status of coral reefs before and after mass bleaching event 2010 in coastal water of pltu paiton

7/18/2019 Status of Coral Reefs Before and After Mass Bleaching Event 2010 in Coastal Water of PLTU Paiton

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IBOC 2012-111

Status of coral reefs before and after mass bleaching event 2010 in coastal water of PLTU

Paiton

Farid K. MUZAKI and Dian SAPTARINI

Ecology Laboratory, Department of Biology

Institut Teknologi Sepuluh Nopember, Surabaya 60111

Email: [email protected], [email protected]

Abstract

Coral reef mass bleaching caused by increasing of sea temperature that induced by El Nino

phenomenon in May to June 2010 had been reported from several parts of Indonesian waters,

including Situbondo and adjacent area in East Java. During July 2010 to October 2012, we haveaccessed condition of coral reef in coastal water of PLTU Paiton, based on percentage of life

coral cover. The study was conducted on three observation sites by Line Intercept Transect

(LIT) method with 100 meter length of transects. In July 2010, life coral cover ranged from

33.4% to 44.35%, with bleached coral exceeding 5.61% to 16.48%. At the same time, we

observed that at 3 m depth, massive coral and Acropora were more susceptible to bleaching.

While at 8 m depth, bleaching commonly occurred to massive coral, mushroom coral, foliose

coral and submassive coral . In 2011, we found that some of coral colonies are able to recover

from bleaching; showed by significantly decreasing percentage of bleached coral (0.3% to

1.14% only, while life coral cover are 54.32% to 71.5%, respectively); and most of non-

Acropora coral are able to recover, while some colonies of Acropora were dead and already

covered by turf algae. The percentage of life coral cover was also increased in 2012, ranging

from 66.98% to 76.04%. It can be concluded that most of coral colonies, especially non-

Acropora forms, in PLTU Paiton water are relatively resistant and able to recover after mass

bleaching event.

Keywords : coral reef status, mass bleaching 2010, PLTU Paiton

INTRODUCTION

Coral reefs are very complex ecosystem with high biodiversity though susceptible to anythreats and disturbances. Over one to two last centuries, human population growth and

development have greatly altered not only local environment but also global environment as a

whole. These changes include the increase in greenhouse gasses/GHGs concentration thought

to be one major cause of global climate change (Buddemeier et al ., 2004).

One of the most prominent effects of global climate change is the increase of average sea

water temperature that can trigger coral bleaching (Buddemeier et al ., 2004; Obura 2004;

Manzello et al . 2007; Baker et al . 2008). Coral bleaching is defined by the loss of coral color

caused by the degradation of Symbiodinium population (Zooxanthellae symbiotic) and/or their

pigments (Douglas, 2003). Coral bleaching is a stress response which could be caused by some

environment variables, especially by the increase of sea water temperature, either by natural

or anthropogenic factors.



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A rise in sea surface temperatures in the Andaman Sea had reported in 2010 (WCS, 2010).

According to NOAA, temperatures in the region peaked in late May of 2010, when the

temperature reached 34 degrees Celsius; 4 degrees Celsius higher than long term averages for

the area. The anomaly had reported to causing mass coral bleaching in Srilanka, Thailand,

Malaysia and many part of Indonesia (WCS, 2010), as well as in northern coast of Java.

In northern coast of East Java, 2010 mass coral bleaching event apparently detected in PLTU

Paiton and Pasir Putih regions. In PLTU Paiton water, we observed that bleached coral

exceeding to 5.15% - 16.48%. In late 2010 to early 2011, sea surface temperatures came to be

normal, which induced coral colonies to recover. This study sought to present a semi-

quantitative analysis on recovery ability and status of coral reef after bleaching in PLTU Paiton

water. In this study, bleaching response was considered to be either bleaching or mortality in

response to thermal stress by corals.

MATERIALS AND METHOD

Site description

The study was conducted on coral reef around coastal water of PLTU Paiton (Paiton Power

Plant), Probolinggo Regency, East Java. Among several coral reefs systems, there were three

station choosen, namely Water Intake (WI, 7042’42.3” S - 113

035’15.2” E), Water Discharge

(WD, 7042’53.9” S - 113

035’48.8” E) and Mercusuar (MR, 7

042’02.5” S - 113

034’26.1” E). The

geographic positions of each station are shown in the Figure 1.

Figure 1. Location map of study area



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Almost all of coral colonies in WI and WD, including reef building taxa (i.e. Porites spp, Favia

spp, Lobophyllia spp and Favites spp), arose from establishment of coral recruits on concrete

blocks which are formerly used as breakwater and reclamation materials. Over times,

planktonic larvae of coral used the blocks as a settlement sites which in turn forming a new

coral reef on the areas. At present, dominant coral lifeforms in WI are massive corals of Porites

spp and several foliose corals of Pavona frondens, Merulina scabricula and Montipora foliosa.

Only a few colonies of branching corals found at WI station, including Acropora formosa, A.

humilis, A. hyacinthus dan A. loripes.

As well as in WI, major reef building corals in WD stations dominated by massive coral,

especially from genera Porites, Lobophyllia, Favia, Diploastrea and Favites. Of the foliose

coral, Leptoseris explanata, Pectinia spp dan Pachyseris spp are the most dominant taxa. The

occurrence of branching Acropora represented by Acropora nasuta, A. florida and A.

divaricata.

Reef builder taxa in MR station are quite different from those in WI or WD stations. At this site,

the most dominant coral taxa are branching corals Acropora nobilis, A. formosa, and A.

divaricata; foliose coral such as Montipora spp and fungiid corals such as Fungia horrida and F .

fungites.

Observation method

The observation of coral lifeform and species was conducted in four periods; July 2009, June

2010, September 2011 and October 2012. The method used is Line Intercept Transect /LIT with

100 meters line transects for each location. The observed parameters are coral lifeform, coralspecies, and percentage of life coral coverage. In this study, bleaching response was

considered to be either bleaching or mortality in response to thermal stress by corals.

Category of lifeform refers to AIMS ( Australian Institute of Marine Science) (English et al .,

1994) and Keputusan Kepala Bapedal No.Th. 2001. The identification of coral species refers to

Allen (1994), Carpenter & Niem (1998), Suharsono (1996) and Suharsono (2004).

RESULTS AND DISCUSSION

Sea water temperature

The results of sea water temperature measurement in 2009 to 2012 are showed in the Table 1

below;

Table 1. Values of Sea Water Temperature Measurement of PLTU Paiton Coastal Water

Period TemperatureStation

WI WD MR

2009Sea surface 30 33 30

Sea bottom 29 31 29


Sea bottom 32 33 30


Sea bottom 29 30 28


Sea bottom 30 29 28



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It should be noted that, at 2010, maximum in situ temperatures were recorded at the onset of

the bleaching event which ranged between 31-350C on sea surface and 30-33

0 on sea bottom

among sites. The highest temperatures were noted at WD (Water Discharge), which was as

much as 1-20C higher than any other sites. From 2009 to 2010, the average increase was 1-2

0C;

in which estimated to influencing the change of coral coverage percentage in the study site.

The temperature in WD seems remain higher at all observation periods compared to other

stations.

Resilience of coral after mass bleaching

Percent of life coral and dead coral cover in PLTU Paiton coastal water from 2009 to 2012 are

shown on the following Table 2.

Table 2. Percentage of Live and Bleached Coral in PLTU Paiton Coastal Water

Period TemperatureStation

WI WD MR

2009% life coral 54.09 48.6 43.96

% dead coral 2.73 0 0

2010% life coral 33.4 40.12 44.35

% dead coral* 16.48 11.88 5.61

2011% life coral 71.3 54.32 71.5

% dead coral 0 0.3 0

2012% life coral 76.04 66.98 75.57

% dead coral 0 0 0

From Table 2, it is clearly known that from 2009 to 2010, percent coral cover in station WI and

WD were decreased while percent of bleached corals colonies were increased. This condition

estimated to be influenced by increasing of sea temperature. From 2011 to 2012, sea surface

temperatures came to be normal. In this period, we observed that most of coral colonies that

bleached at 2010 are able to recover from bleaching, resulting in an increasing of percent coral

cover.

Compared to 2009, the bleached coral percentages were increased in all of observation

stations at 2010; as much as 5.61% in MR (Mercusuar), 16.48% in WI (Water Intake) and

11.88% in WD, respectively. At 3 m depth, massive coral and Acropora were more susceptible

to bleaching. While at 8 m depth, bleaching commonly occurred to massive coral, mushroom

coral, foliose coral and submassive coral . Furthermore, coral bleaching are commonly occurred

on Porites, Acropora, Fungia, Goniopora, Favites, Platygyra, Pectinia dan Lobophyllia.

In previous study (Saptarini and Muzaki, 2010), coral bleaching typically occurred in 3 m depth

because shallow waters will have higher temperature than deep waters. Besides, temperature

changes often occur in shallow waters during day-night change. It can be assumed that

temperature increases and fluctuations triggered coral bleaching and affected coral growth inshallow areas.

Notes:

* percent cover at mass bleaching event



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In station WI, percent coral cover had increased from 33.4% in 2010 to 71.3% in 2011 and

76.04% in 2012. In contrast, no bleaching events were recorded from 2011 to 2012, therefore

showing a rapid recovery processes after mass bleaching. That significant increasing of percent

coral cover was possibly not merely caused by recovery of previously bleached coral colonies

(such as Porites, Diploastrea and Acropora) but may also be caused by growth of existing coral

colonies and establishment of new coral recruitments.

A significant increasing of percent coral cover was also observed in station MR, from 44.35% to

71.5% and 75.57%, respectively. In this station, there were relatively few bleached corals at

2010 (mainly detected in Fungia). As same as in WI, growth of existing coral colonies (mainly

branching Acropora) and establishment of new coral recruitments probably act as prominent

factors causing increasing of percent coral cover.

Since WD was located around outlet canal of PLTU Paiton that produce hot water effluent , it

should be noted that increasing temperature in WD was possibly not merely caused by

anomaly of sea level temperature (as occurred in Andaman Sea and other region). Coral

colonies in WD probably were well adapted to fluctuation of hot-cold water masses, therefore

only few percent of bleached corals in 2010; even the highest increasing temperature (either

sea surface or sea bottom) occurred in that area.

Mass coral bleaching is one of the major threats to coral reef ecosystems (Sampayo et al.,

2008 & Wilkinson, 2008). Often mass coral bleaching events are as a result of the prolonged

exposure of corals to unusually warm ocean temperatures, resulting in the expulsion of

symbiotic algae from host corals. However, not all coral taxa are equally susceptible to

bleaching (Loya et al., 2001). Some taxa may bleach, whereas others exposed to the same heatstress may not bleach or show intermediate signs of bleaching.

Bleaching can be defined as the loss color of coral, caused by the releasing of Zooxanthellae

inside coral polyp (Douglas, 2003). Zooxanthellae supplied about 95% of its photosynthesis

products (amino acid, sugar, carbohydrate, and short peptides) to coral polyp which used this

nutrition for respiration, growth, and deposition of CaCO3 (Lesser, 2004). So, the released

Zooxanthellae of coral polyp gave an impact of the decreasing coral ability to undergo

metabolism.

Bleached coral also more susceptible to diseases and overgrown by algae (Westmacott et al .,

2000) therefore, if this stress continues, coral will die. But, if coral can adapt to this condition,

coral can stay alive and get new population of Zooxanthellae (Obura, 2005).

We found that lifeform of massive, submassive, foliose and encrusting are more resistant and

more capable to recover (higher resilience potential) after mass bleaching event. Coral genera

of Porites, Lobophyllia, Favites, Favia, Leptoseris, Pachyseris, Goniopora and Platygyra are

more resistant than branching forms (i.e. Acropora, Pocillopora and Seriatopora) or mushroom

corals (i.e. Fungia). In addition, some of coral colonies that bleached in 2010 are already

overgrown and covered by turf algae and/or other organisms (tunicate and sponges) and

sediment particles.

We also noticed that most of those resistant corals genera are recognized as k-strategy

colonies, including those with relatively slow of growth rate but high capability to competewith other organisms (Sorokin, 1993), and also more resistant to environmental stresses.



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Several colonies that able to recover or continue to grow after mass bleaching event are

clearly depicted on Figure 2 and Figure 3.

a b

c d

e f

Figure 2. Several coral colonies that are capable to recover after 2010 mass bleaching event: a and b. in

WD station; c and d. in WI station; e and f. in WI station



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Buddemeier, R.W., J.A. Kleypas and R.B. Aronson. 2004. Coral Reefs and Global ClimateChange: Potential Contributions of Climate Change to Stresses on Coral Reef

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Figure 3. Photographs showing dead Acropora florida (upper photographs) and Acropora sp (lower

photograph) that covered by algae and sediment (red line), while the remaining alive polyps

continue to grow at the edge of the colony (yellow line)



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status of coral reefs before and after mass bleaching event 2010 in coastal water of pltu paiton

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