Assessing coral reef resilience for sustainable resource management (case study in Hon La island, Quang Binh province, Vietnam)

Coral reefs play a crucial role in providing ecosystem services for the coastal communities. However, the resilience of coral reefs is quickly degraded due to both global and local stressors, including climate change and marine pollution. Hon La island in Quang Binh province, Vietnam is one of the most important coral reef ecosystems. However, this area was heavily influenced by human activities and marine pollution. Therefore, the present study is implemented in order to evaluate the resilience of coral reefs in Hon La island for proposing sustainable development solutions. The proposed indicator framework consisted of three dimensions (coral diversity, biodiversity and environment), containing 26 indicators that potentially provided the quantified methods for decision makers to inform a range of management strategies in protecting coral reefs and using natural resources effectively. Results showed that coral reefs in Hon La island had a low resilient index, about 0.369 because of a degradation of diversity, seawater contaminated by oils and the high turbidity. Several solutions were proposed to enhance the resilience of coral reefs, including the establishment of marine protected areas; integrated management of the coastal zone; rehabilitation of coral reefs and application of co-management models. The theoretical framework from the present study could be potentially applied to evaluate the coral reef resilience in other marine areas in Vietnam with appropriate modification

Quantifying organic carbon storage and sources in sediments of Dong Rui mangrove forests, Tien Yen district, Quang Ninh province using carbon stable isotope

The objective of this study is to quantify the organic carbon (OC) storage and its sources in sediments of Dong Rui mangrove forests, Tien Yen district, Quang Ninh province by analyzing TOC (total organic carbon), TN (total nitrogen), C/N ratios, δ13C isotopes and sediment grain sizes. The results showed that the fine-grained sediment fraction (63 µm) ranged from 8.58 to 82.10%; TOC, TN contents, C/N ratios and δ13C values ranged from 0.21 to 10.20%, 0.01 to 0.34%, 15.07 to 46.09 and –27.75 to –25.84‰, respectively. The variation of δ13C and C/N ratios, and the correlation between TOC, TN and the fine-grained sediment fractions indicated that mangrove forests play important roles in OC sequestration and accumulation of fine-grained sediments. The OC storage in sediments varied from 16.7 to 78.3 MgC ha-1 with an average of 57.2 ±14.9 MgC ha-1. Nowadays, the mangrove forest area in Dong Rui is about 2194.1 ha, thus, the total OC in sediment pool up to 45 cm in depth, contained 1.26(±0.3)×105 MgC, equivalent to 4.6(±1.2)×105 Mg CO2. These results demonstrated that the conservation of Dong Rui mangrove forest not only provides opportunities for coastal protection and disaster mitigation and other provision values, but also enhancing carbon sequestration and offsetting greenhouse gas emissions.References Alongi, D.M., 2011. Carbon payments for mangrove conservation: ecosystem constraints and uncertainties of sequestration potential. Environmental Science Policy 14, 462-470. Alongi, D.M., Sasekumar, A., Chong, V.C., Pfitzner, J., Trott, L.A., Tirendi, F., Dixon, P., Brunskill, G.J., 2004. Sediment accumulation and organic material flux in a managed mangrove ecosystem: estimates of land - ocean - atmosphere exchange in peninsular Malaysia. Marine Geology 208, 383-402. Bouillon, S., Connolly, R., Lee, S., 2008. Organic matter exchange and cycling in mangrove ecosystems: recent insights from stable isotope studies. Journal of Sea Research 59, 44-58. Bouillon, S., Rao, A.V.V.S., Koedam, N., Dahdouh-Guebas, F., Dehairs, F., 2003. Sources of organic carbon in mangrove sediments: variability. Hydrobiologia 495, 33-39. Christensen, B., 1978. Biomass and primary production of Rhizophoraapiculata Bl. in a mangrove in southern Thailand. Aquat Bot 4, 43-52. Donato, D.C., Kauffman, J.B., Murdiyarso, D., Kurnianto, S., Stidham, M., Kanninen, M., 2011. Mangroves among the most carbon - rich forests in the tropics. Nature Geoscience 4, 293-297. Furukawa, K., Wolanski, E., 1996. Sedimentation in mangrove forests. Mangroves Salt Marshes 1, 3-10. Hedges, J.I., Keil, R.G., 1995. Sedimentary organic matter preservation: an assessement and speculative synthesis. Marine Chemistry 49, 137-139. Kauffman, J.B., Donato, D.C., 2012. Protocols for the measurement, monitoring and reporting of structure, biomass and carbon stocks in mangrove forests, 86 pp., Center for International Forest Research, Bogor, Indonesia. Kristensen, E., Bouillon, S., Dittmar, T., Marchand, C., 2008. Organic carbon dynamics in mangrove ecosystems: A review. Aquat Bot 89, 201-209. Lamb, A., Wilson, G., Leng, M., 2006. A review of coastal palaeoclimate and relative sea-level reconstructions using δ13C and C/N ratios in organic material. Earth Science Reviews 75, 29-57. Lovelock, C.E., Ruess, R.W., Feller, I.C., 2011. CO2 efflux from cleared mangrove peat. PLoS ONE 6, 1-4. Ong, J.E., 1993. Mangroves - a carbon source and sink. Chemosphere 27, 1097-1107. Quy, T.D., Tue, N.T., 2011. Spatial distribution of total organic carbon (TOC), total nitrogen (TN), TOC/TN ratio, and stable carbon isotopes value (δ13C) in surface sediments of Tien Yen Bay, northeast Vietnam. Vietnam Journal of Earth Sciences 33, 615-624 (In Vietnamese). Reimers, C.E., Suess, E., 1983. The partitioning of organic carbon fluxes and sedimentary organic matter decomposition rates in the ocean. Marine Chemistry 13, 141-168. Richard, M., Angus, M., Tim, H., 2011. The potential for mangrove carbon projects in Vietnam. SNV REDD+, Hanoi. Schumacher, B.A., 2002. Methods for the determination of total organic carbon in soils and sediments. U.S. Environmental Protection Agency, Washington. Siikamäki, J., Sanchirico, N., Jardine, J., McLaughlin, S., Morris, D.F., 2012. Blue carbon: global options for reducing emissions from the degradation and development of coastal ecosystems. Resources for future, Washington. Spalding, M., Kainuma, M., Collins, L., 2010. World atlas of mangroves. Earthscan from Routledge, London. Tuan, H.V., Quy, T.D., Vuong, N.V., Nhuan, M.T., 2012. Orientation of functional zoning for sustainable use of environment and natural resources in Tien Yen Bay. Vietnam Journal of Earth Sciences 34, 486-494 (In Vietnamese). Tuan, M.S., Hanh, N.T.H., 2009. Carbon accumulation of Kandeliaobovata (Sheue, Liu Yong) plantation in the coastal area of Giao Thuy district, Nam Dinh province. Journal of Biology 31, 57-65 (In Vietnamese). Tue, N.T., Dung, L.V., Nhuan, M.T., Omori, K., 2014. Carbon storage of a tropical mangrove forest in Mui Ca Mau National Park, Vietnam. Catena 121, 119-126. Tue, N.T., Hamaoka, H., Sogabe, A., Quy, T.D., Nhuan, M.T., Omori, K., 2011. The application of δ13C and C/N ratios as indicators of organic carbon sources and paleoenvironmental change of the mangrove ecosystem from Ba Lat Estuary, Red River, Vietnam. Environmental Earth Sciences 64, 1475-1486. Tue, N.T., Ngoc., N.T., Quy, T.D., Hamaok, H., Nhuan, M.T., Omori, K., 2012. A cross-system analysis of sedimentary organic carbon in the mangrove ecosystems of Xuan Thuy National Park, Vietnam. Journal of Sea Research 67, 69-76. Van Santen, P., Augustinus, P., Janssen-Stelder, B., Quartel, S., Tri, N., 2007. Sedimentation in an estuarine mangrove system. Journal of Asian Earth Sciences 29, 566-575

INTEGRATED ASSESSMENT OF RISK LEVEL CAUSED BY HAZARDS IN THE COASTAL ZONE OF VIETNAM (CASES STUDY : CAM RANH-PHAN RI COASTAL ZONE)

Joint Research on Environmental Science and Technology for the Eart

CHARACTERIZATION AND MITIGATION OF VIETNAM COASTAL HAZARDS FOR SUSTAINABLE DEVELOPMENT

Joint Research on Environmental Science and Technology for the Eart

Safety and efficacy of fluoxetine on functional outcome after acute stroke (AFFINITY): a randomised, double-blind, placebo-controlled trial

Background Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after stroke improves functional outcome in an ethnically diverse population. Methods AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921. Findings Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 [3%] vs seven [1%]; p=0·018), bone fractures (19 [3%] vs six [1%]; p=0·014), and epileptic seizures (ten [2%] vs two [<1%]; p=0·038) at 6 months. Interpretation Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke

The effect of crab burrows on soil‐water dynamics in mangroves

Many mangrove ecosystem services, such as carbon sequestration, are closely linked to mangrove soil water content, which in turn is thought to depend on animal burrow density and the properties of the sediment in which the burrows are constructed. We measured the water content in the sediment matrix between crab burrows across 26 plots in a typical, fine-grained (clay), mangrove soil in the Mekong Delta, Vietnam. We found that the water content of the sediment matrix remained more or less constant throughout the tidal cycle, and was independent of burrow density. Our results suggest that there is little exchange of water between the burrows and the associated sediment matrix and that burrows act as an independent pipe network transporting water through the mangrove soil. To check and extend our findings, we used a numerical groundwater model to simulate an idealised burrow in a range of sediment types. The model results confirmed that fine-grained mangrove sediments do not drain readily into adjacent animal burrows because of their very low permeability. Our results have important implications for understanding and forecasting mangrove carbon dynamics with sea level rise