Types and abundance of arthropod fauna in relation to physico-chemical properties of the bottom sediment of Warri river, Nigeria

The occurrence of arthropods associated with the bottom sediment of Warri River was investigated, and samples were collected from January 2002 to May 2003. The values of pH, alkalinity, magnesium and total hardness were significantly different (P < 0.01) between the study stations, while organic matter recorded for the bottom sediment shows no significant difference (P>0.05). The dominant fauna were Dipteran larvae, which constitute90.47%. Two rare groups of fauna (Arachnida and Ephemeropterans) were restricted to the upstream (Agbarho) station. Megapus sp. had a single record and is being recorded for the first time in Nigerian water bodies. All theorganisms did not show any correlation with pH, conductivity and percentage (%) organic matter. Fauna densities were maxima only in the dry season period

Toxicity Evaluation and Cytogenetic Screening of Process Water Using a Plant Bioassay

The effect of toxic substances on aquatic lives from a wastewater indiscriminately discharged into the environment during oil and gas exploration activities in Nigeria is the focus of this study. A plant bioassay, the Allium cepa test, was used for the cytogenotoxicity screening of process water on root growth inhibition and chromosome abnormalities in the meristematic roots of the plant. Results of the physicochemical analysis of the wastewater collected from Nigerian Agip Oil Company (NAOC) facility at Ogboinbiri in Bayelsa State at the point of discharge into the environment showed that it had an unpleasant odour, was slightly alkaline (pH 7.72) and had high electrical conductivity (2793.33 μS/cm). Lead, manganese, iron, chromium and nickel were present at amounts (0.13, 0.33, 4.47, 0.17 and 0.10 mg/l respectively) above national (NESREA) and international (USEPA) limits for effluent discharge. Macroscopic evaluation of A. cepa cultivated in the wastewater resulted in significant (p<0.05) concentration-dependent root growth inhibition with an EC50 value of 14.8 % at 96 h. Root tip cells of the onion bulbs processed for cytological studies by the aceto-orcein squash technique after exposure to the wastewater for 48 h at concentrations of 0.5, 1.0, 2.5, 5.0, and 10% (v/v; wastewater/tap water) showed chromosomal aberrations at all concentrations. Statistical analysis of microscopic results show significant (p<0.05) concentration-dependent frequency of aberrant chromosomes and reduction of mitotic index. The findings in this study calls for proper treatment of process water before its discharge into water bodies to avoid cyto-genetic damages to aquatic lives.Keywords: Toxicity, chromosome aberration, Allium cepa, process wate

Ecology of benthic macroinvertebrates in the depositional biotope of a river in southern Nigeria

The ecology of benthic macroinvertebrates was studied in the depositional biotope of a river in southern Nigeria in two contrasting tidally influenced fresh and brackish water stations. Forty five taxa in nineteen families representing seven major groups of benthos were recorded. The molluscan families, dominated by Neridae, Hydrobiidae were restricted to the brackish water station 2 while the insect groups Baetidae and Chironomidae dominated the fresh water station 1. The dominant families, Chironomidae and Hydrobiidae, which are primarily deposit feeders, accounted for 41.2 and 58.8% individual organisms. The distribution of benthos was significantly influenced by season and salinity. The composition, distribution and seasonality of benthos in the study biotope are discussed

Macroinvertebrate community of a post lindane treated stream flowing through derived savannah in southern Nigeria

The study of Macroinvertebrate community of the Edion River was carried out from January to June 2007. Water and benthic samples were collected from three stations monthly and fortnightly respectively. The physico-chemical characteristics include pH (7.05 - 7.98), dissolved Oxygen (DO) (2.50 - 6.67mgl-1), biological Oxygen demand BOD5 (1.10 - 4.80mgl-1), Alkalinity (12.20 - 73.20mgl-1) and Turbidity (0.01 - 1.19NTU). The values recorded were found to be within the range of tropical freshwaters. A total of 43 taxa comprising of 532 individuals, were collected from the study area. Of the total number of individuals recorded, stations 1, 2 and 3 had 207, 190 and 136 respectively. The dominant orders were Diptera (40.15%) and Ephemeroptera (36.96%). The diversity of macrobenthic invertebrates varied at the stations, with taxa richness highest at station 1 (index, 5.63) and lowest at station 2 (2.67). Water temperature was significantly correlated with dissolved Oxygen and Odonata, while pH was positively correlated (p>0.05, r = 0.5) with most of the parameters. All the parameters except water level and the macrobenthic invertebrate did not show any significant difference (P>0.05) at the study stations. The low relative abundance of the species may be attributed to the impact of human activities along the river catchment area.Keywords: Macroinvertebrates, dominant, taxa, physicochemical parameters, inland water, Nigeria

Hydrobiological studies on Warri River Nigeria. Part II: seasonal trend in the physico-chemical limnology

Investigation of the physical and chemical parameters of Warri River was carried out to assess the impact of human activities on the aquatic ecosystem. Most parameters had their values markedly lower during the wet season than the dry season, indicating much of dilution in the stations due to runoff. The data collected differ significantly (P0.05) at the study stations. Correlation coefficient revealed that conductivity was positively significantly correlated (

Implications of pesticide usage in Nigeria

The occurrence of pesticides in our environment as a result of the indiscriminate or intentional use has resulted in its persistence in the environment, thereby affecting the ecosystems and non target organisms. Acute and chronic pesticide poisoning usually results from consumption of contaminated food, chemical accident in industries and occupational exposure in agriculture. About 15,000 metric tons of pesticides comprising about 135 pesticide chemicals are imported annually into the country. They are the major causes of cancer, cardiovascular disease, dermatitis, birth defects, morbidity, impaired immune function, neurobehavioral disorder and allergy sensitization reaction. In Nigeria, food test carried out on 217 different food items revealed the presence of DDT, Aldrin and Dieldrin to be above maximum allowable concentration level which ranged from 1.2-2160μg kg-1. The detection of these pesticides in soil, drinking water and other animals is of great interest. The failure to establish data-base from past incidents in order to avert future occurrences has posed a huge problem to the society at large. The need for epidemiological data collection from past exposure, development of less toxic pesticides and legal requirement regarding toxicological and ecological effect before the importation of pesticides into the country will further reduce the impact of toxic pesticides on human health in the country.Key words: Pesticides, Environment, Health, Pollution, Nigeria

Assessment of policies and legislation that affect management of Wetlands in Nigeria

The beneficial ecosystem services provided by wetlands in Nigeria are continuously subjected to considerable stress that has consequences for human wellbeing. An understanding of the policies and legislation governing wetland can help enhance their management. Therefore, this paper reviews existing policies and legislation that affect management of wetlands in Nigeria. It draws upon the contents of the laws and policy documents acquired from government and non-governmental organizations. The paper assesses the level of attention given to wetlands and identifies some informal measures, together with 35 federal legislative acts, six international conventions, and voluntary measures relevant to wetlands management. Results indicate that the existing legislation gives little attention to wetland management. This led the authors to conclude that the reason for wetland degradation is not the lack of laws or policy documents, but weak enforcement of existing ones. In this light, the paper calls for an integration of wetland management strategies and a strict enforcement of existing laws whilst stressing that effort should target a comprehensive national wetland policy of a holistic approach. © Society of Wetland Scientists 2012