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Presentation delivered by Robert Diaz during the GEF STAP session during the 6th GEF Biennial International Waters Conference in 2011 in Dubrovnik, Croatia.
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Global Nitrogen Cycle, Global Nitrogen Cycle, Eutrophication, and Coastal Hypoxia:Eutrophication, and Coastal Hypoxia:
State of Knowledge andState of Knowledge andManagementManagement
Global Nitrogen Cycle, Global Nitrogen Cycle, Eutrophication, and Coastal Hypoxia:Eutrophication, and Coastal Hypoxia:
State of Knowledge andState of Knowledge andManagementManagement
Robert J Díaz
http://www.vims.edu/deadzone/
Robert J Díaz
http://www.vims.edu/deadzone/
Bringing the problem into focusBringing the problem into focusBringing the problem into focusBringing the problem into focus
How Eutrophication/Hypoxia Became a How Eutrophication/Hypoxia Became a Global ProblemGlobal Problem
Economic growth from expanding population caused increasing input of nutrients to coastal areas over last 60 years resulted in system overload.
Strong correlation through time between:
population growth and agriculture expansion
increased nutrient discharges and disruption of global cycles
increased primary production
increased occurrence of hypoxia and anoxia.
7,000,000,000 by end of 2011.
9,000,000,000 by 2050.
www.abe.msstate.edu
Bringing the problem into focusBringing the problem into focusBringing the problem into focusBringing the problem into focus
• From the start of the ‘Industrial Revolution’ in 1700s it has taken >100 years to alter global Carbon Cycle.
• With the start of the ‘Green Revolution’ in 1940s it took <50 years to alter global Nitrogen Cycle.
• From the start of the ‘Industrial Revolution’ in 1700s it has taken >100 years to alter global Carbon Cycle.
• With the start of the ‘Green Revolution’ in 1940s it took <50 years to alter global Nitrogen Cycle.
Fate of Haber-Bosch NitrogenFate of Haber-Bosch NitrogenFate of Haber-Bosch NitrogenFate of Haber-Bosch Nitrogen
•14% of N produced in Haber-Bosch process enters the human mouth...... if you are a vegetarian.
•4% of N used for animal production enters human mouth.
•82% of N is lost to the environment.
•14% of N produced in Haber-Bosch process enters the human mouth...... if you are a vegetarian.
•4% of N used for animal production enters human mouth.
•82% of N is lost to the environment.
Reactive NitrogenReactive NitrogenReactive NitrogenReactive Nitrogen
Galloway et al. 2008
Global Nitrogen CycleGlobal Nitrogen CycleGlobal Nitrogen CycleGlobal Nitrogen Cycle
Gruber & Galloway 2008
What are Consequences?What are Consequences?What are Consequences?What are Consequences?Caddy 2000
What is at stake for our future?What is at stake for our future?Coastal and Continental Shelf Habitats Coastal and Continental Shelf Habitats
Fisheries ProductionFisheries Production
What is at stake for our future?What is at stake for our future?Coastal and Continental Shelf Habitats Coastal and Continental Shelf Habitats
Fisheries ProductionFisheries Production
Eutrophication Driven Dead ZonesEutrophication Driven Dead ZonesOxygen Minimum ZonesOxygen Minimum Zones
Eutrophication Driven Dead ZonesEutrophication Driven Dead ZonesOxygen Minimum ZonesOxygen Minimum Zones
Helly & Levin 2004Helly & Levin 2004Diaz et al. 2010Diaz et al. 2010
550 Hypoxic Areas
60 Hypoxic Areas in recovery
250 Eutrophic Areas in Danger of Hypoxia
OMZ Touching 1,150,000 km2 of Seabed
550 Hypoxic Areas
60 Hypoxic Areas in recovery
250 Eutrophic Areas in Danger of Hypoxia
OMZ Touching 1,150,000 km2 of Seabed
Area of Ecosystem AffectedArea of Ecosystem AffectedArea of Ecosystem AffectedArea of Ecosystem Affected
Hypoxic Habitat:
Total Area (Km2)
Hypoxic Area
(Km2)
Habitat Hypoxic
Global Flow Lost to Hypoxia
Shelf fromOMZ
26,600,000 1,150,000 4.3% 0.4%
Shelf fromNutrients
26,600,000 170,000 0.6% 0.1%
EstuariesNutrients
1,800,000 70,000 6.9% 0.4%
Costanza et al. 1997, Helly and Levin 2004, Diaz and Rosenberg 2008
What are the direct causes?What are the direct causes?What are the direct causes?What are the direct causes?
•Coastal dissolved oxygen trends•are driven by:
•Runoff from land
•Point discharges
•Global climate change
•Coastal dissolved oxygen trends•are driven by:
•Runoff from land
•Point discharges
•Global climate change
Two Part Key to Future HypoxiaTwo Part Key to Future Hypoxia
Diaz & Breitburg 2010
Management of HypoxiaManagement of HypoxiaManagement of HypoxiaManagement of Hypoxia•Prevention and long-term remediation can be
achieved by reducing excess nutrients (N & P) entering from the land, atmosphere, and groundwater.
• Nutrient reduction will require:
Knowledge of local environmental conditions.
Diagnosis of main nutrient sources.
Integrated, cross-sector land & sea management.
•Prevention and long-term remediation can be achieved by reducing excess nutrients (N & P) entering from the land, atmosphere, and groundwater.
• Nutrient reduction will require:
Knowledge of local environmental conditions.
Diagnosis of main nutrient sources.
Integrated, cross-sector land & sea management.
Management ofManagement of Hypoxia HypoxiaManagement ofManagement of Hypoxia Hypoxia
•Science supporting hypoxia reduction is complex.
•But
•Current scientific understanding is sufficient to support managing in an ecosystem context.
•Science supporting hypoxia reduction is complex.
•But
•Current scientific understanding is sufficient to support managing in an ecosystem context.
Recovered with Nutrient ManagementRecovered with Nutrient Management
60 systems have responded positively.
Mangement of HypoxiaMangement of HypoxiaMangement of HypoxiaMangement of Hypoxia
• Causes and effects are embedded in economic and societal values:
Land-use and development policies can constrain nutrient reduction actions.
Changing relationship of ecosystem response to nutrients and hypoxia.
Coastal regime changes or threshold shifts will require managers to work with new conditions
• Causes and effects are embedded in economic and societal values:
Land-use and development policies can constrain nutrient reduction actions.
Changing relationship of ecosystem response to nutrients and hypoxia.
Coastal regime changes or threshold shifts will require managers to work with new conditions
Not all hypoxia can be readily controlled butcase-specific knowledge can clarify solutions.
Policy Issues to Overcome to Policy Issues to Overcome to Solve HypoxiaSolve Hypoxia
Policy Issues to Overcome to Policy Issues to Overcome to Solve HypoxiaSolve Hypoxia
•Management Side: Cross-sector mission conflicts.
Inadequate pollution management.
Low environmental awareness among policymakers and public as to the ecological and economic costs.
Lack of a master plan for the coastal area as a whole (Coastal Zone Planning).
•Management Side: Cross-sector mission conflicts.
Inadequate pollution management.
Low environmental awareness among policymakers and public as to the ecological and economic costs.
Lack of a master plan for the coastal area as a whole (Coastal Zone Planning).
Knowledge Gaps to Overcome Knowledge Gaps to Overcome to Solve Hypoxiato Solve Hypoxia
Knowledge Gaps to Overcome Knowledge Gaps to Overcome to Solve Hypoxiato Solve Hypoxia
•Science Side:
Habitat loss/alteration impacts on populations and economies.
Nutrient sources, loadings, and transformations.
Natural factors and climate change.
Provide holistic ecosystem view.
•Science Side:
Habitat loss/alteration impacts on populations and economies.
Nutrient sources, loadings, and transformations.
Natural factors and climate change.
Provide holistic ecosystem view.
