Eutrophication

• Define eutrophication


  The nutrient enrichment of streams, ponds and groundwater, caused when increased levels of nitrogen or phosphorus are carried into water bodies.
• What are the steps of eutrophication?

  1- nutrients wash into river or stream

  2- Algae grow quickly in response to increased nutrients

  3- Algae block sunlight to aquatic plants= slow photosynthesis, less oxygen in water, low DO levels

  4- Decomposer populations increase due to more food(algae) they use up all of the oxygen for respiration = high BOD levels

  5- Fish and other consumers die due to lack of oxygen and lack of producers at the base of the pyramid

  6- Oxygen levels decline and dead organic matter forms sediments on the lake or river - turbidity increases

  7- All life is gone and sediment settles to leave a clear blue lake
• What processes occur in eutrophication

  1) Algal blooms- increase nitrogen and phosphorus are carried into streams, lakes and ground water causing nutrient enrichment

  2) Anoxia - Increase in algae and plankton shade life below resulting in anoxia

  3) Change in species composition- Increased build up in dead matter leads to changes in species composition
• What is natural eutrophication?


  A process of primary succession
• What is anthropogenic eutrophication?

  Human activities cause phosphorus(domestic detergents) and nitrogen(air pollution, farm runoff) levels to increase
• What are the impacts of eutrophication?


  - Increased turbidity

  - Rate of sediment deposition increases

  - Net primary productivity higher

  - DO increases

  - Diversity of primary producers changes- dominant species changes

  - Death of aerobic organisms, loss of macrophytes

  - Algal blooms

  - Anoxia

  - Loss of species diversity
• What is the impact on a freshwater ecosystem?

  Loss of submerged aquatic plants - thought to disappear as they lose their energy supply
• What are the physical impacts?

  Ugly

  Smelly and effects aesthetic value of ecosystem
• What is a case study of eutrophication?

  Lake Erie in Canada

  - Rapid anthropogenic eutrophication during 1960s
• What was the impact of the eutrophication in Lake erie?

  - Decline in biodiversity

  - Ecosystems species diversity reduced

  - Oxygen depletion = death of fish

  - Thickening of lake sediment due to build up of dead organic matter
• What are 3 ways that eutrophication can be dealt with?

  1) Altering human activities that produce pollution - replace

  2) Regulate and reduce pollutants at the point of emission - reduce

  3) Clean up and restoration of polluted water by pumping mud from eutrophic lakes
• How can human activities be altered?

  - Phosphate free detergents in the home

  - Reduced residential use of lawn fertilisers

  - Reduced reliance on agricultural fertilisers heavy in phosphorus and nitrogen

  - Soil consevration
• How can eutrophication be regulated and reduced?

  - Sewage treatment modifications

  - Treatment marshes on farms

  - Domestic campaigns
• How can the water bodies be restored?

  - Mud pumping - removal of nutrient enriched sediments

  - Removal of biomass

  - Mechanical removal of plants - removing nitrogen
• How was lake erie saved?

  - University of manitoba established an experimental lake to try and devise a pollution management strategy to prevent eutrophication

  - Legislation to control phosphates in sewage and to remove them from detergents etc.
• Where is the most likely location of a dead zone in this watershed

  A
• Eutrophication is a


  Bad sign for ecosystem
• Which process would most likely increase the dissolved oxygen level in a freshwater lake?

  Photosynthesis
• How can an algal bloom (eutrophication) lead to a decrease in dissolved oxygen?

  - Decreased light penetration limits photosynthesis below the surface.

  and

  - Bacteria consume oxygen as they decompose dead algae and other organisms.
• We can prevent eutrophication by

  - Picking up dog poop and putting it in the trash.

  - Landscaping with native plants that need less fertilizer

  - Not using fertilizer on our lawns
• The two critical nutrients in eutrophication are...

  - Nitrates

  - Phosphates
• A new golf course is built next to a river. Over the past several months, the nitrate levels of the water in the river have been increasing. Which best explains the cause of the increasing nitrate levels?

  Runoff from fertilizer
• Eutrophication is caused by:

  Excess nutrients building up in the water.
• Why does fertilizer pollution stimulate the growth of algae in a pond?

  Algae are producers and use the fertilizer's nutrients to rapidly multiply.
• Eutrophication causes:


  The killing of fish.
• Which would most likely happen if too many nutrients entered an estuary?

  Algal blooms would lower dissolved oxygen levels, causing fish to suffocate.
• How do excess nutrients typically enter a body of water?

  Rain water washes lawn and agricultural fertilizers into the ecosystem.
• Why do nitrates and phosphates cause algal blooms?


  They are critical plant nutrients.
• In eutrophication, dissolved oxygen levels decrease because...

  Bacteria use it as they decompose organic material.
• The scientists measured hypoxia levels. What is hypoxia?

  Opxygen deficiency.
• As P and N build up, the probability of _______________ increases.

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


  Excessive amounts of nutrients speed up the eutrophication process.
• How does eutrophication cause the death of aquatic organisms

  The lack of oxygen in the water.
• Dead algae and plants are decomposed by:

  Bacteria
• How does swine farming contribute to eutrophication?

  By hog waste runoff.