Biological indicators are organisms or biological responses used to assess the health of an ecosystem. They can include species like frogs, fish, or insects that reflect the quality of their environment. Changes in their populations or behaviors can signal shifts in environmental conditions, such as pollution or habitat loss. These indicators are valuable tools in environmental monitoring and conservation efforts. For example, the presence of certain macroinvertebrates in water can indicate its cleanliness, while the decline of pollinator species may highlight issues affecting plant reproduction. Understanding these indicators helps scientists and policymakers make informed decisions.