Climate Change and Coral Reefs
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This document summarizes a presentation on climate change and coral reefs. It discusses the basics of coral biology and ecology, how climate change is the main threat to corals through coral bleaching. Local threats like nutrient pollution can also negatively impact corals by lowering their resilience and recruitment. Recent mass bleaching events in 2014-2017 have caused severe damage to coral reefs worldwide. Long term solutions to address climate change are still needed to reverse its impacts on coral reef ecosystems.
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Climate Change and Coral Reefs
- 1. Picture: Tokashiki, Kerama Islands, Okinawa Japan Climate Change and Coral Reefs Nov 4, 2016 Takashi Nakamura Univ. of the Ryukyus takasuke@sci.u-ryukyu.ac.jp
- 2. Outline 1. Basics of corals 2. Climate change as the threat to corals “Coral bleaching” 3. Local threats 4. Possible solutions
- 3. Basics of corals Biology & ecology
- 4. Class: AnthozoaClass Scyphozoa Jerry fish Semaeostomeae Coronatae Phylum: Cnidaria Subclass Octocorallia Soft coral Alcyonacea Pink coral Tube coral Stolonifera Blue coral Heriopora Subclass: Hexactinia Sea anemone Actiniaria Zoantharia Class Hydrozoa Anthomedusae Fire coral Milleporidae Order: Scleractinia ~ Common reef-building Corals Coral Taxonomy: Who’s related? 1-1. The taxonomy of coral
- 5. Planula larvae (Planktonic) Coral Biology: Life history Settle on substrate 0.5 mm “Polyp” 0.5 mm Forms “colony” with clones “Spawning” Release Sperms & Eggs 1-2. The Life history of coral
- 6. Coral colony Coral branch Plant or Animal ? Coral reef Polyp Close up View T. Kamiki 100 Photosynthetic algae ‘Zooxanthellae’ 1-3. The Coral –algal symbiosis 1~3 million/㎠ tissue surface
- 7. Symbiosis Amino acid, lipid, O2 Photosynthesis Coral CO2, NH4 + Algae Symbiosis w/ algae ~ A strategy to survive 1-4. The Coral –algal symbiosis ‘Zooxanthellae’ ‘Coral’ provides up to 90 % of host energy requirements (Muscatine 1967, etc.)
- 8. Colonies to reef = habitats for others Leaf-likeEncrusting short-branching Free living Tabulate Branching Massive 1-5. Coral colonies and reef structure
- 9. Why corals are important? 2-1. The importance of coral reefs
- 10. of worlds’ coast line of fish species of total fisheries catch 1/6 1/4 1/10 Where coral reefs are located? UNEP (2006) 2-2. World map of Coral reefs
- 11. Ecological aspects Q: Coral reef ~ less than ?% of the Ocean Shelter / Reproduction / Nursery siteFood source More than 25% Of Marine fish species Spalding et. al. (2001) Home to an estimated 2 million species in < 2% of the Ocean 2-3. The importance of coral reefs I
- 12. Tourism Recreation Estimated Economic values > US$ 0.7 million／km2・year UNEP (2006) Fishery Socio-economical aspect Medicine Loss of up to US$ 8200 million for the Indian Ocean was estimated for 1998 mass bleaching event alone 2-4. The importance of coral reefs II
- 13. Source: WRI, Reefs at risk revisited, 2011
- 14. Climate change as the threat to corals
- 15. “Coral bleaching” Greatest threats to coral reef ecosystem induced by environmental stresses
- 16. Increase in Sea surface temperature (SST) SSTs in the Pacific, Atlantic and Indian Ocean Highest in the last 40,0000 years Hughes (2003) Increased 0.4～0.7℃ in the last century Trend in the north Pacific Ocean http://www.data.kishou.go.jp/kaiyou/db Year by year difference 5 years average Long-term trend AnnualSSTdifference(℃) Year
- 17. Significant example：Global scale “bleaching” event in 1998 with El Niño Thermal anomaly Regional/global climate change
- 18. Corals growing in a shallow reef area NOW, What’s wrong with this picture? Photograph by Loya Y . Nearly dead corals due to environmental stress Coral reefs are in trouble!! 3-1A. The definition of “Bleaching”
- 19. 2007 2008 Enormous damage to the coral reefs are expected due to the climate change in the next 30 years （4th IPCC Report 2007） （Bellwood et al. 2004) Exponential increase in the last several decades Year Increasing reports and attention to Coral Bleaching Cumulativenumberofbleachingreports
- 20. 1. Zooxanthellae are expelled from the coral hosts (digested) 2. Pigments within zooxanthellae are degraded What happen to corals? “Bleaching” is a stress response that results when the coral-algae relationship breaks down StressColony Colony close up Zooxanthellae 3-1B. The definition of “Bleaching”
- 21. Environmental stress induces “Bleaching” Coral “Bleaching” zooxanthellae Strong light Brown et al. (1994) High water temperature Hoegh-Guldberg & Smith (1998) Viral infection (Kushmaro et al. 1996) UV radiation (Shick 1989) Sedimentation /suffocation Desalinization （VanWoesik et al.1995) Growth inhibition Mortality Corals are Highly sensitive to environmental change Coral Polyp3-2A. The causes of “Bleaching”
- 22. 1 hour 2 hours 3 hours 4 hours 5 hours 6 hours 7 hours 0 Hour Apply strong light to single polyp of coral colony (at 26 oC) 24 hours 3 days 5 days Polyp’s been bleached Zooxanthellae expelled Bleaching by strong light stress 3-2B. The causes of “Bleaching”
- 23. Bleaching as worldwide threat Reef Manager’s Guide to Coral Bleaching (2006) 3-3B. Impact of “Bleaching” The incidence and severity of mass coral bleaching events has increased continuously over the last two decades.
- 24. Bleaching as worldwide threat 3-3B. Impact of “Bleaching” The incidence and severity of mass coral bleaching events has increased continuously over the last two decades. Reef Manager’s Guide to Coral Bleaching (2006)
- 25. Baker et al. (2008) Estuarine, Coastal and Shelf Sciences Documented bleaching events and regions Mass scale Coral Bleaching :Timeline Phuket, Thai June 2010 2010: Mass scale Bleaching in “Coral triangle (from Indian Ocean to Philippines)”; The worst case since 1998 (CNN Oct.21)
- 26. 2014-2017 Mass bleaching events 2014: Guam ~ Northern Marianas, Marshalls, Florida keys 2015: PNG, Fiji, Samoa, Maldives, Indonesia, Caribbean, Panama, Kiribati, Hawaii 2016: French Polynesia, New Caledonia, Fiji, GBR, Japan 2017: Indian Ocean, Kenya, Florida keys
- 27. 2014-2017 Mass bleaching events 2014: Guam ~ Northern Marianas, Marshalls, Florida keys 2015: PNG, Fiji, Samoa, Maldives, Indonesia, Caribbean, Panama, Kiribati, Hawaii 2016: French Polynesia, New Caledonia, Fiji, GBR, Japan 2017: Indian Ocean, Kenya, Florida keys “The worst case” mass scale Bleaching (Source: NOAA bleaching watch)
- 28. Sekisei lagoon, Okinawa Japan Yaeyama Islands Population: 54,000, Area: 592 km2
- 29. NOAA (2016) April May June July August September October November December No stress Watch Warning Alert1 Alert 2 2016 NOAA bleaching alert in Ryukyu Archipelago Ave. No. of typhoons approach Yaeyama: ~3.5 typhoons / year No. of typhoons approached in 2016 : 0 typhoon until late September !!
- 30. Example from Okinawa mass bleaching this year (Sekisei lagoon) >95% bleached at 35 sites for 10 species out of 11 sampled. >80% mortality in mid Oct. *Worst bleaching impact record since 1998
- 31. Example: Tabular coral 98.4% bleached Acropora hyacinthus Tokyo Kyuei © Non-bleached Early bleaching Half bleached Fully bleached Dead
- 32. Sekisei Lagoon (Milky Way) Sept. 6, 2016
- 33. This year… survey on these damaged reefs Fecundity of survived colonies: Recruitment density on natural substrate: <20 % of 2016… Recovery potentials of Sekisei coral community are severely impaired
- 34. Post-bleaching- mass mortality in Sekisei Live coral cover declined from 60% to <5% Average mortality by Bleaching : 70% Live coral cover declined from 50% to <5% Average mortality by Bleaching : 78% Site 23 “Marugoo” Site 30 “Taketomi”
- 35. Sekisei Lagoon (Milky Way) May. 6, 2017
- 36. Post-bleaching- Algae increased in Sekisei lagoon Live coral cover (%) Kojima et al. Turf algae cover (%) Macro algae (%) *** *** N/S Live coral cover (%) Turf algae cover (%)
- 37. Increasing trend of coral bleaching events is recognized as “clear and present problem” due to climate change Other than climate change… Impacts of Bleaching can be minimized by reducing locally induced stresses such as sedimentation, land reclamation, over harvesting, sewage/pollution etc. However, we still have no sufficient way to reverse the climate change trends and it’s impact to reefs yet.
- 39. Munday et al. (2008) Bleaching impact at Community level Erosion reduces habitat complexity
- 40. Most corals can’t compete with them especially in nutrient-rich environment Macro/micro algae domination inhibits coral recovery
- 41. How long will it last?
- 42. Yoron Island Kagoshima Prefecture Population: 5,400 Area: 20 km2 Impacted by 1998 Mass bleaching event
- 43. Kyuden TerasakiTerasaki- kurohana inner Minata Minata inner Akasaki Coral heads Akasaki Kyanion Tomori Pricia Sea-man’s inner Sea-man’s Ohganeku coast Sites (14 total) Fu-sha East
- 44. Kyuden TerasakiTerasaki- kurohana inner Minata Minata inner Akasaki Coral heads Akasaki Kyanion Tomori Pricia Sea-man’s inner Sea-man’s Ohganeku coast Sites (14 total) Fu-sha East
- 45. Outer reef: High coral cover in 2016 Corals Soft corals Macro algae Turf algae Lime stone Sand K. Kojima （Msc. Thesis）
- 46. 1960’s 1980’s Inner reef: very low coral cover Corals Soft corals Macro algae Turf algae Lime stone Sand 2010’s K. Kojima （Msc. Thesis）
- 47. Why ?? Not much hope for lagoon
- 48. What we should worry? “What we might overlooked in the field?”
- 49. Density of coral recruits (juveniles) as “indicator for coral community recovery” 1 year old Acroporid recruitment ・Density per a Quadrat (1 m x 1 m x 10 ／site) 1 year old colony on settlement tile 12.3㎜ in diameter
- 50. Acroporid recruitment density at each site（1 year +2 years）Yoron Is. Too low to recover !! Outer reefs （9 sites） Inner reefs （5 sites） Not much hope for inner reefs…
- 51. Fertilizer for sugarcane field Raw sewage of stock raising Porous limestone substrate ⇒ Sub-ground water seeps into lagoon Chronic input of: Nitrogen & Phosphate to semi-enclosed lagoon system Geo-social characteristics of Yoron Is. Major industry: Agriculture/farming, tourism and fisheries.
- 52. Nutrient impacts on coral recruitment Planul a larvae Gametes from mature colony of A. digitifera Can terrestrial impacts (e.g., nutrient input) inhibit recuritments’settlement and survival? K. Kojima （Msc. Thesis）
- 53. Lower settlement & survival under nutrient rich treatments n=6 0 10 20 30 40 50 Settlement&survival(%) Exposure to combined （N） and（P） Treatmen t Exposure to （N） and（P） separately K. Kojima （Msc. Thesis）
- 54. How larvae settlement & survival suppressed?Normal polyp (in control seawater) 500 µm 500 µm K. Kojima （Msc. Thesis）
- 55. NASA GISS: Global temp anomaly report 2016 Sea water temperature will continue to rise World temperature deviation in Sept. (baseline: 1951-1980) Temperaturedeviation
- 57. Possible solutions ? Looking for tolerant/robust colonies (host coral/zooxanthellae) “Super-coral” projects (US, Australia, Japan etc.) Transplantation to natural coral reefs to form robust community Limited species, locations…
- 58. Permeable substrate (carbonate limestone) Corals Thermal exchangers Sub-cooler water (saltwater) conditioning Project Impermeable layer Permeable Formation (Limestone) Heat PumpUnderground seawater (cooler !!) Possible solutions ? Geo-engineering approach Corals Corals
- 59. Direct cooling system tested in Samoa, 2009 Provided 1℃ cooler seawater to the lagoon area Before Recovery from bleaching Von Herzen et al. (2012) Supported by; Pacific Island Climate Change Cooperative US Fish and Wildlife Service Department of Marine & Wildlife Resources Federal Aviation Administration American Samoa Power Authority US Geological Survey (Santa Cruz) Cooled area Ambient Limited for small scale…
- 60. What we can do? Reduce local stress !! Global climate impacts are likely amplified by local stresses Deforestation & poor land use ⇒Sedimentation + more nutrient Sewage or nutrient runoff ⇒ Pollution + more nutrient
- 61. Increasing nutrient level in coral reef environment: may impair recovery potentials from thermal disturbance: Lower resilience Threshold nutrient level for coral reef ecosystem should be much lower than temperate ecosystems….
- 62. Soil erosion and sedimentation Chemical pollution Detergents, Herbicides, Fertilizers etc. Overexploitation Visible anthropogenic disturbances
- 63. Coastal development / Dredging
- 64. Also, shoreline alterations: Breakwater Natural: < 60% Altered: artificial: 27% semi- artificial:13% (source: Ministry of environment survey in 1982)
- 65. Even straightening drainage channels: Alterations of land-sea connections (functional loss for bioremediation)
- 66. Local level problem: Sources of Chronic and Less visible changes embedded within our islands, social systems and infrastructures
- 67. Human disturbances can be realized as; Visible phenomena (Technically) Detectable factors Can we really tackle the problems ?
- 68. 1960 in Kitakyushu 2010 Importance of environment was realized during the 1960s’ due to severe pollution–related health disasters In 1960’s Source: Kitakyushu city office Human disturbances to coastal ecosystems in mainland Japan
- 69. What about coasts in subtropical islands? Human disturbances can also be realized as; Visible phenomena (Technically) Detectable factors Human disturbances to coastal ecosystems in Subtropics
- 71. Republic of Palau Coral reef Island country (>500 islands) Population：20,000+ Tourists：110,000~130,000/year Country size：488km2 Coastal length ：629,000km Main industry： Tourism/fishery
- 72. Eco-tour Kayak-tour Snorkel-tour Drop Off First Shark sanctuary Rock Islands Drift dive
- 73. High coral cover Mean coral cover 4.2% ~ 89.3% German Channel Ngaremlengui Ngerdiluches Ngaremlengui Ngerdiluches German Channel 55.0% 5.2% 85.8% Ngelukes – 2 sites Airai Uchelbeluu Uchelbeluu Airai Ngelukes Ngelukes_river 75.8% 75.8% 54.2% 4.2% Nikko 1 & 3 Malakal Taoch 3 Cementary Reef Jake Seaplane PICRC PICRCNikko3Nikko1 Jake Seaplane Malakal Taoch 3 Cementary Reef 89.27%78.3% 65.3% 75.0% 71.7% 80.0% 79.2% Typhoon impacts
- 74. Water quality Over harvesting Trash Sedimentation Over development /construction Sewage
- 75. Malakal reef Sewage effluent at 20 m High nutrients input Flatworm infestation Crown-of-thorns starfish Macroalgae overgrow Malakal reef
- 76. Local Impacts (Sewage） KOROR STATE 18 Km2 (12,700) Airai state 44Km2 (2,700) Palau international Airport Malakal Bay Nikko Bay
- 78. 2.2 3.5 2.2 3.5 4.7 6.0 7.2 8.5 34μg/L 1995 2014 PO4 3- (Surface) 0.9 0.0 Nutrient concentration have increased by 2 times within 20 years EQPB Palau 1997 report
- 79. Sudden increase leads to overuse of ecosystem resources Annual tourists number （from Palau visitor’s authority） 0 5000 10000 15000 20000 25000 30000 35000 40000 45000 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Number of Tourists 2000-2014 Japan Korea PRC China ROC Taiwan US Mainland Guam
- 81. Pristine, Paradise – This is the Heart and Soul of the Palau Brand Experience Tradition of Conservation Palauan People Shaped by Natural Environment Palau’s Brand Promise It is your DNA! NO BODY in this world can be like PALAU It is the REASON TO BELIEVE Why Palau (water) is so profound
- 82. 63,328 89,161 80,578 82,397 88,175 79,259 71,887 85,593 109,057 118,754 105,066 140784 161,931 140,000 60,000 80,000 100,000 120,000 140,000 160,000 180,000 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Annual tourists number (decline in 2015-2016)
- 83. PAN Fund Pan Office Green Fee ($30/tourist) State gov. State gov. State gov.State gov. PAN site PAN site PAN site PAN site PAN site PAN site PAN site PAN site To protect Palau’s critical biodiversity and ensure the resources are effectively conserved Sustainable funding mechanism Protected Area Network (PAN) Financially & technically Support monitoring and training of rangers
- 84. In case of “Coral reef Islands” conservation, 1. Realize the uniqueness & history of each island/reefs (local) 2. Understand the current status (global and local) 3. Recognize problems (global and local) 4. Share information & solutions by networking 5. Cooperate to tackle these problems together Acknowledgements: Part of these studies have been supported by Japanese Ministry of Environment, JSPS Research fund “Kakenhi A” (leader: S. Harii ) and “Kakenhi B (leader:T. Shinbo) and Collaborative research supported by JST/JICA SATREPS (leader: T. Nakamura). Thank you
- 85. Thank you for your attention ありがとうございました Arigato-gozaimasi-ta