The toxicity of diesel and petrol on Sesarma huzardi: an aftermath of oil spillage on a tropical mangrove ecosystem

摘要

The effects of diesel spillage on a mangrove ecosystem at Atlas Cove, Lagos, Nigeria and the relative acute toxicity of diesel and petrol on mangrove hairy crab, Sesarma huzardi was reported and investigated respectively. The oil spill effects on mangrove ecosystem were evaluated through collection and identification of the dead macro invertebrate and destroyed vegetation along with the physico-chemical characterization of water samples taken from 4 different stations. The acute toxicity was carriedout using 96h static non-renewal bioassay method. The spilled diesel killed a total of 345 individual animals (9 species). S. huzardi accounted for highest number (39.4%) of individuals killed while Callinectes amnkola (0.9%) accounted for the least. Thespilled diesel killed I55 stands of Achrosticum aureum and 232 stands of Rhizophora racemosa. The observed physico-chemical parameters (TSS, 548.0-842.0mg/L; TDS, 5181.0-7078.0mg/L; DO, 3.8-6.0mg/L; BOD, 25.0-76.0mg/L and THC, 2.0-30SO.Omg/L) reflectedperturbational stress due to the spilled diesel. Based on derived 96hLC_(50)and toxicity factor, petrol (96hLC_(50), 3.70ml/L) was found to be 9 times more toxic than diesel (96hLC_(50), 35.40ml/L) on S. huzardi. ANOVA showed significant difference (P<0.05) in the quantal response (mortality) of S. huzardi to different concentrations of diesel and petrol at 24, 48, 72 and 96h of exposure. Considering the importance of mangrove ecosystem to the nation's economy, it is important that clean-up/ rehabilitation measures are conducted using techniques which minimize ecological and public amenity damage.This should be followed with a recovery assessment of the impacted ecosystem.