COMPARATIVE ASSESSMENT OF THE MACROBENTHIC FAUNA DIVERSITY AND HEAVY METALS BIOACCUMULATION IN CANAL, OGBE CREEK AND ABULE-AGEGE CREEK IN AKOKA, LAGOS. NIGERIA.

The comparative study of the heavy metal accumulation and the biodiversity of macro-benthic fauna of Ogbe creek, Abule-agege creek and University of Lagos (Unilag) canal (Second Gate) were investigated. Sampling of macro-invertebrates were carried out in each station using a sweep net, all samples were grouped, identified, counted and recorded. Water, sediment and macro-invertebrate samples were taken and analyzed for heavy metals; Cadmium (Cd), Lead (Pb), Zinc (Zn), Nitrate (NO3 2-) and Phosphate (PO3 2-). Unilag canal (second gate) recorded the highest physico-chemical parameters (Temperature 28.110oC ± 30.870oC; Turbidity 37.700 ± 21.000 NTU; Total Dissolved Solids 0.135 ± 1.730mg/l; Ph 6.470±7.180 and Salinity 0.120 ±0.200g/kg) while Ogbe creek recorded the highest dissolved oxygen (14.730±46.700mg/L). The highest concentrations of heavy metals were recorded in Unilag canal (second gate) followed by Abule-agege creek, while Ogbe creek recorded the least. Assessment of macro-benthic fauna in these locations recorded a total of 17 taxa and 356 individuals. Ogbe creek had the highest diversity of macro-benthic organisms comprising of 8 taxa mostly Insects, Abule-agege creek recorded 3 taxa (mainly Decapoda) while Unilag canal (second gate) had only Chordates (Poecilia reticulata). The species diversity indicated by Margalef's and Shaanon weiner's indices respectively were both highest in November due to the increase in the number of species. The rate of bioaccumulation of heavy metals (Cd, Pb, Zn, Nitrate and Phosphate) in Ogbe creek assessed in Penaeus sp, Gyrinus and Physa sp was higher in Physa sp compared to the others. Zinc had the highest concentration while lead had the least in all the organisms. Given the importance of macro-invertebrates in the aquatic ecosystem food chains, which later serve as food for humans, there is need to protect the quality of these water bodies from direct discharge and run offs form urban settlements. [ABSTRACT FROM AUTHOR]