Zoologist (The)

Inferring the allometric growth coefficient of juvenile African mud catfish, Clarias gariepinus (Burchell, 1822), using Bayesian and Frequentist regression models

2024-04-07T16:29:16+00:00

Statistics is essential in biological and ecological scientific research. However, the default Frequentist statistics based on p-value and null hypothesis testing is often misused and misinterpreted, hence causing reproducible crises. The p-value concept deserved further examination because it has been irretrievably lost. Therefore, there is dire need for reform in the default Frequentist statistics as practiced by researchers because of the perils of p-values. Bayesian statistics, using the tools of Bayes Factors and posterior distributions derived from priors and likelihood function; rooted in Bayes’ Theorem is one of the suggested alternatives. Frequentist (least square) and Bayesian (specifying uniform Jeffreys-Zellner-Siow prior, r-scale =0.35) regression models, a standard statistical protocol in fisheries were applied to determine the allometric growth coefficient based on length (mm) and weight (g) measurements of juvenile African mud catfish, Clarias gariepinus from Epe Lagoon. The growth coefficient, b=3.20, 95% Confidence Interval [3.07, 3.34], t(96)=47.55, p<0.001 was significant with 96% explanatory power (R²=0.96).While Bayesian method, with 96% explanatory power (R²=0.96), also estimated, b=3.20, (with Credible Interval between 3.06 and 3.32). The Bayes Factor (>100) suggested the data is more plausible under the alternative model than the null model, but p-value cannot quantify evidence in support of alternative hypothesis, since p-value can only reject or fail to reject a null hypothesis. These findings suggested that juvenile C. gariepinus thrived in Epe Lagoon. Therefore, Bayesian inference is a robust substitute for Frequentist regression model in fisheries.

Morphological features and length-weight relationships of Sarotherodon galilaeus from Oyan Lake, Southwestern Nigeria

2024-04-07T16:38:42+00:00

Oyan Lake is one of the major sources of fish protein supply to many parts of Southwestern Nigeria. Investigation was conducted on the biometrics, length-weight relationship and condition factor of Sarotherodon galilaeus in Oyan Lake. Fish samples were obtained from fishermen using gillnets, hook and line, cast nets and traps. One hundred and thirty samples of S. galilaeus were collected for the study, comprising eighty-three (83) males and forty-seven (47) females with sex ratio of 1:0.57 (male:female). The mean total lengths for combined sexes, males and females were 15.5±0.15, 15.7±0.19 and 15.3±0.26cm while the mean total weights were 81.0±2.78, 83.8±0.56 and 75.9±4.70g, respectively. No significant difference (p>0.05) was observed between mean total lengths of males and females. However, mean weight of males was significantly higher (p<0.05) than females. Mean eye diameter (EYD) and length of caudal peduncle (LCP) were significantly higher (p<0.05) in females. The range of number of pectoral rays (PRA) (12-14), number of pelvic rays (PVR) (4-5), number of anal spines (ANS) (2-3) and number of pelvic spines (PEVS) (1, no range) were the same in both sexes. There was strong correlation between weight/total length (r=0.93) and total length/length of dorsal fin base (r=0.72), while there was no correlation between body depth/head length. The mean condition factor (k) were 2.07±0.02 (combined sexes), 2.08±0.03 (males) and 2.03±0.03 (females). Growth was isometric for both sexes: males, 3.24 and females, 3.06. The results suggested that Oyan Lake is suitable for S. galilaeus.

Ecto- and helminths of Columba livia and Streptopelia roseogrisea in Alimosho community, Lagos State, Nigeria

2024-04-07T16:58:09+00:00

Fifty wild columbids (25 each of Columba livia and Streptopelia roseogrisea) were trapped in Alimosho, Lagos State, Nigeria from January to June 2022 and examined for ectoparasites and intestinal helminths following standard procedures. Three (6%) of the birds were infested with two species of ectoparasites. Prevalence and mean intensity of infection were: Gonoides gigas 6% and 0.34±SD; Columbicola columbae 6% and 0.14±SD respectively. Thirty-two (64%) of the birds were infected with helminths, represented by three species of cestodes and one species of nematode. The prevalence and mean intensity of infection of the cestodes were as follows: Raillientina echinobothrida 50% and 25±SD), Raillientina tetragona 40% and 20±SD and Raillientina cesticillus 20% and 10±SD, while the nematode recovered was Ascarida galli with prevalence and mean intensity of infection of 4% and 2±SD. Only 9.4% of the birds studied harboured triple infections, while 6.3% of the birds had double infection. The prevalence of gastro intestinal helminths within Streptopelia roseogrisea was higher for cestodes (p< 0.05) and for ectoparasitic infestation, Gonoides gigas had the highest prevalence (6%; p< 0.05). The overall prevalence (64.00%) of parasitic infection among columbids in this study was high, with Raillientina sp, a zoonotic parasite, dominating the infections. This demands for control, considering the close proximity of pigeons to man.

Biosynthesis, characterization and antivenom activities of Moringa oleifera silver nanoparticles: an experimental approach

2024-04-07T17:11:58+00:00

Moringa oleifera has been previously established to possess neutralizing potentials against Echis ocellatus venom. This study however, investigated the bioefficacy of silver nanoparticles biosynthesized from M. oleifera leaf extract aimed at improving its bioactivity against E. ocellatus venom-induced toxicities using in vivo and in vitro methods. The intrinsic characteristics of the produced M. oleifera-Silver nanoparticles (MO-AgNPs) were carried out using energy dispersive X-ray, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Fourier-transform infrared spectroscopy. Twenty-five male Wistar rats divided randomly into five groups (n=5) were used for the antivenom study. Group 1 received saline while groups 2 to 5 were envenomed intraperitoneally with 0.22mg/kg (LD₅₀) of E. ocellatus venom. Group 2 was left untreated while groups 3 to 5 were treated with 0.2ml of antivenom, 5 and 10mg/kg MO-AgNPs post-envenomation, respectively. Blood and tissue of treated rats were analyzed for heamatological parameters and histopathology, respectively. The MO-AgNPs formation was confirmed with a colour change from light brown to yellowish-brown with maximum SPR band at 420nm from UV-Vis analysis, indicating a reflection of the bio-reduction of Ag⁺ to Ag⁰. The Transmission electron micrographs showed well dispersed spherical AgNPs with average particle size of 15.7nm. Treatment with MO-AgNPs caused a significant improvement of acute anemia, leucopenia and thrombocytopenia induced by the venom in the envenomed treated rats. Also, MO-AgNPs inhibited the haemorrhagic, haemolytic and anticoagulant activities of the venom. Tissue lesions observed in heart of envenomed untreated rats were attenuated after treatment with MO-AgNPs. The biosynthesized MO-AgNPs exhibited potent neutralizing potentials than M. oleifera crude extract against E. ocellatus venom toxicities.

Physico-chemical parameters, heavy-metals and soil particle distribution of Liverpool axis of Badagry Creek, Lagos, South-western Nigeria

2024-04-07T17:24:13+00:00

Heavy metal pollution is a serious issue of concern worldwide because it can bioaccumulate in aquatic organisms and transferred through the food chain to harm humans. Information on the heavy metal pollution of aquatic ecosystems is essential to protect life. Therefore, this study was undertaken to determine the physico-chemical parameters of surface water, soil particle distribution (SPD) and heavy metals in two shellfish species in Liverpool axis of Badagry Creek, Lagos State, Nigeria. Twelve physico-chemical parameters and four heavy metals were studied using standard methods. The results showed that maximum temperature was 31.0±1.00˚⁰C; turbidity, 118.00±50.90NTU; dissolved oxygen (DO), 13.3±3.8mg/l; dissolved carbon dioxide (COD), 67.7±19.1mg/l; total hardness, 173.0±63.1mg/l; conductivity, 39.2±12.2μS/cm and chloride was 2.0±0.7mg/l. Water quality parameters showed significant spatial variations (p<0.05) among sample stations. Pearson’s correction matrices revealed high correlation of DO with nitrate (r = 0.61), total hardness (r=0.62) and COD (r=0.52) at p<0.05. The heavy metal concentrations (mg/kg) in the shellfishes, Callinectes pallidus and Farfantepenaeus notialis were: lead, 0.05±0.05 and 0.04±0.02; copper, 2.03±0.17 and 0.84±0.18; zinc, 3.51±0.44 and 1.99±0.2 and cadmium, 0.02±0.02 and 0.03±0.04 respectively. These levels were not above the WHO standards (for heavy metals in fish and shell fish). The sediment particle distribution (SPD) showed that Liverpool Jetty had 19.05% coarse sand and 43.91% fine sand, while Apapa Jetty had the highest amount of clay 45.29% in the environment. Heavy metals in shellfishes were above the WHO standards.

Antifertility potential of the extracts of Aloe barbadensis Miller on the testes and reproductive hormones of male rats

2024-04-07T17:32:14+00:00

There is a plethora of effective female contraceptives with varied efficacy, usability, and acceptability levels but not for males, who have condoms with a high failure rate and vasectomy with poor reversibility. This study was to determine the antifertility potential of the extracts of Aloe barbadensis as a herbal contraceptive for males. Gel and aqueous leaf extracts of Aloe barbadensis were administered orally to thirty-five sexually matured albino male rats for 30 days, to determine their effects on the reproductive hormones and histopathology of the testes. The animals were divided into 7 groups A, B, C, D, E, F, and G. Each group was for a treatment regimen having 5 rats. Group A, the Control, was given a normal ration and water. Groups B, C, and D were administered 10mg/kg, 30mg/kg, and 70mg/kg of fresh A. barbadensis gel daily for 30 days while groups E, F, and G were administered 10mg/kg, 30mg/kg, and 70mg/kg of aqueous leaf extract respectively. A significant reduction in testosterone levels (p<0.05), insignificant reduction in follicle-stimulating hormone levels, and an increase in luteinizing hormone levels that were also not significant (p>0.05) were observed. Histopathological alterations of disrupted cytoarchitecture, absence of Leydig cells, and scanty spermatozoa in the lumen of seminiferous tubules were observed in the tissues of the testes of the treated groups of rats, and as such the extracts may be possible effective natural antifertility agents for males although, toxic constituents of the plant extracts should be screened out before it is allowed for consumption.