Mangrove Ecosystem and Crude oil: Reactions of Mangrove Ecosystem to Acute and Chronic Crude oil Contamination

Oil spillages in mangrove ecosystems can be problematic hence, the need to source for bioremediation strategies from within the ecosystem. Red mangrove seedlings were carefully uprooted from mangrove soil of Ugbokodo community of Uvwie Local Government Area of Delta State, Nigeria. These acclimatized seedlings were exposed to acute treatment of one-time application of 150 ml crude oil and chronic treatment of weekly application of 20 ml crude oil. Mangrove seedlings’ reactions to crude oil were investigated by observing their stem height, stem girth, numbers of leaves and leaf area fortnightly for 90 days. Also, chemical parameters (pH, heavy metals, and total petroleum hydrocarbon-TPH) were analyzed to determine the effects of the crude oil on the mangrove soils. The findings revealed notable degrees of growth in the mangrove seedlings and seedlings with chronic treatment recorded a higher increase of growth. The highest decrease in pH was observed in soil with chronic treatment (SWCT) from 5.55 at day 0 to 5.18 at day 9. The highest decrease in TPH concentration was observed in SWCT from 958.4 ppm at day 0 to 412.33 ppm at day 90. There was a decrease in the concentrations of heavy metals except for Pb in soil with acute treatment (SWAT) during the 90 days incubation period. The findings revealed that mangrove plants exposed to acute and chronic contamination both have phytoremediative abilities but seedlings with chronic treatment demonstrated greater phytoremediative capacity and acute contamination of crude oil has more adverse effect on the mangrove soil ecosystem than chronic contamination.