RENEWABLE

ACUTE TOXICITY AND INHIBITORY RESPONSE OF MARINE MICROALGAE (Skeletonema costatum Cleve 1873) EXPOSED TO WATER-SOLUBLE FRACTIONS OF CRUDE OIL, DIESEL, SPENT ENGINE OIL AND THEIR COMPOSITE MIXTURE

B. O. Bello — 2024-03-25

Petroleum oils and their derivatives continue to devastate marine and coastal water ecosystems despite significant technological advancements in extraction and transportation systems. This is particularly true given their toxicity to sentinel organisms including Skeletonema costatum. This study assessed the potential of water-soluble fractions (WSFs) of crude oil, diesel, spent engine oil, and their composite mixture, to inhibit the growth of marine microalgae, Skeletonema costatum. At 72 hours after exposure, the sensitivity of test organisms to the WSF of various petroleum hydrocarbons were assessed using potential inhibition of cellular growth. The inhibition concentrations (IC₅₀) were determined as diesel 1.08% (10.8 g/l) > spent engine oil 2.27% (22.7 g/l) > crude oil 4.57% (45.7 g/l) > composite mixture 5.54% (55.4 g/l). The control population revealed an initial cell density of 2x10⁴ cells/ml to an average of 33.92x10⁴ cells/ml. The WSF of crude oil and its derivative hydrocarbons caused increasing inhibition of cellular growth as exposure concentrations increased. It was observed that trace levels of the hydrocarbons caused underlying cellular response which later manifested in growth inhibition of S. costatum. Petroleum hydrocarbons, even in trace levels, may contaminate marine water systems and exert toxicity on microalgae, leading to disruptions in the aquatic food chain.

PHENOTYPIC VARIABILITY REVEALED DIFFERENTIALLY HETEROGENEOUS TRAITS IN LONGNECK CROAKER, Pseudotolithus typus (Bleeker, 1863), ACROSS EPE AND LAGOS LAGOONS, NIGERIA

O. O. Oyebola — 2024-03-27

The adaptive phenotypic flexibility, descriptive and discreteness characteristics of Pseudotolithus typus obtained from Epe and Lagos lagoons in southwestern Nigeria were investigated to ensure precise identification, management and conservation of the species. Six meristic counts and 15 morphometric measurements were collected from mature Pseudotolithus typus obtained from Epe and Lagos Lagoons. Data on phenotypic and heterogeneous attributes were analysed using descriptive statistics, linear regression, and Discriminant Factor Analysis (DFA). Meristic values ranged from 2.00±0.00 (Eye) - 30.80±1.16 (Dorsal-Fin-Rays) and 2.00±0.00 (Eye) - 31.03±0.76 (Dorsal-Fin-Rays) in Epe and Lagos lagoons, respectively. Dorsal Spine Count had a higher variation at Epe (Coefficient of Variation, CV=5.58%) than Lagos lagoon (CV=4.65%). Morphometric values ranged from 4.25±0.51 (Orbital Length) - 28.77±1.54 (Head Length) in Epe Lagoon; and 3.52±0.22 (Pectoral Fin Width) - 28.35±1.75 (Body Depth) in Lagos Lagoon. Caudal Peduncle Length (CV=34.02%) and Mouth Height (CV= 12.44%) had the highest variation in Epe and Lagos Lagoons; respectively. Generally, 56.25% and 37.50% of the attributes had CV>10% in Epe and Lagos Lagoons. Cross-validation of group membership revealed 95.0% (entire), 93.3% (Epe) and 96.7% (Lagos) correctness of the apriori groupings. Pseudotolithus typus population demonstrated taxonomic sanctity, but differentially flexible phenotypes across Epe and Lagos lagoons. This indicates the adaptive potential and survivability of the species in multiple lagoon environments.

INFLUENCE OF TEMPERATURE ON EARLY GROWTH OF Pterocarpus santalinoides L’Hérit. ex DC.

C. Fredrick — 2024-05-13

This study evaluated the effect of temperature on the early growth of Pterocarpus santalinoides seedlings. In a completely randomized experiment, 80 randomly selected seedlings were subjected to four temperature regimes namely: 20/27±3°C, 22/30±3°C, 25/33±3°C and 27/35±3°C. Initial measurements of seedling growth variables were done, four months after sowing and bi-monthly thereafter for twelve months. Variables such as seedling height, stem collar diameter, number of leaves, root length, shoot and root fresh and dry weights, moisture content, total weight and root to shoot ratio were monitored. Data were analysed using Analysis of Variance and Duncan Multiple Range Test was used to separate significantly different means. There were significant differences in the height, collar diameter, number of leaves, root length and biomass of Pterocarpus santalinoides seedlings grown at different temperatures. After four months, the highest height (35.05 cm) was observed for 22/30±3°C treatment, while lowest (28.11) was for 27/35±3°C. From 6 to 12 months, the highest heights: 31.37 cm, 38.04 cm, 45.15 cm and 50.51 cm, respectively, were observed for 25/33±3°C treatment, while the lowest (31.37 cm, 38.04 cm, 45.15 cm and 50.51 cm) were for 20/27±3°C treatment. Highest collar diameters (5.34 mm, 6.88 mm, 8.65 mm, 9.83 mm and 10.48 mm) were observed at 27/35°C±3°C and lowest 3.82 mm, 4.42 mm, 5.86 mm, 6.61 mm and 8.61 mm) at 20/27^oC±3°C, from 4 to 12 months. The longest (44.88 mm) and least (30.58 mm) root lengths were observed at 25/33°C±3°C and 20/27^oC±3°C, respectively. Pterocarpus santalinoides seedlings grew at all tested temperature regimes, with better growth observed at 25/33^oC and 27/35^oC.

EFFECTS OF SALT STRESS ON VEGETATIVE PROPAGATION OF Pterocarpus santalinoides L’Hérit. ex DC.

C. Fredrick — 2024-06-19

The influence of salt stress on sprout length, collar diameter, leaf and branch production, and survival rate of Pterocarpus santalinoides stem cuttings was assessed. In a completely randomized design with five treatments: (0, 5, 10, 15 and 20 grams of salt), 20 cuttings were exposed to each of the five salt solutions. Data were analyzed using descriptive and inferential statistics. There were significant differences in the growth variables across treatments. However, sprout length at six weeks, did not significantly differ. Growth variables decreased with increase in salt stress, with control and 20 g displaying the highest and lowest growth attributes, respectively. Seedlings in control treatments had the highest sprout length (20.65 mm, 28.30 mm, 32.15 mm and 40.35 mm) at 6, 8, 10 and 12 weeks, respectively, while 20 g treatment had the least (15.95 mm, 17.78 mm, 19.80 mm and 25.80 mm). Number of leaves (13.25, 18.75, 22.13 and 36.13), branches (3.50, 4.88, 7.50 and 9.25) and collar diameter (3.50 mm, 4.88 mm, 7.50 mm and 9.25 mm) were highest for control over the 6, 8, 10 and 12 weeks. Stem cuttings of Pterocarpus santalinoides may not thrive well in saline soils, because of the negative effects of salt on seedlings.

MORPHOLOGICAL RELATIONSHIPS, PHYSIOLOGICAL AND OXIDATIVE STRESS RESPONSES OF MALE AND FEMALE AFRICAN SNAKEHEAD (Parachanna obscura Gunther, 1861) FROM EPE LAGOON, LAGOS, NIGERIA

O. K. Kareem — 2024-12-23

Sex-specific oxidative stress response in fish is a widely postulated phenomenon but with limited empirical information on most tropical freshwater fishes. This study was carried out to determine morphological relationships among sexes of Parachanna obscura from Epe Lagoon, Nigeria. It also assessed the physiological and oxidative stress responses of the sexes. Sixty samples of Parachanna obscura were obtained from fishers’ catch and examined for sex, morphometric (18) and meristic (6) characters. Blood samples (?3 ml) were collected from the caudal peduncle vein for haematological analysis. Liver tissues were obtained from male and female samples, homogenized and then assessed for total antioxidant activity (H₂O_2,CAT, GSH, SOD, GPX, GST, MDA and MPO). Data were analysed using descriptive statistics and t-test analysis. Sexual dimorphism was not markedly visible, while all morphometric parameters and meristic counts were consistent between sexes, except for the weight. Females (169.25±52.58 g) were significantly larger than males (159.44±56.78 g). Blood parameters were not significant different between sexes. In addition, the antioxidants and liver enzymes revealed no sex-related differences in activities. These implies that physiological and oxidative responses to environmental stress were similar for both sexes.

ASSESSMENT OF HEAVY METAL CONTENT AND ANTIMICROBIAL ACTIVITY OF WILD MUSHROOM (Ganoderma sp.) IN LAGOS STATE, NIGERIA

L. N. Ofodile — 2025-02-10

Limited efforts have been made to identify and document medicinal macrofungi flora such as Ganoderma species in Nigeria. This study investigated the heavy metal contents, antimicrobial potentials, and molecular characteristics of Ganoderma species from Lagos State, Nigeria. Samples were digested and analyzed for heavy metal contents using Atomic Absorption Spectrophotometry (AAS), while antimicrobial activity was evaluated through the agar well diffusion method. Internal transcribed spacer sequences (ITS1 and ITS4) from four isolates were analyzed using GenBank BLAST. Two species were identified as G. enigmaticum and G. mbrekobenum. Five heavy metals; lead (0.27±0.02 – 0.51±0.19 ppm), cadmium (6.20±4.47 - 9.12±1.80), chromium (0.24±0.47 – 0.36±0.12 ppm), nickel (5.96±0.72 – 7.19±1.25 ppm) and manganese (7.62±0.59 – 11.51±0.31 ppm) were quantified. The Ganoderma spps. exhibited inhibitory activities against Salmonella typhi, Escherichia coli, Candida albicans, Pseudomonas aeruginosa and Staphylococcus aureus at 10 mg/mL, 20 mg/mL 30 mg/mL and 40 mg/mL. The heavy metals were within safe limits established by the World Health Organization, indicating minimal health risks to the general public. The findings suggest that Ganoderma species were safe for consumption and potential sources of novel antimicrobial agents. Hence efforts should be focused on promoting the sustainable utilization of these wild mushrooms.

ALLELOPATHIC EFFECTS OF LEAF EXTRACTS OF Leucaena leucocephala (Lam.) de Wit AND Elaeis guineensis Jacq. ON THE GERMINATION, GROWTH AND YIELD OF Zea mays L.

B. A. Shaibu — 2025-03-07

This study assessed the allelopathic effects of leaf extracts of Leucaena leucocephala (Lam.) de Wit and Elaeis guineensis Jacq. on the germination, growth and yield of maize. Fresh leaves of Leucaena leucocephala and Elaeis guineensis were air-dried, ground to powder and used to prepare leaf extracts at two concentrations: 3% and 6%. Ten maize seeds were sown in petri-dishes; three petri-dishes representing each treatment, with two replicates per treatment. Number of germinated seeds were recorded daily to determine germination percentage, germination speed, seed vigour index and mean germination time. Three maize seeds were planted in each of 100 polythene pots, twenty pots representing each treatment. The experiment was replicated in another 100 pots with fertilizer application. Plant height, collar diameter, number of leaves and biomass were assessed fortnightly for 12 weeks. Number of days to flowering and number of days to fruiting were also assessed. From the germination experiment, 3% Elaeis and 3% Leucaena had the highest germination percentage (100%), followed by 6% Elaeis (96.7%), while the control had the least (90%). The 3% Leucaena had the highest germination speed (4.81), followed by 3% Elaeis (4.67), while 6% Leucaena had the least (3.99). The 3% Elaeis had the highest seed vigour index (1133.33), followed by 3% Leucaena (1066.67), while 6% Leucaena had the least (780). Control had the longest germination time (2.68 days/seed), followed by 6% Leucaena (2.540 days/seed), while 3% Leucaena had the shortest (2.13 days/seed). There were significant differences in the heights of maize across the treatments. The 6% Elaeis + Urea had the highest height (76.42 cm), while 3% Elaeis had the least (49.58 cm). The 3% Elaeis had the highest collar diameter (8.59 mm), followed by 6% Elaeis (8.44 mm), while control had the least (7.28 mm). The 3% Leucaena had the highest number of leaves (9.00), followed by 3% Elaeis (8.96), while 6% Leucaena had the least (8.12). The 3% Elaeis treatment had the highest biomass (50.41 g), followed by 3% Leucaena (48.94 g), while 6% Leucaena had the least (46.1 g). There were significant differences among the yields of maize across the treatments, with 3% Leucaena + Urea having the highest yield (28.48g), while 3% Elaeis had the least (8.70 g). Lower concentrations of Leucaena leucocephala and Elaeis guineensis had inhibitory allelopathic effects on the growth and yield of maize while higher concentrations had stimulatory effects.

VEGETATIVE PROPAGATION OF AFRICAN WALNUT (Plukenetia conophora (Müll Arg) AS AFFECTED BY PROPAGATOR, PLANT PARTS AND ROOTING MEDIA

V. I. Alaje — 2025-03-10

Plukenetia conophora is a seasonal fruiting liana with recalcitrant seeds that are highly competed for by man and rodents. This reduces seedling production from seeds, hence the need for alternative methods of production such as vegetative propagation. One thousand one hundred and twenty (1120) double node cuttings of P. conophora were set up in a factorial arrangement using a completely randomized design with four rooting media, two propagator chambers and two plant parts, with seven replications. At the end of the 12^th week, data collected on rooted cuttings (%), shoot length (cm), number of leaves, number of roots and root length (cm) were subjected to analysis of variance and significant means were separated using Duncan multiple range test at 5% probability level. The results showed that the basal part of cuttings in sterilized river sand, placed inside the mist propagator produced the best result (87%), while the least rooting capacity (20%) was obtained for terminal cuttings rooted in unsterilized topsoil. The use of propagator and type of rooting media had significant effects on the number of roots produced by P. conophora cuttings. Cuttings placed in the propagator chamber had the highest number of leaves (7.31±3.11), while plant part had a significant effect on the shoot length, with terminal cuttings producing the highest shoot length (3.92±5.96 cm). Plukenetia conophora could be propagated vegetatively with due considerations to the parts of plant, media and the rooting environment.

DNA BARCODING OF WILD CICHLID (Tilapia guineensis) FROM SELECTED WATER BODIES IN SOUTHWESTERN NIGERIA

A. B. Usman — 2025-03-13

Proper identification of organisms such as fish is essential for breeding programmes and species conservation. One of the most fundamental requirements in taxonomy is the ability to classify scientifically using DNA barcoding, because it correctly links biological specimens to actual species. This study aimed to establish a barcoding reference database for Tilapia guineensis and assessed the effectiveness of Cytochrome C Oxidase subunit I (COI) gene for species-level fish identification. DNA was isolated from fresh fish tissue (caudal fin) using the phenol-chloroform isoamyl alcohol method, and quantified with a spectrophotometer. The barcode gene region 5? of the mitochondrial Cytochrome Oxidase subunit 1 (CO1) was amplified using the Fish F1 primer. Amplified products were visualized using 1% agarose gel electrophoresis, then purified and sequenced unidirectionally. The sequences acquired were edited, examined, aligned, and compared to sequences from the Gene Bank. Phylogenetic tree was created using populations and other sequences from the Gene Bank. Three major clusters were formed, with 99% similarity in identification among populations. Also, 94% - 96% similarity was detected with other species from other countries. This study demonstrated a high level of confidence and accurate taxonomic identification of fish species from the water bodies in Southwestern Nigeria. Hence, pure Tilapia guineensis strains could be obtained from the wild as broodstocks.