Tropical Freshwater Biology

Anthropogenic impact on macroinvertebrates distribution and physicochemical characteristics of a tropical stream in north-central Nigeria

2023-12-05T16:21:50+00:00

Emu is a tropical stream in Northcentral Nigeria that serves as the water source for drinking and other domestic activities for Kusotachin communities, Niger State, Nigeria. This study evaluates the impact of anthropogenic activities on the ecological health of the stream using physicochemical parameters and macroinvertebrate assemblages. Macroinvertebrates were collected for a period of 8 months (July 2021 to February 2022) using modified kick sampling techniques, and the physicochemical parameters were determined using standard sampling and analytical procedures. Samples were collected from four different stations which are characterized by various anthropogenic activities across the stream bed. With the exception of depth, the measured physicochemical parameters showed no significant (P>0.05) difference between the sampling stations. However, there were significant (P<0.05) differences in air temperature, pH, electrical conductivity, total alkalinity, total hardness, dissolved oxygen, chemical oxygen demand, phosphate, and nitrate between the sampling months. A total of 506 individuals, from 30 species in eight groups of macroinvertebrates were identified. Hemiptera were the most represented group with 57.07% abundance, followed by Odonata with 27.44%, Arachnida (4.14%), Coleoptera (3.93%), Ephemeroptera (2.55%), Diptera (2.17%), Mollusca (1.38) % and the least abundance was 0.19% observed in Decapoda and Oligochaeta. The Canonical correspondence analysis (CCA) showed little or no correlations between the determined macroinvertebrates and physicochemical parameters. CCA axis 1 accounted for 44.94% of the variation of the macroinvertebrates data set with an Eigenvalue of 0.30. CCA axis 2 accounts for 30.5% of data set of macroinvertebrates and an Eigenvalue of 0.20 while CCA axis 3 accounts for 24.55% variation in data set with an Eigenvalue of 0.16. Overall, the low abundance of Ephemeroptera and the absence of other pollution-sensitive macroinvertebrate groups such as Plecoptera and Trichoptera, combined with deteriorating surface water quality, is an indication of pollution stress caused by various anthropogenic activities as the vegetative nature of the stream was the primary factor responsible for the macroinvertebrate assemblage structure.

Geospatial seasonal environmental impacts on the distribution and abundance of Schistosoma haematobium vectors in two districts of the Ase River Catchment, Delta State, Nigeria

2023-12-05T17:07:54+00:00

Snails of the genus, Bulinus are known to transmit urinary schistosomiasis. Longitudinal limnological and Bulinus surveys were geospatially performed at 11 study sites frequently visited by humans for 24 months using APHA and scooping/hand-picking techniques in the Ase River, Delta State. The collected snails were subsequently identified, counted, and recorded. The results of the physicochemical parameters [water temperature (0C), Total Dissolved Solids (TDS), Electrical Conductivity (EC), pH, Dissolved Oxygen (DO), and Biochemical Oxygen Demand (BOD)] showed monthly and study site variations. All physicochemical parameters analyzed were significantly different (P<0.05) in both years except air temperature (P > 0.05). A total of 2,345 Bulinus species were collected, with year A (1,101) and year B (1,244) having their highest Relative Abundance (R.A) of 17.17% and 16.80% in July. The interannual Bulinus R.A was not significant (p = 0.9990; F = 1.49x10-006, df = 1). However, the monthly R.A was significantly different (F = 22.99, df =11) and accounted for 95.83% of the total variance. Bulinus R.A varied within and between years, with lower abundance in the dry season. Lagos-Iyede, Iyede-Ame, Onogboko, and Itobi-Ige study sites had the highest Bulinus R.A in both years with no significant difference (P < 0.0001; F = 0.2015, df = 10). Nevertheless, the monthly abundance was significantly different (F = 73.84, df = 11). This study identified Bulinus truncatus, B. globosus, and B. senegalensis and B. globosus had the highest (47.98%) R.A, followed by B. truncatus(37.06%) and B. senegalensis (14.99%). Geospatially, B. truncatus, B. globosus, and B. senegalensis R.A peaked at Iyede-Ame with 15.30%, 16.80%, and 27.64% respectively and the difference was significant (F = 12.46, df = 10). In year A, Principal Component Analysis revealed that B. truncatus had a strong association with DO and BOD, while B. globosus and B. senegalensis correlated positively with water temperature, TDS, EC, and pH. Comparatively, B. globosus R.A was strongly influenced by EC and TDS in the year B. TDS and EC exhibited a strong association.

An ecotoxicological appraisal of polychlorinated biphenyls in the blue whiting (Micromesistius poutassou, Risso 1826) from cold storage facilities in Benin City, Nigeria

2023-12-05T17:22:19+00:00

Polychlorinated biphenyls (PCBs) are halogenated organic pollutants that remain a threat to wildlife and man. The present study strove to fill an existing gap in knowledge while at the same time providing vital consumer information that could ultimately safeguard human health with regard to the PCB burden in the Blue Whiting Micromesistius poutassou (mean total length: 31.46 ± 0.87 cm; mean weight: 498.25 ± 0.48 g) sourced from cold storage facilities in Benin City, Nigeria, applying Gas Chromatographic technique. The overall mean values (Mg/kg) for PCB congeners in M. poutassou ranged from 0.01813 for PCB 189 to 0.1306 for PCB 126 with a total (ƩPCB4) of 0.1929. The mean PCB values (Mg/kg) in M. poutassou according to cold storage points ranged from 0.0156 (PCB 189) at Uselu to 0.137 (PCB 126) also at Uselu with no observed significant difference (P>0.05) in the mean concentrations of PCBs 118, 157 and 189 in M. poutassou between cold storage points. The hazard quotient (HQ) values ranged from 0.00906 (PCB 189) to 0.0653 (PCB 126) while the toxic equivalency (TEQ) was 0.013075. The estimated daily intake (EDI) and estimated annual intake (EAI) values for PCBs were both at a peak for PCB 126 with figures of 0.000068 Mg/person/day and 0.024 Mg/person/year. The percent (%) quota for PCBs in M. poutassou ranged from 9.39 % (PCB 189) to 67.70 % (PCB 126). The spatial total (Mg/kg) for PCBs in M. poutassou ranged from 0.1808 at Oba market to 0.2013 at Uselu while the temporal total (Mg/kg) for PCBs in M. poutassou ranged from 0.1888 in September to 0.1943 in October. The fish species was considered safe for human consumption as the observed levels of PCBs fell within International thresholds. Continuous monitoring of PCB levels in M. poutassou was however recommended.

Cyanobacteria of a Man-Made lake in Southern Nigeria

2023-12-05T17:42:05+00:00

A study of the Ikpoba dam was undertaken to explore the taxonomic composition of blue-green algae. Twenty-six taxa of blue-green algae comprising three Orders, five Families and 16 genera were identified. The bulk of the taxa (12) belong to the Oscillatoriales and Family Oscillatoriaceae. Others were Chroococcales, Chroococcaceae (6) and Nostocales (8). These span through a variety of morphological types of unicellular forms (Chroococcus), colonial forms (Microcystis, Merismopedia Calothrix and Gloeotrichia, Gomphosphaeria and Snowella) to filamentous forms (Oscillatoria, Nostoc, Achroonema, Scytonema, Spirulina, Phormidium, Moorea (Lyngbya), Dolichospermum and Anabaena). Of the collection, the heterocystous and nitrogen fixing forms were Anabaena, Nostoc and Oscillatoria species. Global distribution of the identified cyanobacteria in the Ikpoba Reservoir shows the species with the highest global distribution is Calothrix parietina, and the one with the least global distribution is Phormidium cincinnatum. The toxin-producing genera include Anabaena, Lyngbya, Microcystis, Nostoc and Oscillatoria. Bloom formation of such taxa presents implication for human and animal health, coupled with increased water treatment costs for the reservoir as a source of water supply

Gastro-intestinal parasites in African Mudcatfish (Clarias Gariepinus) of Ijebu Igbo Market, Ogun State, Nigeria

2023-12-05T17:55:52+00:00

The study was to identify gastro-intestinal parasites of Clarias gariepinus obtained from Ijebu Igbo, Ijebu-North Local Government Area of Ogun State, Nigeria. A total of 40 Clarias gariepinus were purchased from the market and examined parasitologically for gastro-intestinal parasites. The parasites were identified using standard identification chart. Four (4) helminth parasites comprising of 2 nematodes and 1 cestode and acanthocephala each were isolated from the fish species. Organisms identified are majorly present in the intestine are Procamallamus sp and Contracaeccum sp (nematoda), Caryophyllaeidae sp (Cestoda) and Neoechinorhynchus rutili (Acanthocephala). The males had the highest percentage prevalence (21.7%) while the females had the least (11.8%) prevalence. Conclusively, fishes from Ijebu Igbo market should be adequately cooked to prevent the ingestion of gastro-intestinal parasites which could lead to loss of body nutrients, anaemia, ulcers, lesions, skin shredding, erratic behaviour and at times death in man.

Morphological features and molecular identification of African sicklefish, Drepane Africana (Osório, 1892) off the Niger Delta Coast, Nigeria

2023-12-05T18:14:49+00:00

African sicklefish, Drepane africana is the only member of the family Drepaneidae found and reported in Nigerian waters. Despite its prominence in catches there is a dearth of detailed published information on morphological features and molecular identification of the species off the Niger Delta coast. This study was carried out to assess its morphological, morphometric (truss and conventional) and meristic characters, as well as DNA sequence. Samples of D. africana (n=2,143) were collected between April, 2013 and September, 2015 from seven sampling stations off the Niger Delta coast, Nigeria. The morphometrics (conventional and truss) and meristic characters of the fish were studied. DNA sequencing of the samples were also carried out. Data were analyzed using descriptive statistics and Principal Component Analysis (PCA). There was no variation in the numbers of all the meristics characters counted except in the number of pelvic fin spine, anal fin spine and atlas. The mean of total length, body depth and pectoral fin were 26.6±5.5, 15.1±1.8 and 11.7±1.0 cm respectively. The first four principal components (PCs) of the truss measurement accounted for 93% of the variation in the population, PCA revealed that the observed differences mainly were from the posterior and dorsal part of the fish. The range of 98-100% definitive identity matches of the species with GenBank records shows that all the sequenced samples have been correctly identified as Drepane africana.

Effects of thyme (Thymus vulgaris) and cinnamon (Cinnamomum zeylanicum) on the microbial load of smoke dried European hake fish (Merluccius spp) stored under ambient temperature

2023-12-05T18:30:38+00:00

This study was carried out to determine the effect of Thyme marinade (sample B), Cinnamon marinade (sample C) and a combination of both spices (sample D) on the microbial load of stored smoked-dried Merluccius sp. Comparative analysis of the microbial load of each treated fish samples during ambient storage was done biweekly for six (6) weeks and then samples of each treatment were taken to the laboratory periodically. Sample A was the control, smoke dried fish without any treatment. The fish samples were analysed using Potato Dextrose Agar and Nutrient Agar for fungi and bacteria respectively. The initial microbial load before storage showed that the highest number of bacteria counts occurred in smoke-dried Merluccius sp. Sample A (control) had the highest (2.8×10³ ) bacterial load while the lowest was in smoke-dried Merluccius sp. treated with cinnamon only (sample C, 1.8×10³ ). The highest fungi count was in sample B (thyme) 7.5×10² and lowest fungi count was in sample D (thyme and cinnamon) 2.4×10². After six weeks, sample B (thyme) had the highest fungi count 2.6×10⁴ while sample D (thyme and cinnamon) had the lowest fungi count 9.6×10³. Prevention of spoilage due to microbiological, enzymatic, or chemical changes, and shelf-life extension of fish are typically carried out with the recommended useful chemical preservatives, such as sodium benzoates, sodium nitrite, and sulfur dioxide, on the other hand accumulation of these artificial preservatives in tissues can be hazardous to human health. Storage of fish without natural or artificial preservatives would ultimately lead to quicker spoilage, thereby leading to financial losses to fish processors and marketers. Use of natural preservatives such as thyme and cinnamon would help to prevent theses hazards to human health and losses caused due to spoilage during storage.