The effect of ambient mercury on growth, food conversion and haematological parameters on the African freshwater cichild, oreochromis niloticus

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Date
2015
Journal Title
Journal ISSN
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Publisher
University of Dar es Salaam
Abstract
The effects of ambient HgCl2 on haematological parameters, Hg bioaccumulation and growth in the freshwater cichlid, Oreochromis niloticus were investigated. Ambient HgCl2 affected fish during the 35 days exposure period. On day 2, O. niloticus exposed to 100μg Hg/l concentration showed irregular erratic swimming, frequent surfacing and rapid opercula movement. The highest accumulation of Hg was found in the gills compared to muscles. A significant decline of RBC was evident on day 2 in fish exposed to 100 µg Hg/l. On days 14, 21 and 28, the RBC had significantly decreased (p<0.01) in fish exposed to 10, 50 and 100 µg Hg/l. With prolonged exposure the study showed that there was a significant decrease in Hb on days 21 (p<0.001), 28 and 35 (p<0.05) in fish exposed to 100 µg Hg/l. Furthermore, a significant decrease (p<0.01) of PCV on days 14 and 21 in fish exposed to 100 µg/l ambient Hg was apparent. On days 28 and 35, a significant decrease (p<0.05) in MCHC occurred in fish exposed to 50 and 100 µg Hg/l. The MCH values of exposed fish were observed to increase significantly on day 2 (p<0.01) followed by a significant decrease on day 21 (p<0.05) in fish exposed to 100 µg Hg/l. On day 2 there was a significant increase (p<0.01) in the MCV in fish exposed to 100 µg Hg/l. A significant decrease in the feeding rates were observed in fish exposed to 100 µg Hg/l on days 28 and 35 (p<0.05). A significant decrease in the absorption rates was observed on days 28 and 35 only in fish exposed to 100 µg Hg/l (p<0.05. Fish exposed to 10, 50 and 100 µg Hg/l showed a significant decrease in growth rates on days 21, 28 and 35 (p<0.01). It is recommended that a prolonged study on adaptive physiological mechanisms and reproduction should be carried out.
Description
Available in print form, East Africana Collection, Dr. Wilbert Chagula Library, Class mark (THS EAF TD 427.M4P34)
Keywords
Mercury, Environmental aspects, Aquatic organisms, Effect of water pollution on
Citation
Palapala, F. M. (2015) The effect of ambient mercury on growth, food conversion and haematological parameters on the African freshwater cichild, oreochromis niloticus, Master dissertation, University of Dar es Salaam, Dar es Salaam