No abstract

No abstract

ABSTRACT:The acute and sublethal toxicity of an organophosphate pesticide (Chloropyrifos) on the juvenile of Tilapia guineensis was evaluated to determine its effect on the survival, body functions and heamatological values. The fish was exposed to varying levels of the toxicant (0.0125mg/l; 0.025mg/l; 0.05mg/l and 0.1mg/l) using 96hrs static bioassay to determine the median lethal concentration and median lethal time for the different concentrations. The mortality was found to increase with exposure and increase in concentration. The 96hrs median lethal concentration was 0.002mg/l while the 96hr median lethal time of 56.2hrs; 42.7hrs; 31.1 hrs and 18.2hrs were recorded for 0.0125mg/l; 0..025mg/l, 0.05mg/l and 0.1mg/l respectively. The operculum beat frequency (F = Cal 6.89 > P = 3.49) 0.05 and Tail beat frequency (F = Cal 4.46 > P (3.49) 0.05 were significantly affected by the exposure. A sublethal exposure to various concentrations (0.0006mg/l; 0.00125mg/l, 0.0025mg\l, 0.005mg/l) were observed to cause a progressive reduction in the number of leucocyte (F -Cal 15.4 > P (3.01) 0.05 and erythrocyte (F-Cal 14.39 > P(3.01)0.05 of the fish.The reduction in leucocye and erythrocyte number was significant indicating that the fish became anaemic.These conditions were more severe in the higher concentrations of the pesticide. @JASEM

No abstract

No abstract

Studies on the species composition, relative abundance, spatial distribution and diversity of phytoplankton assemblages in the Cross River Estuary were carried out for twenty-four months, across six (6) sampling stations. A total of 105 species of 57 genera, belonging to 5 families was observed. Bacillariophyceae (Diatom) was the most abundant phytoplankton family, constituting 71.58% of total Algal density, followed by Chlorophyceae (Green algae) with 13.84%, Cyanobacteria (Blue-green algae) with 12.69%, while Euglenophyceae (Green flagellates) and Dinophyceae (Dinoflagellates) recorded 0.88% and 1.01% respectively, of total phytoplankton abundance. Bacillariophyceae showed progressive importance from stations 1 to 6 while chlorophyceae and Euglenophyceae were more abundant in stations 1, 2, and 3. Cyanobacteria however, showed no spatial bias, whereas Dinophyceae were observed only in stations 4, 5 and 6. Bacillarlophyceae was the most dominant family, while chlorophyceae and cyanobacteria were observed to be subdominant groups. Similarity of species occurrence was generally observed in stations 1 and 2, station 3 and 4 and stations 5 and 6. Analysis of variance (ANOVA) showed significant variation (P<0.05) in community structure between stations 1, 5 and 6 whereas stations 1, 2 and 3 showed no significant difference (P>0.05) in composition of phytoplankton assemblages. High abundance of certain cyanobacteria taxa indicated environmental degradation. @JASEM

The potentials of the invasive duckweed species, Lemna paucicostata to remove pollutants from aquatic environment was tested in a constructed wetlands as an ecological based system for the phytoremediation of petroleum hydrocarbons in crude oil-contaminated waters within 120 days. Total petroleum hydrocarbons in wetlands and tissues of duckweed were analyzed using gas chromatography with flame ionization detector following established methods while the experimental data were subjected to the first-order kinetic rate model to understand the remediation rate of duckweed in wetlands. L. paucicostata effected a significant (F = 253.405, P < 0.05) removal of hydrocarbons from wetlands reaching 97.91% after 120 days. Assessment on the transport and fate of hydrocarbons in duckweed indicated that L. paucicostata bioaccumulated less than 1% and significantly biodegraded 97.74% of hydrocarbons in wetlands at the end of the study. The experimental data reasonably fitted (r 2 = 0.938) into the first-order kinetic rate model. From the result of the study, it is reasonable to infer that L. paucicostata is an effective aquatic macrophyte for the removal of petroleum hydrocarbons in moderately polluted waters. The expansion of the chemical industry after the dawn of the industrial age has significantly increased the levels of contaminants entering the natural and human environment. Among the many chemical industries, the petrochemical industry is a major player in the global energy landscape despite significant investment and interest in alternative energy. Today, petroleum remains a significant energy demand in modern society. In spite of all the necessary safety and precautionary approach in the petroleum industry, oil spill is an inevitable occurrence in the production, transport, processing and consumption of crude oil 1,2. The continuous advancement in offshore exploration has increased the level of exposure of hydrocarbons into aquatic environment, particularly freshwater, creating a cascade of negative impact on organisms relying on freshwater resources 3,4. Oil spills in water leads to extensive damage of water resources including sensitive habitats. It suffocates aquatic life and renders water unfit for communal and domestic use 5. Over the years, various technological approach has been developed for the treatment of oil spill in marine and coastal waters, as well as rivers, streams, wetlands, swamps and lakes 6-9. Chemical methods involving the application of dispersants and in situ burning have unintended consequences despite the success recorded with such application 8,10. The unintended effects with the application of chemicals for oil spill cleanup have given opportunities to the development of biological and nature-based solutions over the past three decades for the remediation of contaminants in aquatic environment 7,11. The usefulness of plants in the biological remediation of contaminants has been expanding over the years. Several species of plants with the potentials to remove a wide range of contaminants fro...

No abstract