Can preserving humble seagrass help protect us from the extremes of human-induced climate change? The oceans have long been recognised by science as vital for capturing carbon and renewing the atmospheric balance that preserves life on earth. While vast amounts carbon are captured by phytoplankton, less well known has been the role played by seagrasses in storing carbon, cleansing the air and providing essential habitat for marine life. Based on latest UTS marine research, this public lecture reveals the essential place of seagrasses in global ecology, the growing threats to its continued viability and the work that is being done to rehabilitate the areas of seagrass habitat already lost. Professor Bill Gladstone Marine biologist Bill Gladstone applies scientific understanding to solve problems in marine conservation and environmental management. His interests lie in assessing conservation values in marine ecosystems, the selection and management of marine parks, and community participation in marine conservation. He has worked throughout NSW, the Great Barrier Reef, Torres Strait, the Coral Triangle, and the Middle East. Dr Peter Macreadie Marine ecologist Peter Macreadie is a UTS Chancellor’s Postdoctoral Research Fellow. His research cover a wide range of systems; from deep-sea reefs to intertidal oyster reefs. Peter’s current research focuses on seagrasses to better understand how their resilience to climate change can be improved, and how can we capitalise on their ability to capture and store atmospheric carbon. Professor Peter Ralph Peter Ralph has been working with seagrasses since the early 90’s, when he pioneered the use of optical methods of measuring photosynthesis to examine the impact of pollution on seagrass health. More recently, he is developing new tools to assess the ability of an entire seagrass meadow to fix carbon. This work is now part of an international research agenda lead by the International Union for Conservation of Nature (IUCN) to demonstrate the importance of seagrasses in the global carbon cycle. UTSpeaks is an annual free public lecture series presented by UTS experts discussing a range of important issues confronting contemporary Australia. Use the hashtag #utspeaks to tweet about the lecture on Twitter.

1. UTSpeaks: Keeping seas green
17 November, 2011
CAN PRESERVING HUMBLE SEAGRASS HELP PROTECT US FROM
THE EXTREMES OF HUMAN-INDUCED CLIMATE CHANGE?

2. What are we talking about?
● Bill Gladstone
– Values and services
– Loss and recovery
● Peter Macreadie
– Seagrass as a carbon sink
– Carbon capture and storage
● Peter Ralph
– Protecting seagrass carbon

3. Seagrasses
● Marine flowering plants
● Australia: a global hotspot
– Greatest number of
seagrass species (50%)
– Largest area (95,000 km2)
Mcleod et al 2011

4. 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
NSW DPI 2008
– human capacity constraints

5. Values and Services: Biodiversity
● Structural complexity of seagrass
– epiphytes
– periphytes
– encrusting invertebrates
– infauna
– mobile fauna
– fishes, rays, invertebrates
– birds
● Charismatic fauna
– dugong, turtles, seahorses
reeframblings.co.uk
● ~ 60 threatened and endangered
species rely on seagrass

6. 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
Unsworth et al. 2010
● Economic and social value of
artisanal seagrass-based fisheries

7. Values and Services
Blue Carbon
Marine Biodiversity Fish Nurseries
Coastline and
Coastal Water Quality Beach
Stabilisation
Source: Forest Trend
• Climate Change Adaptation
• Sustaining Community Resilience and Coastal Livelihoods

8. Value, Appreciation, Understanding
Orth et al. 2006

9. Scientists’ Concerns for Seagrass

10. Loss of Seagrass
Location % Seagrass ● Global losses
area lost
– 29% of known area
Clarence River 60%
– 7% per year
Lake Macquarie 44%
Tuggerah Lakes 50%
Port Hacking 60%
Botany Bay 58%
NSW 50% CSIRO

11. Human Activities Damaging Seagrasses
● More than 1 billion people live within 50
km of seagrass
● In situ impacts
– dredging, scouring
– changes in water flow Seagrasswatch
– trawling
– smothering, shading
– contamination
● Indirect impacts
– eutrophication
– sedimentation
– increasing water temperature
– introduced species

12. Consequences of Seagrass Loss
● 70% decline in seagrass
cover 40% decline in
commercial fish catches
– Western Port Bay (Vic)
● 22% decline in seagrass
Pittwater.nsw.gov.au
cover 30% decline in
commercial and
recreational fish catches
– Adelaide

13. Recovery of Seagrass
● Vegetative growth
Cosmos
● 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

14. Recovering Seagrass: Manly Cove
NSW DPI

15. Recovering Seagrass: Manly Cove
Bring Back the Fish

16. Recovering Seagrass: Shoal Bay
R Carraro

17. Recovering Seagrass: Shoal Bay
18 months
Recovery begins with colonisation by Halophila

18. Recovering Seagrass: Manly Cove
Eco Divers
18 months
Local environmental factors and condition of seagrass meadow
might compromise recovery potential

19. Values, 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

20. Climate change lingo
● Carbon dioxide (CO2)
is most significant
human-produced
greenhouse gas
● Greenhouse effect =
global warming ≈
climate change
Kosland Science
Museum

21. Climate Change: How are we doing?
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)

22. Fighting 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 istockphoto
place!

23. Carbon Farming
1. Reducing greenhouse gas
emissions
1. Capturing and storing carbon in
vegetation and soils (creating
„carbon sinks‟) RDAMR
Terrestrial only. Not aquatic.

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

25. Global area: Tropical Rainforests vs. Seagrasses
Tropical rainforests
2.5 times the
area of
Australia
Destination
360
Seagrasses
The area of
VIC or NSW OR
(?)
IndexO

26. Carbon burial: Tropical Rainforests vs. Seagrasses
C m-2 y-1
Tg C yr-1

27. Seagrasses are long-term sinks
● 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.

28. Carbon farming: too good to be true?
‘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
iStockPhoto

29. 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

30. When sinks become sources…
Unhealthy meadows can
turn from being carbon
sinks, to carbon sources
Source Sink
OpenLig
ht

31. Positive O2 flux Negative O2 flux
Carbon sink Carbon source

32. Measuring FLUX of carbon and oxygen
Ponlachart
Chotikarn
O2 flux
Light
level
Night Day Night
Andrew

33. How do we study carbon capture and storage?

34. What impact have humans had on coastal carbon sinks?
Industrial developments:
• Tanneries
• Sewerage farms
• Breweries
• Quarries Algernon Talmadge
R.A.
• Oil refineries
• Sand mining
• Port construction
Consequences:
• Loss of seagrass, mangroves,
and saltmarsh
• Increases in algae
Proni

35. Paleoreconstruction: going back in time

36. Industrialization weakens coastal carbon sink
Fingerprinting of
stored carbon
(„carbon stock‟)
CoreMedia

37. Take 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

38. 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?

39. 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
biosequestration

40. Drained marshes emit CO2
● Sacramento Delta
– 1,800 km2 of wetlands (not seagrass)
wikipedia
● 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

41. 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.

42. How to protect seagrass carbon?
● create incentives for coastal conservation and restoration
activities
● create disincentives to damage coastal ecosystems

43. Better 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

44. Past 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

45. International carbon credits
● finance to encourage sustainable management
– Norway-Indonesia
● Australia-Indonesia Carbon Partnership
● Australia could buy Indonesian “ecosystem restoration concessions”
– Australian Clean Energy Scheme
wikipedia
● How can seagrass be included in a carbon accounting scheme?

46. Seagrass 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)

47. 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

49. 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

50. Co-benefits of protecting seagrass
Blue Carbon
Marine Biodiversity Fish Nurseries
Coastline and
Coastal Water Quality Beach
Stabilization
Source: Forest Trend
• Adapt to climate change
• Sustain community resilience and coastal livelihoods

51. Acknowledgements
Bring Back the Fish