Fish and Pollution

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Learning Objectives:

• Explain the factors that support the survival of fish
• Describe the ways in which pollution harms fish
• Develop and list steps that humans can take to minimize pollution and ensure the health of fish

Teacher Background:

Human activity can change aquatic ecosystems in ways that can harm fish and other organisms. For example, thermal pollution from factories raises the temperature of water. This can kill fish that are adapted to lower water temperatures and can also decrease the amount of oxygen dissolved in the water, which aquatic animals need to survive. The removal of plants from the land allows silt (fine soil) to be carried from fields and construction sites to cover fish spawning areas. Fertilizer runoff from farms and lawns adds excess nutrients to waterways, which can cause harmful algae growth. Algae can be toxic to fish and can decrease the amount of dissolved oxygen in the water. Storm runoff can also carry solid pollution into aquatic ecosystems. Aquatic ecosystems can be harmed by air pollution that causes acid rain. Some fish require a narrow pH range in order to survive and may be killed by the acidity. Acidic waters also leach more aluminum from the surrounding environment. Aluminum is toxic to many fish. In this lesson, students identify what fish need to survive and learn about how human activity can change aquatic environments in ways that are detrimental to survival of fish and other aquatic animals.

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