NUSANTARA BIOSCIENCE ISSN: 2087-3948 Vol. 7, No. 2, pp. 180-184 E-ISSN: 2087-3956 November 2015 DOI: 10.13057/nusbiosci/n070221 Bioaccumulation and distribution of 137 Cesium in the Humpback Grouper Fish (Cromileptes altivelis) KETY MELINDA 1,♥ , HENY SUSENO 2,♥♥ , WAHYU PRIHATINI 1 1 Department of Biology, Faculty of Mathematics and Natural Sciences, Pakuan University. Jl. Pakuan, Bogor 16143, West java, Indonesia. Tel./Fax. +62-251-8312206,  email: ketymelinda@yahoo.com, wahyu_prihatini@yahoo.co.id 2 Center for Technology of Radiation Safety and Meteorology, National Nuclear Energy Agency. Jl. Lebak Bulus Raya 49, South Jakarta, Indonesia. Tel./Fax. +62-21-7659409,  email: henis@batan.go.id Manuscript received: 12 August 2015. Revision accepted: 30 November 2015. Abstract. Melinda K, Suseno H, Prihatini W. 2015. Bioaccumulation and distribution of 137 Cesium in the Humpback Grouper Fish (Cromileptes altivelis). Nusantara Bioscience 7: 180-184. Humpback grouper fish (Cromileptes altivelis) is a highly valuable export commodity of food products. The high demand of this species needs to be supported by the intensive coastal aquaculture. However, the coastal aquaculture has been jeopardized by several threats, for an example radionuclide pollutant 137 Cesium ( 137 Cs) generated from nuclear reactor wastes. The pollutant accumulation in fish occurs because of continuing exposure to the pollutant-containing medium. This research was conducted from May to June 2015 at the Laboratory of Oceanic Radioecology, Center for Technology of Radiation Safety and Meteorology, National Nuclear Energy Agency, South Jakarta. This research observed the level of bioaccumulation and distribution of 137 Cs in C. altivelis bodies. Radionucleid 137 Cs of 2 Bq/mL concentration was inducted to two groups of fish, i.e. medium size (average body mass of 65.8 g ) and small size (average body mass of 34.7 g ). The calculation of concentration factor values at steady state (CF ss ) was done to determine the level of bioaccumulation 137 Cs in fish body. The distribution of 137 Cs in fish body was analyzed by calculating the percentage of accumulation 137 Cs in a certain organ to the total accumulation in fish body. The results showed that the value of CFss of medium size fish was 1.23 and CFss for small fish was 2.01. It means that small size fish accumulated 137 Cs almost twice as much as larger fish. The accumulation of 137 Cs in C. Altivelis was found most in its muscle (meat), which was 63.34%. This research findings provide reason for us to be more careful in consuming humpback grouper fish coming from 137 Cs polluted water due to the impact of biomagnifications of 137 Cs in fish. Keywords: Bioaccumulation, 137 Cesium, concentration factor, Cromileptes altivelis INTRODUCTION Humpback grouper fish Cromileptes altivelis is one of reef fish species in Indonesia with high economic potential for consumable fish. The demand from domestic and foreign markets has increased over years. The export selling price for C. altivelis is about US $ 45 per kilogram (Jitunews 2015). The high demand of C. altivelis cannot be met only by harvesting naturally growing fish, but it also needs to be provided through aquaculture (BBAP Situbondo 2013). Floating net method is a commonly used in C. altivelis aquaculture and one of the locations of this aquaculture is at Jakarta Bay area. The C. altivelis aquaculture in coastal area has been threatened by many things, for an example radioactive pollution of 137 Cesium ( 137 Cs). There has been a global debate about food material safety, including the safety level for radioactive exposure. In Japan, the safety level for 137 Cs contained in fish is 600 Bq/kg and in Europe, it is 1250 Bq/kg. However, in Codex Guideline Level, the standard for 137 Cs contamination in food is 1000 Bq/kg (Codex 2011). The nuclear related research activities in Serpong Nuclear Area (SNA) potentially release products of fission reaction, including 137 Cs, to the environment. This release is commonly airborne which eventually will be deposited at soil and water. The SNA’s neighbouring Cisadane River, ending up in Jakarta Bay, has probably been exposed to 137 Cs. This radioactive may then be accumulated in bodies of animal species in that ecosystem (Suseno 2013). C. altivelis is a predatory fish which might accumulate heavy metals due to biomagnification along the food chain. Heavy metals cannot be destroyed during metabolism. Therefore, when heavy metal contaminated fish is eaten by bigger predatory fish, the metal will be accumulated inside predatory fish bodies. Heavy metal accumulation occurs since there is a continuing contact between fish and the polluted medium. Heavy metals enter fish bodies via three ways, i.e. food, gill and diffusion on skin surface (Sahetapy 2011). Suseno (2013) studied bioaccumulation of 137 Cs in fresh water snail (Pila ampullacea) and found that concentration factor of 137 Cs in P. ampullacea was 13.2 – 27.6 mL/g. The level of accumulation in P. ampullacea was influenced by its body mass but it was not dictated by water pH. Malek et al. (2004) reported that in fish species of Silurus asotus, 75% 137 Cs accumulation was found in its muscle and the accumulation level was higher in juvenile than in adult individuals. The same pattern was also found in fish species of Oncorhynchus mykiss (Baudin et al. 2000).