Stomach Content Analysis Of Chrysichthys Nigrodigitatus (Lacepède, 1803) Of The Lagos Lagoon Nigeria With Respect To Microphyto Benthos
Jeyol, M’ember Catherine
Department of Biological Sciences, Federal University Wukari
Umar, Nuvalga Jacob
Department of Marine Sciences, University of Lagos
Keywords: Blue-green algae, Chrysichthys nigrodigitatus, Diatoms, Food items, Lagos lagoon, Stomach contents
Abstract
Stomach content analysis provides important insight into fish feeding patterns, accurate description of fish diets and feeding habits and also provides the basic for understanding trophic interactions in aquatic food webs. The aim is to ascertain the type of food consumed by macrobenthic fauna in the marine ecosystem and to identify the sediment composition of the microphyto benthos species that constitute their natural feed component in the Lagos Lagoon. The diet of 200 specimens of Chrysichthys nigrodigitatus were investigated in the Lagos Lagoon, Nigeria from September 2015 to December 2015 by the numerical and occurrence methods using Malian traps set over night. Triplicate sediment samples were collected in September, October, November and December 2015 using a Van Veen grab and the microphyto benthos species were identified microscopically. Results revealed that the highest numbers of empty stomachs were observed in September 2015. Ten categories of food items were identified in C. nigrodigitatus which are; Leaves, fibres, Crab parts, shells, scales, bones, worms, insect parts and micro algae. Blue-green algae and Diatom were the two major groups of microphytobenthos taxa identified in C. nigrodigitatus. The microphytobenthic taxa identified includes Blue-green algae (Anabaena sp., Aphanocapsa sp., Mycrocystis sp.) and Diatoms (Navicula sp., Cyclotella sp., Synedra sp., Nitzschia sp. The result also showed that the stomach content of C. nigrodigitatus has many microphytobenthic taxa both by occurrence and abundance. Their opportunistic omnivore feeding mechanism which is passive feeding mechanism gives the species wider prey abundance. Hence microphytobenthos are important food source for benthic fauna.