Vol. 2, Issue 1 (2017)
Effects of Water hyacinth (Eichhornia crassipes Solm) infestation on water quality, fish diversity and abundance in the Nyanza Gulf Lake Victoria
Author(s): *Edwine Yongo, Nicholas Outa, Steve Omari Ngodhe
Abstract: The present study compared two stations; hyacinth infested and non-infested areas. The mean (± SD) water temperature of the infested and non-infested areas were 25.60±4.390C and 24.62±4.940C respectively. Dissolved oxygen 2.44±1.14 mgl-1 of the infested area was significantly lower than non-infested (4.24±0.96 mg l-1) (p<0.05). The mean pH of infested and non-infested areas were 6.05±1.04 and 7.62±0.42 respectively. The lowest (6.97±01.83 mg l-1) nitrate was recorded in infested and the highest (11.34±1.46 mg l-1) in non-infested areas. Infested station had high fish diversity (2.00) and evenness (0.93). In the infested area, Protopterus aethiopicus (35%) had the highest abundance, followed by Clarias gariepinus (28%), while in the non-infested, Lates niloticus had the highest abundance (23%) followed by Oreochromis niloticus (18%). The abundance of haplochromines, C. gariepinus and P. aethiopicus in the infested area is attributed to their ability to tolerate low oxygen levels. The L. niloticus and Rastrineobola argentea are sensitive to low oxygen.
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