Correlations between the activities of microbial communities and water quality in an earthen pond were investigated monthly during the shrimp growing period. The TAN gradually decreased compared to the beginning time, thereby resulting in an overall decrease of 81.3%. In contrast, the overall nitrate concentration increased 46.3% over this same period. Microbial community analysis using PCR-DGGE showed that changes in community dynamics that occurred during the shrimp growing period might be correlated to water quality. Overall, there were 3 groups of microbial dynamics. The 1st was observed in all investigations, was microflora found in the shrimp culturing system, which included the following: Nitrosomonas eutropha, Exiguobacterium SKRP 5, and Exiguobacteria sp. CNJ771. The 2nd involved the replacement of bacteria from one type to another, such as from Flavobacteriales bacterium to Aquiflexum balticum, which are involved in shrimp shell degradation. The 3rd consisted of microbes observed at only one time point, such as Synechococcus sp. Y0011 (W0), and Stenotrophomonas maltophilia (W3), or at several time points, such as Pseudomonas lanceolata (W0 and W3) and Burkholderia sp. WBF2 (W1 and W2). Although this third group of bacteria was not found at all time points tested, the group was important for balancing the shrimp culturing system, which is important for a successful shrimp cultivation.

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More than two decades that the Gulf of Thailand (GOT) has been installed with petroleum hydrocarbon production platforms, currently over 400 platforms were installed and operated. Since mercury is a common contaminant in petroleum hydrocarbon production in Southeast Asia, minimal risk and environmental integrity should be concerned. Mercury concentration in surface sediment collected from the Gulf of Thailand in 2003 (89 stations), 2012 (174 stations) and 2013 (45 stations). Sedimentological characteristics, readily oxidizable organic carbon and calcium carbonate were determined. All analyses were carried out in our laboratory using cold vapor atomic absorption spectroscopy. The results show an increase in trace amount of mercury in the Gulf's sediment. Average concentrations of mercury in surface sediments in the lower GOT collected in 2003, 2012 and 2013 were 24.4±9.00, 34.9±21.5 and 41.4±15.3 μg/kg dry weight (carbonate free basis). It is coincident to an increment in the number of platforms for natural gas exploration and production in the Gulf of Thailand. Spatial distribution of mercury in the sediments indicates a clearly linked to the exploration, development, production, and processing in petroleum and gas operation. Although the elevation of mercury level in the GOT's sediment does not showed high risk yet, treating and recycling of mercury contaminated substances generated during production are required in order to minimize the health risk in consumption of seafood collecting from the GOT.