Eutrophication

• Step 1

  The fertilizer is spread on the land by a tractor.
• Step 2

  The fertilizer is washed down by rain and absorbed by the soil.
• Step 3

  The fertilizer is transported to a lake by underground water.
• Step 4

  The presence of the fertilizer in the lake causes overgrowth of the algae and other aquatic plants.
• Step 5

  No sunlight can reach the lower part of the lake, causing algae to do as they cannot photosynthesise.
• Step 6

  The bacteria decomposes the algae.

  • bacteria uses up all the oxygen in the lake making it anoxic.
• Why do the organisms die?

  Due to the lack of oxygen that was consumed by the bacteria.
• What happens to the dead organisms?

  the organisms are broken down by decomposers.