1. Balance in the Ecosystem
7.EC.5B.3 Analyze and interpret data to predict how changes in the number of organisms of one species affects the balance of an ecosystem.

2. Balance of an Ecosystem
Changes in the environment can occur due to changes in populations.
Changes in populations can occur when new members enter a population or when members leave a population.
This will have an effect on the population density (the number of organisms in the given amount of space) for a particular area.

3. Births & Deaths
New births are the main way that organisms are added to a population.
The number of births in a population during a certain amount of time is called the birth rate.
Deaths are the main way that organisms leave a population.
The number of deaths in a population during a certain amount of time is called the death rate.

4. Immigration and Emigration
The size of the population can change when members move into or out of the population.
Immigration is when organisms move in from another environment.
When part of the population leaves the environment, this is known as emigration.

5. Carrying Capacity
The natural slowing of population growth as it nears Earth’s carrying capacity is due to an increase in the death rate and a decrease in the birth rate as a result of:
Food and water shortages
Pollution of the environment
Spread of diseases

6. Effects of Increasing Populations
An increasing population can have an effect on the amount of available clean water.
If clean water is being depleted at a greater rate than it can be purified, it is not considered renewable (resource that can be replaced naturally by nature at a similar rate at which it is used) in our lifetime.

7. Effects of Increasing Populations
An increasing population can have an effect on the amount of waste that is produced.
Although there are mechanisms in place to control the disposal of some waste products, more waste is produced than can be managed effectively.
Some waste products require complicated and costly means for removal once they are introduced into the environment.