Projected changes to coral reefs, mangroves and seagrasses Recall location within program, recalling climate to habitats then stocks/organisms

Based on......

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

Coral reefs major part of habitats, but this talk is more than reefs Coral reefs major part of habitats, but this talk is more than reefs. Interconnectivity among habitats.

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

Corals must build skeletons fast enough to withstand natural forces of erosion waves cyclones & storms Balance battle of erosion and accretian. Gowth to overcome forces . Point out bioeroders later. bleaching predators coral eaters

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 How corals grow… symbiosis. Cells of algae in photo.

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 Threshold bleaching- 30-31 NOAA bleaching alerts Healthy - unbleached Stressed - bleached Recently dead

Stresses – ocean acidification 30% extra CO2 entered ocean Changes ocean chemistry Harder to form skeletons Greater coral erosion Refer back to johan’s talk. Result, corals have to compete with other erosive forces,

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 West New Britian. Not a total disappearance of corals…. But simplification. Fabricius et al 2011

Source: http://coralreefwatch.noaa.gov/satellite/vs/index.html

Projected Effects of Climate Change on Coral Ecosystems Take out sea

Projected Regional 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 pH is a logarithmic scale, a difference of one pH unit is equivalent to a tenfold difference in hydrogen ion concentration. a = since 1960

Warmer water temperatures Reefs very high vulnerability Increased bleaching, ~1% loss per year by 2035 Average los of 1% per year…expecting to continue if not get worse. Recent observations

More acidic ocean Reefs have high vulnerability Weaker reef frameworks Growing quickly, future not grow quickly, dead coral dissolution more easily. Aragonite threshold, already in deep ocean, so low will dissolve. Softer easier for bioerosion.

Stronger storms and heavier rainfall Moderate vulnerability of reefs More disturbances = less time to recover Turbidity- runoff light penetration,

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

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

CORAL DOMINATED TO ALGAL DOMINATED REEFS

Projected loss of coral reefs 2050 A2 2100 >90% Loss Of Coral Cover by 2100

Mangroves: role & value

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

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

Projected loss of mangroves in VANUATU From 25 km2 today: Year Mangrove area (%) 2035 -10 2050 -50 2100 -60 CAN REFERENCE

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 Burn -

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

Projected loss of seagrass in Vanuatu From ?? km2 today: Year Seagrass area (%) 2035 -5 to -20 2050 -5 to -30 2100 -10 to -35

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 Adaptations talk…

Conclusions Coral reefs, mangroves and seagrasses in Vanuatu 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