Abstract
This study examined the effect of different concentrations of bonny light crude oil on the development and growth of the tadpoles of the crowned bullfrogs. After series of range finding tests (RFT) the tadpoles of H. occipitalis were exposed to acute and sub-lethal log concentrations of 0.00 ppm, 1.00 ppm, 1.30 ppm, 1.48 ppm, 1.60 ppm, 1.65 ppm and1.69 ppm of different fractions of bonny light crude for 96 hours. The various fractions of crude recorded no significant differences in mortalities (P > 0.05) for three- and four-weeks old tadpoles. The mortalities increased with increase in concentration of toxicants. The tadpoles recorded 75% mortalities in Water Soluble Fraction (WSF), 65 % mortalities in Water Insoluble Fraction (WIF) and 70 % and 75 % mortalities respectively in Whole Crude (WC). The WSF of crude showed the lowest LC50’s in the tadpoles ranging from 1.51 ± 0.17 ppm with (lower limit 1.45 and upper limit 1.55) to 1.61 ± 0.37 ppm with (lower limit 1.58 and upper limit 1.65). WIF showed the highest LC50’s in the tadpoles ranging from 1.62 ± 0.42 with (lower limit 1.59 and upper limit 1.66) to 1.69 ± 0.41ppm with (lower limit 1.55 and upper limit 1.62). The WC showed an LC50’s range of 1.60 ± 0.37 ppm with (lower limit 1.56 and upper limit 1.64) to 1.63 ± 0.32 ppm with (lower limit 1.59 and upper limit 1.66). Results shows that increased toxicity produced higher mortalities in tadpoles of H. occipitalis (an endangered species). This study therefore advocates that Oil companies should adhere to the current WHO / FEPA regulatory limits of 0.2 mg/l to 14.0 mg/l for C5 – C22 hydrocarbons to ensure the survival of its vital ecological niche. 
 Mowang, A. D. | Department of Zoology and Environmental Biology, University of Calabar, Nigeria.
Highlights
IntroductionThe introduction of crude oil (petroleum) can be very fatal to a population of amphibians including eggs and larval forms (tadpoles) directly or indirectly
The introduction of crude oil can be very fatal to a population of amphibians including eggs and larval forms directly or indirectly
This research was aimed at determining the rates of mortality of three and four weeks old tadpoles, manifestation time and survival time of H.occipitalis treated with different concentrations of Water Soluble Fraction (WSF), Water Insoluble Fraction (WIF) and Whole Crude (WC) fractions of bonny light crude and to estimate the LC50 of exposure after 96 h of crude on three and four weeks old tadpoles of H. occipitalis
Summary
The introduction of crude oil (petroleum) can be very fatal to a population of amphibians including eggs and larval forms (tadpoles) directly or indirectly. Reproduction could be impaired by environmental interference This could occur in adult reproductive function, inhibiting breeding behaviour, gamete formation, or fertilization. This could result in the disruption of development and growth of the young. Crude oil pollutants have varying effects on frogs. In a study conducted in a laboratory at Upsala University in Sweden, more than 50% of frogs exposed to various levels of estrogen-like pollutants existing in natural bodies of water in Europe and the United States became females. Another study by Enyamremu et al, (2007) was on the effect of sub-lethal levels of bonny light crude oil and its water soluble and insoluble fractions on stress enzymes in tadpoles (xenopus laevis) following two- and four-weeks exposure at different concentrations. Another study by Enyamremu et al, (2007) was on the effect of sub-lethal levels of bonny light crude oil and its water soluble and insoluble fractions on stress enzymes in tadpoles (xenopus laevis) following two- and four-weeks exposure at different concentrations. Mahaney (1994) found that while hatching success of Hyla cinerea eggs was not significantly impacted by exposure to 10,55 and 100 mg/ι of crankcase oil, growth rates of larvae exposed to higher concentrations of oil were significantly retarded
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
