Notes on the biology and ecology of sudanonautes floweri(de man, 1901; crustacea: brachyura: potamoidea: potamonautidae) in river ogbomwen, southern nigeria

Investigation into some aspects of the biology and ecology of the freshwater crab, Sudanonautes floweri(De Man, 1901) in River Ogbomwen, Edo State, southern, Nigeria was carried out between February and July 2006. The study revealed that the crab species were widespread and abundant in the river. Abundance in terms of number and biomass was more during the wet season with at a peak in the months of June and July. The crab grew allometrically attaining a maximum total length and weight of 11.5 cm and 65 g respectively. The condition factor ranged from 8.60-9.45. These values did not vary with size and sex of the crab but showed seasonal variations. Females of Sudanonautes floweriwere more abundant although not significantly different from the expected 1:1 ratio. There were some sexually matured females with stages III gonad development. Fecundity estimate ranged from 400 to 650 eggs. The gonadosomatic index varied between 14.97 and 24.11%. Feeding habits varied slightly with size with larger sized crabs feeding on more and varied food particles. Generally, Sudanonautes flowerifed predominantly on detritus, crustaceans, fish, algae, filaments, diatoms and sand grains