Impact of water quality on seagrass meadow at Tanjung Kupang

Abstract

Seagrasses which colonize near shore ecosystem may be used as indicator of environmental health since it is vulnerable to the changes of water and environmental quality. Six species of seagrasses were found at Tanjung Kupang, Johor which are identified as Halophila ovalis, Halophila minor, Halophila spinulosa, Enhalus acoroides, Halodule pinifolia and Thalassia hemprichii. Meanwhile three species were found at Teluk Buih, Mersing identified as Enhalus acoroides, Halodule pinifolia and Cymodocea rotundata. Heavy metals (As, Cd, Cr, Cu, Pb and Hg) were analyzed using ICPMS and Halophila minor have the highest accumulation of heavy metal among the species. Thalassia hemprichii turned out to be strongest accumulator for Cd (0.016 mg/g dry weight) and Halophila ovalis for Hg (0.044 mg/g dry weight). The results obtained for water quality analysis exceeded the Interim Marine Water Quality Standard except for Pb (0.0014 to 0.0066 mg/L) and Total Cr (0.1486 to 0.105 mg/L). Dredging activities for land reclamation could be a possible release of heavy metals to the seawater since the concentration of heavy metal decrease in the following order: sediment > water > seagrass leaves. Therefore, Halophila minor has the potential to be used as bioindicator since it accumulates higher concentration of heavy metal compared to other species. Two rivers, Sungai Pok Besar and Sungai Pok Kecil, situated near the seagrass bed is classified as Class III based on Water Quality Index.