Now showing items 1-3 of 3

    • Conference paper

      Acute toxicity of mercury to Oreochromis niloticus fingerlings 

      MLA Cuvin-Aralar - BIOTROP Special Publication, 1991 - SEAMEO BIOTROP
      Fingerlings of Oreochromis niloticus were exposed to the following mercury (as HgCl2) concentrations: 0.005, 0.01, 0.02, 0.03, 0.04, 0.05 and 0.06 mg l-1 Hg of water. Hyperactivity and erratic swimming were the first indications of mercury intoxication. Scoliosis, a curvature in the mid-trunk region, was observed in some fish in the 0.03 - 0.06 mg l-1 Hg tanks. The occurrence of scoliosis is significantly correlated with mercury concentration. The 24 hour LC50 (0.0375 mg l-1 Hg) did not differ significantly with the 96 hour LC50 (0.0350 mg l-1 Hg).
    • Article

      Effects of long-term exposure to a mixture of cadmium, zinc, and inorganic mercury on two strains of tilapia Oreochromis niloticus (L.) 

      MLA Cuvin-Aralar & EV Aralar - Bulletin of Environmental Contamination and Toxicology, 1993 - Springer Verlag
      Tilapia are an economically important group of fish. They have a short generation period of 3-6 months, and exhibit successive breeding. In addition, their fast growth, herbivorous or omnivorous feeding habits, high food conversion efficiency, ease of spawning, ease of handling, resistance to disease and good consumer acceptance make this group of fish highly popular in aquaculture in Asia, Africa and other developing countries. Tilapia have been the subject of research on pollution effects over the last decade. The purpose of this study was to determine growth, accumulation and depuration responses of 2 strains of the Nile tilapia, Oreochromis niloticus, chronically exposed to a mixture of heavy metals including cadmium, zinc and mercury.
    • Article

      Survival and heavy metal accumulation of two Oreochromis niloticus (L.) strains exposed to mixtures of zinc, cadmium and mercury 

      MLA Cuvin-Aralar - Science of the Total Environment, 1994 - Elsevier
      Two Nile tilapia strains of Oreochromis niloticus (L.) (Cichlidae, Teleostei) fingerlings were exposed to mixtures of zinc, cadmium and mercury. The two strains used were Chitralada or NIFI (originally from the National Inland Fisheries Institute, Thailand) and CLSU (from the Freshwater Aquaculture Center of the Central Luzon State University, The Philippines). Short-term (10 days) exposure to a metal mixture of 5 mg 1−1 zinc (Zn), 0.5 mg 1−1 cadmium (Cd) and 0.02 mg l−1 mercury (Hg) gave significantly higher survival percentage in the NIFI strain compared with the CLSU strain. Similar exposure conditions using larger and older fingerlings of the two strains also showed a slightly higher survival percentage in the NIFI strain but the difference was not significant. Prolonged exposure of the fingerlings to a lower concentration of the metal mixture (1.0 mg l−1 Zn, 0.1 mg l−1 Cd, 0.01 mg l−1 Hg) also resulted in similar survival percentages between the two strains at the end of the 60 days run. Whole body accumulation of Zn was significantly higher in CLSU than in NIFI after 14-day exposure to the low concentration metal mixture. There was no significant difference in the accumulation of Cd and Hg between the two strains. Of the three metals, Hg had the highest bioaccumulation factor (BF) which was ∼900–1000, followed by Cd with 255–280 and Zn with 180–195 times the nominal concentration in the water. Concentration of Cd and Hg in fish tissues increased with exposure period while the concentration of Zn was maintained in NIFI and decreased in CLSU between the 6th and 14th day of exposure, suggesting that Zn (an essential element) accumulation maybe regulated by both strains.