Post-spill Behavior in an Oil Contaminated Mangrove Stand Avicennia marina (Forssk.) Vierh in U.A.E. PDF

Keywords

Defoliation, reproductive effort, seedlings recruitment, anomalous growth, oil hydrocarbons, physiological responses

Abstract

The effect of post-spill defoliation and the subsequent readjustment in resource allocation was investigated in relation to individual reproductive fitness of the monotypic mangrove stands Avicennia marina in Umm Al-Qwain Bay, northeastern United Arab Emirates. The effects of the persistence of high levels of oil hydrocarbons in the sediments after the spill on propagule dispersal, seedling recruitment, and anomalous vegetative growth forms were also studied. Growth and physiological performance of the new individuals produced from polluted and unpolluted vegetations were compared under glasshouse conditions. Vegetative recovery of the oiled mangrove stands from post-spill massive defoliation had a negative effect on all stages of plant reproductive events including flowering, fruiting and propagule dispersal. Persistence of toxic levels of oil hydrocarbons in the substrate has further reduced the possibility of successful establishment of the new generation in the contaminated site. A significant correlation exists between the levels of hydrocarbons in the sediments and the degree of anomalies in shoot growth of seedlings (r^2 = 0.862) and the newly growing pneumatophores (r^2 =0.827). Improving substrate condition by reducing levels of toxic hydrocarbons would increase the chance for better recruitment and performance of the new generation of seedlings. Active rehabilitation processes at the site may enhance the site productivity and minimize time for natural recovery.