Browsing by Author "Balirwa, John Stephen"

Now showing 1 - 1 of 1
  • No Thumbnail Available
    Item
    Ecological separation in Barbus species in Lake Victoria
    (University of Dar es Salaam, 1984) Balirwa, John Stephen
    In a field study carried out in various parts of the Lake Victoria basin, 14 species of Barbus were recorded. Field and laboratory investigations revealed various levels of ecological separation between the species: A survey of various habitats indicated that environment (whether lacustrine or riverine), nature of the bottom, depth and exposure influenced the species distribution in lacustrine and riverine areas. A majority of the species were found to occur in shallow inshore and riverine areas. Barbus profundus and B. altianalis were the two most common Barbus in deeper water. Gut analyses indicated that for the most part the species are omnivorous and opportunistic in feeding habit. Differences in feedings patterns were reflected mainly in the varying relative importance of different food categories in different species. Prey availability appeared to be a major factor influencing diet in the species. Fish from riverine areas relied heavily on higher plant material, Ephemeroptera, chironomids and detritus. Molluscs, crustaceans, chironomids, Chaoborus and algae were the most important food categories utilised by fish in the lake. In B, profundus, extreme reliance on Chaoborus seemed to indicate specialization. The type of food ingested was shown to be related to the size of fish in B. altianalis and B, paludinosus. Seasonal and short term differences in feeding appeared to be minimal However, data did not give a complete picture of the effect of seasonal and diurnal changes on feeding habits in the species. These studies in conjunction with previous work on the reproductive biology of the species seem to indicate that apart from Barbus profundus other Barbus species have not progressed far towards becoming fully adapted to lacustrine conditions.