Which term refers to organism that are used monitor the health of environment?

The term "bioindicators" refers to organisms that are used to monitor the health of an environment. Bioindicators (species, organisms or groups of organisms) can be used to determine the quality and health of the ecosystem it is a part of, and can be either:

Responsive: These are species or organisms that show a measurable response to particular changes in the environment.

Cumulative Impact: These are organisms that respond progressively and proportionally to increased levels of pollution or other environmental changes over a period of time.

Bioindicators are species or organisms that are particularly sensitive to changes in the environment, and whose presence or absence, abundance or health, can provide information about the overall health of the ecosystem. They can be used to assess the impact of pollution, climate change, and other human activities on the environment.