A species that is necessary to maintain

ecosystem health. Without this species,

the ecosystem would change

drastically.

A species that is responsible for

breaking down dead organisms in an

ecosystem.

A substance that pollutes something in

the ecosystem (e.g., air, water, soil).

A Community of interacting organisms

and their environment. It includes both

living and nonliving things.

When there are no individuals left of a

species.

An organism that can be used to

determine ecosystem health. These

organisms can serve as a warning

signal that something in the ecosystem

is changing.

A scientist who studies a humans’

impact on ecosystems and helps

develop solutions to ecosystem problems.

A group of organisms that have similar

individuals and are able to exchange

genes through breeding to produce

offspring that are able to reproduce.

Shallow pools of seawater that exist as

separate bodies of water, usually only

during low tide.