Oju Richard Ibor

This study has investigated the changes of haematological profile of Clarias gariepinus exposed to sub-lethal concentration of deltamethrin over a 28 days exposure period. Sub-adults C. gariepinus (weight 134.21± 43.01g and length 17.34± 5.92cm) were exposed to control (0.00) 0.005, 0.011, 0.022 and 0.044 ppm concentrations of deltamethrin for 28-days. Significant changes were induced by the deltamethrin on the haematological parameters of C. gariepinus fish after 28 days exposure. We observed a concentration and exposure duration (time) dependent alterations in fish exposed to deltamethrin compared with control. Also, the red blood cells, haemoglobin and haematrocrit count, mean corpuscular volume, mean cell haemoglobin concentration, lymphocytes, platelets and white blood cells decreased significantly in deltamethrin exposure concentrations compared with control. Blood parameters showed a time-dependent decreased across exposure groups and concentrations. Results presented herein indicates a concentration and time-dependent alterations in hematological profile of C. gariepinus suggesting a negative physiological effects of deltamethrin on the hematological status of fish.

In applying bioanalytical approaches, the aim of this study was to determine the toxicity of contaminants derived from a solid waste dumpsite in Calabar (Nigeria), by investigating the alterations of lipid and estrogen signaling pathways in Poeciliopsis lucida hepatocellular carcinoma-1 (PLHC-1) cells and compared to in vivo African catfish (Clarias gariepinus), using polar, nonpolar and elutriate extraction methods. Cells were exposed for 48 hr period to different concentrations of the contaminant extracts. The PLHC-1 cells were evaluated for lipid responses as follows adipoRed assay, retinoid x receptor (rxr), peroxisome proliferator-activated receptor isoforms (ppar-& alpha; and & gamma;), estrogen receptor (er-& alpha;) and vitellogenin (vtg) transcripts. The lipid signaling activation was also assessed in vivo using C. gariepinus, where hepatic levels of ppar-& alpha; were determined at both transcript and functional proteins levels. Data showed variable-, extract type and concentration-specific elevations in mRNA and protein levels for lipidomic and estrogenic effects. These effects were either biphasic at low and high concentrations, depending upon extract type, or concentration-dependent elevations. In general, these toxicological responses may be attributed to soil organic and inorganic contaminants burden previously derived from the dumpsite. Thus, our data demonstrate a unique lipid and endocrine-disruptive chemical (EDC) effects of each soil extract, suggesting multiple and complex contaminant interactions in the environment and biota. Analysis of numerous soil- or sediment-bound contaminants have numerous limitations and cost implications for developing countries. Our approach provides a bioanalytical protocol and endpoints for measuring the metabolic and EDC effects of complex environmental matrices for ecotoxicological assessment and monitoring.

Nigeria's most consumed potable water plastic wastes are indiscriminately dumped into agricultural soil despite their ability to become microplastics. The study evaluates the potential impacts of these microplastics on soil physico-chemical parameters, soil bacterial diversity and functions as well as antibiotic resistance. Soil sample was collected using a sterile hand-held auger and its physico-chemical parameters evaluated. Baseline microplastic concentration was determined via the flotation method while microbial isolates were obtained from the test (enriched with microplastics) and control samples using cultural technique and metagenomics. Metagenomic next-generation sequencing (mNGS) was done using the Illumina Miseq platform. The cluster of orthologous genes (COG) tool was used in the prediction of bacterial functional roles. Replicate readings were analysed using analysis of variance (ANOVA) and means compared using the student’s t test. Observed baseline microplastic concentration was 0.08 particles/g of soil. The addition of the microplastics to the soil sample decreased the concentrations of some metals (iron, zinc, lead and nickel) while cobalt concentration, pH level and microbial counts increased. Microbial count and pH clustered together while iron, magnesium, nitrate, nitrite, chromium, cobalt, total organic carbon, zinc, lead, and nickel showed positive loading values suggesting that the addition of microplastics could alter them. Dominant taxa were proteobacteria, unknown, firmicutes at the phyla level. At the level of species, Pseudomonas species dominated microplastics incubated soil while potential pathogenic species such as Klebsiella dominated the control sample. A higher level of multi-drug resistance and altered metabolisms was observed in the test sample. Sachet water microplastics could have serious implications for public health and food security.

Riparian vegetation and built-up density along the urbanised section of the Calabar river were estimated using NDVI (Normalised Differential Vegetation Index) and NDBI (normalised differential built-up index), respectively. Four sampling stations representing riparian density and built-up gradients i.e. Station 1 (sparse riparian + high-density built-up), 2 (sparse riparian + high to intermediate-density built-up), 3 (moderate riparian + intermediate to low-density built-up) and station 4 (moderate riparian + low-density built-up) were selected. Station-specific variations of metal (Pb, Cd, Cr, Fe and Cu) in surface water and benthic macro-invertebrate communities were examined between January and December 2013 and correlated using redundancy analysis (RDA). Buffer analysis revealed that stations having low NDBI with over 120 m dense riparian areas showed a marked abundance of muddy/coarse substrate while sparse riparian areas showed siltier and sandier substrate. Redundancy analysis revealed a marked delineation of macroinvertebrate occurrence with the riparian density of stations. High diversity macroinvertebrate assemblages showed a strong positive association with alkaline pH, the density of riparian vegetation and substrate type. This first report highlights the critical relationship between riparian density, water quality and benthic macroinvertebrates in a tropical river.