International Journal of Environmental Research University of Tehran ISSN: 1735-6865 EISSN: 2008-2304 Vol. 3, Num. 1, 2009, pp. 85-94

International Journal of Environmental Research, Vol. 3, No. 1, Winter, 2009, pp. 85-94

Trace Metal Contents in the Porites Corals of Peninsular Malaysia

Lee, J.N. and Mohamed, C.A.R^*

Marine Ecosystem Research Centre (EKOMAR), Faculty of Science & Technology, University Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
*Corresponding author E-mail: carmohd@ukm.my

Received 10 March 2008; Revised 16 July 2008; Accepted 25 July 2008

Code Number: er09009

ABSTRACT

The concentration contents of Ca, Mg, Sr and Zn in Porites corals from Pulau Langkawi, Pulau Redang and Pulau Tioman were presented. The corals were cleaned and the growth rate examined visually. The growth rate of Porites in Malaysia waters was between 5 to 25 mm yr^-1 and each band was selected for determining the metal contents using the Atomic Absorption Spectrophotometer (AAS). The mean values of Ca (42.1 %), Mg (1184 μg/g), Sr (6276 μg/g) and Zn (60.6 μg/g) were calculated from each annual skeleton band representing the yearly growth. Porites coral from Pulau Langkawi shows a high content of Zn (118 μg/g) representing the water surrounding the island was highly polluted and also shows the uptake of Sr and Ca in the coral skeleton was related to the content of Zn, where Sr and Ca contents decreases when the concentration of Zn was more than 50 μg/g. Terrestrial runoff from Sumatera and west coast of Peninsular Malaysia are presumed to be the cause of pollution in Malacca Straits.

Key words: Coral, Porite, Trace element, Peninsular Malaysia

INTRODUCTION

Corals have been long recognized as marine bio-monitors, such as rainfall, runoff and upwelling events through the use of δ ¹⁸O, Ba/Ca, Cd/Ca and Mn/Ca (Linn et al., 1990; Shen et al., 1992; McCulloch et al., 1994; Gagan et al., 1998; Fallon et al., 1999). In the meantime, corals have been used to monitor past sea surface temperature (SST) through chemical, Sr/Ca, U/Ca, Mg/Ca, B/ Ca and isotopic δ ¹⁸O in the aragonite skeletal lattice (Cole and Fairbanks 1990; Beck et al., 1992; Mitsuguchi 1996; Fallon et al., 1999; McCulloch and Esat 2000). Yet, coral usage in environmental pollutions based on the abundance of trace metals and rare earth elements is less developed (Howard and Brown 1986; Brown 1987; Shen and Boyle 1987; Hanna and Muir 1990; Scott 1990; Sholkvits and Shen 1995; Guzman and Jarvis 1996) as last reported by Bastidas and Garcia in year 1999.

According to Sinclair (2005), trace elements in the skeleton of tropical corals are now widely used as proxies for physical and chemical processes in the world oceans. All these studies have contributed significantly to the understanding of past climate variability, however after more than 120 years of research in this field the exact process by which corals form their skeleton is still not fully understood (Gattuso et al., 1999; Cohen and McConnaugley 2003; Allemand et al., 2004). The aragonite secreted by coral polyps is an orthorhombic form of calcium carbonate (CaCO₃) which is less stable than calcite. It can contain various minor and trace elements, mainly divalent cations such as Sr, Ba, Mg, Zn, Pb and Mn (Corrège, 2006). Despite the incorporation mechanism, corals have shown to be good tracers of pollutants in the marine environment (Shen and Boyle 1987; Hanna and Muir 1990; Guxman and Jimenez, 1992; Bastidas and Garcia, 1999). And coral reefs are mostly found in tropical water only. Coral reefs are widely spread around Peninsular Malaysia especially in the west coast. Coral community structures in the west coast of Peninsular Malaysia were dominant with Porites massive life form, and the east coast with a variety of life form categories of Montipora & Acropora (Toda et al., 2007). Banded aragonite corals have been useful records of surface water composition changes over time because annual & sub-annual sections can be assigned ages based on growth patterns (Linn et al., 1990). In this study, we used Porites corals to determine variation contents of Ca, Mg, Sr and Zn from various sampling stations as a signal for pollution levels.

MATERIALS & METHODS

Malaysia is located at South East Asia (Fig. 1). with population over 27 million people. Malaysia’s coral reefs extend from the renowned “Coral Triangle” connecting it with Indonesia, Philippine, Papua New Guinea and Australia (Maritime Institute Malaysia 2006). Coral reef types in Malaysia are situated on the Sunday Shelf in relatively shallow water. Most reefs are shallow fringing reefs in the offshore islands. In Malaysia, the conservation of coral reefs is largely achieved through the establishment of marine protected areas. Malaysia has designated 136 marine protected areas including non fishing area, marine parks and marine reserve (Maritime Institute Malaysia 2006).

Pulau Redang was the first island to be declared as marine protected area in 1983. It lies 46 km north-east of Kuala Terengganu state, off the east coast of Terengganu. Further south of east coast of Peninsular Malaysia, lies Pulau Tioman, 32 km off the coast in the state of Pahang. It has eight main villages and the most populated at Kampong Take in the north side. Yet, the densely forested island is still sparsely inhabited and is surrounded by numerous coral reefs. Langkawi is an archipelago of 99 islands at the northern of Malacca Straits, 30 km off the mainland coast as Kedah state. The largest island is Pulau Langkawi with 45,000 populations. Langkawi was declared as tax-free island in 1987 to promote tourism. The island’s airport was upgraded and ferry links were increased with other developments.

OnAugust 2004, two coral samples of Porites were obtained from Pulau Tioman at 02^o 46.76’N, 104^o 07.01’E. The size of each coral sample more than 100 mm in diameter was collected from the water depth of 6 m. The Porites coral with a size of 101 mm and 7 bands labeled as PPTA and a size of 107 mm with 9 bands as PPTB. Then on September 2004, coral sample was also collected from Pulau Redang (05^o 46.46’N 103^o 03.59’E). The coral head size was 68 mm in diameter with 9 bands and collected at the water depth of 5 m labeled as PPR.During May 2005, sampling at the west coast of Peninsular Malaysia was done in Pulau Langkawi (06^o 09.59’N 099^o 48.52’E). The Porites coral was collected at the water depth of 1.5 m and the entire colony of 68 mm. The Porites coral from Pulau Langkawi (PPL) consists of 7 bands. These corals were prepared for trace metal analysis by washing with de-ionizer distilled water (DDH₂O) and weak acid (0.02M HNO₃) to remove surface contamination.

Massive Porites corals were cut into 2 cm slices using a diamond saw. The slices were washed with DDH₂O. After drying the slices, the coral was examined visually to identify chronological (yearly) bands (Fig. 2). Then, every layer was cut by small diamond saw and grounded using an agate mortar. About 0.5 g of powder samples were taken from each layer for analysis. Each of the power samples was dissolved in 5 ml of hydrofluoric acid, 10 ml of nitric acid and 3 ml of perchloric acid on the hotplate for 2 hours. After dissolution, dried sample continue adding with 50 ml of 0.5 M nitric acid and determine the concentration of trace metals using the Atomic Absorption Spectrometry (AAS). This procedure was evaluated with Standard Reference Material 1633b (Coal Fly Ash) with the percentage value of similarity 87% to 113%.

RESULTS & DISCUSSION

Porites corals growth rate obtained from this study is in the range of 5 to 25 mm yr^-1 (Table 1). The growth rate depends on the location and the environment of the coral reef. The water quality of Pulau Langkawi is totally different from Pulau Redang and Pulau Tioman. The physical parameter for each sampling station is shown in (Table 2). The temperature and salinity is still in the range of coral reef distribution although the salinity in Pulau Langkawi is slightly higher than Pulau Redang and Pulau Tioman.The variation of Zn shows that Pulau Langkawi and Pulau Redang have an increasing trend in the year of 1999 to 2001 for Pulau Langkawi and 1997 to 2001 for Pulau Redang (Fig. 3a, b). Meanwhile, the level of Zn in Pulau Langkawi is the highest (> 57.3 μg/g) compare to Pulau Redang with content between 31.8 μg/gto 48.3 μg/g. Porites at Pulau Tioman shows lowest content of Zn with the average of 23.6 μg/g. The content of Zn in Pulau Tioman shows variation of up and down in PPTB in the year of 1996 to 2001. While in the PPTA shows decreased from 1998 to 2001 but after year 2001 the content of Zn increase gradually for both corals.

The content of Sr in Pulau Tioman is in the average of7207 μg/gfor PPTA and 7238 μg/g for PPTB while the concentration for PPR is slightly low with an average of 7127 μg/g. Then the lowest content (4478 μg/g) was found in PPL sample. Similar trend also happen with the content of Ca in all the samples. The Ca content in PPL is in the range of 15.5 % and 31.5 %. Meanwhile PPR is in the range of 49.5 % and 52.6 %. The contents of Ca in PAPT and PBPT were in the average of 48.9 % and 50.0%.The content of Mg for PPL is similar to the Sr trend with ranging from 606 μg/g to 1334 μg/g. PPR shows higher content of Mg with an average of 1213 μg/g. PPTA shows the highest content of Mg comparing to other corals with 3205 μg/g at the depth of 67 mm or equivalent to the year of 1999. Meanwhile for PPTB, the content of Mg is at the average of 1000 μg/g at the surface till the depth of 79 mm. Then, it increase to 2071 μg/g at the deepest layer of 107 mm.The Porites sp. from Pulau Langkawi (9.7 mm yr^-1) and Pulau Redang (7.5 mm yr^-1) have lower growth rate compare to Pulau Tioman with an average of 13 mm yr^-1. This means that the coral in Pulau Tioman calcified faster than other places where the PBPT growth in 9 years for 107 mm while the PPR reach only 68 mm of the same age. Calcification of coral much depends on the surrounding water parameters, terrestrial runoff and stress. Temperature is an important tool affecting calcification rate in coral. However in this study, temperature is at the average of 31°C and the coral growth from each places are different.The differences of salinity in Pulau Langkawi from other islands might cause stress to the coral. Meanwhile the pH reading for Pulau Langkawi is high (9.11) because of the limestone at the surrounding water. The erosion of limestone (CaCO₃) increases the pH in the surrounding water. There is no study yet on the effect of pH on the coral reef. But the coral in Pulau Langkawi also face other stress such as high sedimentation rate. It is noted that millions of tons of sediment particles are transported annually by major rivers of the east coast of Sumatra and the west coast of Peninsular Malaysia to the coastal water of the Malacca Straits (Soegiarto, 2000).Comparing Zn content to other places, Pulau Tioman and Pulau Redang are between the range of 2.25 to 42 μg/g as likes the Papua New Guinea and Vanezuela high with the sediment loads (Table 3). Zn content in PPL is triple higher than other places. This shows the surrounding water of Pulau Langkawi is highly polluted. Hija River coral with highest content of 34.3 μmol/mol of Zn also serves as a pollution indicator. Zinc is enriched in the coral skeleton relative to seawater (distribution coefficient D_Zn=11; Shen & Boyle 1988). The loads of Zn into seawater are mainly from terrestrial runoff and soil.Zn and Pb are mostly used as anthropogenic and pollution monitoring in coral. Lead appears to be bound directly into the calcium in the coral lattice and is enriched relative to the seawater (distribution coefficient D_Pb=2.3; Shen & Boyle 1987, 1988). The effect of Zn to the calcification is less known. This study shows that Zn appears to be absorbed in coral lattice when Zn reaches a certain level and decrease the ability of absorbing Sr and Ca in the coral lattice. Fig. 4a, b. shows the content of Sr, Mg and Ca that decreases when the content of Zn was more than 50 μg/g. This study has found that the uptake of Sr and Ca that used as SST proxy is not influences by the content of Zn. According to Sinclair (2005), if the temperature condition become more extreme, the enzymes that transport Ca ions would become less efficient, resulting in a lowering of the active Ca²⁺ transport and a decreasing calcification rate. The result shown in Figure 4a, b indicate the Sr and Ca is affected by the high Zn content and yet the Sr/Ca ratio (0.014 0.017) is still in the range comparing to the Rea Sea (0.022) and Davies Reef (0.019). This indicates that the coral is a good proxy for SST and also as pollution indicator at the same time.This result of Sr is almost similar to the studies in Davies Reef, Great Barrier Reef with 7463 μg/g (Sinclair et al., 1998). The content of Ca in PPR (51.3%) and PPT (49.4%) is in the range from Davies Reef (38.3%) and Rea Sea (58.4%). The content of Ca in PPL is 25.75%. Since Sr and Ca is widely used as proxy for sea surface temperature, the trend of Sr and Ca should be similar because of the ratio (Sr/Ca) is use to calculate the SST. This study shows the uptake of Sr and Ca in the coral skeleton is related to the content of Zn. Unlike Zn, Sr lies long residence time in the ocean or static behavior over the short time scales of glacial cycles. Sr is added to the ocean by rivers and hydrothermal exchange and removes from the ocean by carbonate deposition, both in the form of aragonite and calcite (Stoll &Schrag, 1998).Comparing the metals content at PPTA and PPTB, the average content is almost the same but the yearly content is different. This shows that the ability of each corals for metal up taking is different and also they are few meters apart. Differences in the metal profiles of the Ihatub corals imply that the location and depth of the coral samples are important factors to consider even if distances of only a few hundred meters separate them (David 2003). It also stated that high metal levels on the outermost 5 mm of coral samples is probably due to metals associated with tissue that remains in the organic rind of the corals. But this situation does not happen in this study. The outer layer of each coral did not state high metal content. The methods of rinsing the corals with de-ionizer distill water (DDH2O) and weak acid (0.02M HNO3) is useful to remove surface contamination.

CONCLUSION

Hard coral such as Porites sp widely found in Malaysia waters have growing rate ranged from 5 mm yr^-1 to 25 mm yr^-1. The mean values of Ca, Mg, Sr and Zn were fluctuated from each annual skeleton band representing the yearly growth. Porites coral from Pulau Langkawi shows a high content of Zn representing the water surrounding the island was highly polluted and also shows the uptake of Sr and Ca in the coral skeleton was related to the content of Zn, where Sr and Ca contents decreases when the concentration of Zn was more than 50 μg/g. Study also found that the uptake of Sr and Ca as indicator for sea surface temperature proxy was not influences by the content of Zn. Finally, in the stress marine environment conditions, Porities species very useful as bio-pollution indicator for trace elements uptake and sediment loading as showed by Pulau Langkawi corals. Most of the sediment loading in the Malacca Straits was coming from the west coast Peninsular Malaysia and Sumatera Island.

ACKNOWLEDGEMENTS

This research was supported by the Grant IRPA 08-02-02-10023EAR. The authors would like to thank the laboratory assistants of University Kebangsaan Malaysia and members of Land-Ocean-Atmosphere-Interaction for their assistance in the field and analysis of samples.

REFERENCES

• Allemend, D., Ferrier-Pagès, C., Furla, P., Houlbrèque, F., Puverel, S., Reynaud, S., Tambutté, E., Tambutté, S., Zoccola, D. (2004). Biomineralisation in reef-building corals: from molecular mechanisms to environmental control. CR Palévol 3, 453-467.
• Bastidas, C., Garcia, E. (1999). Metal content of the reef coral Porites asteroides: an evaluation of river influence and 35 years of chronology. Mar. Poll. Bull. 38, 899-907.
• Beck, J.W., Edwards, R.L., Ito, E., Taylor, F.W., Recy, J., Rougerue, F., Joannot, P., Henin, C. (1992). Sea-surface temperature from coral skeletal strontium/calcium ratios. Science 257, 644-647.
• Brown, B.E. (1987). Heavy metals pollution on coral reeds. In: Salvat, B. (Ed.), Human Impacts of Coral Reefs: Facts and Recommendations. Antenne Museum EPHE French Polynesia, 119-134.
• Cole, J.E., Fairbanks, R.G. (1990). The Southern Oscillation recorded in the oxygen isotopes of corals from Tarawa Atoll. Paleoceanography 5, 669-689.
• Cohen, A.L., McCommaughey, T.A. (2003). Geochemical perspectives on coral mineralization. Rev. Mineral Geochem., 54, 151-187.
• Correge, T. (2006). Sea surface temperature and salinity reconstruction from coral geochemical tracers. Paleogeogr. Paleoclimatol. Paleoecol., 232, 408-428.
• Fallon, S.J., McCulloch, M.T., van Woesik, R., Sinclair,
• D.J. (1999). Corals at their latitudinal limits: Laser ablation trace element systematics in Porites from Shirigai Bay, Japan. Earth Planet Sci. Lett., 172, 221-238.
• Fallon, S.J., White, J.C., McCulloch, M.T. (2002). Porites corals as recorders of mining and environmental impacts: Misima Island, Papua New Guinea. Geochim. Cosmochim. Acta, 66, 45-62.
• Gagan, M.K., Ayliffe, L.K., Hopley, D., Cali, J.A., Mortimer, G.E., Chappell, J., McCulloch, M.T., Head, M.J. (1998). Temperature and surface-ocean water balance of the mid-Holocene tropical Western Pacific. Science 279, 1014-1017.
• Gattuso, J.P., Allemand, D., Frankignoulle, M. (1999). Photosynthesis and calcification at cellular, organism and community levels in coral reefs: a review of interactions and control by carbonate chemistry. Am. Zool., 39, 160-183.
• Guzman, H.M., Jarvis, K.E. (1996). Vanadium century record from Caribbean reef corals: A tracer of oil pollution in Panama. Ambio, 25, 523-526.
• Guzman, H.M., Jimenez, C.E. (1992). Contamination of coral reefs by heavy-metals along the Carribean coast of Central America: (Costa Ricaand Panama). Mar. Poll. Bull., 24, 554-561.
• Hanna, R.G., Muir, G.L. (1990). Rea Sea corals as biomonitors of trace metal pollution. Envir. Mon. Assess., 14, 211-222.
• Howard, L.S., Brown, B.E. (1986). Metals in tissue and skeleton of Fungia fungites from Phuket Thailand. Mar. Poll. Bull., 17, 569-570.
• Linn, L.J., Delaney, M.L., Drufflel, E.R.M. (1990). Trace metals in contemporary seventeeth century Galapagos coral-records seasonal and annual variations. Geochim. Cosmochim. Acta, 54, 387-394.
• McCulloch, M.T., Esat, T. (2000). The coral record of last interglacial sea levels and sea surface temperatures. Chem. Geol., 169, 107-129.
• McCulloch, M.T., Gagan, M.K., Mortimer, G.E., Chivas, A.R., Isdale, P.J. (1994). A high-resolution Sr/Ca and δ ¹⁸O coral record from he Great Barrier Reef, Australia, and the 1982-1983 El-Nino. Geochim. Cosmochim.Acta, 58, 2747-2754.
• Mitsuguch, T., Matsumoto, E., Abe, O., Uchida, T., Isdale, P.J. (1996). Mg/Ca thermometry in coral skeletons. Science, 274, 961-963.
• Ramos, A.A., Inoue, Y., Ohde, S. (2004). Metal contents in Porites corals: Anthropogenic input of river run-off into a coral reef from an urbanized area, Okinawa. Mar. Poll. Bull., 48, 281-294.
• Scott, P.J. (1990). Chronic pollution recorded in coral skeletons in Hong Kong. Journal of Experimental Marine Biology and Ecology, 139, 51-64.
• Sinclair, D.J. (2005). Correlated trace element “vital effects” in tropical corals: A new geochemical tool for probing biomineralization. Geochim. Cosmochim.Acta, 69, 3265-3284.
• Sinclair, D., Kinsley, L., McCulloch, M. (1998). High resolution analysis of trace elements in corals by laser ablation ICP-MS. Geochim. Cosmochim.Acta, 62, 18891901.
• Shen, G.T., Boyle, E.A. (1987). Lead in corals: reconstruction of historical industrial fluxes to the surface ocean. Earth Planet Sci. Lett., 82, 289-304.
• Shen, G.T., Boyle, E.A. (1988). Determination of lead, cadmium and other trace metals in annually banded corals. Chemical Geology 67, 47-62.
• Shen, G.T., Cole, J.E., Lea, D.W., Limm, L.J., McConnaughey, T.A., Fairbanks, R.G. (1992). Surface ocean variability at Galapagos from 1936-1982: Calibration of geochemical tracers in corals. Palaeoceanography, 7, 563-588.
• Sholkovitz, E., Shen, G.T. (1995). The incorporation of rare earth elements in modern corals. Geochim. Cosmochim.Acta, 59, 2749-2756.
• Soegiarto, A. (2000). Pollution management and mitigation in the Straits of Malacca: priorities, uncertainties and decision making. In: Shariff, M., Yusoff, F.M., Gopinath, N., Ibrahim, H.M., Nik Mustapha, R.A. (Eds.) Towards Sustainable Management of the Straits of Malacca. Malacca Straits Research and Development Studies, University Putra Malaysia. Malaysia, 503-518.
• Stoll, H.M., Schrag, D.P. (1998). Effects of Quaternary sea level cycles on strontium in seawater. Geochim. Cosmochim. Acta, 62, 1107-1118.
• Toda, T., Okashita, T., Maekawa, T., Alfian, B.A.A.K., Rajuddin, M.K.M., Nakajima, R., Chen, W., Takahashi, K.T., Othman, B.H.R., Terazaki, M. (2007). Community Structures of Coral Reefs around Peninsular Malaysia. Journal of Oceanography, 63, 113-123.

© Copyright 2009 - Graduate Faculty of Environment University of Tehran

The following images related to this document are available:

Photo images