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| Author(s): |
Juliano de Carvalho Cury
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba. , gráficos, tabelas. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2002-07-02 |
| Examining board members: |
Marcio Rodrigues Lambais;
Marco Antonio Nogueira;
Jorge Luiz Mazza Rodrigues
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| Advisor: | Marcio Rodrigues Lambais |
| Field of knowledge: | Agronomical Sciences - Agronomy |
| Indexed in: | Banco de Dados Bibliográficos da USP-DEDALUS; Biblioteca Digital de Teses e Dissertações - USP |
| Location: | Universidade de São Paulo. Biblioteca Central da Escola Superior de Agricultura Luiz de Queiroz; t631.4; C982a |
| Abstract | |
Mangroves are at constant risk of degradation due to industrial and harbor activities in the estuaries. Among potentially harmful activities, the petrochemical industries are important contamination sources for mangroves. Information on the effects of oil hydrocarbons on bacterial communities in mangrove soil is lacking. The objective of this work was to determine variations in the activities and metabolic and genetic diversities of microbial communities in an oil contaminated mangrove soil. The area studied is located in the Bertioga Channel (Santos, SP), and was contaminated by an oil spill in 1983. Samples were collected from three spots in a 300 m transect between the Iriri River and the mangrove-slope contact, and named: P1, spot in the vicinity of the riverbank; P2, intermediary spot; P3, spot in the vicinity of the oil spill (mangrove-slope contact). Chemical analyses of samples from these spots showed that the remaining oil concentration was higher at P3 and decreased towards P1, probably due the influence of flooding and tide reflux. From each spot, triplicate subsamples representing layers: 0-5, 5-10, 10-15, 15-20, 20-30, 30-40, 40-50, 50-60, 60-70, 70-80, 80-90 and 90-100 cm (except in P3, where sampling at depths higher than 80 cm was not possible) were collected. Soil samples were subjected to the following analyses: pH, Soil Humidity, Most Probable Number of Heterotrophic Bacteria (MPN), C-biomass, Basal Respiration (BR), Substrate Induced Respiration (SIR), Metabolic Quotient (qCO2), Metabolic Diversity and Genetic Diversity. The MPN of aerobic heterotrophic bacteria was 3.5 times higher in P3 than in P1 and P2. The microbial biomass did not show significant differences between sampled spots. However, significant differences were observed for sampling depths. The highest values of C-biomass were observed in 0 to 5 cm layers. The BR was significantly affected by factors SAMPLING SPOT and SAMPLING DEPTH. In P3, the average BR was 39% higher than in P1 and P2. Among sampling depths, the highest values for BR were observed at 50 to 100 cm. The SIR was significantly affected by the interaction between factors SAMPLING SPOT and SAMPLING DEPTH, and was highest in P3 at 0 to 5 cm. The average qCO2 was 45% lower in P2 than in P1 and P3. The metabolic diversity, based on the ability to use C-sources, did not differ among sampling spots, but showed a gradual decrease at greater depths. Analyses of Bacteria 16S rDNA amplicons by DGGE revealed lower species richness (SE) in P3, as compared to P1 and P2, which was probably associated with residual oil contamination. Archaea showed less variation in the samples. Hierarchical clustering showed that Bacteria community structures were more similar among sampling spots than sampling depths, whereas Archaea community structures were more similar among sampling depths than between sampling spots. In general, these results suggest that 20 years after an oil spill, Bacteria communities had been altered in a fashion that changed the community structure, but which did not affect their activity or function. (AU) | |