UTSpeaks: Keeping seas green17 November, 2011UTSpeaks: Keeping seas green17 November, 2011

CAN PRESERVING HUMBLE SEAGRASS HELP PROTECT US FROM THE EXTREMES OF HUMAN-INDUCED CLIMATE CHANGE?

● Bill Gladstone– Values and services– Loss and recovery

● Peter Macreadie– Seagrass as a carbon sink– Carbon capture and storage

● Peter Ralph– Protecting seagrass carbon

What are we talking about?What are we talking about?

SeagrassesSeagrasses

● Marine flowering plants

● Australia: a global hotspot– Greatest number of

seagrass species (50%)– Largest area (95,000 km2)

Mcleod et al 2011

Where is it, how much is there, how is it changing?Where is it, how much is there, how is it changing?

● Global seagrass area 177,000 - 600,000 km2

● Mapping seagrass:– diver surveys– side scan sonar– aerial imagery– satellite remote sensing

● Uncertainties in estimates of seagrass area and rate of change:

– technological constraints– lack of historical data – environmental constraints– human capacity constraints

NSW DPI 2008

Values and Services: BiodiversityValues and Services: Biodiversity

● Structural complexity of seagrass– epiphytes– periphytes– encrusting invertebrates– infauna– mobile fauna– fishes, rays, invertebrates– birds

● Charismatic fauna– dugong, turtles, seahorses

● ~ 60 threatened and endangered species rely on seagrass

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Values and Services: Fish Nurseries Values and Services: Fish Nurseries

● 50% of the world's fisheries rely on seagrass

● Seagrass-associated prawn fisheries in North Qld: $1500 ha-1 yr-1

● Seagrass-supported fisheries in South Australia: $100 million yr-1

● Economic and social value of artisanal seagrass-based fisheries

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Values and ServicesValues and Services

Blue Carbon

Coastal Water Quality

Fish NurseriesMarine Biodiversity

Coastline and Beach Stabilisation

Source: Forest Trend

• Climate Change Adaptation

• Sustaining Community Resilience and Coastal Livelihoods

Value, Appreciation, UnderstandingValue, Appreciation, Understanding

Orth et al. 2006

Scientists’ Concerns for SeagrassScientists’ Concerns for Seagrass

Loss of SeagrassLoss of Seagrass

● Global losses– 29% of known area– 7% per year

Location % Seagrass area lost

Clarence River 60%

Lake Macquarie 44%

Tuggerah Lakes 50%

Port Hacking 60%

Botany Bay 58%

NSW 50% CSIRO

Human Activities Damaging SeagrassesHuman Activities Damaging Seagrasses

● More than 1 billion people live within 50 km of seagrass

● In situ impacts– dredging, scouring– changes in water flow– trawling– smothering, shading– contamination

● Indirect impacts– eutrophication – sedimentation– increasing water temperature– introduced species

Seagrasswatch

Consequences of Seagrass LossConsequences of Seagrass Loss

● 70% decline in seagrass cover 40% decline in commercial fish catches– Western Port Bay (Vic)

● 22% decline in seagrass cover 30% decline in commercial and recreational fish catches– Adelaide P

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Recovery of SeagrassRecovery of Seagrass

● Vegetative growth● Germination from seed bank● Seed dispersal● Rafting

● Halophila: months● Zostera: years● Posidonia: decades

● Success of seagrass restoration, transplants: 30%– Cost $8,000 to $1 m per hectare

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NSW DPI

Recovering Seagrass: Manly CoveRecovering Seagrass: Manly Cove

Recovering Seagrass: Manly CoveRecovering Seagrass: Manly Cove

Bring Back the Fish

Recovering Seagrass: Shoal BayRecovering Seagrass: Shoal Bay

R Carraro

Recovering Seagrass: Shoal BayRecovering Seagrass: Shoal Bay

18 months

Recovery begins with colonisation by Halophila

Recovering Seagrass: Manly CoveRecovering Seagrass: Manly Cove

Eco Divers

18 months

Local environmental factors and condition of seagrass meadow might compromise recovery potential

Values, Impacts, ConservationValues, Impacts, Conservation

● Seagrasses provide human society with valuable goods and services

● Despite the impacts of their loss, seagrasses continue to decline and natural recovery processes are slow

● The potential for carbon biosequestration by seagrasses (Blue Carbon) provides further support for their conservation

Climate change lingoClimate change lingo

Kosland Science Museum

● Carbon dioxide (CO2) is most significant human-produced greenhouse gas

● Greenhouse effect = global warming ≈ climate change

US Dept of Energy report (Nov 2011):

● “Biggest jump ever in global warming gases”

● CO2 output in 2010 was 6% higher (512 million tonnes) than in 2009

● Greenhouse gas emissions were higher than the worst-case scenario outlined by climate experts (the IPCC)

Climate Change: How are we doing?Climate Change: How are we doing?

Fighting climate change using natureFighting climate change using nature

● Reducing greenhouse gas emissions is necessary, but how do we get rid of all the emissions already floating around the atmosphere?

● Biosequestration: nature’s way of capturing and storing carbon in sediments

● It’s the same process that created fossil fuels in the first place!

istockphoto

Carbon FarmingCarbon Farming

1. Reducing greenhouse gas emissions

2. Capturing and storing carbon in vegetation and soils (creating ‘carbon sinks’)

Terrestrial only. Not aquatic.

RDAMR

Could seagrasses be the most powerful carbon sinks on the planet?Could seagrasses be the most powerful carbon sinks on the planet?

Global area: Tropical Rainforests vs. SeagrassesGlobal area: Tropical Rainforests vs. Seagrasses

Tropical rainforests

Seagrasses

OR

2.5 times the area of

Australia

The area of VIC or NSW

(?)

Destination 360

IndexOZ

Carbon burial: Tropical Rainforests vs. SeagrassesCarbon burial: Tropical Rainforests vs. Seagrasses

C m-2 y-1

Tg C yr-1

● Terrestrial forests typically store carbon for decades, whereas seagrasses store carbon for millennia!

● Carbon rich deposits can be >10-m thick

● Unlike terrestrial soils, the sediment in seagrass meadows do not become saturated with carbon

● Why? Because the sediments accrete vertically in response to rising sea levels.

Seagrasses are long-term sinksSeagrasses are long-term sinks

‘Leakage’ is a big concern

● Increasing forest productivity can trigger CO2 release from soils

● Increasing CO2 levels in terrestrial soils can stimulate production of other greenhouse gases

Carbon farming: too good to be true?Carbon farming: too good to be true?

iStockPhoto

Do seagrass meadows leak carbon?Do seagrass meadows leak carbon?

Could 1000s of years of ancient carbon leak out into the atmosphere if seagrass meadows are disturbed?

Likely mechanism: loss of seagrass meadows (i.e. the ‘top layer’) exposes buried carbon to the forces of nature

Source

When sinks become sources…When sinks become sources…

Sink

Unhealthy meadows can turn from being carbon sinks, to carbon sources

OpenLight

Negative O2 flux

Carbon sourceCarbon source

Positive O2 flux

Carbon sinkCarbon sink

Measuring FLUX of carbon and oxygenMeasuring FLUX of carbon and oxygen

O2

flux

Night Day Night

Light

level

Ponlachart Chotikarn

Andrew Hume

How do we study carbon capture and storage?How do we study carbon capture and storage?

What impact have humans had on coastal carbon sinks?What impact have humans had on coastal carbon sinks?

Industrial developments:• Tanneries• Sewerage farms• Breweries• Quarries• Oil refineries• Sand mining• Port construction

Consequences:• Loss of seagrass, mangroves, and

saltmarsh• Increases in algae

Proni

Algernon Talmadge R.A.

Paleoreconstruction: going back in timePaleoreconstruction: going back in time

Industrialization weakens coastal carbon sinkIndustrialization weakens coastal carbon sink

Fingerprinting of stored carbon (‘carbon stock’)

CoreMedia

Take home messages so farTake home messages so far

● Highly efficient carbon biosequestration

● Large carbon storage in seagrass sediment

● Carbon stays in the sediment for a long time

● Degradation results in substantial carbon emissions and loss of biosequestration

How to protect seagrass carbon?How to protect seagrass carbon?

● What is Blue Carbon?

● What don't we know?– Can a degraded meadow release it stored carbon?

● How do currently protect plant-based carbon?– How can we protect seagrass carbon?

● What is happening internationally?

● What can you do locally?

Is there carbon leakage ????Is there carbon leakage ????

Assume it “comes out quicker than it goes in”

Assume the loss of seagrass leads to substantial CO2 emissions and loss of highly efficient biosequestrationSacramento Delta example

Drained marshes emit CO2Drained marshes emit CO2

● Sacramento Delta – 1,800 km2 of wetlands (not seagrass)

● has released 1 GtCO2 (1,000,000,000 tons of CO2)

• 50% of tree biomass in Californian forests• 1.5% of California total GHG emissions

● C sequestered over 5,000 years, released in 100 years

wikipedia

Do degraded seagrasses emit CO2?Do degraded seagrasses emit CO2?

● Yes

● Does it contribute to the atmospheric CO2?

– we don’t know,

– If they do, then seagrasses matter, because their loss will further enhance climate change.

How to protect seagrass carbon?How to protect seagrass carbon?

● create incentives for coastal conservation and restoration activities

● create disincentives to damage coastal ecosystems

Better to conserve than restoreBetter to conserve than restore

● Conserve = Dual benefit

● More efficient to sustainably manage than to allow loss and then attempt to re-colonise

● Restoration may be necessary

wikipedia wikipedia

Past methods of protecting carbonPast methods of protecting carbon

● Kyoto Protocol (1997)– Countries agreed to limit GHG emissions

• “flexible mechanisms” to meet these limits• Annual inventory• Doesn’t include coastal wetlands

● Copenhagen Accord (2009)– Ratify REDD

● Cancun Agreement (2010)– Ratify REDD+ which includes mangroves (not seagrass)– Blue Carbon recognised

International carbon creditsInternational carbon credits

● finance to encourage sustainable management– Norway-Indonesia

● Australia-Indonesia Carbon Partnership

● Australia could buy Indonesian “ecosystem restoration concessions” – Australian Clean Energy Scheme

● How can seagrass be included in a carbon accounting scheme?

wikipedia

Seagrass carbon accountingSeagrass carbon accounting

● Does seagrass loss actually leads to increased atmospheric CO2?

● IPCC needs to recognise sediment-based C storage– above-ground biomass is easy to count and satellites can monitor

● Develop a seagrass carbon budget protocol:– quantification – verification of stock over time– how long does the carbon remain within the financial unit– estimate of risk of loosing stock (insurance)

● Engage with a carbon trading market – voluntary market already operational for mangrove (Blue Carbon)

How is IUCN helping this happen?How is IUCN helping this happen?

● creating political awareness

● helping NGO generate public awareness

● drafting policy for IPCC, such as REDD+

● establishing a international research and policy agenda

What can you do?What can you do?

● Ask questions about removal of local seagrasses

● Ask questions if you see seagrass dying

● Engage with community monitoring of seagrasses

● Support seagrass restoration programs

● Increase public/political awareness of Blue Carbon

Blue Carbon

Coastal Water Quality

Fish NurseriesMarine Biodiversity

Coastline and Beach Stabilization

Co-benefits of protecting seagrassCo-benefits of protecting seagrass

Source: Forest Trend

• Adapt to climate change

• Sustain community resilience and coastal livelihoods

AcknowledgementsAcknowledgements

Bring Back the Fish