Sex Ratio of Purple Lagoon Crabs Goniopsis Pelii (Herklots, 1851) From the Lagos Lagoon - Nigeria

Abstract

The sex ratio of the mangrove crab, Goniopsis pelii was studied in Lagos lagoon southwest Nigeria, from February to July 2012. The crab species was sorted in sexes. The research is to provide a base line data on the percentage of male and female species of Goniopsis pelii. The product of the investigation shows that the number of females was found to be more abundant than the males in the study which implies that the lagoon is a breeding ground for crabs. The   highest number of female crabs was proof for the month of May (39) followed by April and July (37), then February (36), June (34) and March (24). While the male was most profuse for the month March (36) followed by June (26), then February (24), April and July (23) and May (21). The sex ratio was high despite the polluted nature of the site. The calculated Chi-square (X²) test shows that female Goniopsis pelii were significantly more abundant than the male (P ≤ 0.05). The total number of male crabs is 169 while the female crabs are 191. The ratio for the male to female Goniopsis pelii is 1:1.

Keywords: Lagoon crab, Sex ratio, Lagos, Goniopsis pelii.