Watershed Unit

Eutrophication is caused by

• excess nutrients building up in the water.

• industrial point-source pollution.

• unlined landfills and septic tanks.

• wastewater from homes mixing with drinking water.

How does eutrophication cause the death of aquatic organisms

• the build up of carbon dioxide in the water

• the lack of nitrogen in the water

• the lack of carbon dioxide in the water

• the lack of oxygen in the water

The two critical nutrients in eutrophication are... (select two)

• nitrates

• phosphates

• carbon dioxide

• dissolved oxygen

In eutrophication, dissolved oxygen levels decrease because

• bacteria use it as they decompose organic material

• algae uses it during photosynthesis

• it reacts with hydrogen to form H2O (water)

• fish use it up as they consume algae

Which would most likely happen if too many nutrients entered an estuary?

• Nutrients would be used up by the fish and plants, keeping the estuary in balance.

• Algal blooms would lower dissolved oxygen levels, causing fish to suffocate.

• Algal blooms would decrease, leaving few food resources for fish.

• Nutrients would sink to the bottom, increasing soil deposition.

Why should farmers be concerned about unused nitrate fertilizer contaminating surface water and groundwater supplies?

• Unused nitrates reduce algae growth.

• Unused nitrates increase oxygen in the water.

• Excessive amounts of nutrients cause overpopulation of fish.

• Excessive amounts of nutrients speed up the eutrophication process.

In eutrophication, what directly causes the death of fish?

• The plants use up oxygen in respiration

• The fish are poisoned by high CO₂ levels

• Bacteria use up oxygen in respiration

• The fish use up oxygen in respiration

In eutrophication, what does 'algal bloom' refer to?

• The rapid increase in the number of bacteria

• The rapid increase in the number of plants

• The rapid decrease in the number of fish

• The rapid increase in the amount of nitrates in the river

Which is the correct order of changes that occur during eutrophication?

• Aquatic plants cannot photosynthesize and die. Algal blooms blocks light from entering lower levels of a pond or lake. The fish and other aquatic organisms die. The bacteria decompose the algae, and they use up a lot of oxygen during this process. The algae die.

• Algal blooms blocks light from entering lower levels of a pond or lake. Aquatic plants cannot photosynthesize and die. The algae die. The fish and other aquatic organisms die. The bacteria decompose the algae, and they use up a lot of oxygen during this process.

• Algal blooms blocks light from entering lower levels of a pond or lake. Aquatic plants cannot photosynthesize and die. The algae die. The bacteria decompose the algae, and they use up a lot of oxygen during this process. The fish and other aquatic organisms die.

• Aquatic plants cannot photosynthesize and die. Algal blooms blocks light from entering lower levels of a pond or lake. The bacteria decompose the algae, and they use up a lot of oxygen during this process. The algae die. The fish and other aquatic organisms die.

An increase in the amount of nutrients in a lake is known as

• calcification

• cellular respiration

• eutrophication

• photosynthesis