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, S. O. Agbo, G. E. Olumayede, O. S. Lawal — Mon, 25 Mar 2024 00:00:00 +0000

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, O. Onadokun, S. O. Ogboye — Wed, 27 Mar 2024 00:00:00 +0000

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.

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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

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