CurrentstatusofimplementationforOAstudiesinMalaysia

LocationoftheproposedstudysiteN

400km

Pulau Gaya

STUDYSITE

Sumatra

PulauPayar

TarutaoNationalPark

SOUTHCHINASEA

PulauBidong

P.Payar

P.Lembu

P.Kaca

N

STRAITOFMALACCA

1km

MarineParkCentre

PulauPayarMarinePark

Pulau Bidong (UMTMarineResearchStation)

UMTMarineResearchStation

N

SOUTHCHINASEA

1km

InvestigatingthediurnalvariationoftheseawaterpHandalkalinityinshallowwatercoralreefofPulau Payar (StraitofMalacca),Pulau Bidong andPulau Gaya(SouthChinaSea)astheproposedsitesoftheocean

acidificationstudy.

DiurnalvariabilityofpHandtotalalkalinity

3dayperiodofobservationatashallowwater coralreefarea

In-situmeasurement&watersamplecollection

Every3hours,watersamplewerecollectedandmeasuredfortheTotalAlkalinity(AT)

HydrolabDS5Xrecordedreadingevery15minute(pH,Temperature,Salinity,DissolvedOxygen,DO)

AragonitesaturationweredeterminedusingtheCO2SYSprogram(LewisandWallace,1998)throughinsituAT,pH,

salinity,temperaturedata.

Methodsthatwereusedtodeterminetheseawatercarbonateparameter

Parameters Unit MeasurementMethods

Temperature °C HydrolabDS5X

Salinity ppt HydrolabDS5X

pH HydrolabDS5X

DissolvedOxygen(DO) mg/L HydrolabDS5X

TotalAlkalinity µmol/kg PotentiometricTitration(Dicksonetal.2007)

AragoniteSaturation ΩAragonite CO2SYSprogram(LewisandWallace,1998)

DiurnalvariationinseawaterpHatthestudyarea

day day daynight night night

• pH trend fluctuates daily following the diurnal pattern which is regulated by the biological activity such as photosynthesis and respiration

Payar(SOM)

Bidong(SCS)

Gaya(SCS)

SeawaterpHatPulauPayar,PulauBidongandPulauGaya

• Decreasing surface seawater pH trend from the Strait of Malacca to the South China Sea

morebasic

lessbasic

Diurnalvariationoftotalalkalinity

day day daynight night night

Payar(SOM)

Bidong(SCS)

Gaya(SCS)

• Total alkalinity (AT) did not show any diurnal trend through out this study.• However, the largest difference of AT was recorded at Payar with the value of 28.92 μmol/kg.• Changes in AT are attributed to calcification or carbonate dissolution (Murillo et al., 2014)

Relationshipbetweentotalalkalinityandsalinity

• Precipitation and evaporation mainly controls the AT variability of surface ocean (Brewer et al., 1986; Millero et al., 1998a)

• Concentrations of the key chemical species (i.e., HCO3

-

CO32-) that contribute to AT

proportionally increase with increasing salinity (Lee et al., 2006)

CO2 ParameterVariation

• pH ranged 7.21 to 7.81°C• Lower pH observed at the southern

region

pH

• ρCO2 ranged 710 to 3151 µatm

• Higher ρCO2 observed at the southern region

ρCO2 (µatm)

• Aragonite saturation ranged 0.57 to 2.26• Low saturation state observed at the

southern region• At extremely marginal state

Aragonite Saturation (ΩAra)

CO2 ParameterVariation

Hoegh-Guldberg et al. 2007: Ωarag = 3.3

Shamberger et al. 2011

Saturation States in the Pacific

(Shambergeretal.2011)

(ReefsatRiskRevisited 2011)

Saturation state in our region

Carbonateenvironmentcomparison• Pulau Bidong and Pulau Gaya

– Higher AT were recorded at these sites, 2161.78 μmol kg-1 and2160.45 μmol kg-1 respectively.

– The pH at both sites are lower than Payar as denoted by the higherH+ concentration in the seawater.

– Aragonite saturation in the seawater at both sites were recorded atadequate (3.41) and marginal (2.99) level respectively.

• Pulau Payar– Lower AT (2140.77 μmol kg-1) means the capacity of the seawater

buffer system to neutralize acidic pollution is reduced.– At present, the seawater carbonate system is maintained because of

the pH value (pH 8.14).– Only a small amount of acidic pollution is needed to disrupt the

carbonate system equilibrium.– Optimal aragonite saturation state in Payar contributes to the high

coral calcification rate in the area.

CurrentstatusofimplementationforOAstudiesinMalaysia

• AllrequiredCAUs,BMUsandARMshavebeenmanufacturedbutasyetnotdeployed

• diurnalvariationsurveyofselectedstationhasbeencompletedfortemperature,salinity,pHDO,aragonitesaturationandtotalalkalinity

• Coralcoveranddiversitystudiesareplannedfor2016-2017).Bioticsurvey(georeferenced,cover,diversity)iscurrentlybeinganalysed.

• Localorganizingcommittee• IOC/WESTPAC• Mr.WenxiZhu• PhuketMarineBiologicalStation