SENSITIVITAS Nitzschia sp TERHADAP TEMBAGA DAN KADMIUM

The use of representative test organism with the tested material is absolutely critical factor in a bioassay. Various tropical test organism has been widely used in Indonesia such as fish, sea urchins, fish and phytoplankton. Phytoplanktons such as Chaetoceros gracilis, Tetraselmis sp., Isochrysis sp., Pavlova sp., live in the water column have been well documented. However, benthic phytoplankton such as Nitszchia sp. not widely known. This paper aims to examine the potential of Nitzschia sp. as a sediment bioassay test biota. Parameters studied were growth curve and sensitivity to cadmium and copper. The results showed that the growth of Nitszchia sp. increased rapidly on the fourth day until the sixth day. After the sixth day, the growth tends to decrease. Sensitivity to toxicants was indicated by IC50 (Inhibition Concentration) value of 0.078 for copper and 0.26 mg / L for cadmium. The conclusion of this study is, Nitszchia sp. can be used as test organims for sediment bioassays because they meet the minimum density requirements as well as are sensitive to cadmium and copper toxicants.