Decision support tools for managing coral reef systems at

local to regional scales

Jess Melbourne-ThomasGEF International Waters Conference

October 2009

Modelling and Decision Support Working Group

Coral reef systems around the globe are vastly different (e.g. Indo-Pacific reefs versus Caribbean reefs, offshore atolls versus coastal systems) how can we develop a generic model structure that is capable of capturing these differences?

Representing inter-reef connectivities is crucial to a regional-scale approach, but the type and quality of connectivity data available differs greatly between regions how can we design an approach to represent regional-scale connectivities that is flexible and portable?

Key challenges

Key challengesThe dynamics of coral reefs and associated human systems are inextricably linked

how can we couple biophysical and socioeconomic dynamics to capture diverse indicators of reef state?

In addressing these issues, we need to ensure that the models we develop are robust

what processes can we use for training and testing the models?

Addressing the challenges

1. Assembling the pieces - developing a generic model framework

2. Testing the framework - Meso-American Reef system

3. Demonstrating portability - Philippines/South China Sea region

4. Coupling biophysical and socioeconomic dynamics - the Mexican Caribbean

Assembling the pieces1. Local scale ecological model

herbivoressmall

piscivores

urchinslarge

piscivores

macroturf

spawning corals

brooding corals

macroalgae

grazed EACBenthos Consumers

Assembling the pieces2. Connectivity via larval transport

herbivoressmall

piscivores

urchinslarge

piscivores

macroturf

spawning corals

brooding corals

macroalgae

grazed EACBenthos Consumers

larval transport for corals, fish and urchins

Assembling the pieces3. Human impacts and disturbances affect local and regional scale processes

herbivoressmall

piscivores

urchinslarge

piscivores

macroturf

spawning corals

brooding corals

macroalgae

grazed EACBenthos Consumers

hurricanes

fishing

coastal development

Testing the frameworkThe Meso-American Reef system (MAR)

1. Can the model reproduce a healthy reef state in the absence of fishing and disturbance?

2. Does the model reproduce broad-scale dynamics over the past 30 years given a schedule of known disturbance events?

macroturf

coral

macroalgae

timestep (years)

1. Can the model reproduce a healthy reef state in the absence of fishing and disturbance?

Predicts community structure of a healthy reef systemStable trajectories in benthic dynamics over long time series

Testing the framework

1. Can the model reproduce a healthy reef state in the absence of fishing and disturbance?

Predicts community structure of a healthy reef systemStable trajectories in consumer dynamics over long time series

Testing the framework

piscivores

herbivores

urchins

timestep (years)

Testing the frameworkEmergent spatial variability driven by patterns of larval connectivity

1

2

3

4

5

subregion 1 2 3 4 5

subregion 1 2 3 4 5

Testing the frameworkEmergent spatial variability driven by patterns of larval connectivity

Regional variation in the ratio of herbivores : piscivores

Low fish recruitment to Chinchorro

1

2

3

4

5

1980 1990 2000 present

1980 – present: increasing fishing pressure (selective for large piscivores) [entire region]

1980 – present: increasing nutrient/sediment inputs from coastal development [entire region]

1986 – 1990: decline in hard coral cover due to white band disease and bleaching [subregion 4]

1983 – 1984: urchin mortality event [entire region]

1988: Hurricane Gilbert [subregion 1]

1998: Coral bleaching event [subregions 1, 2, 3 & 5], Hurricane Mitch [subregions 4 & 5]

2000: Hurricane Keith [subregion 4]

2001: Hurricane Iris [subregions 4 & 5]2002: Hurricane Isidore [subregion 1]2005: Hurricanes Wilma and Emily [subregion 1]

2007: Hurricane Dean [subregions 2 & 3]

Timeline for the MAR: 1980 – present

2. Does the model reproduce broad-scale dynamics for the MAR over the past 30 years given a schedule of known disturbance events?

Testing the framework2. Does the model reproduce broad-scale dynamics for the MAR over the past 30 years given a schedule of known disturbance events?

Correspondence between model output and observations of reef condition

coral algae

Mexico

Belize

Honduras

Mexico

Belize

Honduras

= hurricane

= bleaching/disease

Testing the framework2. Does the model reproduce broad-scale dynamics for the MAR over the past 30 years given a schedule of known disturbance events?

Correspondence between model output and observations of reef condition

Mexico

Belize

Honduras

Mexico

Belize

Honduras

herbivores piscivores urchins

South China Sea

Sulu SeaKalayaan Islands

Demonstrating portabilityPhilippines / South China Sea (SCS) region

500km

1

5

2

3

4

1 2 3 4 5

Emergent variability

1

2

3

4

5

South China Sea

Timeline for the Philippines-SCS: 1960 – present

1980 1990

1998: Bleaching event [entire region]

1986: muro-ami banned [entire region]

2006: Typhoon Cimaron [subregion 1] Typhoons Xansane and Durian [subregion 2], COTS outbreak [subregions 1, 2 & 4]

1991: Mt. Pinatubo eruption [subregion 1]

1960 1970 2000 present

1960 – present: increasing fishing pressure [entire region]

1960 – present: increasing nutrient/sediment inputs from land clearing [subregions 1 – 4]

1990s: advent of pa-aling and decline in dynamite fishing [entire region]

1962: Typhoon Lucy [subregion 5]

1987: Typhoons Betty and Nina [subregion 2] 1989: Typhoons Gordon and Angela [subregion 1]

1993: Typhoon Koryn [subregion 1]1995: Typhoon Angela [subregion 2]

1999: Typhoon Dan [subregion 1]

2004: Typhoon Nanmadol [subregion 1], COTS outbreak [subregion 3]

1983: Bleaching event [subregion 1]

1965 – 1990: increase in destructive fishing [subregions 1 – 4] 1990 – present: decrease in destructive fishing

Scenarios for the Philippines: Marine

Reservesfish biomass (g/m2) herbivores, piscivores

benthic cover (%) coral, algae

(1) Reserve placement based on larval connectivity between subregions

(2) Reserve placement based on larval connectivity within subregions

(2) + additional management (reduced fishing pressure in northern subregions and gear restrictions)

Best recovery of fish biomass and coral cover

Scenarios for the Philippines: Coral Bleaching

H = Healthy

NS = Nutrification + Sedimentation

BL10 = Coral bleaching once every 10 years

BL5 = Coral bleaching once every 5 years

Synergistic effects of coral bleaching and nutrification + sedimentation on coral cover

Dissemination

Demonstrating the importance of managing water quality to build resilience

Dissemination

Predicting distributions of potential reef futures under alternative management approaches

indicator of reef state

frequ

ency

of m

odel

out

com

es

Socio-economic model (SimReef)

Biophysical model

lobsters

Coupling biophysical and socioeconomic models for the Mexican Caribbean

Socio-economic model (SimReef)

Biophysical model

lobsters

Coupling biophysical and socioeconomic models for the Mexican Caribbean

coral and algal cover (%)

bankruptcies (# boats) and profits (1000 US$)

fish and lobster catches (tonnes)

Coupling biophysical and socioeconomic models for the Mexican Caribbean:Preliminary Validation