Presentation delivered by Robert Diaz during the GEF STAP session during the 6th GEF Biennial International Waters Conference in 2011 in Dubrovnik, Croatia.

1. Global Nitrogen Cycle,Global Nitrogen Cycle,
Eutrophication, and Coastal Hypoxia:Eutrophication, and Coastal Hypoxia:
State of Knowledge andState of Knowledge and
ManagementManagement
Robert J Díaz
diaz@vims.edu
http://www.vims.edu/deadzone/

2. Bringing the problem into focusBringing the problem into focus

3. How Eutrophication/Hypoxia Became aHow 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.e
du

4. Bringing 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.

5. Fate 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.

6. Reactive NitrogenReactive Nitrogen
Galloway et al. 2008

7. Global Nitrogen CycleGlobal Nitrogen Cycle
Gruber & Galloway 2008

8. What are Consequences?What are Consequences?
Caddy 2000

9. What is at stake for our future?What is at stake for our future?
Coastal and Continental Shelf HabitatsCoastal and Continental Shelf Habitats
Fisheries ProductionFisheries Production

10. Eutrophication Driven Dead ZonesEutrophication Driven Dead Zones
Oxygen Minimum ZonesOxygen Minimum Zones
Helly & Levin 2004Helly & Levin 2004
Diaz 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

11. Area of Ecosystem AffectedArea of Ecosystem Affected
Hypoxic
Habitat:
Total Area
(Km2)
Hypoxic
Area
(Km2)
Habitat
Hypoxic
Global
Flow Lost
to Hypoxia
Shelf from
OMZ
26,600,000 1,150,000 4.3% 0.4%
Shelf from
Nutrients
26,600,000 170,000 0.6% 0.1%
Estuaries
Nutrients
1,800,000 70,000 6.9% 0.4%
Costanza et al. 1997, Helly and Levin 2004, Diaz and Rosenberg 2008

12. 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

13. Two Part Key to Future HypoxiaTwo Part Key to Future Hypoxia
Diaz & Breitburg 2010

14. Management 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.

15. Management ofManagement of HypoxiaHypoxia
•Science supporting hypoxia reduction
is complex.
•But
•Current scientific understanding is
sufficient to support managing in an
ecosystem context.

16. Recovered with Nutrient ManagementRecovered with Nutrient Management
60 systems have responded positively.

17. Mangement 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
Not all hypoxia can be readily controlled but
case-specific knowledge can clarify solutions.

18. Policy Issues to Overcome toPolicy 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).

19. Knowledge Gaps to OvercomeKnowledge 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.