This study describe the reproductive biological characteristics and population parameters of the goby, Pseudapocryptes elongatus (Cuvier, 1816), in the coastal mud flat areas of the Mekong Delta, Vietnam. A total of 1058 specimens was collected from January 2004 to June 2005 and results showed that the breeding season occurred with two spawning peaks in July and October. Length at first maturity (L(m)) was 15.4 and 16.3 cm for females and males, respectively. The batch fecundity estimates ranged from 2,652 to 29,406 hydrated oocytes per ovary in the fish ranging from 12.8 to 22.4 cm TL. Length frequency data of the goby ranging from 9.0 to 24.0 cm TL were analyzed using the FiSAT II software. The von Bertalanffy growth parameters were determined as L8 = 25.9 cm, K = 0.66 year(-1) and t(o) = - 0.26 year(-1). The longevity (t(max)) of the goby was estimated to be 4.55 years. There were two recruitment peaks with very different magnitudes and the means of these two peaks were separated by an interval of 5 months. Length at first capture (L(c)) was 10.05 cm, the instantaneous fishing mortality rate (F = 1.38 year(-1)) and natural mortality rate (M = 1.46 year(-1)) accounted for 49 and 51% of the total mortality (Z = 2.84 year(-1)), respectively. Relative yield-per-recruit and biomass-per-recruit analyses gave E(max) = 0.65, E0.1 = 0.55 and E0.5 = 0.33. Results show that the fish stock is subjected to growth overexploitation.
In the present study, samples of pond water, sediment and farmed species were collected at 12 fish and shrimp farms in Malaysia, Thailand and Vietnam to determine the biodiversity and environmental distribution of chloramphenicol-resistant (CmR) mesophilic heterotrophs in Southeast Asian aquaculture sites. Following isolation on Iso-Sensitest agar supplemented with 35mug ml(-1) Cm and dereplication using (GTG)(5)-PCR fingerprinting, 557 genotypically unique CmR strains were subjected to polyphasic identification. The 557 mesophilic heterotrophic CmR isolates represented 18 different genera largely dominated by the genera Escherichia (40.2%), Pseudomonas (11.7%), Acinetobacter (11.1%), Klebsiella (7.5%) and Bacillus (5.9%). A total of 439 CmR isolates were further assigned to 31 described species or species groups, mainly including organisms that have been associated with various human opportunistic infections such as Escherichia coli (n=219), Pseudomonas putida (n=47), Klebsiella pneumoniae (n=38) and Acinetobacter baumannii (n=23). Strains of Escherichia, and most notably, of E. coli, were the only common group of CmR heterotrophs irrespective of country, sample type or farm type. Together with other predominant but less widespread groups such as acinetobacters and pseudomonads, the results of this biodiversity study suggest that E. coli can be regarded as a potential indicator of Cm resistance in Southeast Asian aquaculture environments.
Rice straw residue management is still facing many problems worldwide. This study used two environmentally friendly methods to investigate the effects of rice straw burning activity on water-extracted carbohydrate content in long-term paddy soil. Soil samples were collected at a depth within 0-15 cm at the paddy field before and after burning rice straw (pre-burning and post-burning), then extracted by distilled water at the ratio of 1:10 (soil: water) for measuring hot water (at 80 °C) and water extracted carbohydrate (at 25 °C) (HECH and WECH). The results showed that burning rice straw did not alter soil organic carbon (SOC); however, soil pH increased approximately 8.3%. Meanwhile, WECH and HECH ranged from 233 to 630 mg kg-1, with the highest HECH in Pre-burning treatment, while the lowest amount addressed WECH of Post-burning treatment. Extracted carbohydrate decreased after burning rice straw compared to Pre-burning soil. On the other hand, hot water increased 39-58% of carbohydrates compared to water extraction. We conclude that burning rice straw did not affect SOC but tends to reduce their labile carbon pools, and the heating process likely degrade part of SOC when extracted at high temperatures.
Childhood obesity prevalence is shooting up at a phenomenal rate worldwide, leading to long-term devastating consequences. A great number of studies have investigated factors contributing to the increase in BMI of children and adolescents. School-based, home-based and clinic-based solutions have been suggested as possible viable strategies, among which school-based interventions is believed to produce a noticeable effect on a massive scale. However, the question of whether school interventions, especially school education exert significant impact on childhood obesity or not, is left with mixing results. This article aims to holistically review the relationship between school education and childhood obesity. Various factors are covered, including health education, nutrition education, school nutrition, physical education, teachers' awareness, teaching practice and school stress, In all, school education is not the answer to childhood obesity but just part of it. More attempts from other stakeholders (parents, community, policy makers, researchers, etc.) should be made in order to solve this complicated puzzle.
Aquaculture systems are highly complex, dynamic and interconnected systems influenced by environmental, biological, cultural, socio-economic and human behavioural factors. Intensification of aquaculture production is likely to drive indiscriminate use of antibiotics to treat or prevent disease and increase productivity, often to compensate for management and husbandry deficiencies. Surveillance or monitoring of antibiotic usage (ABU) and antibiotic resistance (ABR) is often lacking or absent. Consequently, there are knowledge gaps for the risk of ABR emergence and human exposure to ABR in these systems and the wider environment. The aim of this study was to use a systems-thinking approach to map two aquaculture systems in Vietnam - striped catfish and white-leg shrimp - to identify hotspots for emergence and selection of resistance, and human exposure to antibiotics and antibiotic-resistant bacteria. System mapping was conducted by stakeholders at an interdisciplinary workshop in Hanoi, Vietnam during January 2018, and the maps generated were refined until consensus. Thereafter, literature was reviewed to complement and cross-reference information and to validate the final maps. The maps and component interactions with the environment revealed the grow-out phase, where juveniles are cultured to harvest size, to be a key hotspot for emergence of ABR in both systems due to direct and indirect ABU, exposure to water contaminated with antibiotics and antibiotic-resistant bacteria, and duration of this stage. The pathways for human exposure to antibiotics and ABR were characterised as: occupational (on-farm and at different handling points along the value chain), through consumption (bacterial contamination and residues) and by environmental routes. By using systems thinking and mapping by stakeholders to identify hotspots we demonstrate the applicability of an integrated, interdisciplinary approach to characterising ABU in aquaculture. This work provides a foundation to quantify risks at different points, understand interactions between components, and identify stakeholders who can lead and implement change.