Assessment of oil refinery waste on Rhizophora mangle L. seedling growth in mangroves of Todos os Santos Bay, Bahia, Brazil

Abstract

Seeds of Rhizophora mangle L. were planted and comparatively assessed in six mangroves of Todos os Santos Bay, Bahia, Brazil. Five of the mangroves were on the north of the bay, an area under the influence of oil activities: two areas around the Landulpho Alves Refinery in Mataripe, and in Madre de Deus Island, Pati Island, and Fontes Island. The control site was a mangrove located on the south of the bay at Jiribatuba on Itaparica Island. In January and March, 1994, 1995 and 1998, sets of seeds were established and distributed in a pattern at regular intervals of 0.1, 0.5 and 1.0 m from one another. Every 3 months, the seedlings were assessed for fixation, height, number of lateral branches, surface area and wet and dry weight of leaves. During 1998, five individual seedlings were removed for biomass determination every 6 months. All variables were co-related with environmental conditions. After 12 months, a significant growth pattern difference ( p<0.05) was noted between seedlings from the mangrove around the refinery and those from Jiribatuba, mainly related to the rates of fixation higher than 50% and growth of leaves and precocious lateral branches to the two most impacted mangroves around the refinery, and Madre de Deus and Pati Islands. This branching was not observed on the seedlings grown in the mangroves of Fontes Island and Jiribatuba. The construction of an effluent emission channel into one of the mangrove area from the refinery began in 1998. One hundred and twenty-five seedlings 1 yr in age and other young plants died following direct contact with these effluents in February, 1999.