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UTSpeaks: Keeping Seas Green

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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.

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UTSpeaks: Keeping Seas Green

  1. 1. UTSpeaks: Keeping seas green17 November, 2011 CAN PRESERVING HUMBLE SEAGRASS HELP PROTECT US FROM THE EXTREMES OF HUMAN-INDUCED CLIMATE CHANGE?
  2. 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. 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. 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. 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. 6. Values and Services: Fish Nurseries● 50% of the worlds 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. 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. 8. Value, Appreciation, Understanding Orth et al. 2006
  9. 9. Scientists’ Concerns for Seagrass
  10. 10. Loss of SeagrassLocation % Seagrass ● Global losses area lost – 29% of known areaClarence River 60% – 7% per yearLake Macquarie 44%Tuggerah Lakes 50%Port Hacking 60%Botany Bay 58%NSW 50% CSIRO
  11. 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. 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. 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. 14. Recovering Seagrass: Manly CoveNSW DPI
  15. 15. Recovering Seagrass: Manly Cove Bring Back the Fish
  16. 16. Recovering Seagrass: Shoal BayR Carraro
  17. 17. Recovering Seagrass: Shoal Bay 18 months Recovery begins with colonisation by Halophila
  18. 18. Recovering Seagrass: Manly Cove Eco Divers 18 monthsLocal environmental factors and condition of seagrass meadow might compromise recovery potential
  19. 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. 20. Climate change lingo ● Carbon dioxide (CO2) is most significant human-produced greenhouse gas ● Greenhouse effect = global warming ≈ climate change Kosland Science Museum
  21. 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. 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. 23. Carbon Farming1. Reducing greenhouse gasemissions1. Capturing and storing carbon invegetation and soils (creating„carbon sinks‟) RDAMRTerrestrial only. Not aquatic.
  24. 24. Could seagrasses be the mostpowerful carbon sinks on the planet?
  25. 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. 26. Carbon burial: Tropical Rainforests vs. Seagrasses C m-2 y-1 Tg C yr-1
  27. 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. 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. 29. Do seagrass meadows leak carbon?Could 1000s of years ofancient carbon leak outinto the atmosphere ifseagrass meadows aredisturbed?Likely mechanism: lossof seagrass meadows(i.e. the „top layer‟)exposes buried carbonto the forces of nature
  30. 30. When sinks become sources…Unhealthy meadows canturn from being carbonsinks, to carbon sources Source Sink OpenLig ht
  31. 31. Positive O2 flux Negative O2 flux Carbon sink Carbon source
  32. 32. Measuring FLUX of carbon and oxygen Ponlachart ChotikarnO2 flux Light level Night Day Night Andrew
  33. 33. How do we study carbon capture and storage?
  34. 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 constructionConsequences:• Loss of seagrass, mangroves,and saltmarsh• Increases in algae Proni
  35. 35. Paleoreconstruction: going back in time
  36. 36. Industrialization weakens coastal carbon sinkFingerprinting ofstored carbon(„carbon stock‟) CoreMedia
  37. 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. 38. How to protect seagrass carbon?● What is Blue Carbon?● What dont 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. 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. 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. 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. 42. How to protect seagrass carbon?● create incentives for coastal conservation and restoration activities● create disincentives to damage coastal ecosystems
  43. 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. 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. 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. 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. 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
  48. 48. 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
  49. 49. 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
  50. 50. Acknowledgements Bring Back the Fish

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