Masalah pencemaran sumber air tawar dan kesan ketoksikan logam telah mendapat perhatian di serata negara. Dua
spesies organisma air tawar daripada filum moluska Filopaludina sumatrensis dan Corbicula fluminea didedahkan
kepada tiga logam terpilih iaitu arsenik (As) kromium (Cr) dan selenium (Se) pada kepekatan berbeza selama 96 jam di
dalam makmal terkawal. Kadar kematian dinilai serta kepekatan kematian median (LC50) dan masa kematian median
(LT50) dihitung. Nilai LC50 dan LT50 didapati menurun dengan pertambahan masa dan kepekatan pendedahan bagi
kedua-dua spesies dan kesemua logam. Keputusan daripada kajian ini memperlihatkan ketoksikan logam As, Cr dan Se
semakin meningkat dengan peningkatan kepekatan dan masa pendedahan logam kepada F. sumatrensis dan C. fluminea.
Nilai LC50 96 jam As, Cr dan Se bagi F. sumatrensis adalah 4.22, 3.78 dan 45.92 mg/L dan 11.84, 2.23 dan 35.63 mg/L
masing-masing bagi C. fluminea. Keputusan menunjukkan Cr adalah logam paling toksik terhadap F. sumatrensis dan
C. fluminea. Trend ketoksikan logam bagi kedua-dua moluska ini adalah sama iaitu Cr > As > Se.
Water quality analysis of the seven feeder rivers in Tasik Chini was carried out from October 2004 to December 2005. A total of nine sampling sites were selected in this study, namely: Sungai Datang (St.1), Sungai Cenahan (St. 2), downstream of Sungai Gumum (St. 3), mid of Sungai Gumum (St. 4), Sungai Kura-kura (St. 5), Sungai Melai (St. 6), Sungai Jemberau (St. 7), upstream of Sungai Paya Merupuk (St. 8), and downstream of Sungai Paya Merupuk (St. 9). Eleven water quality parameters were selected and analyzed in-situ and ex-situ during two sampling seasons. Laboratory analyses were carried out according to the HACH and APHA. Results of the study indicated that the pH content ranged from 3.2 to 6.32, dissolved oxygen 0.27 to 6.4 mg/L, conductivity from 14.33 to 85.7 µS/cm and temperature from 24.1 to 32.1˚C. Total dissolved solids ranged from 22.67 to 184 mg/L, total suspended solids from 1.17 to 79.11 mg/L and turbidity from 4.67 to 28.67 NTU. Nutrients such as ammonical nitrogen (0.01 to 0.57 mg/L), nitrate (0.7 to 2.9 mg/L), phosphate (from not detectable to 0.50 mg/L) and sulphate (from not detectable to 2.0 mg/L) were also studied. This showed that most of the feeder rivers have contributed to high nutrients values in Tasik Chini. Statistically, the relationship between water quality parameters were correlated as very weak and moderately correlated (R2= 0.40). Phosphate and sulphate were significantly correlated as positive slope; turbidity and nitrate showed negative slope with discharge during both the seasons (R2=0.651; R2=0.624). Recent activities such as deforestation, mining, agriculture and tourism have taken place in the surrounding areas of the lake. These activities were expected to influence the stability of the water quality of the feeder river of Tasik Chini.
Kajian kepelbagaian dan penyebaran ikan di Tasik Chini telah dijalankan menggunakan jaring insang sebagai alat penangkapan. Sebanyak lapan stesen pensampelan telah dipilih (habitat berbeza) di seluruh tasik dan pensampelan telah dilakukan secara rawak di kawasan yang terpilih. Sejumlah 24 spesies ikan telah direkodkan yang terdiri daripada 944 ekor ikan. Kebanyakan ikan yang direkodkan adalah terdiri daripada famili Cyprinidae. Spesies dominan yang ditemui di Tasik Chini ialah loma (Thynnichthys thynnoides), cemperas (Cyclocheilichythys apogon) dan potok (Notopterus notopterus). Hasil ujian t-berpasangan menunjukkan terdapat perbezaan bermakna kepadatan ikan yang ditangkap di antara waktu siang dan waktu malam (p = 0.01, α = 0.05) dan spesies pemangsa didapati paling dominan pada waktu malam. Kepelbagaian dan kepadatan ikan didapati lebih tinggi semasa pensampelan musim monsun yang dipercayai kesan daripada kemasukan ikan-ikan dari Sungai Pahang melalui Sungai Chini.
This study attempts to assess the impact of various types of land use along Sungai Langat and describes hydrological
change and water quality variation along this river. This study also determines water quality of Sungai Langat based on
low flow dry period Q100,7 using the application of QUAL2K. Dissolved oxygen (DO), pH, temperature and conductivity
were measured in situ. Biochemical oxygen demand (BOD5
), ammonia nitrogen (NH3
-N) and total suspended solid (TSS)
were analysed according to the standard methods (APHA). Water quality data was referred to National Water Quality
Standards for Malaysia (NWQS) proposed by Malaysian Department of Environment (DOE) to estimate Sungai Langat
water quality status. Four important water quality parameters namely DO, BOD5, NH3
-N and TSS were simulated with
QUAL2K version 2.07 for 83.67 km. As regard to individual parameter, DO classified this river into class III, BOD5 in
Class II, NH3
-N in Class IV and TSS in Class I. Based on QUAL2K simulation for low flow scenario, the results clearly
demonstrates a gradually reduction of DO and BOD5 whereas NH3
-N and TSS display opposite. Only NH3
-N was found
significantly increase which cause low water quality class towards the downstream. Three parameters namely DO, BOD5
and NH3
-N show effects of industrial which approximately located at the middle of river stretch. The TSS was contributed
to the river system at the upstream and downstream of the river stretch which most likely from sand mining activity which
located at Sungai Long, Cheras (near R5) and Sungai Semenyih (R11).
Tiga spesies ikan air tawar iaitu Rasbora sumatrana (Cyprinidae), Poecilia reticulata (guppy; Poeciliidae) dan Carrasius
auratus telah didedahkan kepada kromium (Cr) dan selenium (Se) yang mempunyai julat kepekatan yang berbeza selama
4 hari (96 jam) di dalam makmal. Kadar kematian dicatatkan dan kepekatan kematian ambang (LC50) dan masa kematian
ambang (LT50) dihitung. Nilai LC50 kepekatan kematian median (LC50) dan masa kematian median (LT50) didapati
berkurang dengan peningkatan kepekatan logam dan masa pendedahan bagi kesemua spesies ikan. Nilai LC50 bagi
pendedahan selama 96 jam bagi R. sumatrana, P. reticulata dan C. auratus kajian ini masing-masing bagi Cr adalah
20.91, 19.85, 28.31 mg/L dan bagi Se pula 0.21, 3.03, 0.24 mg/L. Se mempamerkan ketoksikan paling tinggi terhadap
tiga spesies ikan air tawar ini apabila mempunyai nilai LC50 96 jam paling rendah jika dibandingkan dengan Cr.
Fish biodiversity in Malaysia is under pressure due to overexploitation, pollution, and climatic stressors. Nevertheless, the information on fish biodiversity and species vulnerability status is not well documented in the region. Therefore, a study on fish species composition and abundance in the Malacca Strait of Malaysia has been conducted for the purpose of monitoring biodiversity, determining the risk of species extinction, and identifying factors influencing biodiversity distribution. The sampling was conducted based on a random stratified sampling method from the three zones of sampling locations, i.e., estuary, mangrove, and open sea area of Tanjung Karang and Port Klang of Malacca Strait. Higher species diversity was recorded at Tanjung Karang coastal and mangrove areas (H' = 2.71; H' = 1.64) than Port Klang coastal and mangrove areas (H' = 1.50, H' = 0.29), an indication that the Port Klang area is comparatively more vulnerable. The study also explored sampling location, habitat, and IUCN red list as the influencing factors for fish biodiversity. Applying IUCN red list, this study identified one Endangered and one Vulnerable species with the forecasted increasing landing for both species. Our findings suggest the urgent need for the implementation of conservation measures as well as the continuous monitoring of fish biodiversity in the area.