Hydrogen radicals, nitrogen radicals, and the production of O3 in the upper troposphere

The concentrations of the hydrogen radicals OH and HO2 in the middle and upper troposphere were measured simultaneously with those of NO, O3, CO, H2O, CH4, non-methane hydrocarbons, and with the ultraviolet and visible radiation field. The data allow a direct examination of the processes that produce O3 in this region of the atmosphere. Comparison of the measured concentrations of OH and HO2 with calculations based on their production from water vapor, ozone, and methane demonstrate that these sources are insufficient to explain the observed radical concentrations in the upper troposphere. The photolysis of carbonyl and peroxide compounds transported to this region from the lower troposphere may provide the source of HOx required to sustain the measured abundances of these radical species. The mechanism by which NO affects the production of O3 is also illustrated by the measurements. In the upper tropospheric air masses sampled, the production rate for ozone (determined from the measured concentrations of HO2 and NO) is calculated to be about 1 part per billion by volume each day. This production rate is faster than previously thought and implies that anthropogenic activities that add NO to the upper troposphere, such as biomass burning and aviation, will lead to production of more O3 than expected.     

The sensitivity and specificity of two methods for detecting Fasciola infections in cattle.

Counts of Fasciola spp. eggs in faeces and measurements of antibody concentration to the excretory/secretory antigens of Fasciola spp. by ELISA were related to the numbers of flukes in the livers of 92 cattle killed in the abattoirs of Hanoi City, Vietnam. In this population, about 22% of the cattle had no flukes, another 22% had between 1 and 10 flukes, 44% between 11 and 100 flukes and 12% had more than 100 flukes in their livers. Of the 14 animals less than 2 years of age, only three were infected. At 2 years of age the mean number of flukes per liver was 10 whereas at 3 years and older, the mean varied between 60 and 80 flukes. Prevalence of infection was 78.3%. No eggs of Fasciola spp. were detected in the faeces of one third of infected cattle and 60% of the counts were less than 100 eggs per gram. The sensitivity of the egg counting method was 66.7% and specificity 100%, overall accuracy was 73.9%. Corresponding values for the ELISA method were 86.1, 70 and 82.6%, respectively. The positive and negative predictive values for the egg counting method were 100 and 45.5% and for the ELISA method were 91.2 and 58.3%, respectively.     

Contribution of Fish Production to Farmers’ Subjective Well‐being in Vietnam – A Logistic Model

There is a growing awareness of the importance of food fish production on human nutrition, employment, poverty, and recreation. However, the role of aquaculture in livelihoods of fish farmers has not been considered rigorously. With 120 farmers interviewed in a field survey and a cumulative logistic model, this study identifies some determinants of subjective well‐being of small‐scale fish farmers in Vietnam and examines the role of earnings from fish production in generating their happiness. The results confirm that the farmers receive satisfaction from their farm working. Subjective well‐being of the farmers increases with their job satisfaction and cash earnings from fish farming. A doubling in cash returns from fish culture relative to household income raises a farmer’s happiness probability by an estimated 10.6%. Education also affects farmers’ life satisfaction. For better educated farmers, when their satisfaction from fish culture increases by one level, happiness probability is estimated to increase by 0.23%. Wild fish plays an important role in Vietnamese farmers as a doubling in relative income from wild fish captures raises their estimated probability of happiness by 139%.     

Trace elements in <Emphasis Type="Italic">Anadara</Emphasis> spp. (Mollusca: Bivalva) collected along the coast of Vietnam,with emphasis on regional differences and human health risk assessment

This study measured concentrations of 21 trace elements in whole soft tissue of the blood cockle Anadara spp., which is a common food for local people, collected along the coast of Vietnam. Results showed that concentrations of As, Sr, Mo, Sn, and Pb in cockles collected from Khanh Hoa Province in the Central Coastal Zone (CCZ) had higher values than those from the other regions, while cockles collected from the Mekong River Delta (MRD) showed the highest concentrations of Hg. Regional differences in trace element concentrations of the cockle may be due to differences in human activities, i.e., shipyards in the CCZ and agriculture in the MRD. Trace element concentrations measured in the soft tissues of blood cockles investigated here were within safe levels for human consumption following criteria by the European Commission (EC) and the United States Food and Drug Agency, but several specimens had Cd levels exceeding the EC guidelines of 1 μg/g wet weight. The estimated target hazard quotients for trace elements via consuming bivalves were <1, indicating that the cumulative noncarcinogenic risk was completely insignificant. However, the estimated target cancer risk values by assumed inorganic As concentrations seem to implicate consumption of these cockles as posing potential human health concerns.     

Where art thou louse? A snapshot of attachment location preferences in salmon lice on Atlantic salmon hosts in sea cages

Problematic sea lice infestations on farmed Atlantic salmon (Salmo salar) have motivated extensive research and development into new methods to prevent, monitor and control sea lice. Most of these technologies require detailed information on the behaviour, spatial distribution and demography of lice on host fish. This study investigated how salmon lice (Lepeophtheirus salmonis) infestation density varies across the host's surface under sea cage farming conditions. Lice abundance, demography and attachment location were tracked over time, with repeated sampling of 300 individually tagged salmon across three replicate experimental sea cages. The data reveal clear differences in attachment locations according to sex and stage, but with an overall preference for the dorsal surface among mobile stages—dorsal head for adult females and dorsal-posterior section for males and pre-adults. Total lice abundance was highly variable between repeated measures of individual fish, consistent with frequent host-switching or mortality. Total lice numbers also declined between sampling dates, likely due to handling, with lost mobile lice being almost exclusively adult males. As the distribution of sea lice on hosts is likely determined by numerous factors, future image-based automated detection systems should be validated in settings that reflect the complex host–parasite interactions that occur in open farming systems.     

Salinization intensifies the effects of elevated temperatures on Channa striata,a common tropical freshwater aquaculture fish in the Mekong Delta,Vietnam

Fisheries Science - Increasing water temperatures and salinity intrusion due to climate change are serious challenges for freshwater aquaculture. In this study, we assessed the combined effects of...     

Testing the yield of a pilot‐scale bubble column photobioreactor for cultivation of the microalga Rhodomonas salina as feed for intensive calanoid copepod cultures

A dual column photobioreactor (PBR) (2 × 47 L) with mixed CO₂/air bubbling was tested for cultivation of the microalga Rhodomonas salina as food for live feed copepods. In the continuous growth phase, the cell density was relatively stable at 2.40 ± 0.13 × 10⁶ cells/ml at an average dilution rate of 0.46 ± 0.02 per day throughout the 30‐day experiment. The produced algae had a high content of both total fatty acids (TFA) and free amino acids (FAA). Especially, the harvested algae contained a high proportion of poly‐unsaturated fatty acids that made up 80% of the TFA and of essential amino acids (35% of all FAA), implicating desirable components as feed for copepods. The current PBR was sufficient to feed a culture of the calanoid copepod Acartia tonsa at a density of 2,500 adult/L in ca. 500 L culture with a daily yield of approximately 17 × 10⁶ eggs. To be able to sustain the integrated copepods production, the suggested volume of the algae cultures should be ca. 20% of the copepod culture volume.     

Concentrations of trace elements in <Emphasis Type="Italic">Meretrix</Emphasis> spp. (Mollusca: Bivalva) along the coasts of Vietnam

The dominant coastal bivalve in Vietnam, hard clams Meretrix spp., collected from the South Key Economic Zone (SKEZ), the Mekong River Delta, and the Central Coastal Zone (CCZ) were analyzed for 21 trace elements. Comparison of the results from the three regions indicated that levels of most of the trace elements, especially As, Mo, Sn, and Pb, were highest in the samples collected from the CCZ, whereas most of the trace elements were found to be present at relatively low levels in samples from the SKEZ. The high concentrations of these trace elements in the CCZ, a sparsely populated region with less human activity than the other two regions, were believed to have originated from industrial waste produced in a shipyard. Although the trace element concentrations in the bivalves were within safe levels for human-consumption criteria reported by the United State Food and Drug Administration and the European Commission, estimation of cancer risk based on As concentration indicates that the hard clams from the CCZ pose a high risk to consumers. Thus, the industrial waste produced in the less densely populated region might increase the health risk to consumers via the contamination of bivalves commonly used as food.     

Simple allele-discriminating PCR for cost-effective and rapid genotyping and mapping

Background  

Single nucleotide polymorphisms (SNPs) are widely observed between individuals, ecotypes, and species, serving as an invaluable molecular marker for genetic, genomic, ecological and evolutionary studies. Although, a large number of SNP-discriminating methods are currently available, few are suited for low-throughput and low-cost applications. Here, we describe a genotyping method named Simple Allele-discriminating PCR (SAP), which is ideally suited for the small-scale genotyping and gene mapping routinely performed in small to medium research or teaching laboratories.     

Bioaccumulation and distribution of trace elements in tissues of giant river prawn <Emphasis Type="Italic">Macrobrachium rosenbergii</Emphasis> (Decapoda: Palaemonidae) from South Vietnam

ABSTRACT:   Accumulation profiles of 22 trace elements in abdominal muscle, abdominal exoskeleton and the hepatopancreas of the giant river prawn Macrobrachium rosenbergii were analyzed. The giant river prawn is an indigenous freshwater species from South Vietnam, and is cultured commercially and fished in the wild. Samples were collected from Ho Chi Minh City and the surrounding area (SKEZ, South Key Economic Zone), and from the Mekong River Delta between 2003 and 2005. Highest accumulations of essential (Cu, Se and Mo) and toxic (As, Ag, Cd and Hg) elements were observed in hepatopancreatic tissue, except for Mn, Sr, Sn, Ba and V in the exoskeleton and Rb and Cs in muscle tissue. Spatial differences showed concentrations of Cs and Pb in muscle and Sr in exoskeletons from the SKEZ were higher than those from the Mekong River Delta. The opposite trend was observed for Cr, Se and Sb in muscle, Mo, Sb and Tl in exoskeleton, and Se, Hg, Mo, Cd, Sb, Tl and Bi in the hepatopancreas. These differences in trace element concentrations in prawns likely reflect differences in industrialization and human activities between the two regions of South Vietnam.