The effect of physico-chemical parameters on the recruitment pattern of Uca tangeri in Mbo River, Nigeria

Abstract

The effect of physico-chemical parameters of the Mbo River of the recruitment pattern of the West African Fiddler Crab (Uca tangeri) was conducted over a period of twelve months (April 2012 – March 2013). Values of all physicochemical parameters were taken in-situ, using the standard scientific equipment. The crabs were collected with the assistance of fishers using artisanal baited pots, traps and hands (manual) to pick and dislodge them from their nests. Length-frequency data was analyzed using Shepherd’s method incorporated in FISAT software. Monthly variation in dissolved oxygen ranged from 6.1 to 8.6mg/l, pH ranged from 6.7 to 7.5, salinity from 0.5 to 1.0ppt and 27⁰C to 34⁰C for temperature. Monthly variation in the values of dissolved oxygen and temperature were significant (P<0.05). The recruitment pattern of the crab Uca tangeri in Mbo river of Akwa Ibom State, Nigeria, with asymptotic length (L∞) 3.99cm at Von Bertalanffy Growth Function (VBGF) K = 0.10 showed greater recruitment in the dry season from November to April, which coincided with a period of higher salinity and dissolved oxygen, pH and temperature in Mbo River. The physico-chemical variables of the River fell within acceptable limits for the growth and recruitment of crustacean including U. tangeri.