Nitrogen and Phosphorus are often limiting factors in plant growth. Therefore they are used in fertilizers to improve plant growth.

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Eutrophication

• Nitrogen and Phosphorus are often limiting
  factors in plant growth. Therefore they are used
  in fertilizers to improve plant growth.
• However, eutrophication is when there is too
  much of a good thing. Excess amount of these
  nutrients can have harmful affects on aquatic
  (water) ecosystems.

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Eutrophication Too much of a good thing
Eutrophication is the addition of excess
nutrients to an aquatic system
Fertilizers- N and P Detergents- P
Organic waste (manure, sewage)
Algal bloom excessive growth of algae when the
normally limiting nutrients (N or P) are increased
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Eutrophication Cont.

• Overgrowth of algae blocks the light
• - Algae and other plants begin to die and be
  decomposed.
• OR Organic waste can be used directly as food by
  decomposers

Dissolved Oxygen Levels Drop because decomposers
use O2
Can result in fish kills and decline of other
species
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Review with your table partner

• What is the initial effect on a lake if excess
  nutrients get into a lake from runoff of
  fertilizers on farms?

An increase in the population of algae an
algal bloom
Note that algae are photosynthetic organisms- how
do the algae themselves affect the amount of
oxygen?
Photosynthesis gives off oxygen, so while the
algae are living they increase the amount of
oxygen in a lake.
The end effect of eutrophication (excess
nutrients) is low oxygen in a lake. Explain why
this occurs.
The mass of algae blocks the light and causes an
increase in decomposition of dead algae and
plants. The decomposers use up the oxygen.
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Eutrophication Animation
http//www.youtube.com/watch?vUGqZsSuG7ao
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Puget Sound Dead Zones
http//www.youtube.com/watch?v4JTxVxL_yFM
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Eutrophication