physiology, or number of an indicator species, scientists can monitor the health of its whole environment.

Crayfish, for example, can indicate the quality of freshwater, because changes in water acidity are stressful to them. The health of corals can indicate trends such as seawater rise and sea temperature fluctuation, which in turn are signals of climate change. Peregrine falcons are an indicator of pesticides; DDT, for example, causes their

Create your free account to continue reading

No credit card required. Unlimited access to free content.
Or get a Premium Subscription to access the best of Nat Geo - just $19
SUBSCRIBE

Read This Next

SeaWorld violated the Animal Welfare Act. Why is it still open?
'World’s worst shipwreck' was bloodier than we thought
World’s first ultrasounds of wild manta rays reveal a troubling truth

Go Further

Subscriber Exclusive Content

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet