Lecture by Professor Takashi Nakamura

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.

38. Local threats:
Lower resilience

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

56. Global warming…
Possible solutions ?

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

70. Republic of Palau

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

77. Sewage treatment …

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