The Biology of the Hairy Mangrove Crab Sesarma huzardii from Lagos Lagoon, Nigeria

Abstract

Some aspect of biology of the hairy mangrove crab Sesarma huzardii was studied. A total of five hundred and one (501) samples of Sesarma huzardii were collected from the mangrove swamp of Lagos lagoon front. Samples were examined for a period of six months (March, 2012 to August, 2012). The growth pattern, food and feeding habits, condition factor, sex ratio and reproduction biology of the crab were investigated. The summary of the length-weight relationship showed Log W= Log 0.6932 + 0.8787 Log L(n = 501, r = 0.4665) which reveals a negative allometric growth. Stomach content reveals S. huzardii to be an opportunistic omnivore as stomach content showed the presence of algae filament (34.8%), Nitzschia lineris (26.5%). Navicula cuspidate was the most abundant with 36.9%. The least abundant was Oscillatoria limnosa 1.6% by numerical method and by the frequency of occurrence, Navicula cusipadate also constituted the most abundant food items with 1.31%, Nitzschia  linearis with 0.69%, algae filament  was 0.93 and Oscillatoria limnosa was 0.22%.  The sex ratio was 1:0.38 as the males were twice the number of females. Result for condition factor was 3.79 for both sexes and from the investigation they where three female that were ovigerous out of 501 samples analyzed. Sersama huzardii was more abundant from March to May and a decline in abundance from June to August. Generally, the analyses of Sesarma huzardii reported in this study are within normal limits.

Keywords: Sesarma huzardii, growth pattern, food and feeding habit.