1. Eutrophication in Water bodies
By: Kelly Toy

2. Overview What is Eutrophication Eutrophication management Experiments
Nitrogen or Phosphorus control Debate
Case Study: Baltic Sea
Recommendations

3. 1. What is Eutrophication?
Definition
Sources
Process
Importance

4. Definition - Eutrophication
Degradation of water bodies from overfertilization of nitrogen (N) and phosphorus (P), resulting in excess plant biomass and consequently oxygen and habitat depletion.
Seagrasses covered with attached
algae in a Danish estuary.
Removing microalgal blooms at the Olympic Sailing Venue, China.

5. Excess N and P from Human Activities
N and P enters water through
Runoff
Wastewater treatment and industrial discharges
Agriculture
Excess fertilizers, manure
Combustion of fossil fuels
N in air  acid rain  water

6. Eutrophication Process
Excess
N +P
Growth of Plant biomass
Blooms die and sink to sediment
Fish and wildlife die
Anoxia (no O2) in deep waters
Bacteria consume oxygen to degrade dead biomass
Denitrification
(no N) occurs in anaerobic conditions
N-fixing cyanobacteria dominate
Internal loading
of P, system is
N-deficient
Cyanobacteria is worse than algae
N-deficient system promotes cyanobacteria to thrive

7. Why does Eutrophication matter?
Global expansion of dead zones
oxygen depleted areas where fish and wildlife are extinct
Decreased biodiversity
New species invasion
Toxic algal blooms (some cyanobacteria)
Aesthetically unpleasing
Severe impacts on fisheries
Economic detriment industries relying on water quality/ aquatic ecosystems (tourism)

8. 2. Eutrophication Management Experiments
1970’s Schindler Experiment
Response
Effects on Lakes and Estuaries

9. 1970’s experimentation 37-years long with entire-ecosystem lakes
D.W. Schindler found:
P controls phytoplankton
Reducing N increased cyanobacteria
Response:
U.S. and Europe ban P in detergents
Ramp up P removal in wastewater treatment plants
Only N inputs
N + P inputs
Experimental Lake 226
Ontario, Canada

10. Effect on Lakes and Estuaries
Water quality in lakes improved dramatically
Eutrophication in estuaries increased
N pollution grew tremendously since the 1970’s
N contributes to eutrophication in estuaries
(no N-fixing cyanobacteria, N can limit growth)
Definitons
Lake- Freshwater surrounded by land
Estuary- Freshwater inlet connects to ocean outlet
Salinity varies throughout water body

11. Dead Zones in Estuaries
146 coastal regions affected by anoxia
Eliminating fish and bottom-feeding life forms
Size of dead zones growing
Gulf of Mexico dead zone- state of New Jersey

12. 3. N or P Control Debate
Evidence for each side

13. Debate: N or P control?
Reducing P increased eutrophication in estuaries
Reducing N increased N-fixing cyanobacteria
Expert Liminologists are still debating which nutrient controls eutrophication
cannot perform Schindler experiments in estuaries
Each water body is condition specific
Region and environment/ecosystem

14. 4. Case Study: Baltic Sea Description High Societal Stakes
Recommendations

15. Case Study: Baltic Sea 9 countries bordering Low salinity estuary
N-fixers abundant
Spatial extent and intensity of Hypoxia (low O2) growing

16. Dual Nutrient reduction strategy
Abatement plan was signed by all Baltic Sea countries in 2007 cost $4 billion/year
Upgrade P urban sewage treatment
decrease eutrophication to levels in

17. High Societal Stakes $$
Swedish Department of Agriculture calculates N reductions in the plan cannot be fulfilled unless a large part of Swedish agriculture is shut down
Damaging aquatic ecosystem
Economic detriment to fishing and water industries
Many Countries input
Many Countries affected

18. 5. Recommendations Results should be well tested Expensive
Other ways to mitigate Eutrophication

19. Recommendation
All beneficial effects of dual N and P control must be robustly predicted before implementing high cost of nutrient reductions
N abatement is a very expensive pilot study
May favor cyanobacteria instead of water quality
Do not install N removal technologies at ww treatment plant yet
Continue P reductions to reduce sedimentation
Reduce both N + P at the source

20. In the meantime
We can reduce N and P inputs without expensive treatment
Control Measures for Runoff of both N and P:
Decreased use of fertilizers
Containment and treatment of manure
Tillage practices that conserve soil
Vegetative buffers along shoreline
Maintenance and restoration of wetlands
Convert croplands sensitive to erosion to other uses that do not pollute waterways
Eating less meat – fewer fertilizers needed to grow grain for livestock and less manure

21. Conclusion Eutrophication is destroying aquatic ecosystems
Experiments and Observations
How do we manage N and P?
Expensive
Societal effects on Countries

22. References
Carpenter, S.R. Phosphorus control is critical to mitigating eutrophication. PNAS 2008, 105,
Conley, D.J. et al. Hypoxia-Related Processes in the Baltic Sea. Environmental Science and Technology 2009, 43,
Schindler, D.W. et al. Eutrophication of lakes cannot be controlled by reducing nitrogen input: Results of a 37-year whole-ecosystem experiment. PNAS 2008, 105,
Lewis, W.M.; Wurtsbaugh, W.A. Control of Lacustrine Phytoplankton by Nutrients: Erosion of the Phosphorus Paradigm. International Review Hydrobiology 2008, 93,
Conley, D.J. et al. Controlling Eutrophication: Nitrogen and Phosphorus. Science 2009, 323,
Howarth, R.; Paerl, H.W. Coastal marine eutrophication: Control of both nitrogen and phosphorus is necessary. PNAS 2008, 105, E103.
Schindler, D.W.; Hecky, R.E. Reply to Howarth and Paerl: Is control of both nitrogen and phosphorus necessary? PNAS 2008, 105, E104.
Schindler, D.W.; Hecky, R.E. Eutrophication: More Nitrogen Data Needed. Science 2009, 324,
Schelske, C.L. Eutrophication: Focus on Phosphorus. Science 2009, 324, 722.
Conley, D.J. et al. Response (to Eutrophication Policy Forum Debate). Science 2009, 324,
Bryhn, A.C.; Hakanson, L. Coastal eutrophication: Whether N and/or P should be abated depends on the dynamic mass balance. PNAS 2009, 106, E3
Schindler, D.W.; Hecky, R.E. Reply to Bryhn and Hakanson: Models for the Baltic agree with our experiments and observations in lakes. PNAS 2009, 106, E4.
Bryhn, A.C.; Hakanson, L. Eutrophication: Model Before Acting. Science 2009, 324, 723.
Jacoby, C.A.; Frazer, T.K. Eutrophication: Time to Adjust Expectations. Science 2009, 324,