This investigation explores the efficacy of employing ultrasonic cavitation and coupling it with advanced oxidation processes (hydrogen peroxide and Fenton's reagent) for reducing the levels of total ammonia nitrogen in fish pond water containing Tilapia fishes. Ultrasonic cavitation is a phenomenon where the formation, growth and collapse of vaporous bubbles occur in a liquid medium producing highly reactive free radicals. Ultrasonic probe system (20 kHz with 750 W and 1000 W) was used to induce cavitation. Besides, to intensify the process, ultrasonic cavitation was coupled with hydrogen peroxide and Fenton's reagent. Using SERA colour indicator test kits, the levels of ammonium, nitrite and carbonate hardness were measured. The results obtained from this study clearly show that the advanced oxidation processes are more efficient in reducing the ammonium and nitrite levels in fish pond water than using ultrasound alone. The pH and carbonate hardness levels were not affected significantly by ultrasonic cavitation. The optimal treatment time and ultrasound power to treat the water samples were also established. Energy efficiency and cost analysis of this treatment have also been presented, indicating that ultrasonic cavitation coupled with hydrogen peroxide appears to be a promising technique for reducing total ammonia nitrogen levels in the fish pond water.
Aquaculture is a growing industry with a great potential towards the contribution of the country’s total
fish requirement. Serious efforts have been done to develop and improve the production of fish by rearing high value fish in tanks or ponds. Under the Third National Agricultural Policy (1998-2010), the target is to annually produce 1.93 million tonnes of fish worth approximately RM8.3 billion by the year 2010. Consequently, the development of an automatic fish feeding machine can be very beneficial to the growth of the aquaculture industry. This device was developed to overcome labour problems in the industry and introduce a semi-automatic process in the aquaculture industry. It has the ability to dispense dried fish food in various forms such as pellets, sticks, tablets or granules into fish tanks or ponds in a controlled manner for a stipulated time. The automatic fish feeder is controlled by a digital timer and it is capable of feeding the fish in accordance with a pre-determined time schedule without the presence of an operator, and at a feeding rate of 250g/min. The feeder can be adjusted to the desired height and conveniently moved around to be positioned adjacent to the pond or tank. Meanwhile, its hopper can be covered and easily dissembled to change the size of the hopper to accommodate different capacities of feed. This automatic fish feeder can be implemented in aquaculture system to convenience to fish culturists.
Seasonal changes in Ephemeroptera, Plecoptera and Trichoptera (EPT) community was studied at rivers in Gunung Jerai Forest Reserve, Kedah, Malaysia. The rivers were visited monthly from September 2007 to August 2008 to sample aquatic insects using D-pond nets. More EPT were found in the wet season (10664 individuals) compared with the dry season (6599 individuals). In all rivers, ephemeropteran populations was highest during the wet season (z=-2.465, p=0.014). Meanwhile, the plecopteran population was low and almost constant throughout seasons in all rivers (z=-2.280, p=0.023). Trichopterans exhibited the highest peak of abundance in the dry season (z=-6.096, p=0.00). Concomitantly, higher diversity was recorded in the dry season (29 taxa) compared with 25 taxa recorded in wet season from all rivers. Tupah River had the most diverse EPT assemblage during the dry season. In wet season, the abundance of ephemeropterans genera such as Baetis, Platybaetis, Campsoneuria and Thalerosphyrus increased tremendously especially in Teroi River.
Trophic variation in food web structure occurs among and within ecosystems. The magnitude of variation, however, differs from system to system. In ephemeral pond ecosystems, temporal dynamics are relatively more important than in many systems given that hydroperiod is the ultimate factor determining the presence of an aquatic state. Here, using stable isotopes we tested for changes in trophic chain length and shape over time in these dynamic aquatic ecosystems. We found that lower and intermediate trophic level structure increased over time. We discuss these findings within the context of temporal environmental stability. The dynamic nature of these ephemeral systems seems to be conducive to greater levels of intermediate and lower trophic level diversity, with omnivorous traits likely being advantageous.
The acquisition of Photorhabdus insect-related (Pir) toxin-like genes in Vibrio parahaemolyticus has been linked to hepatopancreatic necrosis disease in shrimp. We report the whole-genome sequences of genetically virulent and avirulent V. parahaemolyticus isolated from a Malaysian aquaculture pond and show that they represent previously unreported sequence types of V. parahaemolyticus.
Infection by the microsporidian parasite Enterocytozoon hepatopenaei (EHP) has become a significant problem in the shrimp cultivation industry in Asian countries like Thailand, China, India, Vietnam, Indonesia, and Malaysia. The outbreak of this microsporidian parasite is predominantly related to the existence of macrofauna-carriers of EHP. However, information about potential macrofauna-carriers of EHP in rearing ponds is still limited. In this study, the screening of EHP in potential macrofauna-carriers was conducted in farming ponds of Penaeus vannamei in three states in Malaysia, namely Penang, Kedah, and Johor. A total of 82 macrofauna specimens (phyla: Arthropoda, Mollusca, and Chordata) were amplified through a polymerase chain reaction (PCR) assay targeting genes encoding spore wall proteins (SWP) of EHP. The PCR results showed an average prevalence of EHP (82.93%) from three phyla (Arthropoda, Mollusca and Chordata). The phylogenetic tree generated from the macrofauna sequences was revealed to be identical to the EHP-infected shrimp specimens from Malaysia (MW000458, MW000459, and MW000460), as well as those from India (KY674537), Thailand (MG015710), Vietnam (KY593132), and Indonesia (KY593133). These findings suggest that certain macrofauna species in shrimp ponds of P. vannamei are carriers of EHP spores and could be potential transmission vectors. This study provides preliminary information for the prevention of EHP infections that can be initiated at the pond stage by eradicating macrofauna species identified as potential vectors.
The approach of this paper is to predict the sand mass distribution in an urban stormwater holding pond at the Stormwater Management And Road Tunnel (SMART) Control Centre, Malaysia, using simulated depth average floodwater velocity diverted into the holding during storm events. Discriminant analysis (DA) was applied to derive the classification function to spatially distinguish areas of relatively high and low sand mass compositions based on the simulated water velocity variations at corresponding locations of gravimetrically measured sand mass composition of surface sediment samples. Three inflow parameter values, 16, 40 and 80 m(3) s(-1), representing diverted floodwater discharge for three storm event conditions were fixed as input parameters of the hydrodynamic model. The sand (grain size > 0.063 mm) mass composition of the surface sediment measured at 29 sampling locations ranges from 3.7 to 45.5%. The sampling locations of the surface sediment were spatially clustered into two groups based on the sand mass composition. The sand mass composition of group 1 is relatively lower (3.69 to 12.20%) compared to group 2 (16.90 to 45.55%). Two Fisher's linear discriminant functions, F 1 and F 2, were generated to predict areas; both consist of relatively higher and lower sand mass compositions based on the relationship between the simulated flow velocity and the measured surface sand composition at corresponding sampling locations. F 1 = -9.405 + 4232.119 × A - 1795.805 × B + 281.224 × C, and F 2 = -2.842 + 2725.137 × A - 1307.688 × B + 231.353 × C. A, B and C represent the simulated flow velocity generated by inflow parameter values of 16, 40 and 80 m(3) s(-1), respectively. The model correctly predicts 88.9 and 100.0% of sampling locations consisting of relatively high and low sand mass percentages, respectively, with the cross-validated classification showing that, overall, 82.8% are correctly classified. The model predicts that 31.4% of the model domain areas consist of high-sand mass composition areas and the remaining 68.6% comprise low-sand mass composition areas.
It is generally accepted that organisms that naturally exploit an ecosystem facilitate coexistence, at least partially, through resource partitioning. Resource availability is, however, highly variable in space and time and as such the extent of resource partitioning must be somewhat dependent on availability. Here we test aspects of resource partitioning at the inter- and intra-specific level, in relation to resource availability in an atypical aquatic environment using an isotope approach. Using closely related key organisms from an ephemeral pond, we test for differences in isotopic signatures between two species of copepod and between sexes within each species, in relation to heterogeneity of basal food resources over the course of the ponds hydroperiod. We show that basal food resource heterogeneity increases over time initially, and then decreases towards the end of the hydroperiod, reflective of the expected evolution of trophic complexity for these systems. Resource partitioning also varied between species and sexes, over the hydroperiod with intra- and inter-specific specialisation relating to resource availability. Intra-specific specialisation was particularly evident in the omnivorous copepod species. Our findings imply that trophic specialisation at both the intra- and inter-specific level is partly driven by basal food resource availability.
Even though microalgal biomass is leading the third generation biofuel research, significant effort is required to establish an economically viable commercial-scale microalgal biofuel production system. Whilst a significant amount of work has been reported on large-scale cultivation of microalgae using photo-bioreactors and pond systems, research focus on establishing high performance downstream dewatering operations for large-scale processing under optimal economy is limited. The enormous amount of energy and associated cost required for dewatering large-volume microalgal cultures has been the primary hindrance to the development of the needed biomass quantity for industrial-scale microalgal biofuels production. The extremely dilute nature of large-volume microalgal suspension and the small size of microalgae cells in suspension create a significant processing cost during dewatering and this has raised major concerns towards the economic success of commercial-scale microalgal biofuel production as an alternative to conventional petroleum fuels. This article reports an effective framework to assess the performance of different dewatering technologies as the basis to establish an effective two-stage dewatering system. Bioflocculation coupled with tangential flow filtration (TFF) emerged a promising technique with total energy input of 0.041 kWh, 0.05 kg CO2 emissions and a cost of $ 0.0043 for producing 1 kg of microalgae biomass. A streamlined process for operational analysis of two-stage microalgae dewatering technique, encompassing energy input, carbon dioxide emission, and process cost, is presented.
Palm oil processing is a multi-stage operation which generates large amount of effluent. On average, palm oil mill effluent (POME) may contain up to 51, 000 mg/L COD, 25,000 mg/L BOD, 40,000 TS and 6000 mg/L oil and grease. Due to its potential to cause environmental pollution, palm oil mills are required to treat the effluent prior to discharge. Biological treatments using open ponding system are widely used for POME treatment. Although these processes are capable of reducing the pollutant concentrations, they require long hydraulic retention time and large space, with the effluent frequently failing to satisfy the discharge regulation. Due to more stringent environmental regulations, research interest has recently shifted to the development of polishing technologies for the biologically-treated POME. Various technologies such as advanced oxidation processes, membrane technology, adsorption and coagulation have been investigated. Among these, advanced oxidation processes have shown potentials as polishing technologies for POME. This paper offers an overview on the POME polishing technologies, with particularly emphasis on advanced oxidation processes and their prospects for large scale applications. Although there are some challenges in large scale applications of these technologies, this review offers some perspectives that could help in overcoming these challenges.
Microcosm experiments simulating the occurrence of early mortality syndrome/acute hepatopancreatic necrosis disease (EMS/AHPND) in white shrimp production ponds were performed in 30-L aquariums. Healthy white shrimp, Litopenaeus vannamei, were reared in aquariums containing EMS/AHPND-free hatchery or pond water. Raw pond sludge, collected from shrimp ponds where EMS/AHPND had occurred, was added to some test aquariums, while others were treated with sterilized pond sludge. In some aquariums, water pH was increased from 7.5 to 8.8. Microcosms with stable pH (around 7.5) and/or autoclaved sludge served as controls. The combination of raw sludge and increased pH induced EMS/AHPND and killed white shrimp, whereas raw sludge/stable pH and autoclaved sludge/increased pH combinations did not affect healthy shrimp. Thus, EMS/AHPND outbreaks are due not only to the causative agent but also to environmental stresses such as pH fluctuation. These findings contribute to improved management in shrimp production farms.
Electrocoagulation has proven to be an effective method in the treatment of wastewater. This study evaluated the decolourisation of Palm Oil Mill Effluent (POME) using electrocoagulation (EC) batch reactor by utilising aluminium as sacrificial electrode. POME sample source from a final discharged pond at a palm oil mill was characterised for its colour, chemical oxygen demand (COD), pH, conductivity and turbidity; were found to be 2707 PtCo, 3909 mg/L, 7.63, 12.82 mS/cm and 755 NTU respectively. The respective effects of operating parameters such as pH (3 to 11), applied voltage (5 V to 20 V), plate gap (7.5 to 11.5 cm) and operating time (1 to 8 hours) were investigated. The decolourisation of POME was observed to increase with increasing voltage and operating time. Highest removal efficiency was observed at pH 5, 20 V applied voltage, 9.5 cm plate gap and at 8-hour operating time with colour removal efficiency of 89, 79, 78 and 64% respectively. From the findings, it can be concluded that electrocoagulation process using aluminium electrodes is a reliable technique for the removal of colour from POME.
Unlike those in the mainland of Southeast Asia, the Cladocera of the Malay Archipelago has not been intensively studied, except for the state of Sabah in the north-eastern part of the Borneo island. This study aimed to complete the inventory of the Cladocera in Sabah by looking at different types of water bodies including oxbow lakes, small lakes, reservoirs, ponds, ditches and paddy fields. From 32 sites examined, 35 species of cladocerans, nine of which were new records to Sabah, were found from 25 localities. With this new finding, the total number of cladoceran species in Sabah increased to 39 species, including five species of Sididae, four species of Daphniidae, one species of Moinidae, five species of Macrothricidae, two species of Ilyocryptidae, and 22 species of Chydoridae. Only 8 % ( three species) of Sabah cladocerans are true planktonic. This study illustrated that most cladocerans were associated with substrates in the littoral zone and thus appropriate sampling methods should be employed in different microhabitats for comprehensive biodiversity assessment.
An experiment was carried out in 6 earthen ponds to investigate the effects of stocking density on growth, survival and production of Thai climbing perch (Anabas testudineus). Three stocking densities (treatments) were compared: ponds with 350, 400 and 550 individuals per decimal (0.01 acre). All treatments were randomly assigned and in duplicate. Artificial feed containing 34% crude protein was applied initially 20% of total fish weight per day. Gradually the feeding rate was reduced to 15, 12, 10, 8 and 5% of total fish weight per day. Feeding rates per pond were adjusted fortnightly after weighing minimum 20% of the fish stocked. The duration of the experiment was 90 days. Results showed that all growth parameters were higher in ponds with lower stocking density than the ponds with higher stocking density, while total fish yield was higher in ponds with higher stocking density than in the ponds with lower stocking density. Cost-benefit analysis revealed that all three systems were economically profitable. However, the ponds with a stocking density of 550 individuals per decimal were the most profitable system. More research is still needed to further optimize stocking density of Thai climbing perch in aquaculture ponds. Until then, stocking 550 individuals of Thai climbing perch per decimal will yield a good production to fish farmers in the South and South-East Asian regions.
In aquatic environments, Vibrio and cyanobacteria establish varying relationships influenced by environmental factors. To investigate their association, this study spanned 5 months at a local shrimp farm, covering the shrimp larvae stocking cycle until harvesting. A total of 32 samples were collected from pond A (n = 6), pond B (n = 6), effluent (n = 10), and influent (n = 10). Vibrio species and cyanobacteria density were observed, and canonical correspondence analysis (CCA) assessed their correlation. CCA revealed a minor correlation (p = 0.847, 0.255, 0.288, and 0.304) between Vibrio and cyanobacteria in pond A, pond B, effluent, and influent water, respectively. Notably, Vibrio showed a stronger correlation with pH (6.14-7.64), while cyanobacteria correlated with pH, salinity (17.4-24 ppt), and temperature (30.8-31.5 °C), with salinity as the most influential factor. This suggests that factors beyond cyanobacteria influence Vibrio survival. Future research could explore species-specific relationships, regional dynamics, and multidimensional landscapes to better understand Vibrio-cyanobacteria connections. Managing water parameters may prove more efficient in controlling vibriosis in shrimp farms than targeting cyanobacterial populations.
Anaerobic treatment processes to remove organic matter from palm oil mill effluent (POME) have been used widely in Malaysia. Still the amounts of total organic and total mineral released from POME that may cause degradation of the receiving environment need to be verified. This paper proposes the use of the hydrodynamic equations to estimate performance of the cascaded anaerobic ponds (CAP) and to calculate amounts of total organic matter and total mineral released from POME. The CAP efficiencies to remove biochemical oxygen demands, chemical oxygen demands, total solids and volatile solids (VS) as high as 94.5, 93.6, 96.3 and 98.2 %, respectively, are estimated. The amounts of total organic matter and total mineral as high as 538 kg VS/day and 895 kg FS/day, respectively, released from POME to the receiving water are calculated. The implication of the proposed hydrodynamic equations contributes to more versatile environmental assessment techniques, sometimes replacing laboratory analysis.
The biodegradation characteristics of palm oil mill effluent (POME) and the related microbial community were studied in both actual sequential anaerobic ponds in Malaysia and enrichment cultures. The significant degradation of the POME was observed in the second pond, in which the temperature was 35-37 °C. In this pond, biodegradation of major long chain fatty acids (LCFA), such as palmitic acid (C16:0) and oleic acid (C18:1), was also confirmed. The enrichment culture experiment was conducted with different feeding substrates, i.e. POME, C16:0 and C18:1, at 35 °C. Good recovery of methane indicated biodegradation of feeds in the POME and C16:0 enrichments. The methane production rate of the C18:1 enrichment was slower than other substrates and inhibition of methanogenesis was frequently observed. Denaturing gradient gel electrophoresis (DGGE) analyses indicated the existence of LCFA-degrading bacteria, such as the genus Syntrophus and Syntorophomonas, in all enrichment cultures operated at 35 °C. Anaerobic degradation of the POME under mesophilic conditions was stably processed as compared with thermophilic conditions.
Compensatory growth (CG) may be an adaptive mechanism that helps to restore an organisms' growth trajectory and adult size from deviations caused by early life resource limitation. Yet, few studies have investigated the genetic basis of CG potential and existence of genetically based population differentiation in CG potential. We studied population differentiation, genetic basis, and costs of CG potential in nine-spined sticklebacks (Pungitius pungitius) differing in their normal growth patterns. As selection favors large body size in pond and small body size in marine populations, we expected CG to occur in the pond but not in the marine population. By manipulating feeding conditions (viz. high, low and recovery feeding treatments), we found clear evidence for CG in the pond but not in the marine population, as well as evidence for catch-up growth (i.e., size compensation without growth acceleration) in both populations. In the marine population, overcompensation occurred individuals from the recovery treatment grew eventually larger than those from the high feeding treatment. In both populations, the recovery feeding treatment reduced maturation probability. The recovery feeding treatment also reduced survival probability in the marine but not in the pond population. Analysis of interpopulation hybrids further suggested that both genetic and maternal effects contributed to the population differences in CG. Hence, apart from demonstrating intrinsic costs for recovery growth, both genetic and maternal effects were identified to be important modulators of CG responses. The results provide an evidence for adaptive differentiation in recovery growth potential.
Salmonella enterica subsp. enterica serovar Typhi is a human-restricted pathogen that causes typhoid fever. Even though it is a human-restricted pathogen, the bacterium is also isolated from environments such as groundwater and pond water. Here, we describe the genome sequence of the Salmonella enterica subsp. enterica serovar Typhi PM016/13 which was isolated from well water during a typhoid outbreak in Kelantan, Malaysia, in 2013.
This study presents a mathematical model examining wastewater pollutant removal through
an oxidation pond treatment system. This model was developed to describe the reaction
between microbe-based product mPHO (comprising Phototrophic bacteria (PSB)), dissolved
oxygen (DO) and pollutant namely chemical oxygen demand (COD). It consists
of coupled advection-diffusion-reaction equations for the microorganism (PSB), DO and
pollutant (COD) concentrations, respectively. The coupling of these equations occurred
due to the reactions between PSB, DO and COD to produce harmless compounds. Since
the model is nonlinear partial differential equations (PDEs), coupled, and dynamic, computational
algorithm with a specific numerical method, which is implicit Crank-Nicolson
method, was employed to simulate the dynamical behaviour of the system. Furthermore,
numerical results revealed that the proposed model demonstrated high accuracy when
compared to the experimental data.