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LESSONS FROM CORAL REEF DEVASTATION, REORGANISATION, AND RECOVERY Nick Graham
@naj_graham www.lec-reefs.org
Williams & Graham (2019) Func Ecol
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Uncertain futures in the Anthropocene
Williams & Graham (2019) Func Ecol
LESSONS FROM CORAL REEF DEVASTATION, REORGANISATION, AND RECOVERY - - PDF document
LESSONS FROM CORAL REEF DEVASTATION, REORGANISATION, AND RECOVERY - - PDF document
LESSONS FROM CORAL REEF DEVASTATION, REORGANISATION, AND RECOVERY Nick Graham @naj_graham www.lec-reefs.org Early reef species existed with the dinosaurs Williams & Graham (2019) Func Ecol 1 Uncertain futures in the Anthropocene
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Greg Torda “Roughly half of the corals
- n the #GreatBarrierReef
died in the past 18 months (from global warming).” Terry Hughes
BLEAK TIMES!
Fiji Japan Maldives Seychelles
… and of course it wasn’t just the GBR
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Hughes et al. 2018 Science
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Graham et al. PLOS ONE 2008
Change in coral cover through 1998
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REEF TRAJECTORIES FOLLOWING MAJOR BLEACHING
REGIME SHIFT
(9 sites)
RECOVERY
(12 sites)
Graham et al. 2015 Nature
Recovery versus regime shifts
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7 REGIME SHIFT
(9 sites)
RECOVERY
(12 sites)
Graham et al. 2015 Nature
Recovery versus regime shifts
Robinson et al. 2019 Global Change Biol
Novel fish communities
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Wilson et al. 2019 Coral Reefs
Boom and bust of keystone structure
1994 2005 2008 2011 2014 2017
Massive coral Branching coral Total coral
Branching coral recovery post-1998 Branching coral loss in 2016 Bleaching Bleaching
PREDICTORS OF RECOVERY
Graham et al. 2015 Nature Rugosity Juvenile coral density Depth Herbivore biomass Nutrients
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Hughes et al. 2010 TREE MacNeil et al. 2015 Nature
Nutrient pollution and fishing are pervasive NUTRIENTS
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MacNeil et al. Nature Eco Evo 2019
Coral cover dynamics on the GBR
MacNeil et al. Nature Eco Evo 2019
Acropora cover dynamics on the GBR
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MacNeil et al. in review
Water quality mediates coral recovery on the GBR
- 17% improvement in catchment water quality would enable
many reefs to recover between bleaching events to 2050
D’Angelo & Wiedenmann 2014 Curr Opin Env Sust
High nitrogen, low phosphorus High nitrogen AND phosphorus Slower growth Bleaches easier Faster growth Bleaches at higher threshold
Not all nutrients are bad
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Fox et al. Curr Biol 2018
Corals feed more in naturally nutrient rich waters
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INVASIVE RATS Seabirds bring nutrients from open ocean
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Graham et al. 2018 Nature
Seabirds & nutrients higher on rat-free islands
Graham et al. 2018 Nature
Huge nutrient subsidy
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Graham et al. 2018 Nature
Huge nutrient subsidy Fish aged and growth assessed using otoliths
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Graham et al. 2018 Nature
Fish grow faster with seabird nutrient subsidies
UNDERWATER SURVEYS OF FISH COMMUNITIES AT EACH ISLAND
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Graham et al. 2018 Nature
Fish biomass higher with seabird nutrient subsidy
Graham et al. 2018 Nature
47% higher total fish biomass
Fish biomass higher with seabird nutrient subsidy
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CORAL BLEACHING Coral bleaching
Benkwitt, Wilson & Graham GCB (2019)
Shifts to calcifying algae next to seabird islands
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Savage 2009 Sci Reports
Seabird nutrient enhance coral growth FOUR times !! FISHING
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Robinson et al. Nature Eco Evo (2019)
James Robinson
Fisheries following coral loss
CPUE
Ecology alone is far from enough
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Kittinger et al. 2012 Ecology & Society
Marrying social and ecological systems
Hicks et al. 2016 Frontiers Ecol & Environ
Underlying social drivers of change
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McClanahan et al. 2015 Cons Bio
Gear-based management
More gears restricted Protected areas
- Implications for algal dominated systems, biodiversity, and changing
fisheries compositions
- Reducing terrestrial nutrient pollution will be essential for some reef
systems to recover
- Not all nutrients are bad, and natural flows should be re-instated
- Diverse approaches to ecosystem-based fisheries management
should be explored
CORAL REEFS ARE CHANGING
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