This study was conducted to assess the effects of ovaprim and pituitary extract on the reproductive performances of Heterobranchus longifilis (African catfish). A total of twenty broodstock, 12 males and 8 females with mean weight of 2 kg each were selected for breeding following the external morphological characteristics and standard breeding procedure. The water parameters for indoor culture tanks during the study were optimal for breeding: dissolved oxygen – 5.18 mg L-1 ; pH 7.31; temperature, 27.6 ˚C. The result revealed no significant (P > 0.05) differences in water quality parameters between the culture tanks for artificial and natural hormonal applications in this study. The percentage fertilization, hatchability, survival and fry production success were: 84.25 %, 92. 31 %, 88.14 % and 68.42 %; and 75.17 %, 69.57 %, 64.33 % and 33.66 %, respectively, for pituitary extract and Ovaprim®. Pituitary extract recorded higher values and significantly performed better (P < 0.05) between the two treatments. This indicates that the use of natural pituitary extract is equally as effective as the use of the artificial hormone Ovaprim® for the artificial propagation of Heterobranchus longifilis. It is therefore recommended.

Elechi Creek of the Upper Bonny Estuary, Port Harcourt, Nigeria and its resources are economically significant. Still, the Creek is a sink receiving various anthropogenic effluents from its surroundings. The study determined the epixylon assemblage and some physico-chemical parameters [temperature, pH, electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), biological oxygen demand (BOD), phosphate, sulphate, and nitrate] of the Creek. Surface water and epixylon sample collections from three stations followed standard methods between August and November 2021. Epixylon samples were analyzed microscopically. A total number of 461 individuals, 30 genera and 37 species from 6 families, namely: Bacillariophyceae (18 species), Chlorophyceae (9 species), Cyanophyceae (5 species), Chrysophyceae (1 species), Dinophyceae (3 species), Euglenophyceae (1 species) of epixylic algae were recorded. Pollution- indicator genera were Cyclotella, Nitzschia, Synedra, Cocconeis, Tabellaria, Melosira (Bacillariophycea) Ankistrodesmus, Chlorella, Closterium (Chlorophyceae), Oscillatoria and Phormidium (Cyanophyceae). Spatially, sulphate (137.02±25.00 mg/L) exceeded the NESREA standard (100 mg/L, respectively), while temperature (30.00±1.72 ℃), pH (6.70±0.79), TDS (2308.92±858.14 mg/L), DO (6.56±0.78), BOD (1.78±0.71 mg/L), nitrate (0.92±0.18 mg/L) and phosphate (0.25±0.06 mg/L) were within NESREA standard (<40 ℃, 6-9, 2000 mg/L, 6.0 mg/L, 3.0 mg/L, 9.1 mg/L and 3.5 mg/L, respectively). EC (4959.50±1836.34 µs/cm) exceeded the WHO standard (900 µs/cm). The presence of dominant Bacillariophyceae, some bioindicator species, and higher EC and sulphate denotes organic pollution in Elechi Creek. The study recommends thus periodic monitoring of Elechi creek and environmental awareness programmes to mitigate pollution and safeguard the health of the residents around this Creek.

Microplastic pollution has been considered an issue of considerable concern for society and aquatic ecosystems due to plastics' unlimited applications and admirable properties. This review paper investigated various groups and sources of microplastics, their potential impacts on aquatic biodiversity, and the mitigation and treatment measures. Microplastics were grouped according to their sources as primary and secondary microplastics. Primary microplastics are generated more from land-based activities (98%) than sea-based activities (2%). Sources of primary microplastics are personal care products, industrial scrubbers, plastic powders, and microbeads, among others. While sources of secondary microplastics are losses of plastic materials during natural disasters, material lost or discarded from fishing vessels and aquaculture facilities, and oil and gas platforms, among others. Microplastics cause toxic effects, reduced food intake, delayed growth, oxidative damage, abnormal behaviour, a barrier to lipid metabolism, and affect fishes at molecular levels, causing genetic damage whereby microplastics absorb polycyclic aromatic hydrocarbons, which cause immunotoxicity, neurotoxicity and genotoxicity to marine species. Mitigation measures to reduce the microplastic pollution's effects include the removal of microbeads from personal care products, improved reuse, recycling and recovery of plastics, improved separation efficiency at wastewater treatment points and development of clean-up and bioremediation and phytoremediation techniques. Treatment methods include microfiltration, ultra-filtration, nanofiltration and reverse osmosis. Microplastics have varying effects on aquatic organisms, but these impacts can be mitigated and treated with different techniques and policy instruments. Therefore, the study recommends avoiding disposing of, reusing, recycling and recovering plastic substances in the aquatic environment for safe and clean waters.

The indiscriminate discharges of anthropogenic effluents containing heavy metals from the surrounding residential buildings and industries into Woji Creek are alarming and of environmental concern. This research thus aimed to compare the bioconcentrations of Lead (Pb), Cadmium (Cd) and Chromium (Cr) in the water and mudskippers (Periophthalmus barbarus) of Woji Creek to ascertain their suitability for human consumption. Samples of water and mudskippers were analyzed for these heavy metals using Atomic Absorption Spectrophotometer between October 2019 and September 2020. Water and P. barbarus samples were collected from three locations and transported to the laboratory for heavy metals analyses. The results showed that Pb, Cd and Cr concentrations (mg/L) in water were 0.741±0.550, 0.80±0.034 and 2.867 respectively, while that of fish (mg/Kg) were 3.554±0.91, 2.083±0.91 and 4.987±0.60 respectively. All the heavy metal concentrations studied exceeded the permissible limits of FMEnv and WHO. The hierarchy of heavy metal concentrations in both water and fish was Cr>Pb>Cd. All the metals studied exhibited significant (P<0.05) higher values in water in the dry season than wet season except Cr, while in fish, all were higher in the wet season than in the dry season except Pb. The bioconcentration factor showed that P. barbarus has a high potential to concentrate heavy metals in their body. The study showed that Woji Creek is under stress, and its P. barbarus is heavy metal-contaminated and unsuitable for human consumption. The study, therefore, recommends that there should be proper biomonitoring to avoid indiscriminate anthropogenic activities in the area.

The unregulated release of nano-particles into the environment induces toxicity in living organisms by interfering with normal cell processes. This study investigated the toxicity effects of both lethal and sub-lethal concentrations of ZnO-NPs on biochemical enzymes in the tissues of African catfish, Heterobranchus longifilis, by exposing to lethal concentrations (0.00, 60.00, 80.00, 100.00 and 120 mg/l) and sub-lethal concentrations (0.00, 6.00, 8.00, 10.00 and 12.00 mg/l) of ZnO-NPs for 96 h and 45 d in static renewal bioassays with continuous aeration respectively. After the exposure periods, blood was collected through the caudal fin of the fish from control and exposure groups and sacrificed to remove the gills and liver for biochemical assay. The results revealed a significant (P<0.05) increase in the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), acetyl cholinesterase (AChE), and the levels of total protein and glucose also increased significantly (P<0.05) in the blood, gills and liver with increase in the concentrations and exposure periods compared to the control. The alterations in the biochemical enzymes of the fish indicated that the release of ZnO-NPs into aquatic environment could be dangerous and may cause health risk in man through food chain.

Surface water degradation is increasingly becoming a national issue in Nigeria as it affects the suitability of water for its various uses. The preliminary study of the physicochemical parameters and water quality index of the Orogodo River was conducted to ascertain the extent of degradation from multiple sources of contamination. Water samples were collected from four sites that were impacted by various anthropogenic activities along the Orogodo River in Delta State during the months of February (number of samples = 16) and September (number of samples = 16) 2020. The water samples were analyzed using standard methods. The results of the physicochemical analysis using ANOVA showed significant differences (P<0.05) only in biochemical oxygen demand and turbidity across the four sites. The biochemical oxygen demand (3.05±2.47) and turbidity (8.35±5.162) at site 3 espectively that is a major abattoir discharge point were above the Nigeria Standard for Drinking Water Quality acceptable limits for drinking water and could portend harm to water users and ecosystem integrity. The water quality index analysis revealed that sites 1 and 4 showed good water quality and those of sites 2 and 3 showed poor water quality. The study demonstrated that water quality index analysis and physicochemical characteristics were critical factors in evaluating the deteriorating conditions of the Orogodo River. Periodic monitoring of the river quality and integrity is vital as the river water will require extensive treatment for safe usage.

Organosomatic and Haematological Indices are commonly reported in fisheries studies because they are easily determined and can be excellent predictors of adverse health in fish. The objective of the present study was to evaluate the toxicity effect of an organophosphate (dimethoate 40% EC) on catfish (Clarias gariepinus) juvenile using majorly two indices Hepatosomatic Index (HSI) and Haematological parameters. The fishes were exposed to three sub lethal concentrations 0.01 mg/l, 0.15 mg/l and 0.29 mg/l and monitored for 28 days. Result showed a significant decrease in the Hepatosomatic Index (HSI) of the treated groups when compared with the control recording 2.36g, 2.49g and 2.47g for 0.29mg/l, 0.15mg/l and 0.01mg/l respectively. Catfish (Clarias gariepinus) exhibited alteration which was significant (P<0.05) in the total white blood cell count amongst other checked parameters such as Red Blood Cell Count, Packed Cell Volume and Haemoglobin. Result of the study indicates potential toxicity of Dimethoate to juveniles of Clarias gariepinus for which aquatic environment must be continuously monitored.

This study was conducted to investigate the quality of some drinking water supply sources in Four-Corners, Ikom Local Government Area, Cross River State, Nigeria using World Health Organization (WHO) recommended standards for drinking water. The supply sources (three springs, three boreholes and three different products of sachet water) were randomly selected for the study. The water samples were subjected to physico-chemical and bacteriological analyses. Temperature, pH and conductivity were determined using handheld meters at sampling sites while other parameters were determined in the laboratory. The bacteriological analysis was carried out through membrane filtration techniques. Results from the physico-chemical test showed that pH, conductivity, chromium, copper, nickel and zinc for all the water supply sources were compliant with WHO standard while temperature, total hardness, calcium, iron and magnesium were higher than WHO standard limits. Total dissolved solids and turbidity were not detected in all the water samples from the three different water supply sources. Faecal coliforms were found in all the water sources, which points to the fact that the three water sources were unsafe for human consumption. The findings of this study deduced that none of the water supply sources met the WHO standards for drinking. Considering the potential impacts of unsafe drinking water, recommendations to save the situation have been made.

In this study, fish pond water was collected from the artificial pond in the Department of Fisheries, University of Benin, Benin City, Edo State. The pond water was analyzed for some physicochemical parameters such as: temperature (T), pH, electrical conductivity (EC), total dissolved solids (TDS), total suspended solids (TSS), dissolved oxygen (DO), biochemical oxygen demand (BOD), total Kjeldahl nitrogen (TN), total phosphorus (TP), turbidity (Turb), chemical oxygen demand (COD), hardness (Hard), alkalinity (Alk) and bacteria count (BC). Biological treatment by mechanical aeration and chemical treatment with calcium hydroxide were carried out on the pond water. The treated pond water was characterized to evaluate the effectiveness of the treatments. Results obtained revealed increase in pH and dissolved oxygen after treatment but decrease in other parameters. The biological and chemical treatments were effective in reducing the concentration of most of the parameters. The treated pond water can be reused for irrigation but must undergo recarbonation to reduce pH and increase alkalinity.

This research was carried out between January and July 2021 in Akoko South West Local Government Area of Ondo State, Nigeria. Three sites in each of the eight towns of the Local Government Area were visited and sampled to determine and evaluate the relationship between mosquito species and biotic factors in the mosquito breeding environment. At each site mosquito larvae were collected and flora and fauna at each site were identified. The flora identified included grasses, green Algae, Pride of Barbados and others, while the fauna identified included Damsel flies, Dragon flies, Tadpoles, Midges, Lizard. The Damsel flies, Dragon flies and Tadpoles dominate the fauna distribution chart while Green Algae has the highest percentage of the flora distribution chart followed by grasses and pride of Barbados with the least percentage. The correlation coefficient indicated a positive relationship between larva density and flora while larva density and fauna showed some negative relationship. Adequate understanding of vector ecology is needed to control mosquito particularly in deploying environmental modification around host settlements. This understanding will better serve over deployment of chemicals into such sites that may affect non-targeted organisms.