<![CDATA[Sampah domestik, aktivitas industri, dan proses pertanian berkontribusi terhadap cemaran logam berat seperti Pb, Cd dan Hg di perairan Sungai Kaligarang. Cemaran logam berat menimbulkan terjadinya stres oksidatif, yaitu ketidakseimbangan antara oksidan dan antioksidan. Indikator stres oksidatif adalah malondialdehida (MDA) dan enzim katalase (CAT). Penelitian ini bersifat deskriptif dengan pendekatan crossectional untuk mengetahui kandungan Pb, Cd dan Hg serta aktivitas enzim CAT dan MDA pada organ hati ikan Mas (Cyprinus carpio L.) dan ikan Nila (Oreochromis niloticus L.), yang dipelihara dalam Karamba Jaring Apung (KJA) di sungai Kaligarang, Semarang. Analisis kadar Cd, Pb dan Hg menggunakan Atomic Absorption Spectrophotometer (AAS). Aktivitas katalase dan kadar MDA ditentukan menggunakan spektrofotometer. Uji normalitas data mengunakan Shapiro-wilk (p>0,05). Perbedaan kadar Pb, Cd dan Hg antara ikan mas dan ikan nila dianalisis menggunakan uji t tidak berpasangan, dengan taraf kepercayaan 95%. Data yang diperoleh menunjukkan bahwa kadar logam berat Pb, Cd dan Hg serta kadar MDA mengalami peningkatan di dalam organ hati dari minggu ke-2, ke-4 dan ke-6. Aktivitas enzim katalase meningkat dari minggu ke-2 ke minggu ke-4 dan menurun pada mingu ke-6. Logam berat Pb, Cd dan Hg perairan berpengaruh terhadap kadar Pb, Cd dan Hg ikan nila, tetapi tidak berpenaruh terhadap Pb ikan mas. Logam berat Pb, Cd dan Hg diduga penyebab terbentuknya ROS dan berakibat timbulnya stres oksidatif. Katalase merupakan enzim antioksidan yang dapat digunakan sebagai biomarker stress oksidatif dan toksistas logam berat pada ikan air tawar, serta indikator yang sensitif terhadap cemaran perairan. Domestic waste, industrial activities, and agricultural processes contribute to heavy metal contamination such as Pb, Cd and Hg in Kaligarang river. Heavy metal contamination causes oxidative stress, which is an imbalance between oxidants and antioxidants. Indicators of oxidative stress are catalase enzymes (CAT) and malondealdehyde (MDA). This research is a descriptive crossectional approach to determine the content of Cd, Pb and Hg and the activity of catalase enzymes and malondeladehide (MDA) in goldfish (Cyprinus carpio L.) and parrot fish (Oreochromis niloticus L.), which were kept in floating net cages on the Kaligarang river. Fish which were used in this research were 2.5 months old, the weight were 19-25 grams, and the average of body length were 8-12 cm. Fish samples were 20 goldfish and 20 parrot fish. Analysis of Cd, Pb and Hg levels used Atomic Absorption Spectrophotometer. Catalase activity was determined used a spectrophotometer with 240nm wavelength. Whereas MDA determination used spectrophotometer at a wavelength of 532-534 nm. Data normality test was determined using Shapiro-wilk (p> 0.05). Differences levels of Pb, Cd and Hg between goldfish and parrot fish were analyzed using unpaired t test, with a 95% confidence level. Statistical analysis was determined using SPSS for windows 17.0. The data which was obtained showed that the levels of heavy metals Pb, Cd, Hg, and MDA experienced an increase in liver since the 2nd, 4th and 6th weeks. Catalase enzyme activities increased from 2nd until 4th week and decreased in 6th week. Heavy metals of Pb, Cd and Hg affect the levels of Pb, Cd and Hg of parrot fish, but didnot not affect in goldfish. Heavy metals of Pb, Cd and Hg are thought to be the cause of ROS formation and result in oxidative stress. Catalase is an antioxidant enzyme that can be used as a biomarker of oxidative stress and heavy metal toxicity in freshwater fish, as well as sensitive indicators in water contamination.]]>
