Download presentation
Presentation is loading. Please wait.
1
Projected changes to coral reefs and mangroves
2
Based on......
3
What we will discuss Projected changes to atmospheric and oceanic conditions Ecosystems supporting fish Fish stocks/aquaculture species Implications for economic development, food security and livelihoods Adaptations and policies to reduce threats and capitalise on opportunities
4
Outline Requirements for good coral growth
Recent stresses on coral reefs Projected effects on coral reefs Mangroves
5
Requirements for good coral growth
Warm water temperatures Shallow well-lit waters Low sediment and nutrients Right ocean chemistry Ω >3.3 Warmest parts of oceans Narrow temperature range
6
Corals must build skeletons fast enough to withstand natural forces of erosion
waves tropical cyclones sunshine 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 fresh water also causes bleaching Healthy - unbleached Stressed - bleached Recently dead
9
Stresses - ocean acidification
30% extra CO2 entered ocean Prevents greater warming! BUT 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
Local stressors: reef status: Samoa
Low risk Medium risk High risk Very High risk Medium risk or higher 0% 6% 43% 51% 100%
12
Projected effects of climate change
13
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 Tropical cyclones 9 Number of tropical cyclones may decrease but likely to be more intense a = since 1960
14
Warmer water temperatures
Very high vulnerability Increased bleaching, ~1% loss per year by 2035
15
More acidic ocean Reefs have high vulnerability Weaker reef frameworks
16
Stronger storms and heavier rainfall
Moderate vulnerability More disturbances = less time to recover
17
Higher sea level Some corals may keep up Loss of deeper corals
18
Opportunities for management interventions
Anthony & Maynard 2011
19
Coral reefs will not disappear entirely BUT MUCH SIMPLER ECOSYSTEMS
What CC means for coral reefs Bleaching and diseases Weaker skeletons Physical destruction Less time to recover between disturbances Healthy reefs better able to cope Can adaptation occur? Coral reefs will not disappear entirely BUT likely to be MUCH SIMPLER ECOSYSTEMS
20
Mangroves: role
21
Vulnerability of mangroves
Most vulnerable to: sea-level rise decreasing rainfall increasing cyclone intensity Ability to adapt by migrating landward as sea-level rises but human barriers may constrain movement Overall moderate vulnerability to climate change
22
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
23
Projected loss of mangroves in Samoa
From 7.5 km2 today Year Mangrove area (%) 2035 -10 2050 -50 2100 -60
24
Key adaptations Build resilience of coral reefs and mangroves 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
25
Conclusions Coral reefs and mangroves in Samoa 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
Similar presentations
![Climate Change Impacts in the United States Third National Climate Assessment [Name] [Date] Hawai’i & Pacific Islands.](/15/4630128/big_thumb.jpg "Climate Change Impacts in the United States Third National Climate Assessment [Name] [Date] Hawai’i & Pacific Islands.>")
