KEY CONCEPT Pollution of Earth’s freshwater supply threatens habitat and health.

Water pollution affects ecosystems. Pollution can put entire freshwater ecosystems at risk. Did you know that only some parts of medicine get used by the body, and the rest is waste? hormones: male fish show female characteristics decreases species populations toxins accumulate up the food chain

Water pollution affects ecosystems Runoff from farms contain fertilizers that stimulate plant and algae growth. Plant and algae growth will rob the aquatic environment of oxygen that may lead to the dying off of fish populations.

Scientists determine the health of an ecosystem using indicator species. Indicator species provide a sign of an ecosystem’s health. Amphibians - Frogs are an indicator species because the skin of tadpoles and adults is water-permeable. Frogs come into direct contact with pollutants that can cause deformities such as extra arms, legs, and body tumors.

Biomagnification causes accumulation of toxins in the food chain. Some pollutants are Fat-soluble. These chemicals are stored in the body and passed up the food chain. This process is called biomagnification.

Foster’s Tern provides scientists clues about the pollution in the San Francisco Bay. This indicator species is a top predator The main part of the Foster’s Terns diet is fish. Scientists find large amounts of chemicals contaminants (mercury and PCB’s) in the tissue of dead chicks

Biomagnification causes accumulation of toxins in the food chain. Pollutants can move up the food chain. predators eat contaminated prey pollution accumulates at each stage of the food chain Top consumers, including humans, are most affected.