No abstract

Several studies indicate that burrows play an essential role in burrowing fish, especially mudskippers, but little is known on burrow morphology and utilization of Periophthalmodon septemradiatus. This study was therefore conducted at five sampling sites from the estuary to upper reaches of Hau River to contribute to the knowledge of the behavior of Pn. septemradiatus, via in situ and ex situ observations of the utilization of burrow structures. Burrows made by polyester resin were used to determine their morphology. The male mudskippers Pn. septemradiatus were observed to excavate burrows using their mouths during the low tide. The burrows' shapes were found to be J, U and W, with 1-3 openings and one bulbous chamber. The chamber was used as egg container where the mudskipper deposits their fertilized eggs. W-shaped burrows were found to be interconnected chambers where the mudskipper used it to change direction of movements inside the burrow. For the J-and U-shaped burrows, the commonality at all five sites was identified. The W-shaped burrows were common and were only found at two sites (Long Duc and An Lac Tay). For the burrows' structure, the openings to the surface were oval, circular and bulbous in shape. Yet, there were variations between sites, and the burrows' size was similar during the dry and wet seasons. At different sites, the depth of the burrows seasonally changed. The burrows used by mudskipper provide shelter, spawning sites, and access to feeding grounds for other mudskipper species. 'Fish Use for conducting Research' singed by Vice Head of Department of Research Affairs on 8 th November 2018 for the study from April 2017 to April 2019. Burrow structureThe burrow structures of Pn. septemradiatus were studied in situ, by creating casts of burrows at field sites when the fish relocated out of burrows, to avoid polyester resin's effect on fish. The constructed burrows by Pn. septemradiatus were

No abstract

An artificial neural network (ANN) model was used to predict the cyanobacteria bloom in the Dau Tieng Reservoir, Vietnam. Eight environmental parameters (pH, dissolved oxygen, temperature, total dissolved solids, total nitrogen (TN), total phosphorus, biochemical oxygen demand and chemical oxygen demand) were introduced as inputs, whereas the cell density of three cyanobacteria genera (Anabaena, Microcystis and Oscillatoria) with microcystin concentrations were introduced as outputs of the three-layer feed-forward back-propagation ANN. Eighty networks covering all combinations of four learning algorithms (Bayesian regularisation (BR), gradient descent with momentum and adaptive learning rate, Levenberg–Mardquart, scaled conjugate gradient) with two transfer functions (tansig, logsig) and 10 numbers of hidden neurons (6–16) were trained and validated to find the best configuration fitting the observed data. The result is a network using the BR learning algorithm, tansig transfer function and nine neurons in the hidden layer, which shows satisfactory predictions with the low values of error (root mean square error=0.108) and high correlation coefficient values (R=0.904) between experimental and predicted values. Sensitivity analysis on the developed ANN indicated that TN and temperature had the most positive and negative effects respectively on microcystin concentrations. These results indicate that ANN modelling can effectively predict the behaviour of the cyanobacteria bloom process.

Internal Circulation reactor (IC reactor) is an anaerobic digestive system with the capability to treat high-load Chemical Oxygen Demand (COD) of industrial wastewater (e.g. brewery, potato starch, pulp and paper). IC reactor advantages include of the following: only small areas required, shock load resistance, produces more biogas and uses less energy compared to the Upflow Anaerobic Sludge Blanket (UASB) reactor. BIOPAQ@ICX is an upgrade to BIOPAQ@IC that has higher efficiency, lower volume, able to build from the current anaerobic reactor, and its trial has produced positive results in many different countries and with various types of wastewater. A case study of the wastewater treatment plant at Saigon Paper’s mills shows that the IC reactor COD removal rate is over 80% when the COD is not over 2300 mg/L; Volumetric Load Rate (VLR) is 6–14 kgCOD/m3.day and the removal rate is higher with a higher load and could reach 80% at 14 kgCOD/m3.day; granular sludges settle very well, and the three-phase separator is efficient of preventing sludge from washing out; pH, Total Suspended Solids (TSS), alkalinity, Volatile Fatty Acids (VFA), N-NH4+, P-PO4 3-, Ca, SO4 2- were also analysed and indicated that the IC reactor is operating well.