The role of Yssichromis species (Pisces: Cichlidae) in the trophic ecology and foodwebs of Lake Victoria

Many haplochromine cichlids coexisted in Lake Victoria before the upsurge of Nileperch. The introduction of the Nile perch led to depletion of many haplochromines andother fish species in Lake Victoria. The impact of Nile perch predation onhaplochromines differed for different haplochromine trophic groups. Yssichromisfusiformis (G) and Yssichromis laparogramma (G) are among the species that havesurvived in the lake. Yssichromis spp. was studied with the aim of determining theirtrophic role, food and feeding habits. Samples were collected from Bugaia, Buvumachannel and Napoleon Gulf in the northern part of Lake Victoria. The food ofYssichromis spp. varied with size of fish. Both Y fusiformis and Y laparogramma fed onCopepods, Cladocerans, Chaoborus and Chironomids. Juvenile Yssichromis spp. fedexclusively on zooplankton comprising Cyclopoid copepods, Calanoid copepods andCladocera. The relative importance of Chironomid larvae and Calanoid copepods washigher in Bugaia than in Buvuma channel while Cyclopoid copepods and Chironomidpupae were relatively less important in Bugaia. The main food items that Yssichromisspp. fed on in Buvuma channel were Chironomid larvae Cyclopoid copepods,Cladocerans and Calanoid copepods. In Napoleon Gulf, fish caught from commercialfishery of Rastrineobola argentea (P) had fed on Chaoborus and Chironomids. Overall,Yssichromis spp. fed on more zooplankton in Buvuma than in Bugaia. Yssichromis spp.and R. argentea are presently the most abundant zooplanktivores in the northern part ofLake Victoria and are playing an important trophic role as major consumers ofzooplankton and insect larvae in the foodweb of the lake ecosystem. Yssichromis spp. arebridging the transfer of energy from the lower to the higher trophic levels as secondaryconsumers. The fishery is still not contributing to the direct conversion of the primaryproducts, the phytoplankton and detritus that were efficiently utilised by the diversehaplochromine trophic groups that existed before the Nile perch boom.

Bibliographic Details

Main Authors:	Ebong, I., Wandera, S.B., Ogutu-Ohwayo, R.
Format:	book_section biblioteca
Language:	English
Published:	Fisheries Research Institute 2000
Subjects:	Fisheries,
Online Access:	http://hdl.handle.net/1834/35233
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