Relative toxicity of
spent lubricant oil and detergent against benthic macro-invertebrates of a west
african estuarine lagoon
L.O. Chukwu and
C.C. Odunzeh
Aquatic Toxicology and Ecophysiology
Laboratory,
Department of Marine Sciences, University
of Lagos, Akoka,
Lagos, Nigeria
(Received: 6 April, 2005 ; Accepted: 1July, 2005)
Abstract: The relative acute toxicity of spent lubricant oil and detergent was
evaluated against hermit crab, Clibanarius africanus (Aurivillus) and
periwinkle, Tympanotonus fuscatus
(L) from the Lagos
lagoon in laboratory bioassays. Based on the derived toxicity indices, the
detergent (96 hr LC50 = 5.77ml/l) was found to be 1.73 times more
toxic than spent engine oil (96 hr LC50 = 10.01ml/l) when acting
singly against C africanus
and 18.73 times (96 hr LC50-48.67 ml/l) more toxic (96 hr LC50
= 911.57 ml/l) when acting singly against T. fuscatus. On the basis of the
computed susceptibility factors, C.africanus was found to be about eight times and
ninety-one times more susceptible to the toxic effect of detergent and spent
lubricant oil respectively. The randomized analysis of variance (ANOVA) showed
that there was significant difference (Fcal
58.83 Ftab 3.87; DF 13; p>0.05) between
all treatments of spent lubricant oil and detergent during the 96 hr exposure
period of test animals. At 5% level of significance the Student Neuman-Keuls (SNK) test further revealed significant
differences in the mean mortality response of test animals exposed to toxicants
at all concentrations and untreated control. The results obtained in this study suggest that the
estuarine benthic macroinvertebrates, which play key
roles in the environment, may serve as useful in-situ sentinels for biomonitoring
studies of petroleum pollutants in fragile aquatic ecosystems such as the Lagos lagoon.
Key words: Relative toxicity, Spent
oil, Detergent, Macroinvertebrate.
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