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Modeling Threats to Coral Reefs and Economic Impacts

Modeling Threats to Coral Reefs and Economic Impacts. Lauretta Burke World Resources Institute (WRI). P - S - R. Pressure. State. Response. Threats can change condition and productivity. Threats Overfishing Sewage Discahrge Increased Sediments and Nutrients Mangrove Removal.

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Modeling Threats to Coral Reefs and Economic Impacts

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  1. Modeling Threats to Coral Reefs and Economic Impacts Lauretta Burke World Resources Institute (WRI)

  2. P - S - R Pressure State Response

  3. Threats can change condition and productivity

  4. Threats Overfishing Sewage Discahrge Increased Sediments and Nutrients Mangrove Removal Change in Coral condition LCC Diversity Coral extent Coral growth Threats can change condition and productivity Change in Productivity • Fish Production • Visual appeal from divers • Shoreline Protection

  5. Fish Productivity Fish Catch Fishing Costs Changes in Good / Service

  6. Visual Appeal to Divers Some divers go to other destinations Some divers do fewer dives Some retire Changes in Good / Service

  7. Shoreline Protection Services (Will take longer to observe) May result in increased routine erosion Less protection during big storms Changes in Good / Service

  8. Assumptions required for these links • Physical • Economic

  9. Assumptions required for Fisheries • Productivity for different reef quality levels (based on synthesis of literature) 2. Hand over to economists to evaluate implications of change in price and In fishing costs.

  10. Assumptions required for Dive Tourism • Diver “balk rate” due to change in reef condition (based on published and unpublished dive industry surveys and synthesis of expert opinion)

  11. Why model threats to reefs? • Raise awareness about threats to coral reefs • Establish linkages between human activity and coral condition • Develop a standardized indicator of threat to coral reefs from human activities • Promote sharing and improvement of information through data integration and distribution

  12. Spatial Threat Analysis • Scale Dependent • More detailed data yield more precise results

  13. Threat Analysis Approach • Define threats (or categories) • Identify contributing factors • (Stressors and physical factors) • Consider how to operationalize indicators of threat • Data availability • Rules / model • Calibration and Validation of model results

  14. Examples • Reefs at Risk – Coastal Development • Reefs at Risk – Watershed-based Threat • Population Pressure Indicator for Tobago • Land cover and watersheds in Tobago

  15. Threat: Coastal Development • Dredging, land filling and reclamation • Mining of sand and coral • Runoff from construction • Sewage discharge • Impacts from tourism Replace photo

  16. Coastal Development Analysis Method • Proxy Indicators Mapped “Stressors” Airports Dive Centers Cities Towns

  17. Model Rules for Coastal Development

  18. Coastal Development Analysis Method • Proxy Indicators • Distance from development features Threats Estimated Medium High Estimated Threat From Coastal Development

  19. Coastal Development Analysis Method • Proxy Indicators • Distance from development features • Coastal Population Pressure Reefs Classified Reefs Threatened by Coastal Development Low Medium High

  20. Low Medium High Finding: COASTAL DEVOPMENTthreatens an estimated one-third of Caribbean coral reefs. Estimated threat

  21. Threat: Sediment and Pollution from Inland Sources • Land clearing • Poor agricultural practices • Fertilizer and pesticide runoff

  22. Watersheds are critical units for analysis and management Elevation Puerto Rico

  23. Watersheds are critical units for analysis and management Watersheds & Rivers Puerto Rico

  24. Watersheds are critical units for analysis and management Pour points Puerto Rico

  25. Watershed-based analysis

  26. Model Overview • Watershed-based Analysis • Relative erosion rates are estimated for all land areas • Relative erosion rates (and sediment delivery) are summarized by watershed • Sediment dispersion estimated from river mouths

  27. Analysis Method Relative Erosion Potential – • USDA’s Revised Universal Soil Loss Equation (RUSLE) • Combines four factors into single index • slope • precipitation • soil characteristics • land cover type

  28. Analysis Method Relative Erosion Potential – • USDA’s Revised Universal Soil Loss Equation (RUSLE) • Combines four factors into single index • slope • precipitation • soil characteristics • land cover type

  29. Low High Land Cover Type Effects Erosion Rates Relative Erosion Rate Land Cover Type

  30. Erosion Factors by Land Cover Type

  31. Relative Erosion Potential – four factors used Land Cover Type Slope Soil Porosity Precipitation

  32. Relative Erosion Potential (REP)

  33. Relative Erosion Potential (REP)

  34. Relative Erosion Potential (REP) Mean REP by watershed

  35. Relative Sediment Delivery Sum of REP for watershed, adjusted by watershed size, is assigned to the river mouth

  36. Sediment Dispersion Plumes estimated based on sediment delivery and distance from the river mouth

  37. Reefs Classified by Sediment Threat Low Medium High

  38. Low Medium High Finding: SEDIMENT AND POLLUTION FROM INLAND SOURCES threaten more than one-third of Caribbean coral reefs. Estimated threat

  39. Population Pressure - simple, but meaningful indicator

  40. Scenarios • Open

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