Tropical Freshwater Biology <em>Tropical Freshwater Biology</em> promotes the publication of scientific contributions in the field of freshwater biology in the tropical and subtropical regions of the world. One issue is published annually but this number may be increased. Original research papers and short communications on any aspect of tropical freshwater biology are acceptable. Review articles relevant to the tropics and books for review are welcome. Articles solely concerned with the physical and chemical environment and theoretical issues will be considered occasionally. en-US Authors should transfer the copyright of papers to Idodo Umeh Publishers Limited,Benin City,Nigeria. Publications may not be reproduced, stored in retrieval systems or transmitted in any form or any means without the written permission of the Publishers. (PROF. ANTHONY E OGBEIBU) (PROF. ANTHONY E OGBEIBU) Wed, 24 May 2023 09:29:55 +0000 OJS 60 Preliminary assessment of a degraded river in the Niger Delta, Nigeria using physico-chemical characteristics and water quality index <p>Surface water degradation is increasingly becoming a national issue in Nigeria as it affects the suitability of water for its various uses. The preliminary&nbsp; study of the physicochemical parameters and water quality index of the Orogodo River was conducted to ascertain the extent of degradation from&nbsp; multiple sources of contamination. Water samples were collected from four sites that were impacted by various anthropogenic activities along the&nbsp; Orogodo River in Delta State during the months of February (number of samples = 16) and September (number of samples = 16) 2020. The water samples&nbsp; were analyzed using standard methods. The results of the physicochemical analysis using ANOVA showed significant differences (P&lt;0.05) only in&nbsp; 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&nbsp; espectively that is a&nbsp; major abattoir discharge point were above the Nigeria Standard for Drinking Water Quality acceptable limits for drinking water and&nbsp; 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&nbsp; those of sites 2 and 3 showed poor water quality. The study demonstrated that water quality index analysis and physicochemical characteristics were&nbsp; critical factors in evaluating the deteriorating conditions of the Orogodo River. Periodic monitoring of the river quality and integrity is vital as the river&nbsp; water will require extensive treatment for safe usage.</p> J.I. Izegaegbe, J.A. Edoreh , C.O. Onogbosele Copyright (c) 0 Tue, 23 May 2023 00:00:00 +0000 Hepatosomatic index and haematological profile: A bio monitoring tools for assessing african catfish juveniles (<i>Clarias gariepinus</i>) exposed to dimethoate 40% EC toxicity <p>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&nbsp; catfish (<em>Clarias gariepinus)</em> juvenile using majorly two indices Hepatosomatic Index (HSI) and Haematological parameters. The fishes were exposed to&nbsp; 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&nbsp; 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&nbsp; respectively. Catfish (<em>Clarias gariepinus</em>) exhibited alteration which was significant (P&lt;0.05) in the total white blood cell count amongst other checked&nbsp; parameters such as Red Blood Cell Count, Packed Cell Volume and Haemoglobin. Result of the study indicates potential toxicity of Dimethoate to&nbsp; juveniles of <em>Clarias gariepinus</em> for which aquatic environment must be continuously monitored.&nbsp;</p> A.C. Okoboshi, C.G. Agaoru, J. Ezea, R. Ibeh, J. Udeme, K.E. Ike Copyright (c) 0 Tue, 23 May 2023 00:00:00 +0000 Effect of zinc oxide nano-particles on activities of biochemical enzymes in the tissues of <i>Heterobranchus longifilis</i> <p>The unregulated release of nano-particles into the environment induces toxicity in living organisms by interfering with normal cell processes. This study&nbsp; investigated the toxicity effects of both lethal and sub-lethal concentrations of ZnO-NPs on biochemical enzymes in the tissues of African catfish,&nbsp;&nbsp; <em>Heterobranchus longifilis</em>, 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,&nbsp; 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&nbsp; 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&nbsp; results revealed a significant (P&lt;0.05) increase in the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate&nbsp; dehydrogenase (LDH), acetyl cholinesterase (AChE), and the levels of total protein and glucose also increased significantly (P&lt;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&nbsp; that the release of ZnO-NPs into aquatic environment could be dangerous and may cause health risk in man through food chain.</p> S.I. Abdulkareem, O.D. Owolab Copyright (c) 0 Wed, 24 May 2023 00:00:00 +0000 Microplastics: Potential impacts on aquatic biodiversity <p>Microplastic pollution has been considered an issue of considerable concern for society and aquatic ecosystems due to plastics' unlimited applications&nbsp; and admirable properties. This review paper investigated various groups and sources of microplastics, their potential impacts on aquatic biodiversity, and&nbsp; the mitigation and treatment measures. Microplastics were grouped according to their sources as primary and secondary microplastics. Primary&nbsp; microplastics are generated more from land-based activities (98%) than sea-based activities (2%). Sources of primary microplastics are personal care&nbsp; products, industrial scrubbers, plastic powders, and microbeads, among others. While sources of secondary microplastics are losses of plastic materials&nbsp; during natural disasters, material lost or discarded from fishing vessels and aquaculture facilities, and oil and gas platforms, among others. Microplastics&nbsp; 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&nbsp; and genotoxicity to marine species. Mitigation measures to reduce the microplastic pollution's effects include the removal of microbeads from personal&nbsp; care products, improved reuse, recycling and recovery of plastics, improved separation efficiency at wastewater treatment points and development of&nbsp; clean-up and bioremediation and phytoremediation techniques. Treatment methods include microfiltration, ultra-filtration, nanofiltration and reverse&nbsp; osmosis. Microplastics have varying effects on aquatic organisms, but these impacts can be mitigated and treated with different techniques and policy&nbsp; instruments. Therefore, the study recommends avoiding disposing of, reusing, recycling and recovering plastic substances in the aquatic environment for&nbsp; safe and clean waters.&nbsp;</p> O.A. Bubu-Davies, P.A. Anwuri Copyright (c) 0 Wed, 24 May 2023 00:00:00 +0000 Comparative assessment of bioaccumulation of some heavy metals in water and mudskipper (<i>Periophthalmus barbarous</i>) of Woji Creek, Port Harcourt, Nigeria <p>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 (<em>Periophthalmus barbarus</em>) of Woji Creek to ascertain their suitability for human consumption. Samples of&nbsp; water and mudskippers were analyzed for these heavy metals using Atomic Absorption Spectrophotometer between October 2019 and September 2020.&nbsp; Water and <em>P. barbarus</em> samples were collected from three locations and transported to the laboratory for heavy metals analyses. The results showed that&nbsp; 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&nbsp; 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&nbsp; concentrations in both water and fish was Cr&gt;Pb&gt;Cd. All the metals studied exhibited significant (P&lt;0.05) higher values in water in the dry season&nbsp; 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 <em>P.&nbsp; barbarus</em> has a high potential to concentrate heavy metals in their body. The study showed that Woji Creek is under stress, and its <em>P. barbarus</em> is heavy&nbsp; metal-contaminated and unsuitable for human consumption. The study, therefore, recommends that there should be proper biomonitoring to avoid&nbsp; indiscriminate anthropogenic activities in the area.&nbsp;&nbsp;</p> O.A. Bubu-Davies, B.B Otene , E.S. Ejiko Copyright (c) 0 Wed, 24 May 2023 00:00:00 +0000 Epixylic algae and physico-chemical parameters as indicators of aquatic pollution in Elechi Creek, Port Harcourt, Rivers State, Nigeria <p>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,&nbsp; pH, electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), biological oxygen demand (BOD), phosphate, sulphate, and nitrate] of&nbsp; the Creek. Surface water and epixylon sample collections from three stations followed standard methods between August and November 2021. Epixylon&nbsp; samples were analyzed microscopically. A total number of 461 individuals, 30 genera and 37 species from 6 families, namely: <em>Bacillariophyceae (18&nbsp; species), Chlorophyceae (9 species), Cyanophyceae (5 species), Chrysophyceae (1 species), Dinophyceae (3 species), Euglenophyceae (1 species)</em> of epixylic&nbsp; algae were recorded. Pollution- indicator genera were <em>Cyclotella, Nitzschia, Synedra, Cocconeis, Tabellaria, Melosira (Bacillariophycea)&nbsp; Ankistrodesmus, Chlorella, Closterium</em> (<em>Chlorophyceae), Oscillatoria and Phormidium (Cyanophyceae)</em>. Spatially, sulphate (137.02±25.00 mg/L) exceeded&nbsp; 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&nbsp; (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 (&lt;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,&nbsp; some bioindicator species, and higher EC and sulphate denotes organic pollution in Elechi Creek. The study recommends thus periodic monitoring of&nbsp; Elechi creek and environmental awareness programmes to mitigate pollution and safeguard the health of the residents around this Creek.&nbsp;&nbsp;</p> O.A. Bubu-Davies, O.V. Akosubo-Abraham, C.A. Okoni Copyright (c) 0 Wed, 24 May 2023 00:00:00 +0000 Comparative effect of inducing broodstock with natural and artificial hormones on reproductive performances of <i>Heterobranchus longifilis</i> <p>This study was conducted to assess the effects of ovaprim and pituitary extract on the reproductive performances of <em>Heterobranchus longifilis</em> (African&nbsp; 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&nbsp; morphological characteristics and standard breeding procedure. The water parameters for indoor culture tanks during the study were optimal for&nbsp; breeding: dissolved oxygen – 5.18 mg L-1 ; pH 7.31; temperature, 27.6 ˚C. The result revealed no significant (P &gt; 0.05) differences in water quality&nbsp; parameters between the culture tanks for artificial and natural hormonal applications in this study. The percentage fertilization, hatchability, survival and&nbsp; 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&nbsp; Ovaprim®. Pituitary extract recorded higher values and significantly performed better (P &lt; 0.05) between the two treatments. This indicates that the use&nbsp; of natural pituitary extract is equally as effective as the use of the artificial hormone Ovaprim® for the artificial propagation of <em>Heterobranchus longifilis.&nbsp;</em> It is therefore recommended.&nbsp;</p> A.J. Otoh, M.T. Udo, U.U. George Copyright (c) 0 Wed, 24 May 2023 00:00:00 +0000 Papers Already Published <p>No abstract</p> Anthony E. Ogbeibu Copyright (c) 0 Wed, 24 May 2023 00:00:00 +0000 A Publication of the Freshwater Biological Association of Nigeria <p>No Abstract</p> Anthony E. Ogbeibu Copyright (c) 0 Wed, 24 May 2023 00:00:00 +0000 Tribute to Professor Reginald Victor, Founding Editor of TFB <p>No Abstract</p> Anthony E. Ogbeibu Copyright (c) 0 Wed, 24 May 2023 00:00:00 +0000