a study of the impact of the 2010 coral bleaching event on coral

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A Study of the Impact of the 2010 Coral Bleaching Event on Coral Communities in Wakatobi National Park

April 2010, September 2010 and January 2011

1 The Nature Conservancy – Indonesia Marine Program

Jl Pengembak 2, Sanur 80228, Bali, Indonesia Phone +62-(0)361-287272, Fax +62-(0)361-270737

In cooperation with: 2 Wildlife Conservation Society – Indonesia Marine Program.

Jl. Atletik No.8, Bogor – Jawa Barat, Indonesia Phone +62-(0)251-28342135, Fax +62-(0)251-8357347 Wakatobi National Park Authority Jl. A. Yani, Desa Mandati II, Wangi-Wangi, Wakatobi, Sulawesi Tenggara, Indonesia Phone +62-(0) 404-21851, Fax +62-(0)404-21881

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Published by: The Nature Conservancy – Indonesia Marine Program

Contact:

Rizya Ardiwijaya

The Nature Conservancy – Indonesia Marine Program, Jl. Pengembak No.2,

Sanur 80228, Bali, Indonesia

Phone +62-(0)361-287272, Fax +62-(0)361-270737

Email: [email protected]

Suggested Citation:

Wilson J.R., Ardiwijaya, R.L., R. Prasetia. 2012. A Study of the Impact of the 2010 Coral Bleaching Event on Coral Communities in Wakatobi National Park. The Nature Conservancy. 29 pp.

© 2012, The Nature Conservancy

All Rights Reserved.

Cover Photo: Rizya Ardiwijaya of TNC Indonesia Marine Program is observing coral reef substrate of

Table Coral City, Tomia Island. Photo taken by Joanne Wilson (TNC)

Available from:

The Nature Conservancy’s Indonesia Marine Program

Jl. Pengembak No.2 Sanur 80228

Bali, Indonesia

mailto:[email protected]

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Table of Contents Table of Contents .......................................................................................................................................... ii

Table of Figure ............................................................................................................................................. iii

List of Table .................................................................................................................................................. iii

Executive Summary ....................................................................................................................................... 1

1 Introduction .......................................................................................................................................... 2

2 Methods ................................................................................................................................................ 3

2.1 Wakatobi National Park ................................................................................................................ 3

2.2 Sea Surface Temperature .............................................................................................................. 3

2.3 Coral bleaching surveys ................................................................................................................ 4

2.4 Bleaching susceptible genera ........................................................................................................ 7

3 Results ................................................................................................................................................... 7

3.1 Sea Surface Temperature .............................................................................................................. 7

3.2 Bleaching survey results ................................................................................................................ 7

3.2.1 Bleaching and post bleaching surveys .................................................................................. 7

3.2.2 Coral community composition ............................................................................................ 10

3.3 Differences in bleaching among coral genera............................................................................. 11

3.3.1 Does coral community composition explain differences in bleaching among sites? ......... 14

3.4 Discussion .................................................................................................................................... 15

4 Conclusions ......................................................................................................................................... 16

5 Recommendations .............................................................................................................................. 17

6 Acknowledgements ............................................................................................................................. 17

7 References .......................................................................................................................................... 18

Appendices .................................................................................................................................................. 19

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Table of Figure

Figure 1 Sites of coral bleaching and post-bleaching surveys within Wakatobi Natonal Park 2010-2011 ... 6

Figure 2: Monthly average sea surface temperature (SST) (°C) at Wakatobi National Park for selected

years between 2000 and 2011. Data from NOAA Coral Reef Watch 50-km Satellite Virtual Station

Time Series from http://coralreefwatch.noaa.gov/satellite/index.html . ............................................ 8

Figure 3 Annual degree heating weeks (DHWs) for the last 12 years of Wakatobi area from the near real-

time and retrospective NOAA Coral Reef Watch datasets (Pathfinder 4-km resolution). Data from

Maynard et al. 2012). ............................................................................................................................ 8

Figure 4 Composition (%) of coral colonies condition within Wakatobi National Park. The figure inset is

the same with the main figure by stretching y axis and only show condition during September 2010

and January 2011. S = shallow reef (1-3 m) and D = deeper reef (7-10 m). ......................................... 9

Figure 5: Proportion of all colonies recorded as pale, bleached dead or normal (%) at each site in

Wakatobi National Park from surveys in April 2010, September 2010 and January 2011 at 10m

depth (D) and 3m depth (S). ............................................................................................................... 10

Figure 6: Proportion of the coral community made up of the most abundant 15 genera in Wakatobi

National Park as recorded from 24 sites in September 2010. ............................................................ 11

Figure 7 Proportion of colonies of each coral genera at different bleaching stages in April 2010,

September 2010 and January 2011. Only the top 15 genera/coral type affected by bleaching are

presented. ........................................................................................................................................... 13

Figure 8: Scatter plot of percent of susceptible genera versus percentage of pale or bleached corals

recorded during bleaching surveys in April 2010. The percentage of bleaching susceptible genera in

the coral community explains 42% of the variation of bleaching among sites .................................. 15

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List of Table

Table 1 Coral bleaching and post bleaching survey sites of Wakatobi National Park 2010-2011. S =

shallow, D = deep . ................................................................................................................................ 4

Table 2 Coral condition categories............................................................................................................... 5

Table 3: The proportion of coral colonies in each bleaching state for each genera recorded in April 2010

sorted from the highest to lowest cumulative number of colonies classified as pale, bleaching and

dead colonies. Values were calculated as a average of data from deep and transects. .................... 14

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Executive Summary Wakatobi archipelago is located on the south east tip of Sulawesi Island, central Indonesia in the heart

of the Coral Triangle. Wakatobi is an acronym for the four major islands of Wangi-wangi, Kaledupa,

Tomia and Binongko although this region contains a total of 39 islands and several large atolls. In 1996,

the government of Indonesia declared Wakatobi National Park (Wakatobi NP) protecting 1.39 million

hectares of the islands and surrounding waters.

Wakatobi NP encompasses a diverse range of marine habitats. The main islands are surrounded by

fringing coral reefs. Parallel to the archipelago of main islands are three large atoll reefs. A number of

smaller reefs are located in open waters in the southeastern part of Wakatobi. Wakatobi NP is also

surrounded by major sea straits that function as migratory corridors for large marine species such as sea

turtles and whales – many of which are listed as endangered.

The main threats to Wakatobi NP are over-fishing and over-exploitation of coral reef resources.

However, elevated sea temperatures associated with La Nina/ El Nino climatic events which cause coral

bleaching are emerging as an important threat. Coral bleaching was observed at all survey sites during

annual reef health surveys in April 2010. Quantitative surveys of bleaching incidence could only be done

at 8 sites in April 2010 but were followed by post-bleaching and resilience surveys in September 2010

and January 2011 at 24 sites.

On average, 65% of corals were affected by the bleaching but mortality was estimated at less than 5%.

The most bleaching susceptible genera were found to be Pocillopora, Stylophora, Montipora plates and

tabular and branching Acropora.

Karang Otiolo, at the southern end of the park suffered the highest coral bleaching during April 2010

with 70% affected at deeper reef. Corals at Table Coral City which is dominated by bleaching susceptible

Acropora species were still bleached in September 2010 with 35% of colonies recorded as pale.

There are many factors which indicate this bleaching event was caused by elevated seawater

temperatures and/or high light intensity including

1) the extensive nature of the bleaching throughout the National Park

2) elevated sea surface temperatures from February to May 2010

3) the fact that many of the fully bleached corals were still alive and recovered after temperatures

dropped.

Therefore, it is important to develop a bleaching response plan for WNP. This shoudl include using web-

based products which show regional temperature stress, preparing a team capable of conducting

bleaching surveys and reporting bleaching condition, building and strengthening stakeholder network in

order to share bleaching information, and most importantly to identify management actions to ensure

the health of reefs so they have the best chance of suriviving climate change impacts.

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1 Introduction

Coral reefs are increasingly threatened by the impacts of climate change (Hoegh-Guldberg et al. 2007)

particularly elevated sea surface temperature causing coral bleaching. Bleaching is caused when higher-

than-normal sea temperatures make light toxic to the critical relationship between corals and their food

producing symbiotic algae, the zooxanthellae. Under these conditions the zooxanthalle to be expelled

from the coral polyps which then look white. Bleaching causes corals to starve and is a temporary state;

if the thermal stress abates corals can return to their normal condition but if the stress persists corals

can die in great numbers. These ecologically disastrous events resulted in the loss of 16% of the world’s

coral reefs in 1998 (Wilkinson 2000). In 2010, coral bleaching associated with elevated sea temperatures

associated with an El Nino event affected reefs in many parts of Indonesia (GCRMN, 2010). While the

ultimate causes of climate change i.e. increased worldwide production of greenhouse gases, is beyond

the control of coral reef managers, reefs can be managed in a way so they have the best chance of

surviving elevated sea temperatures and other climate related impacts (see Marshall and Schuttenberg

2007).

One of the reef management strategies to address climate change impacts is to identify sites which may

be ‘resilient’ to climate change impacts and include them in marine protected areas. Resilience refers to

the ability of a reef to either resist or recover from disturbance – in this case climate related impacts. It

is thought that reducing direct human threats such as destructive and overfishing in these critical areas

will increase the chance that coral reefs will survive from climate change impacts.

The main method for identifying these resilient sites is desribed in a protocol for resilience assessments

(Obura and Grimsditch, 2009) which requires quantitative or semi-quantitative measures of 61 factors.

The factors were grouped into:

- The composition and conditon of the bethic community

- The environmental characteristics which may provide relief from heat such as shading or strong

currents

- coral population composition that explains previous coral bleaching history, and evidence of

recovery

- coral associates that promote or threaten recovery processes such as bioeroders

- fish assemblages with a focus on herbivores

- coral connectivity between nearby and distance reef habitat as coral larval sources

- anthropogenic factors that threaten coral reef habitat, and

- existing management that can regulate anthropogenic stress

This protocol was developed after the 1998 mass bleaching event and there has not been many

opportunities to test the ability of resilience assessments to identify which areas would be most affected

by a bleaching event. This would involve testing to see if corals in sites with higher resilience scores are

able to resist or recover from bleaching better than sites with lower scores.

Coral bleaching was observed in April 2010 at Wakatobi National Park (Wakatobi NP), SE Sulawesi,

Indonesia during annual reef health surveys. The impact of the bleaching on these reefs was studied

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during this and follow up surveys. Resilience scores were calculated for each site based on a

combination of measurements and expert opinion and compared to bleaching impact. In addition, we

examined historical thermal stress at these sites and the intensity of stress during the 2010 bleaching

event to help understand factors which may influence the bleaching impact. During reef reef health

surveys in March-April 2009, minor bleaching was noted at many sites but not quantified.

The objective of this study was to assess the impact of coral bleaching in Wakatobi NP in 2010 and to

assess factors which may be more important in understandig the susceptibiliy of Wakatobi reefs to

bleaching.

2 Methods

2.1 Wakatobi National Park

The Wakatobi archipelago is located in Southeast Sulawesi, eastern Indonesia, and is named for the four

major islands there: Wangi Wangi, Kaledupa, Tomia and Binongko. In 1996, 1.39 million ha around

Wakatobi was declared as a Marine National Park, comprising a total of 39 islands, surrounding

mangroves, seagrass beds and coral reefs as well as large atolls and offshore areas. It is one of the most

densely populated Marine National Parks in Indonesia with close to 100,000 residents recorded in 2007

(Hermansyah et al., 2008). Their dependency on marine resources is high, as most of them work as

fishers, either as their main employment or as secondary employment. The current zoning plan includes

three types of non-extractive zones – core (no go, no take), marine protection (no take) and tourism (no

take) which together encompass 2% of the park area but 37% of critical habitats. The remainder of the

park is designated as traditional use zones around the islands for local residents and general use zones

in offshore areas where commercial fishing is allowed. In the past, the reefs of Wakatobi NP suffered

extensive damage due to destructive fishing. Current threats to the health of coral reefs and sustainable

fisheries in WNP are illegal and overfishing, and coral and sand extraction by local communities for

construction materials.

The reefs of Wakatobi can be divided into three major habitat types: fringing mainland reef, submerged

and fringing reefs around outer islands and southern atolls. In general, the underwater contour tends to

be characterised by a shallow reef flat with a steep slope ending in sand around 30-50 m depth. Reefs

are often close to deep waters with strong water dynamics (current and wave) and upwelling in some

areas that brings cool water to the surface.

2.2 Sea Surface Temperature

Sea Surface Temperature (SST) records during the bleaching event were obtained from satellite data

from NOAA Coral Reef Watch Virtual Station at Wakatobi

(http://coralreefwatch.noaa.gov/satellite/current/products_dhw.html). These data were averaged over

a 50km2 ‘pixel’ at 5°S 124°E coordinate, approximately 50 km from the coastline of the islands of

Wakatobi. Weekly data records since 2000 were downloaded from the website and plotted for each

year.

http://coralreefwatch.noaa.gov/satellite/current/products_dhw.html

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Maynard et al. (2012) calculated thermal anomalies from a more precise SST data set at 4-km2

resolution from NOAA Pathfinder satellites. This data set was used to calculate Degree Heating Weeks

(DHW) for Waktobi NP since 1998. One DHW is recorded when temperatures are one degree higher

than normal for one week. Two DHW could be caused by temperatures being two degrees higher than

normal for one week or one degree hotter than normal for two weeks.

2.3 Coral bleaching surveys

Surveys to assess the extent and impact of the 2010 coral bleaching event were conducted in Wakatobi

NP on three occassions. The initial survey was done during the bleaching event in April 2010. Post

bleaching surveys, were conducted in September 2010 and January 2011, five and nine months after the

bleaching, respectively (Table 1). During January 2011, survey several sites from Septemper 2010 were

inaccessible due to weather conditions. A list of survey sites, time of surveys and their attributes are

presented in Appendix 1.

Table 1 Coral bleaching and post bleaching survey sites of Wakatobi National Park 2010-2011. S = shallow, D =

deep .

In April 2010 coral bleaching surveys were done at 8 sites opportunisically during reef health monitoring

surveys in Wakatobi NP. Quantitative surveys were undertaken on reef slopes at 10 m depth (deep) all 8

sites and also at 2-5m (shallow) at 4 of these sites. All colonies larger than 10 cm diameter within a

single belt transect (25 m x 2m) were identified to genera or lifeform and classified as follows: ‘healthy’

(no sign of bleaching), ‘pale’ (color was slightly paler than other healthy colonies), ‘moderate’ (colonies

were very pale but still retained some color), ‘white’ (colony was completely white but still alive and not

Site Reef Health

Abreviation Site No. S D S D S D

Blue Hole BHol -5.444083 123.757883

Bola Tiga Bol3 -5.473117 123.757533

Kaledupa 1 Kal1 5272 -5.473117 123.757533

Kaledupa 2 Kal2 5273 -5.497750 123.820750

Karang Bante KBan 5294 -5.874550 123.986000

Karang Gurita 1 KGur 5265 -5.391800 123.675250

Karang Kaledupa 6 KKl6 5260 -5.778900 123.658917

Karang Kaledupa 8 KKl8 5264 -5.926183 123.737383

Karang Kapota 2 KKp2 5252 -5.561067 123.415450

Karang Kapota 4 KKp4 5254 -5.585483 123.468767

Karang Koko 2 KKok 5287 -6.107091 124.334056

Karang Otiolo 1 KOti 5261 -5.812333 123.613867

Mantigola Mant -5.558267 123.754150

Matahora 2 Mat2 5269 -5.302600 123.653467

Matahora 3 Mat3 5270 -5.338483 123.645683

Moromaho Moro 5288 -6.592610 124.592061

Ndaa 1 Nda1 5279 -5.650483 124.052600

Ndaa 2 Nda2 5280 -5.653017 124.041017

Onemobaa Onem 5276 -5.775951 123.894316

Pak Kasim's PKas -5.464967 123.755283

Palahidu Pala 5293 -5.894117 124.028000

Pulau Sawa 1 PSaw 5277 -5.771033 123.874717

Sampela Samp -5.482050 123.745150

Sombu Somb -5.267917 123.517350

Table Coral City Tabl -5.752317 123.891067

Waha Waha -5.248117 123.527300

2010 Apr 2010 Sep 2011 Jan

No Take

Open Access

GPS Lat GPS LongManagement Reference name

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overgrown with algae), or recently dead colonies (Wilson, 2010). Although bleaching surveys could only

be done at 8 sites, bleaching was noted by field teams at all 42 sites visited for reef health surveys and

considered to be at similar intensity as the bleaching surveys sites (J. Wilson personal observations).

Post bleaching surveys were conducted in September 2010 at 24 sites and in January-February 2011 at

19 sites (Table 1, Figure 1). Data on coral genera and condition were collected at two depths - shallow

(2-5 m) and deep (10 m) - using different methods at each depth. Shallow data were collected on reef

flats and/or reef crest on snorkel, using a random swim method. The observer collected data within at

least 15 circles each 2 m diameter using a 1 meter PVC pipe as radius guidance. Each circle was

separated by 10 kicks. Data from deep sites were collected on SCUBA using three 15 x 1 meter belt

transects or three 25 x 1 m transects at some sites. At both depths all coral colonies greater than 10 cm

were identified to genera and lifeform and the percentage of each colony in normal, pale, bleaching or

dead state was recorded (McClanahan et al., 2001; Obura and Grimsditch, 2009) (Table 2). Each colony

was assigned a single state (normal, pale, bleached or dead) depending on the condition which applied

to the majority of the colony area (see Table 2).

Table 2 Coral condition categories

Colony

condition Other condition measure Notes

Normal - 100% healthy

- > 50% healthy with pale and/or dead

Pale - 100% pale

- ≥ 50% pale with normal and/or dead

Moderate in Apr’10

assigned as pale

Bleaching - B1 (up to 20% bleach colony)

- B2 (21% - 50% bleach colony)

- B3 (51% - 80% bleach colony)

- B4 (80%- 100% bleach colony)

This category

applied in random

swim survey data

collection

Dead - ≥ 50% dead by bleach without bleaching occurrence

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Figure 1 Sites of coral bleaching and post-bleaching surveys within Wakatobi Natonal Park 2010-2011

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2.4 Bleaching susceptible genera Coral genera were assigned to one of three categories of susceptibility to bleaching - susceptible,

intermediate or resistant (Appendix 2). These categories were allocated based on susceptible genera

classifications in Marshall and Baird (2000) and Obura and Grimsditch (2009).

The percentage of corals in each bleaching state and the bleaching associated mortality was calculated

for each site and depth and for each genera. Linear regression was used to compare the propotion of

colonies affected by bleaching with the percentage of the coral community made up of susceptible

genera.

3 Results

3.1 Sea Surface Temperature

In Wakatobi NP, SST was unusually high throughout most of 2010 (Figure 2). Water temperatures stayed

between 30°C and 30.5°C for 9 weeks from March toMay 2010 and winter to spring temperatures (June-

September) were higher than previous years by around 1-2 °C. Maynard et al. (2012) showed that these

elevated temperatures corresponded to a maximum of 6.5 DHW in 2010 compared with 4 DHW in 2002

and 2008 (Figure 3). The thermal anomaly at Wakatobi NP was higher and more prolonged than

previous years. Therefore it is reasonable to conclude that the coral bleaching seen at Wakatobi NP in

2010 was due to stress caused by higher than normal SST.

3.2 Bleaching survey results

3.2.1 Bleaching and post bleaching surveys

Coral bleaching was recorded at all sites surveyed in Wakatobi NP in April 2010. On average 65% of

corals showed some sign of bleaching with 43-56% of corals pale and an additional 10-16% completely

bleached (Figure 4). Mortality due to bleaching was estimated to be low with an average of <1% dead

corals recorded in post bleaching surveys. Karang Otiolo experienced the most severe bleaching (Figure

5). During the bleaching event, the incidence of fully bleached corals was higher on deeper reefs (10 m

depth) (16%) compared to shallow reefs (3 m depth) (10%) (Figure 4). Bleaching of other taxa including

soft corals and anemones was also observed but were not quantified during this survey due to limited

number of observers and time at each survey site.

By the time of the first post bleaching survey in September 2010, when the temperatures has cooled,

most coral colonies had returned to their normal colour. However at Table Coral City, 30% of corals

were still pale in September 2010 and 18% were pale in January 2011. This site is dominated by

bleaching susceptible genera of branching and tabulate Acropora and foliose Montipora. A few fully

bleached colonies (<1%) could still be seen in September 2010 and January 2011 especially in deeper

areas (Figure 4).

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Figure 2: Monthly average sea surface temperature (SST) (°C) at Wakatobi National Park for selected years

between 2000 and 2011. Data from NOAA Coral Reef Watch 50-km Satellite Virtual Station Time Series from

http://coralreefwatch.noaa.gov/satellite/index.html .

Figure 3 Annual degree heating weeks (DHWs) for the last 12 years of Wakatobi area from the near real-time

and retrospective NOAA Coral Reef Watch datasets (Pathfinder 4-km resolution). Data from Maynard et al.

2012).

25

26

27

28

29

30

31

J F M A M J J A S O N D

1 2 3 4 5 6 7 8 9 10 11 12

Tem

pe

ratu

re (°

C)

Months

2000

2002

2004

2006

2008

2010

2011

http://coralreefwatch.noaa.gov/satellite/index.html

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Figure 4 Composition (%) of coral colonies condition within Wakatobi National Park. The figure inset is the same

with the main figure by stretching y axis and only show condition during September 2010 and January 2011. S =

shallow reef (1-3 m) and D = deeper reef (7-10 m).

0%

10%

20%

30%

40%

50%

60%

70%

S D S D S D

2010 Apr 2010 Sep 2011 Jan

Co

mp

osi

tio

n o

f co

ral

con

dit

ion

Pale

Bleaching

Dead0%

1%

2%

3%

4%

S D S D

2010 Sep 2011 Jan

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Figure 5: Proportion of all colonies recorded as pale, bleached dead or normal (%) at each site in Wakatobi

National Park from surveys in April 2010, September 2010 and January 2011 at 10m depth (D) and 3m depth (S).

3.2.2 Coral community composition

The coral community at Wakatobi NP is dominated by massive Porites and Montipora on both shallow

and deep transects (Figure 6). Porites (branching and massive) and Acropora are more abundant on

shallow compared to deep reefs. The composition is likely influenced by the different habitat types with

gentle slopes or reef flats in shallow areas and steep walls in deeper reefs.

0%

20%

40%

60%

80%

100%

D D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S

BHolBol3 Kal1 Kal2 KBan KGur KKl6 KKl8 KKok KKp2 KKp4 KOti Mant Mat2 Mat3 Moro Nda1 Nda2 Onem Pala PKas PSaw Samp Somb Tabl Waha

Co

mp

osi

tio

n o

f co

ral

con

dit

ion 2010 Apr

Normal

Dead

Bleaching

Pale

0%

20%

40%

60%

80%

100%



Co

mp

osi

tio

n o

f co

ral

con

dit

ion 2010 Sep

0%

20%

40%

60%

80%

100%



Co

mp

osi

tio

n o

f co

ral

con

dit

ion 2011 Jan

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Figure 6: Proportion of the coral community made up of the most abundant 15 genera in Wakatobi National

Park as recorded from 24 sites in September 2010.

3.3 Differences in bleaching among coral genera

In Wakatobi NP, the proportion of colonies affected by bleaching differed among genera. The proportion

of colonies in each bleaching state and their bleaching susceptibility is shown in Table 3 and Figure 7. At

Wakatobi NP, bleaching susceptible corals dominate the coral community with twice as many colonies

of susceptible genera as intermediate and three times as many as resistant colonies.

As expected, genera considered susceptible to bleaching were also had high proportion of colonies

recorded as pale or bleached. Branching Seriatopora were most affected by bleaching with all

Seriatopora colonies at 10 m fully bleached while at 3 m, 86% of colonies were bleached and the

remaining 14% were pale (Figure 7). However, Seriatopora colonies comprised less than 1% of the coral

community at both depths (Figure 6).

Stylophora and Pocillopora colonies from family Pocilloporidae were also badly affected by the bleaching

with around 80% of colonies in pale or bleached condition (Figure 7). These genera are considered as

highly susceptible to bleaching (Marshall and Baird 2000) and are an important component of the coral

community at Wakatobi NP (Figure 6).

Acropora corals are also considered highly susceptible to bleaching. However during the bleaching event

in Wakatobi NP only a small percentage of Acropora colonies were recorded as bleached (1-3%) but

many were pale (25-57%) (Figure 7). By September, the bleaching incidence had reduced but paling was

still apparent in some Acropora colonies and this persisted until January 2011 (Figure 7). Most of these

corals were recorded at Table Coral City, one of the only sites in Wakatobi NP which is dominated by

branching and tabulate Acropora and foliose Montipora. This may be due to the fact that water

temperatures continued to be higher than normal after the bleaching event and in September 2010

12

were almost 2 degrees higher than normal (Figure 2). Although Acropora corals are considered to be

susceptible, the proportion of colonies pale or bleached (44%) was not higher than othergenera

considered to be resistant corals (e.g. Fungiids and Faviids).

Bleaching was more obvious in some genera such as Montipora because they were a dominant

component of the coral community making up 24% and 43% of the colonies on shallow and deep

transects respectively (Figure 6) and a high proportion (75%) were bleached or pale. By September 2010,

Montipora colonies had recovered with only 1% of colonies recorded as pale in deep and shallow areas.

In January 2011, 4% of Montipora colonies were pale in deeper areas and 2% had died.

Genera classified as intermediate or resistant were also affected by the elevated water temperatures

with a high proportion of colonies of Gonipora and Diploastrea (Table 3) recorded as pale.

13

Figure 7 Proportion of colonies of each coral genera at different bleaching stages in April 2010, September 2010

and January 2011. Only the top 15 genera/coral type affected by bleaching are presented.

14

Table 3: The proportion of coral colonies in each bleaching state for each genera recorded in April 2010 sorted from the highest to lowest cumulative number of colonies classified as pale, bleaching and dead colonies. Values were calculated as a average of data from deep and transects.

3.3.1 Does coral community composition explain differences in bleaching among sites?

An analysis of the percent composition of the coral community compared to the percent of colonies

affected by bleaching (pale or bleached) for each site at Wakatobi NP showed a strong correlation

(Figure 8). At the 8 sites surveyed, the proportion of the community made up of bleaching suscetpible

taxa explained 43% of the variation in bleaching incidence among the sites. This means that sites with

more colonies of bleaching susceptible genera (Seriatopora, Stylophora, Pocillopora, Acropora) are likely

to be more badly affected by bleaching. This information can be used to identify ‘early warning’ sites for

bleaching assessments if warmer than normal temperatures are predicted or experienced in Wakatobi

NP. These sites are listed in Table 4.

Genus n Normal (%) Pale (%)Bleaching

(%)Dead (%)

Pale +

Bleaching +

Dead (%)

Susceptibility

Seriatopora 25 0 12 88 100 Susceptible

Stylophora 142 16 51 33 84 Susceptible

Porites (branching) 75 20 77 3 80 Intermediate

Pocillopora 223 24 63 9 4 76 Susceptible

Goniopora 8 25 25 50 75 Resistant

Montipora 1240 25 47 28 75 Susceptible

coral branching 339 28 62 10 72 Intermediate

Diploastrea 16 44 56 56 Intermediate

Fungia 104 48 46 6 52 Resistant

Faviidae 441 50 47 3 50 Resistant

Acropora 180 56 43 2 44 Susceptible

Porites (massive) 320 62 37 1 38 Intermediate

Tubipora 8 63 38 38 Resistant

Hydnophora 19 63 32 5 37 Intermediate

coral encrusting 174 72 20 7 28 Intermediate

Symphyllia 19 74 26 26 Resistant

Symphyllia /other massive 26 81 15 4 19 Resistant

susceptible 1810 27 49 24 1 73

intermediate 943 48 46 6 52

resistant 606 51 44 5 49

total 3359

15

Figure 8: Scatter plot of percent of susceptible genera versus percentage of pale or bleached corals recorded

during bleaching surveys in April 2010. The percentage of bleaching susceptible genera in the coral community

explains 42% of the variation of bleaching among sites

Table 4. Top ten sites with highest % composition of bleaching susceptible colonies that are also accessible

Name % colonies from susceptible genera

Shallow or deep Close or far from main islands

1 Table Coral City >85% shallow Close

2 Kaledupa 1 >30% shallow Close

3 Karang Bante 30-40% deep Close

4 Matahora 2 40% deep Close

5 Mantigola 40% deep Close

6 Matahora 3 40% deep Close

7 Kaledupa 2 30-40% deep Close

8 Karang Koko >60% shallow Far

9 Karang Otiolo >60% shallow Far

10 Moromaho >60% shallow Far

3.4 Discussion

The coral bleaching observed at Wakatobi NP was extensive with more than 60% of corals showing some

sign of bleaching and 10-20% of colonies fully bleached. However mortality was low with less than 1% of

colonies recorded as dead due to bleaching. However there are some signs that mortality may have

been underestimated due to the extended time before post bleaching surveys were conducted. A high

proportion of Monitopora colonies were bleached or pale but few were recorded as recently dead in

16

September. Some additional colonies may have died soon after the bleaching but could not be

attributed to bleaching as the cause of mortality could not be determined. However, coral communities

still appeared relatively healthy during post bleaching surveys so we estimate the coral mortality was

not more than 10-15%.

Bleaching typically follows La Nina/El Nino events, which result in sustained regional elevations of ocean

temperature (Baker et.al, 2008). In 2010, a La Nina/El Nino event caused bleaching throughout the Indo

Pacific region (GCRMN 2010). Concurrent studies of coral bleaching impact in Bali and Aceh showed that

while Bali also experienced limited coral bleaching and mortality, the bleaching was more severe in Aceh

with over 50% mortality (Maynard et al 2012). This is despite the fact that Aceh experienced less

thermal stress during the bleaching event. However, it was found that Wakatobi and Bali experience

higher thermal variation during summer months and this may help reefs acclimate to elevated

temperature events. A similar phenomenon was documented in other reefs during this bleaching event

(Guest et al 2012).

These bleaching surveys were conducted by experts from The Nature Conservancy and other partners

with skills in coral identification and recogition of bleaching state. However it would be more

economical and logical for these surveys to be done by local staff from Wakatobi NP and other local

partners. Staff with existing skills in underwater surveys could be trained in these skills relatively easily.

They could also be trained in using satellite based SST products such as NOAA Coral Reef Watch to be

alert to elevated SST events in this region.

While the coral reefs of Wakatobi NP were not badly affected by the bleaching in 2010, it is expected

that the frequency and severity of coral bleaching is likey to increase. Since a high proportion of the

coral community of Wakatobi NP is made up of bleaching susceptible genera, it is likely that the reefs of

Waktatobi NP may be affected by bleaching in the future. One of the best ways that managers can

increase the resilience of reefs to coral bleaching is to ensure reefs have the best chance of recovery

from bleaching or other damage. Two of the most important conditions for coral recovery are the

availability of stable substrate for coral settlement and a diverse and abundant community of

herbivorous fish to keep algal growth in check (Grimsditch and Salm, 2006). Therefore there are two

critical management priorities to improve the resilience of Wakaotobi’s reef. The first is the elimination

of destructive fishing and other activities which damage the substrate of the reef such as coral mining

and rock anchoring. The second is management of fisheries through regulations and enforcement of the

zoning system to ensure healthy populations of herbivorous fish in Wakatobi NP.

4 Conclusions

- Coral bleaching was recorded in Wakatobi in April 2010 and was caused by higher than normal

SST associated with an ENSO event.

- More than 60% of coral colonies were recorded as pale or bleached during April 2010 survey but

mortality was low < 4%.

17

- Karang Otiolo, in the southern atolls suffered the highest coral bleaching with 70% of colonies

bleached or pale on deeper reefs.

- Table Coral City is also a bleaching susceptible site because it is dominated by bleaching

susceptible genera such as Acropora and Montipora .

- Wakatobi was not as badly affected by bleaching as some other sites in Indonesia such as Aceh.

- The key to improving the resilience of Wakatobi NP in the face of future bleaching events is to

manage any threats which will damage the reef substrate such as destructive fishing and to

ensure healthy herbivore populations through fisheries management and enforcement of the

zoning system.

5 Recommendations

- Set up coral bleaching watch system within Wakatobi NP, using the alert system provided by

http://coralreefwatch.noaa.gov/satellite/current/products_dhw.html, and with regular

reporting on the incidence of bleaching when it is predicted from satellite data.

- Include Table Coral City in future routine monitoring as an early warning site for coral bleaching.

- Wakatobi National Park Rangers could become part of a coral bleaching alert network and

capable of conducting coral bleaching surveys.

- Prepare a coral bleaching survey module, national park rangers trained to identify coral

bleaching incidence, conduct simple coral bleaching survey, and trained to data analyses and

simple reporting.

- Need to build community network that is able to inform Wakaotbi NP staff and Local

Government when they see coral bleaching, especially for remote reefs.

- Need to identify source of contingency funding to conduct surveys when bleaching occurs.

- There are two critical management priorities to improve the resilience of Wakaotobi’s reef. The

first is the elimination of destructive fishing and other activities which damage the substrate of

the reef such as coral mining and rock anchoring. The second is management of fisheries

through regulations and enforcement of the zoning system to ensure healthy populations of

herbivorous fish in Wakatobi NP.

6 Acknowledgements

We would like to thanks to the hard work of the monitoring team and enormous support of other

stakeholder. We would like to thank to the Head of Wakatobi National Park authority and TNC-WWF

Wakatobi Project Leader and Head of COREMAP Wakatobi for engage the reef health monitoring that

involve coral bleaching survey. Thanks to TNC Head Quarter for provide Coral Bleaching Response fund

to make the first and second post-bleaching survey. Special thanks to all boat crew of Songampa (WNP),

FRS Menami and Kambala for their invaluable support to take the team to sites.

http://coralreefwatch.noaa.gov/satellite/current/products_dhw.html

18

7 References

Baker, A.C., P.W. Glynn, B. Riegl. 2008. Climate Change and Coral Reef Bleaching: An Ecological

Assessment of Long-term Impacts, Recovery Trends and Future Outlook. Estuarine, Coastal and Shelf

Science (2008) 1-37.

GCRMN (Global Coral Reef Monitoring Network). 2010. Status of Coral Reefs in East Asian Seas Region:

2010. Ministry of Environment, Japan. 121 pp

Grimsditch, G. D. and R.V. Salm. 2006. Coral Reef Resilience and Resistance to Bleaching. IUCN, Gland,

Switzerland. 52pp.

Guest JR, Baird AH, Maynard JA, Muttaqin E, Edwards AJ, et al. (2012) Contrasting Patterns of Coral

Bleaching Susceptibility in 2010 Suggest an Adaptive Response to Thermal Stress. PLoS ONE 7(3):

e33353. doi:10.1371/journal.pone.0033353

Hermansyah, H., M.F. Aziz, M.H. Sofita. 2008. Law Enforcement Statistics 2008. The Judicial Data Centre.

420 pp

Hoegh-Guldberg, O., Mumby P.J., Hooten A.J., Steneck R.S., Greenfield P., Gomez E., Harvell C.D., Sale

P.F., Edwards A.J., Caldeira K., Knowlton N., Eakin C.M., Iglesias-Prieto R., Muthiga N., Bradbury R.H.,

Dubi A., Hatziolos M.E. 2007. ‘Coral reefs under Rapid Climate Change and Ocean Acidification’.

Science 318: 1737-1742.

Marshall, P.A. and A.H. Baird. 2000. Bleaching of corals on the Great Barrier Reef: differential

susceptibilities among taxa. Coral Reefs (2000) 19:155-163.

Marshall, P., Schuttenberg, H. 2006. A Reef Manager’s Guide to Coral Bleaching. Great Barrier Reef

Marine Park Authority Publication, Townsville, Australia.

Maynard J, Wilson J, Campbell S, Mangubhai S, Setiasih N, Sartin J, Ardiwijaya R, Obura D, Marshall P,

Salm R, Heron S, and Goldberg J. 2012. Assessing coral resilience and bleaching impacts in the

Indonesian archipelago. Technical Report to The Nature Conservancy with contributions from

Wildlife Conservation Society and Reef Check Indonesia. 62 pp.

McClanahan, T.R., Muthiga, N.A., Mangi, S., 2001. Coral and algal changes after the 1998 coral

bleaching: interaction with reef management and herbivores on Kenyan reefs. Coral Reefs 19, 380–

391.

Obura, D.O. and G. Grimsditch, 2009. Resilience Assessment of coral reefs – Assessment protocol for

coral reefs, focusing on coral bleaching and thermal stress. IUCN working group on Climate Change

and Coral Reefs. IUCN, Gland, Switzerland. 70 pages.

Wilkinson C.R. 2000. Status of coral reefs of the world: 2000. Global Coral Reef Monitoring Network and

Australian Institute of Marine Science, Townsville, Australia 363 pp

Wilson, J. 2010. Report on Coral Bleaching at Wakatobi National Park – April 2010. The Nature

Conservancy. 10 pp.

19

Appendices Appendix 1: Description of sites surveyed at Wakatobi NP for bleaching and post bleaching surveys 2010-2011.

Survey Period Date Reference name Site Code Mgt_regime

20-Apr-10 Moromaho Moro Core Zone

Karang Koko 2 KKok Marine Protection Zone

Palahidu Pala Local Use

Karang Gurita 1 KGur Marine Protection Zone

Matahora 3 Mat3 Local Use

24-Apr-10 Karang Kaledupa 8 KKl8 Marine Protection Zone

Karang Kapota 4 KKp4 Tourism Zone

Karang Otiolo 1 KOti Tourism Zone

Sombu Somb Community MPA

Waha Waha Community MPA

Bola Tiga Bol3 Tourism Zone

Pak Kasim's PKas Tourism Zone



Blue Hole BHol Tourism Zone



Ndaa 1 Nda1 Local Use


Table Coral City Tabl Tourism Zone



Pulau Sawa 1 PSaw Tourism Zone


Karang Bante KBan Tourism Zone

Karang Kaledupa 6 KKl6 Local Use

Karang Kaledupa 8 KKl8 Marine Protection Zone


Mantigola Mant Local Use

Onemobaa Onem Tourism Zone



Kaledupa 1 Kal1 Local Use

Kaledupa 2 Kal2 Marine Protected Zone






Sampela Samp Local Use




Karang Kapota 2 KKp2 Local Use


Sampela Samp Local Use

Karang Kapota 2 KKp2 Local Use


Matahora 2 Mat2 Marine Protection Zone


24-Jan-11 Sombu Somb Community MPA





































2-Feb-11 Waha Waha Community MPA

30-Jan-11

31-Jan-11

1-Feb-11

2011 Jan

2010 Sep

2010 Apr

30-Sep-10

25-Jan-11

26-Jan-11

27-Jan-11

28-Jan-11

29-Jan-11

24-Sep-10

25-Sep-10

26-Sep-10

27-Sep-10

28-Sep-10

29-Sep-10

21-Apr-10

23-Apr-10

25-Apr-10

21-Sep-10

22-Sep-10

23-Sep-10

20

Appendix 2: Hard coral genera classification of susceptibility

Appendix 3. Average scores for resilience in Wakatobi (Maynard et.al, 2012)

Acropora Acanthastrea Coeloseris

Montipora Alveopora Coscinaraea

Pocillopora Astreopora Ctenactis

Seriatopora Caulastrea Cyphastrea

Stylophora coral branching Dendrophyllia

coral encrusting Distichopora

Cycloseris Echinomorpha

Diploastrea Echinophyllia

Echinopora Euphyllia

Favia Faviidae

Favites Fungia

Goniastrea Galaxea

Hydnophora Gardineroseris

Leptoria Goniopora

Lobophyllia Halomitra

Merulina Heliofungia

Millepora Heliopora

Montastrea Herpolitha

Mycedium Leptastrea

Oulophyllia Leptoseris

Oxypora Pavona

Pachyseris Physogyra

Pectinia Plerogyra

Platygyra Podabacia

Plesiastrea Psammocora

Porites (branching) Sandalolitha

Porites (massive) Stylocoeniella

Scolymia Symphyllia

Symphyllia/other massive

Tubastrea

Tubipora

Turbinaria

Susceptible Intermediate Resistant

21

Appendix 4. Site level susceptible genera composition (%) at deeper (D) reef slope (7-10m) and shallow (S) reefs

(1-3m) in three survey periods

0

20

40

60

80

100D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D


Co

mp

osi

tio

n o

f co

ral

gen

era

(%

) 2010 Apr Stylophora

Seriatopora

Pocillopora

Montipora

Acropora

0

20

40

60

80

100

D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D


Co

mp

osi

tio

n o

f co

ral

gen

era

(%

) 2010 Sep Stylophora

Seriatopora

Pocillopora

Montipora

Acropora

0

20

40

60

80

100

D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D S D


Co

mp

osi

tio

n o

f co

ral

gen

era

(%

) 2011 Jan Stylophora

Seriatopora

Pocillopora

Montipora

Acropora

22

Appendix 5A. Coral genera composition (%) of September 2010 survey, sorted from the highest to lowest

cumulative pale, bleaching and dead colonies condition.


(%)Dead (%)

Pale +

Bleaching +

Dead (%)

Susceptibil ity

Fungia 67 80 14 0.3 6 20 Resistant

Herpolitha 28 82 14 4 18 Resistant

Diploastrea 15 86 11 3 14 Intermediate

Acropora 17 90 9 0.5 1 10 Susceptible

Pocillopora 198 92 5 0.3 2 8 Susceptible

Ctenactis 51 92 4 2 2 8 Resistant

Platygyra 175 93 6 1 7 Intermediate

Hydnophora 12 93 2 4 1 7 Intermediate

Acanthastrea 17 94 6 6 Intermediate

Leptoria 35 94 3 3 6 Intermediate

Physogyra 18 94 6 6 Resistant

Merulina 15 95 3 1 5 Intermediate

Stylophora 196 96 3 1 1 4 Susceptible

Goniopora 174 97 1 1 2 3 Resistant

Leptoseris 177 97 2 2 3 Resistant

Echinopora 332 97 2 2 3 Intermediate

Lobophyllia 126 97 2 2 3 Intermediate

Goniastrea 65 97 1 0.2 1 3 Intermediate

Euphyllia 34 97 3 3 Resistant

Pachyseris 24 97 1 0.5 1 3 Intermediate

Plerogyra 114 97 3 3 Resistant

Montastrea 255 98 1 2 2 Intermediate

Galaxea 37 98 1 1 2 Resistant

Stylocoeniella 57 98 2 2 Resistant

Echinophyllia 243 98 2 2 Resistant

Astreopora 66 98 2 2 Intermediate

Cyphastrea 462 99 1 0.2 0.2 1 Resistant

Leptastrea 156 99 1 1 Resistant

Pectinia 84 99 1 1 Intermediate

Psammocora 92 99 1 1 Resistant


Favia 542 99 0.4 0.2 0.4 1 Intermediate

Montipora 4155 99 0.2 0.2 0.4 1 Susceptible

Favites 465 99 1 0.2 1 Intermediate

Millepora 484 99 1 1 Intermediate

Porites (massive) 5349 100 0.3 0.1 0.4 Intermediate

Pavona 97 100 0.3 0.3 Resistant

Porites (branching) 1858 100 0.3 0.3 Intermediate

Alveopora 8 100 Intermediate

Caulastrea 3 100 Intermediate

Coeloseris 167 100 Resistant

Coscinaraea 8 100 Resistant

Cycloseris 2 100 Intermediate

Dendrophyllia 1 100 Resistant

Distichopora 1 100 Resistant

Echinomorpha 1 100 Resistant

Gardineroseris 31 100 Resistant

Halomitra 6 100 Resistant

Heliofungia 3 100 Resistant

Heliopora 613 100 Resistant

Mycedium 155 100 Intermediate

Oulophyllia 19 100 Intermediate

Oxypora 7 100 Intermediate

Plesiastrea 5 100 Intermediate

Podabacia 9 100 Resistant

Sandalolitha 13 100 Resistant

Scolymia 48 100 Intermediate

Seriatopora 37 100 Susceptible

Tubastrea 11 100 Resistant

Tubipora 67 100 Resistant

Turbinaria 216 100 Resistant

suscept 7186 96 3 0.4 1 4

intemediate 11264 99 1 0.2 0.4 1

resistant 5887 97 2 0.1 1 3

Grand Total 24337

23

Appendix 5B. Coral genera composition (%) from January 2011 survey, sorted from the highest to lowest

cumulative pale, bleaching and dead colonies condition.


(%)Dead (%)

Pale +

Bleaching +

Dead (%)

Susceptibil ity

Ctenactis 20 85 10 5 15 Resistant

Diploastrea 141 87 10 4 13 Intermediate

Euphyllia 11 91 9 9 Resistant

Acropora 1654 92 7 0.1 2 8 Susceptible

Herpolitha 25 92 8 8 Resistant

Pocillopora 1055 94 5 0.2 1 6 Susceptible

Seriatopora 17 94 6 6 Susceptible

Gardineroseris 20 95 5 5 Resistant

Montipora 2475 95 3 1 0.4 5 Susceptible

Leptoria 23 96 4 4 Intermediate

Galaxea 230 96 3 1 4 Resistant

Fungia 519 97 3 0.2 0.2 3 Resistant

Stylophora 497 97 3 0.4 3 Susceptible

Pachyseris 112 97 3 3 Intermediate

Goniopora 112 97 3 3 Resistant

Pectinia 77 97 3 3 Intermediate

Porites (massive) 5545 98 2 0.02 0.5 2 Intermediate

Stylocoeniella 44 98 2 2 Resistant

Astreopora 90 98 2 2 Intermediate

Psammocora 62 98 2 2 Resistant

Merulina 134 99 1 1 Intermediate

Pavona 621 99 0.3 1 0.3 1 Resistant

Goniastrea 580 99 1 0.2 0.2 1 Intermediate

Coeloseris 84 99 1 1 Resistant

Porites (branching) 2822 99 1 0.04 0.04 1 Intermediate

Lobophyllia 93 99 1 1 Intermediate

Plerogyra 95 99 1 1 Resistant

Favia 542 99 0.4 1 1 Intermediate


Mycedium 114 99 1 1 Intermediate

Leptoseris 115 99 1 1 Resistant

Montastrea 281 99 1 1 Intermediate

Echinophyllia 183 99 1 1 Resistant

Cyphastrea 390 99 1 1 Resistant

Turbinaria 217 100 0.5 0.5 Resistant

Favites 414 100 0.2 0.2 Intermediate

Acanthastrea 27 100 Intermediate

Alveopora 14 100 Intermediate

Echinopora 166 100 Intermediate

Hydnophora 94 100 Intermediate

Millepora 455 100 Intermediate

Oulophyllia 12 100 Intermediate

Oxypora 2 100 Intermediate

Platygyra 233 100 Intermediate

Scolymia 52 100 Intermediate

Dendrophyllia 21 100 Resistant

Distichopora 14 100 Resistant

Halomitra 2 100 Resistant

Heliofungia 3 100 Resistant

Heliopora 1035 100 Resistant

Leptastrea 226 100 Resistant

Physogyra 33 100 Resistant

Podabacia 29 100 Resistant

Sandalolitha 8 100 Resistant

Tubastrea 1151 100 Resistant

Tubipora 3 100 Resistant

suscept 5357 94 4 1 1 6

intemediate 11813 98 1 0.1 0.3 2

resistant 5331 99 1 0.1 0.1 1

Grand Total 22501

a study of the impact of the 2010 coral bleaching event on coral

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