Impacts of Livelihood Activities on the Environment and Natural Resources of Can Gio Mangrove Forest, Ho Chi Minh City

In recent years, local livelihood activities in the Can Gio district have increased significantly, including aquaculture practices, aquaculture cultivation, salt-works, forest guard, farming, livestock, tourism, and etc. These livelihood activities have contributed remarkably to the local economy and the improvement of living conditions for local people. However, the burgeoning development of these activities have posed negative impacts on the mangrove ecosystem in Can Gio. In which, the use and exploitation of existing human and natural resources are paid inadequate attention. The purpose of this study is to identify livelihoods by conducting a survey with 536 questionnaire samples in both the buffer and transition zones in Can Gio Mangrove Forest. In addition, the quality of surface water sources was examined by collecting 70 surface water and wastewater samples. The results show that the quality of surface water meets the allowable limits of QCVN 08-MT:2015/BTNMT. The extent of the impact from livelihood activities on the environment of mangrove forest is at the medium level. However, the livelihood of aquaculture cultivation practices has the most affect on the environment and natural resources and is posing negative impacts on the quality of water sources in Can Gio Mangrove Forest. Therefore, these findings will be useful information for decision makers of the local authority in building an appropriate planning for aquaculture cultivation area. Further, irrigation and drainage systems for aquaculture practices need to be invested to control and handle wastes from aquaculture cultivation areas.

Investigating the Correlation of Microplastic Pollution Between Seawater and Marine Salt Using Micro-Raman Spectroscopy

Microplastics (MPs) are synthetic polymer pieces with a size of less than 5 mm that are ubiquitous in the marine environment. They have been recently detected in several wild species and sea products. An indispensable condiment in human food is marine salt that is produced from seawater. Since toxicity studies report potential health impacts when plastic debris is ingested, more attention must be paid to the MP contamination of sea salt and the underlying reasons for this. The central aim of this study is to evaluate the MPs contamination level of sea salt in correlation with the MPs contamination level of seawater in Vietnamese areas. Micro-Raman spectroscopy was employed to determine MPs in the samples collected from three artificial salt pans of Vietnam. The result revealed the presence of MPs in all study areas—Vung Tau (VT;14.54 MPs/L seawater and 114.67 MPs/kg salt), Ly Nhon (LN; 13.14 MPs/L seawater and 63.59 MPs/kg salt), and Can Thanh (9.42 MPs/L seawater and 93.69 MPs/kg salt). The comparisons highlight close correlations in the percentage, shape, size, and color of MPs, especially polyethylene, polyethylene terephthalate, and polypropylene particles extracted from the seawater and its salt. This study proved that seawater is a plastic pollution source for salts produced by traditional seawater evaporation. The study also alerts the prevalence of MPs in the environment and human consumables, thereby indicating that actions must be taken to reduce the pollution of water sources in Vung Tau and at the UNESCO Can Gio Mangrove Biosphere Reserve and improve salt production and refinery processes in order to minimize the number of MPs in final salt products for safe consumption.

High Amylase Production by a Novel Strain of Bacillus amyloliquefaciens M37 Isolated from Can Gio Mangrove Forest, Vietnam

Amylases are one of the most important industrial enzymes and find applications in many areas such as textiles, chemicals, food, and pharmaceuticals. Most of the amylases are derived from microbes. The objective of the present study was to evaluate amylase production by a bacterium isolated from the Can Gio mangrove forest. The bacterium was identified as a species of genus Bacillus based on morphological and biochemical characteristics. The analysis of 16S rRNA sequences was then confirmed that this strain belonged to Bacillus amyloliquefaciens species (100% similarity). The effect of culture conditions such as temperature, pH, and carbon sources on amylase production through shake-flask culture was investigated. Maximum amylase activity of 904 IU/mL was obtained after 24 h of cultivation in LB medium containing 1% soluble starch at 35oC and pH 7.0. The highest enzyme activity of 1279 IU/mL was achieved in the bioreactor after 30 h of cultivation at optimum conditions. In addition, B. amyloliquefaciens M37 can grow on soybean meal medium. The high bacterial cell number of 456 × 109 CFU/g and amylase activity of 1039 IU/g were obtained after 36 h of cultivation. This newly isolated B. amyloliquefaciens M37 could be a potential producer for industrial amylase production and probiotics with commercial implications.

Isolation, Selection and Antimicrobial Activity of Actinomycetes from Mangrove Soil of Can Gio Forest, Hochiminh City, Vietnam

The Can Gio Mangrove is a Biosphere Reserve of UNESCO since 2000 and it is also a well-known example of “mangrove afforestation and reforestation area’’. A total of 63 actinomycetes were isolated from 25 samples of 9 different sites in mangrove forest soil Can Gio, HoChiMinh city, Vietnam. Almost their colonies have round-shaped; milky, white clear and yellow, entire or loabate margin; diameter size of these colonies varied from 0.2 to 3.0 mm. Twenty-nine of 63 tested isolates could produce antimicrobial active metabolites inhibiting at least one of the tested pathogens and 9 isolates were selected for 16S rDNA sequencing. The result showed that genus Streptomyces (8 isolates) and other genera including 1 isolates were Gram-negative bacteria (Stenotrophomonas). The antimicrobial activity and the amplifying genes coding for polyketide synthetase (PKS) and nonribosomal peptide synthetase (NRPS) showed that 8 strains had broad-spectrum antimicrobial activity, mainly against gram-positive bacteria as Bacillus cereus and Staphylococcus aureus.

Green GRDP calculation by total economic value methods: Case study in Cần Giờ mangrove biosphere reserve

In the context that Vietnam develops for international integration, the government has oriented socio-economic development to develop in a sustainable way, not kind of development at all costs. This is clearly shown through the fact that ministries and governmental institutions have adjusted policies and target programs to achieve the millennium goal set by the United Nations to serve the action plan for the sustainable development of the entire nation. From the point of view of sustainable development, many countries around the world have calculated green GDP instead of normal GDP to see that economic development must be closely linked to social progress and environmental protection. Throughout many years of research on the total economic value of a system of environmental resources, especially the total economic value of the humanistic ecology system of Can Gio Mangrove Biosphere Reserve, the author found that there are similarities in the calculation of green GRDP and that of the total economic value of a geographic area. This paper aims to present a conceptual framework to calculate the green GRDP for the Can Gio Mangrove Biosphere Reserve, using total economic value methods. The author also links the United Nations documents and the Statistics Law with the Government of Vietnam's guiding documents for implementing the law to formulate a green GRDP calculation conceptual framework using the methods of total economic value calculation. To calculate the Green GRDP of Can Gio Mangrove Biosphere Reserve by using the total economic value methods is an illustration to convince the validity of the Green GRDP Conceptual Framework. Hopefully there will be many comments from scientists and managers to be able to unify how to calculate green GRDP for mangrove areas and to move towards calculating green GRDP for the national economy, in order to manage the balance between "conservation for development" and "development for conservation" according to the trend of sustainable development.

Long-Term Heavy Metal Retention by Mangroves and Effect on Its Growth: A Field Inventory and Scenario Simulation

The ability of mangroves in taking up and storing heavy metal (HM) helps in reducing HM pollution. However, HMs likewise adversely affect the growth of mangroves. We assess the effects of the long-term soil HMs enrichment on the growth of Rhizophora apiculata forest in the Can Gio Mangrove Forest (Southern Vietnam) in different environmental conditions of soil salinity, ground elevation, and tree density based on a novel set of measured data. These data were analyzed and were used to calibrate and validate for a tree growth model with influencing factors salinity, elevation, tree density, and heavy metals content. Three scenario simulations were performed to predict the mangrove dynamics under different levels of heavy metal pollution in combined environmental conditions of salinity and elevation. Simulation results show the decline of total forest biomass from 1,750,000 tons (baseline scenario with no HM pollution) down to 850,000 tons and 350,000 tons for the current HM pollution and double HM pollution scenarios, respectively. Both data analysis and simulations have shown that although mangroves can assist in reducing HM pollution, the quality and health of this ecosystem will be severely affected if the environment is excessively polluted. In addition, a data-and-model driven management tool is devised for the sustainable management of the mangrove environmental resources.