Diversity and Spatial Distribution of Crabs in the Intertidal mudflat of Cross River Estuary Mangrove Swamp, Southeastern, Nigeria.

摘要

An investigation on Diversity and Spatial distribution of crabs in the intertidal mudflat of Cross River Estuary mangrove swamp, southeastern, Nigeria was carried out at three different stations (Inua abasi, Jamestown and Oron) between January and July, 2015. From the study it is revealed that the crab species were wide spread and abundant in the mangrove swamp. Five species of crab were identify during the study which include; Pachygrapsus gracilis , Uca tangeri , Sersama species and Callinectes amnicola . Crabs abundance was generally high at low tide and mid tide levels, and less at high tide levels, which explain the feeding and burrowing habits of the different crab species. Pachygrapsus gracilis were present in high numerical abundance during the study period with low numerical abundance recorded for Callinectes amnicola which was attributed to variation in salinity and temperature of the mangrove swamp during the study period. There was significant variation (P0.05) in distribution of crab species in the three stations of Cross River Estuary mangrove Swamp but no significant variation (P0.05) in physicochemical parameters in the three stations of Cross River Estuary mangrove Swamp was observed except for salinity which show significant variation (P0.05) in the three stations. Abundance in terms of number and biomass was observed during the wet season and rise to the peak in the month of June and July. Based on the result of findings, salinity and temperature were identified as the major factor regulating the population and distribution of Mangal crab in the Cross River Estuary.