1. Projected changes to coral reefs, mangroves and seagrasses
Solomon Islands Government

2. Based on......

3. Outline Coastal habitats: roles and values
Requirements for good coral growth
Recent stresses on coral reefs
Projected effects of climate change on:
coral reefs
mangroves
seagrasses
Key management measures

5. Requirements for good coral growth
Warm water temperatures
Shallow well-lit waters
Low sediment and nutrients
Right ocean chemistry
Coral reefs grow in the warmest parts of oceans & have a narrow temperature range

6. Corals must build skeletons fast enough to withstand natural forces of erosion
waves
cyclones & storms
bleaching
predators
coral eaters

7. A special relationship
Symbiosis at heart of tropical coral reefs
Photosynthetic algae live within coral animal
Corals get enough energy for rapid calcification
Form structurally complex reefs
Home to thousands of other plants and animals

8. Stresses – higher water temperatures
Stressed corals lose algae (and their pigments)
Coral bleaching
Corals living only ~1-2oC below upper thermal limit
Too much freshwater can also cause bleaching
Healthy - unbleached
Stressed - bleached
Recently dead

9. Stresses – ocean acidification
30% extra CO2 entered ocean
Changes ocean chemistry
Harder to form skeletons
Greater coral erosion

10. Ocean acidification: natural laboratory
High CO2 volcanic seeps, PNG
“Winners” = massive corals
“Losers” = branching, tabulate corals
Reduced coral diversity
Much simpler reef with lower pH
Normal pH = now
Mid pH = 2050
Lower pH = 2100
Fabricius et al 2011

11. Projected effects of climate change

12. Projected climate change
1980–1999
average
2035 A2
2050 A2
2100 A2
Air temperature (°C)
27.4
+0.5 to +1.0
+1.0 to +1.5
+2.5 to +3.0
Sea surface temperature (°C)
27.3
+0.7 to +0.8
+1.2 to +1.6
+2.2 to +2.7
Rainfall: equatorial (%)
Rainfall: subtropics (%)
n/a
+5 to +20
-5 to -20
+10 to +20
Sea level (cm)
+6a
+20 to +30
+70 to +110
+90 to +140
Ocean pH (units)
8.1
-0.1
-0.2
-0.3
Cyclones & storms 9
Number of cyclones/storms may decrease but likely to be more intense
a = since 1960

13. Warmer water temperatures
Reefs very high vulnerability
Increased bleaching, ~1% loss per year by 2035

14. More acidic ocean
Reefs have high vulnerability
Weaker reef frameworks

15. Stronger storms and heavier rainfall
Moderate vulnerability of reefs
More disturbances = less time to recover

16. Higher sea level
Some corals may keep up
Loss of deeper corals

17. Opportunities for interventions
Anthony & Maynard 2011

18. Coral reefs will not disappear entirely BUT MUCH SIMPLER ECOSYSTEMS
What climate change means for reefs
More bleaching and diseases
Weaker skeletons
Physical destruction
Less time to recover between disturbances
Healthy reefs better able to cope
Coral reefs will not disappear entirely BUT
likely to be
MUCH SIMPLER ECOSYSTEMS

19. Mangroves: role

20. Vulnerability of mangroves
Most vulnerable to:
sea-level rise
increasing storm intensity
Ability to adapt by migrating landward as sea-level rises but human barriers may constrain movement
Overall moderate-high vulnerability to climate change

21. Overall vulnerability of mangroves
Sea surface temperature
Solar radiation
Ocean chemistry
Cyclones & storms
Rainfall patterns
Sea level
Nutrients
Mangroves 2035 A2
Very low
Low
Moderate
High
2050 A2
Very high
2100 A2

22. Projected loss of mangroves in Solomon Islands
From 525 km2 today:
Year
Mangrove area (%)
2035
-10
2050
-50
2100
-60

23. Vulnerability of seagrasses
Most vulnerable to:
Warmer waters
Increased rainfall (turbidity)
Increasing storm intensity
Reduced light
Limited ability to adapt
Overall moderate vulnerability to climate change

24. Overall vulnerability of seagrasses
Sea surface temperature
Solar radiation
Ocean chemistry
Cyclones & storms
Rainfall patterns
Sea level
Nutrients
Seagrasses 2035 A2
Moderate
Very low
Low
2050 A2
2100 A2
High

25. Projected loss of seagrass in Solomon Islands
From 66 km2 today:
Year
Seagrass area (%)
2035
-5 to -20
2050
-5 to -30
2100
-10 to -35

26. Key management measures
Build health of coral reefs, mangroves and seagrass by addressing existing threats:
Integrated catchment management
Foster the care of coastal fish habitats
Manage and restore coastal vegetation
New measures to allow future adaptation of mangroves:
Provide for landward migration

27. Conclusions
Coral reefs, mangroves and seagrasses in Solomon Islands are expected to decline in area due to climate change
Acting now to manage existing threats and allow for future adaptation is vital for these habitats
Coastal fisheries that depend on these habitats will be affected as these habitats degrade

28. Thank you