Transcript Slide 1
Modeling Threats to Coral Reefs and Economic Impacts Lauretta Burke World Resources Institute (WRI) P-S-R Threats can change condition and productivity Threats (Pressure) ---> Change in Condition Change in ---> Productivity Threats can change condition and productivity Threats - Overfishing - Sewage Discahrge - Increased Sediments and Nutrients - Mangrove Removal Change in Coral condition Change in Productivity LCC Diversity Coral extent Coral growth Fish Production Visual appeal from divers Shoreline Protection Changes in Good / Service Fish Catch Fish Productivity Fishing Costs Changes in Good / Service Visual Appeal to Divers - Some divers go to other destinations - Some divers do fewer dives - Some retire Changes in Good / Service Shoreline Protection Services (Will take longer to observe) - May result in increased routine erosion - Less protection during big storms Assumptions required for these links 1. Physical 2. Economic Assumptions required for Fisheries 1. Productivity for different reef quality levels (based on synthesis of literature) Reef Condition Healthy Moderate Poor Assumed Maximum Sustained Fisheries Production (mt/km2/yr) 4 2.3 - 2.9 0.7 - 1.7 2. Hand over to economists to evaluate implications of change in price and In fishing costs. Assumptions required for Dive Tourism 1. Diver “balk rate” due to change in reef condition (based on published and unpublished dive industry surveys and synthesis of expert opinion) Reef Condition Healthy Moderate Poor Reduced Diving 0% 1-5% loss 4-10% loss Why model threats to reefs?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 Spatial Threat Analysis • Scale Dependent • More detailed data yield more precise results Threat Analysis Approach 1. Define threats (or categories) 2. Identify contributing factors • (Stressors and physical factors) 3. Consider how to operationalize indicators of threat • • Data availability Rules / model 4. Calibration and Validation of model results Examples • Reefs at Risk – Coastal Development • Reefs at Risk – Watershed-based Threat • Population Pressure Indicator for Tobago • Land cover and watersheds in Tobago Threat: Coastal Development • Dredging, land filling and reclamation • Mining of sand and coral • Runoff from construction Replace photo • Sewage discharge • Impacts from tourism Coastal Development Analysis Method • Proxy Indicators Mapped “Stressors” Cities Airports Towns Dive Centers Model Rules for Coastal Development Subject / Stressor Qualifier High Medium Cities 50,000 to 100,000 Cities Over 100,000 0 -10 km 10 – 25 km Cities Over 1 million 0 - 20 km 20 – 40 km Towns Various sizes various Airports Military and Civilian 0 – 10 km Mines By type Tourist sites Resorts and dive centers Population Pressure Near Coast Low 0 -10 km various 0 – 4 km various various various Coastal Development Analysis Method • Proxy Indicators Threats Estimated • Distance from development features Estimated Threat From Coastal Development Medium High Coastal Development Analysis Method • Proxy Indicators Reefs Classified • Distance from development features • Coastal Population Pressure Reefs Threatened by Coastal Development Low Medium High Finding: COASTAL DEVOPMENT threatens an estimated one-third of Caribbean coral reefs. Estimated threat Low Medium High Threat: Sediment and Pollution from Inland Sources • Land clearing • Poor agricultural practices • Fertilizer and pesticide runoff Watersheds are critical units for analysis and management Elevation Puerto Rico Watersheds are critical units for analysis and management Watersheds & Rivers Puerto Rico Watersheds are critical units for analysis and management Pour points Puerto Rico Watershed-based analysis 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 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 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 Land Cover Type Effects Erosion Rates Relative Erosion Rate Land Cover Type Low High Erosion Factors by Land Cover Type LAND COVER CATEGORY RELATIVE EROSION RATE Forest 15 Shrubland 45 Woody Savanna 60 Savannas 80 Grasslands 125 Permanent Wetlands 80 Croplands 210 Urban and Built-up 210 Cropland/Natural 120 Relative Erosion Potential – four factors used Slope Land Cover Type Precipitation Soil Porosity Relative Erosion Potential (REP) Relative Erosion Potential (REP) Relative Erosion Potential (REP) Mean REP by watershed Relative Sediment Delivery Sum of REP for watershed, adjusted by watershed size, is assigned to the river mouth Sediment Dispersion Plumes estimated based on sediment delivery and distance from the river mouth Reefs Classified by Sediment Threat Low Medium High Finding: SEDIMENT AND POLLUTION FROM INLAND SOURCES threaten more than one-third of Caribbean coral reefs. Estimated threat Low Medium High Population Pressure - simple, but meaningful indicator Scenarios • Open