Cadmium and lead levels in some fish species from Azuabie creek in the Bonny Esturary, Nigeria

The concentrations of cadmium and lead were determined in seven fish species from the Azuabie creek in the upper Bonny estuary of the Niger Delta, which is associated with industrial and abattoir discharges. Cadmium concentrations ranged from 0.01 to 0.06 mg/kg and show no significant difference between species. The concentrations of lead (ranging from 0.104 to 0.310 mg/kg) were significantly higher in Chrysichthys nigrodigitatus and Gobius niger than other species examined. Also,lead was significantly higher than cadmium. The metal concentrations obtained were within values that may be considered safe for human consumption

Accumulation of heavy metals from single and mixed metal solutions by the gastropod mollusc Tympanotonus fuscatus linnaeus from a Niger Delta estuary: Implications for biomonitoring

The usefulness of the intertidal gastropod Tympanotonus fuscatus L as a biomonitor of heavy metals in tropical estuaries was assessed. The periwinkles were collected from a site in the upper Bonny Estuary, Southern Nigeria and exposed in a series of experiments either singly or binary mixtures to copper, zinc and cadmium. The accumulation of Cd was monotonic with increase in exposure concentration with a highly significant linear regression (r2 = 0.999, pZn>Cd but those for Cu and Zn showed reduction as the exposure concentration increased suggesting regulation of these metals. In accumulation from binary mixtures, Cu was synergistic to Cdaccumulation in combinations involving 0.05 mg/L Cu but antagonistic for 0.5 and 1.0 mg/L Cu combinations. Zn was antagonistic to Cd accumulation in mixtures with 0.05 and 1.0 mg/L Zn. Cd didnot show any effect on Zn accumulation in any of the mixtures but it was antagonistic to Cu accumulation in some combinations (1.0 mg/L Cu + 0.05, 1.0 mg/L Cd). It is concluded that T. fuscatusis a good candidate for the biomonitoring of Cd but not for Zn and Cu. The ambient concentrations of Cu and Zn may affect the accumulation of Cd, and need to be considered in the interpretation of Cddata in T. fuscatus

The Effects of Caging on the Colonization of Fouling Organisms in the Upper Bonny Estuary

The effects of caging on the colonization and development of the fouling community in the upper Bonny estuary was studied. The experimental design was such that sets of wooden panels (20x20 cm) were screened with cages constructed with plastic netting while another set was left uncaged. Both sets of panels were submerged below low tide level and sampled fortnightly for seventy-four days. The species settling on the panels (as well as on the mesh of the cage) were identified and examined for percentage cover. Data obtained were subjected to Analyis of Variance or t-tests after arc-sine transformation. Faunal abundance was found to be significantly higher on the mesh of the cage than on the panels (p<0.001). Differences between the caged and uncaged panels were influenced by time as total cover was found to decline with time on the caged panels. Pennaria distichia , Styela sp. and Sabella sp. achieved significantly higher cover on the mesh of the cage than the panels (p<0.001). Some species that settled on the panels ( Balanus sp., Membranipora membranacea , Serpul a sp, Halichondria sp, Crassostrea gasar) were not found on the mesh of the cage, and both Balanus and M. membranacea showed significantly higher abundance on uncaged panels (p<0.05). Current speed and sedimentation may have accounted for much of the difference in settlement between cagaed and uncaged panels. @ JASE

Changes in Total Protein and Transaminase Activities in Clarias Gariepinus Exposed to Diazinon

The aim of the study was to assess the effects induced by diazinon on total protein and transaminase activities in Clarias gariepinus, a common Niger Delta wetland fish. Fish were exposed to varying sub-lethal concentrations of diazinon (1.0, 2.5, 5.0, and 10.0 mg/I). Values decreased as the concentration of the toxicant increased. Plasma total protein and total protein in all organs tested were significantly lower (p<0.05). Plasma alanine amino transferase (ALT) increased at some treatment levels contrary to aspartate amino transferase (AST) in plasma. Activities of ALT and AST decreased as the concentration of diazinon increased in all the organs tested; hence, the effects were dose dependent. It is obvious from this study that diazinon negatively affects total protein and transaminase activities in Clarias gariepinus