Microhabitat association in white-streaked grouper Epinephelus ongus: importance of Acropora spp.

Microhabitat associations are considered to be important for juvenile survivorship and growth of coral reef fishes. The aim of the study was to quantify microhabitat associations between juvenile and adult white-streaked grouper Epinephelus ongus, which supports important fisheries in coral reef areas. Underwater observations revealed that most juveniles were found in bottlebrush Acropora spp., staghorn Acropora spp. and coral rubble and there was a significant positive use of bottlebrush Acropora spp. and a significant negative use of coral rubble. For adults, most individuals were found in bottlebrush Acropora spp. and staghorn Acropora spp., and there was a significant positive use of staghorn Acropora spp. and significant negative use of coral rubble. A habitat choice experiment by using pre-settlement individuals revealed that both bottlebrush Acropora spp. and staghorn Acropora spp. were used as settlement sites, whereas coral rubble was rarely used as a settlement site. Results of the study suggest that juvenile and adult E. ongus showed significantly positive microhabitat associations with bottlebrush Acropora spp. and staghorn Acropora spp., respectively, in the field. Bottlebrush Acropora spp. has smaller inter-branch spaces than staghorn Acropora spp., which could drive patterns of microhabitat associations. In addition, post-settlement processes such as predation may influence the spatial distribution of juveniles. Because Acropora corals are very susceptible to coral bleaching, we predict that rising temperatures from climate change will negatively impact populations of E. ongus.     

Recovery of solid fuel from municipal solid waste by hydrothermal treatment using subcritical water

Hydrothermal treatments using subcritical water (HTSW) such as that at 234 °C and 3 MPa (LT condition) and 295 °C and 8 MPa (HT condition) were investigated to recover solid fuel from municipal solid waste (MSW). Printing paper, dog food (DF), wooden chopsticks, and mixed plastic film and sheets of polyethylene, polypropylene, and polystyrene were prepared as model MSW components, in which polyvinylchloride (PVC) powder and sodium chloride were used to simulate Cl sources.While more than 75% of carbon in paper, DF, and wood was recovered as char under both LT and HT conditions, plastics did not degrade under either LT or HT conditions. The heating value (HV) of obtained char was 13,886-27,544 kJ/kg and was comparable to that of brown coal and lignite. Higher formation of fixed carbon and greater oxygen dissociation during HTSW were thought to improve the HV of char.Cl atoms added as PVC powder and sodium chloride to raw material remained in char after HTSW. However, most Cl originating from PVC was found to converse into soluble Cl compounds during HTSW under the HT condition and could be removed by washing.From these results, the merit of HTSW as a method of recovering solid fuel from MSW is considered to produce char with minimal carbon loss without a drying process prior to HTSW. In addition, Cl originating from PVC decomposes into soluble Cl compound under the HT condition. The combination of HTSW under the HT condition and char washing might improve the quality of char as alternative fuel.     

Special Issue: Statistical mathematics for ecological and environmental data

Environmental and Ecological Statistics -     

Effects of triphenyltin chloride and five other organotin compounds on the development of imposex in the rock shell, Thais clavigera

The imposex promotion activities of six organotin compounds--tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), triphenyltin (TPT), diphenyltin (DPT) and monophenyltin (MPT)--were examined by injection experiments with the rock shell, Thais clavigera (Prosobranchia; Muricidae). TPT and TBT had strong effects on the development of imposex in the rock shell (p<0.001). The other organotin compounds (DBT, MBT, DPT and MPT) had no or less effects on the development of imposex in T. clavigera. The difference between the effects of TPT and TBT was statistically insignificant (p>0.01). The effects of these compounds are estimated, from the relationships between TBT or TPT concentration in tissue and mean penis length of females after injections, to be approximately the same.     

Detection of Hepatitis E Virus in Sewage After an Outbreak on a French Island

A hepatitis E outbreak, which occurred on a small isolated island, provided an opportunity to evaluate the association between the number of hepatitis E cases in the community and the concentration of virus detected in sewage. Samples were collected from the different sewage treatment plants from the island and analyzed for the presence of hepatitis E (HEV) virus using real-time RT-PCR. We demonstrated that if 1–4 % of inhabitants connected to a WWTP were infected with HEV, raw sewage contained HEV at detectable levels. The finding that such a small number of infected people can contaminate municipal sewage works raises the potential of the further distribution of the virus. Indeed, investigating the routes of transmission of HEV, including the potential for sewage effluent to contain infectious HEV, may help us to better understand the epidemiology of this pathogen, which is considered to be an emerging concern in Europe.     

Field study of nitrous oxide production with in situ aeration in a closed landfill site

Nitrous oxide (N₂O) has gained considerable attention as a contributor to global warming and depilation of stratospheric ozone layer. Landfill is one of the high emitters of greenhouse gas such as methane and N₂O during the biodegradation of solid waste. Landfill aeration has been attracted increasing attention worldwide for fast, controlled and sustainable conversion of landfills into a biological stabilized condition, however landfill aeration impel N₂O emission with ammonia removal. N₂O originates from the biodegradation, or the combustion of nitrogen-containing solid waste during the microbial process of nitrification and denitrification. During these two processes, formation of N₂O as a by-product from nitrification, or as an intermediate product of denitrification. In this study, air was injected into a closed landfill site and investigated the major N₂O production factors and correlations established between them. The in-situ aeration experiment was carried out by three sets of gas collection pipes along with temperature probes were installed at three different distances of one, two and three meter away from the aeration point; named points A-C, respectively. Each set of pipes consisted of three different pipes at three different depths of 0.0, 0.75 and 1.5 m from the bottom of the cover soil. Landfill gases composition was monitored weekly and gas samples were collected for analysis of nitrous oxide concentrations. It was evaluated that temperatures within the range of 30–40°C with high oxygen content led to higher generation of nitrous oxide with high aeration rate. Lower O₂ content can infuse N₂O production during nitrification and high O₂ inhibit denitrification which would affect N₂O production. The findings provide insights concerning the production potentials of N₂O in an aerated landfill that may help to minimize with appropriate control of the operational parameters and biological reactions of N turnover.

Implications: Investigation of nitrous oxide production potential during in situ aeration in an old landfill site revealed that increased temperatures and oxygen content inside the landfill site are potential factors for nitrous oxide production. Temperatures within the range of optimum nitrification process (30–40°C) induce nitrous oxide formation with high oxygen concentration as a by-product of nitrogen turnover. Decrease of oxygen content during nitrification leads increase of nitrous oxide production, while temperatures above 40°C with moderate and/or low oxygen content inhibit nitrous oxide generation.     

A numerical experiment of roadside diffusion under traffic-produced flow and turbulence

Roadside air pollution due to heavy traffic is one of the unsettled issues in the atmospheric environment in urban areas. As a practical application of a Computational Fluid Dynamics (CFD) model, a coupled mesoscale-CFD model was applied to the Ikegamicho area of Kawasaki City, Japan. For this study, the effects of traffic-produced flow and turbulence (TPFT) on the dispersion of the pollutants near the heavy traffic road were mainly investigated in an actual urban area. First, a series of preliminary CFD calculations was conducted for a road tunnel field experiment to obtain a fitting parameter for the traffic-produced flow. The calculation was then performed for 24 h in December 2005 around Ikegamicho, and the results were compared with the data at a roadside monitoring post in the area, located 10 m from the boundary of the ground road. In general, the effect of traffic-produced flow and turbulence was limited at the downstream side of the roads. The maximum concentration of NO_x was reduced and smoothed out along the traffic flow by the traffic-produced flow and turbulence on the road. The effects of traffic-produced turbulence on the dispersion of pollutants were greater than those of traffic-produced flow; however, the effects of traffic-produced flow were not negligible. The concentration of pollutants was not particularly dependent on the turbulent Schmidt number because most of the emission sources were introduced as volume sources in the present calculations, and the effect caused by differences in the material diffusion coefficient was not particularly significant at the outside of the road.     

A DFT study on the carbamates formation through the absorption of CO2 by AMP

DFT calculations in gas and aqueous solution phases have been performed to study the mechanism of carbamate formation by the absorption of CO₂ in 2-amino-2-methyl-1-propanol (AMP). The results reveal the importance of considering the effect of water as solvent for the reaction to proceed. Furthermore water molecules play an important role as a basic reactant leading to stable intermediates formation. These results point at a single-step, third order reaction as the most probable mechanism for the formation of carbamate by the absorption process.     

Geosmin degradation by seasonal biofilm from a biological treatment facility

Introduction  

Initial geosmin degradation was closely related to water temperature and natural geosmin concentration of sampling environment. Here, for the first time, we evaluated the biodegradation of geosmin by microorganisms in biofilm from biological treatment unit of actual potable water treatment plant.     

Hydrostatic pressure-induced apoptosis on nauplii of Calanus sinicus

The effect of hydrostatic pressure on embryonic development of the calanoid copepod Calanus sinicus was studied. Differences of pressure effect among blastomere stages, 1-cell, 2-cell, 4-cell, 8-cell, 16-cell, blastula and limb-bud stage, were examined under two pressurizing conditions, abruptly (10 atm/min) and gradually (0.1 atm/min) increasing. Egg hatching success, deformity frequency and apoptotic cell degradation of hatched nauplii were examined. Egg hatching success rate was not significantly different between blastomere stages, and also between pressurizing conditions. Deformity frequencies of hatched nauplii were low in the early 1-cell and 2-cell stages, and high in the later blastula and limb-bud stages, in both abrupt and gradual pressurizing conditions. On the other hand, in regard to difference in pressurizing conditions, deformity frequency in gradual pressurizing was significantly higher than that in abrupt pressurizing rate. Gradual pressure increase seems to be more harmful to C. sinicus eggs than abrupt pressure change. Apoptosis induced in nauplii by hydrostatic pressure was detected for the first time in marine zooplankton. The embryos of C. sinicus are sensitive to pressure variations, that is, these embryos are supposed to sink to deeper waters, incurring greater risk of having deformities. In the field, C. sinicus ascend to the surface and spawn at night. By looking from this upward behavior, eggs are spawned at lower pressure and warmer temperature. Probably, the harmless low pressure and warm temperature lead eggs to hatch early and to recruit successfully.