Observations on some aspects of the biology of Sudanonautes aubryi (H. Milne Edward,1886) (Crustacea: brachyura: potamoidea: potamonautidae) in Orogodo River, Niger Delta, Nigeria

Abstract

Investigation into some aspects of the ecology of the amphibious freshwater crab, Sudanonautes aubryi (H. Milne Edwards, 1886) in Orogodo River at Abavo, Southern-Nigeria was carried out between March and August, 1995. The study revealed that the crab species is wide spread and abundant in the river. There was a seasonal trend in the level of abundance both in number and biomass. The crab showed more abundance at the peak of the rainy season (August). Both adults and juveniles showed a progressive increase from late dry season to mid-rainy season (August). The male–female ratio was 1:1.2. The fluctuation in the number and percentage of gravid females indicated that the crab spawned during the mid-rainy season (June–August). The crab attained a maximum total length and weight of 8.4cm and 89.09g respectively. Its growth pattern was isometric. The mean monthly condition factor (k) ranged from 17.15 to 23.52 and generally showed a monthly fluctuation with a peak in April.

Keywords: sudanonautes aubryi, biomass, gravid, Orogodo River, condition factor

Tropical Freshwater Biology 2003/2004 Vol. 12/13: 105-118