IBOC 2012-111 Status of coral reefs before and after mass bleaching event 2010 in coastal water of PLTU PaitonFarid 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 2 010 had been reported from several parts of Indonesian waters, including Situbondo and adjacent area in East Java. During July 2010 to October 2012, we have accessed 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 coraland 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- Acroporacoral are able to recover, while some colonies of Acroporawere 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- Acroporaforms, in PLTU Paiton water are relatively resistant and able to recover after mass bleaching event. Keywords : coral reef status , mass bleaching 2010, PLTUPaitonINTRODUCTION Coral reefs are very complex ecosystem with high biodiversity though susceptible to any threats 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 cl imate 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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Status of Coral Reefs Before and After Mass Bleaching Event 2010 in Coastal Water of PLTU Paiton
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7/18/2019 Status of Coral Reefs Before and After Mass Bleaching Event 2010 in Coastal Water of PLTU Paiton
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.
7/18/2019 Status of Coral Reefs Before and After Mass Bleaching Event 2010 in Coastal Water of PLTU Paiton
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
2010Sea surface 32 35 31
Sea bottom 32 33 30
2011Sea surface 30 32 29
Sea bottom 29 30 28
2012Sea surface 30 33 30
Sea bottom 30 29 28
7/18/2019 Status of Coral Reefs Before and After Mass Bleaching Event 2010 in Coastal Water of PLTU Paiton
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.
7/18/2019 Status of Coral Reefs Before and After Mass Bleaching Event 2010 in Coastal Water of PLTU Paiton
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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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