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The large number of tailings ponds in my country, coupled with various man-made and natural factors in recent years, leads to the frequent occurrence of tailings pond accidents, causing serious harm. Mastering the number and distribution of tailings ponds is of great significance to prevent tailings pond accidents and carry out emergency management of tailings ponds. For the identification and monitoring of tailings ponds, the traditional survey methods are mainly based on ground surveys, and it is difficult to achieve large-scale and high-frequency detection. With the development of artificial intelligence technology, based on the support vector machine (SVM) method, the automatic extraction of remote sensing image (RSI) information has been realized, and remarkable achievements have been made in the field of remote sensing. This paper takes the tailings pond as the research goal, and based on the analysis of the characteristics of the tailings pond in the RSI, the method of SVM target detection is used to realize the rapid and high-precision identification of the tailings pond. The main contents of this paper are as follows: (1) The accident risk of tailings ponds at home and abroad and the status quo of tailings pond monitoring technology are introduced. (2) The relevant theory of SVM is learned, and the kernel function and corresponding parameter selection method of SVM are discussed in a multiclassification problem. (3) On the basis of determining the kernel function, parameters, and features, the trained model is compared with the original model. The results show that the SVM detection model proposed in this paper has excellent performance in tailings pond image recognition. [ABSTRACT FROM AUTHOR]

Water color is an important representation reflecting the characteristics of its quality in inland lakes or ponds; however, sufficient water color image samples are often difficult to obtain due to the limitation of fishery production. For few color image samples, the existing data enhancement methods based on the depth generation model have the problems of low quality of generated data, difficulty of network training, and so on; moreover, for image classification, traditional methods based on convolutional neural network (CNN) cannot effectively extract the potential manifold structure features in the image and the full connection layer in CNN cannot simulate biological neurons well, resulting in high time cost and low efficiency. In this paper, a water quality classification method has been proposed to solve the above problems, the improved semisupervised triple-generation adversarial network (triple-GAN) algorithm is used to enhance the few water color image samples, and the feature data can then be extracted from enhanced data by manifold learning method t-distributed stochastic neighborhood embedding (t-SNE). Moreover, convolutional spiking neural network (CSNN), in which spiking neural network (SNN) has replaced the original full connection layer of CNN, is used for final water quality classification. The main contribution of this paper is to build a new algorithm framework, introduce triple-GAN and CSNN into the field of classification of few water color image samples for the first time, and make an exploration of integrating artificial intelligence (AI) and water quality analysis problems. By comparing with traditional methods, the proposed method is proved to have the advantages of less time-consuming, low operation cost, and high classification accuracy. [ABSTRACT FROM AUTHOR]

The seepage accident of a tailings pond poses a serious threat to the stability of tailings dams and the surrounding environment. To reduce the occurrence of seepage accidents, this paper studies the identification of seepage hazards, the propagation law of seepage risk, the importance of hazards, and the priority of hazard treatment. To overcome the subjectivity and omission of hazard identification, according to the complexity and dynamics of tailings seepage, this paper proposes the evidence-based identification method of three-dimensional seepage hazards (EIMTSH) to identify the hazards of the tailings seepage system and the relationship between hazards. Then, on the basis of identifying the hazards of the tailings seepage system, the propagation network of seepage risk in tailing ponds (PNSRTP) is constructed based on the complex network theory. By analyzing the characteristics of the PNSRTP, it can be found that the propagation of seepage risk is scale-free and small-world. Through the node deletion method, this paper finds that the nodes with a higher degree value can reduce the network efficiency more quickly and should be governed first. By giving priority to the treatment of hazards with higher degree, the propagation of seepage risk can be reduced more quickly and the risk management level of tailings ponds can be improved, which is helpful to realize the sustainable development of mining production. [ABSTRACT FROM AUTHOR]

Water is the source of life and the foundation for the growth of all things. Water is also an important part of the urban ecological structure. A healthy water environment is the basis for human survival and development, and it is also one of the important conditions for the harmonious development of cities. With the rapid development of the economy and the improvement of the level of urbanization, the water environment pollution in the urban landscape has become more and more serious, such as serious water eutrophication and rapid algae reproduction in the water environment. As plants that can survive in water, aquatic plants have always been an important main body of the water ecological environment. It plays an unparalleled role in water environment purification and comprehensive treatment of water pollution. This paper aims to study the comprehensive management of urban landscape water environment based on the purification and restoration of aquatic plants. It combines the purification and restoration ability of aquatic plants and genetic algorithm to carry out the comprehensive management experiment of urban landscape water environment. The conclusion shows that after the purification and restoration of aquatic plants and comprehensive pollution control, the comprehensive eutrophic substance content of the urban landscape pond water body decreased by 21.7 mg, and the water body transparency increased by 20 cm. [ABSTRACT FROM AUTHOR]

The buildup of tailings in China has expanded dramatically with economic development and industrial demand, and the safety of tailings reservoirs has become increasingly serious. Due to the difficulty in finding a new reservoir site, the expansion approach of building a new tailings dam downstream of the original reservoir area was investigated. The stability of the tailings reservoir after expansion was calculated using the traditional dynamic and static stability solution method and taking into account the unpredictability of dam construction materials and tailings material parameters in the reservoir area. The results reveal that throughout the tailings accumulation process in the new reservoir, the tailings will build a back pressure slope at the original reservoir's initial dam, which can considerably improve the original reservoir's dynamic and static stability. The Monte Carlo method clearly outperforms older methods for tailing pond stability analysis. The results of this paper's calculations will give a theoretical foundation and practical reference for the later management and maintenance of such tailings reservoirs, as well as fresh ideas and insights for comparable projects due to limited site selection. [ABSTRACT FROM AUTHOR]

A new analysis method for the environmental stability of uranium tailing ponds is established in this paper, and the stability intervals and environmental stability rates of indicators are defined in precise mathematical language and analyzed with examples. The results show that the overall environmental stability of this uranium tailings pond is still in a poor state after the first phase of decommissioning treatment, and special decommissioning treatment should be carried out for factors such as pH and radionuclides Po and Pb. Using the powerful nonlinear mapping function of the artificial neural network, a radial basis function neural network algorithm was constructed to predict the environmental stability of the uranium tailing pond. It provides a new feasible method for the comprehensive evaluation technology of uranium tailings ponds. Accuracy in DOA Estimation. The research work in this paper mainly analyzed the environmental stabilization process and stability of decommissioned uranium tailings ponds, proposed a new concept of environmental stability with ecological and environmental protection concepts and gave it a new connotation, established an environmental stability evaluation index system for decommissioned uranium tailings ponds through index screening by using rough set theory, comprehensively considered the influence of environmental factors such as external wastewater and exhaust gas, and realized the multifactor. The system of evaluation indexes for the stability of decommissioned uranium tailings ponds was established by combining multiple factors, and the long-term monitoring and modeling of the environmental stabilization process of decommissioned uranium tailings ponds was carried out by using mathematical methods. The results show that the RBFNN-GA algorithm can reduce the training error of the random radial basis function neural network, improve the generalization ability of the network, and make it capable of handling large data sets. [ABSTRACT FROM AUTHOR]

With the rapid development of industrial and agricultural production, the rapid growth of population, and the acceleration of urbanization, the problem of water pollution is becoming more and more serious. Water shortages and pollution disrupt the balance of ecosystems and seriously limit people's health and rapid economic development. Nowadays, the method of repairing sewage bodies using microbial landscape aquatic plants is attracting more and more attention, and it is a big challenge to maintain the sustainable development of human beings and nature. This paper uses floating rafts to combine microorganisms and landscape aquatic plants to conduct sewage treatment experiments. According to microorganisms, landscape aquatic plants absorb nutrients in the water body, examine the changes in water quality during the restoration of microorganisms' landscape aquatic plants, and establish the growth of microorganisms' landscape aquatic plants. The relationship with changes in water quality aims to provide a theoretical basis for the treatment of slow-flowing water bodies such as lakes, reservoirs, large artificial ponds, and rivers. In this paper, the experiments are divided into four groups (A (experimental sewage + microbial inoculant), B (experimental sewage + plant), C (experimental sewage + microbial inoculant + plant), and D (experimental sewage)). It can be divided into the total nitrogen content, total phosphorus content, and COD value data, and chromaticity detection of each group of the test is continuously monitored weekly to comprehensively detect and observe the repair effect on contaminated water bodies. The experiment proved that the water quality of the three treatment groups was significantly clearer than that of the blank control group, and its clarity: microorganism + plant > microorganism > plant > blank control group. This shows that the combination of microorganisms and landscape aquatic plants can effectively reduce the various pollutants contained in sewage and reduce the color of sewage. Treating sewage using plant technology that combines microorganisms is feasible and promising. [ABSTRACT FROM AUTHOR]

This paper provides an overview of the structure and performance of Chinese integrated pond fish farming systems, based on analysis of survey data for 1013 ponds on 101 farms in eight Chinese provinces. A province-by-province examination of gross and net fish yields supports the traditional Chinese classification of provinces into high, medium and low productivity classes according to fish farm output: average net fish yields for surveyed ponds in each class were 7958.4981 and 3321 kg ha-1 year-1 respectively. The paper includes summaries and analyses of data on fish stocking and harvesting, use of feeds and fertilizers, fish—animal integration, capital inputs, and the overall cost and revenue structure in each productivity class. In addition to variations in aggregate input and output levels, a key difference between productivity classes is seen to lie in the stocking model utilized; filter-feeding fish dominate in poorer areas, while ‘feeding fish’ (grass carp, Ctenopharyngodon idella (Valenciennes), black carp, Myhpharyngodoti piceus (Richardson), and omnivorous carps) dominate in high-productivity provinces. These results are examined in light of regional differences in culturing tradition, socio-economics, infrastructure, climate and geographical factors. [ABSTRACT FROM AUTHOR]

In the recent past, fish farming has gained great prominence in Kenya as the country straggles to meet food security. Nile tilapia (Oreochromis niloticus L.) farming has attracted the most demand, with the use of manure to enhance primary productivity in fish ponds being encouraged as a form of increasing productivity and returns on investment. The objective of this study was to understand the role of Nile tilapia farming in greenhouse emissions (GHGEs) in the region. Generally, there is paucity of such information originating from sub-Saharan Africa. Here, we report the levels of methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) emissions from Nile tilapia fish ponds fertilized with organic and inorganic fertilizers. We also try to establish if there exists any relationship between GHGEs and physicochemical parameters (PCPs). The methane fluxes ranged from 0.001 to 0.043°mg·m−2h−1 in UF ponds, 0.005 to 0.068°mg·m−2h−1 in IF ponds, and 0.001 to 0.375°mg·m−2h−1 in OF ponds. The findings show that the fluxes were significantly different (P < 0.05). Mean fluxes of CO2 did not show significant difference among the treatments (P > 0.05), ranging from −0.180 to 1.40°mg·m−2h−1 in UF ponds, −0.020 to 1.101°mg·m−2h−1 in IF ponds, and −0.049 to 1.746°mg m−2h−1 in OF ponds. N2O mean fluxes were not significantly different (P > 0.05), ranging from −0.628 to 0.326°µgm−2h−1 in UF ponds, −0.049 to 0.187°µgm−2h−1 in IF ponds, and −0.022 to 1.384°µgm−2h−1 in OF ponds. UF had a mean flux of −0.003 ± 0.175°µgm−2h−1, IF had a mean flux of 0.032 ± 0.056°µgm−2h−1 and OF had a mean flux of 0.093 ± 0.324°µgm−2h−1. There was significant difference in the carbon to nitrogen (CN) ratio among the fertilization treatments (P < 0.05), whereas temperature, pH, dissolved oxygen, and conductivity showed no significant difference among the fertilization treatments (P > 0.05). The study observed that fertilization of Nile tilapia ponds significantly increases the release of CH4 emission and the CN ratio. Temperature, conductivity, and CN positively correlated with CH4, CO2, and N2O emissions. Dissolved oxygen showed a negative correlation with CH4 and CO2 emissions while negatively correlated with N2O emissions. The study identified the use of OF as a potential form of fish farming that promotes the emission of GHGEs and calls for adoption of sustainable technologies for the management of organic and inorganic fertilizers before their use in pond fertilization. [ABSTRACT FROM AUTHOR]

To identify the optimal stocking rate of Micropterus salmoides culture in a land-based round pond recirculating aquaculture system, five stocking densities were tested, i.e., D1–D5 with 60, 70, 80, 90, and 100 fish/m2, respectively. The water temperature of the experimental pond was 20.0–26.5°C. The effects of stocking density on culture productivity and physiological indexes of M. salmoides (initial body weight 50.83 ± 7.28 g) were examined. The D1 and D5 treatments exhibited significantly improved growth performance. The population weight gain in the D5 treatment was the highest, which increased by 63.73%, 52.82%, 60.93%, and 45.08%, compared with groups D1–D4 (P < 0.05 , each), and the feed conversion ratio was the lowest, which was decreased by 5.65%, 12.03%, 26.42%, and 21.48% compared with groups D1–D4. The levels of crude protein, essential amino acids, and total free amino acids in muscle tissue of group D3 were higher than those in the other groups. Stocking density did not differ significantly on muscle fatty acid composition P > 0.05 , each). The activities of serum AKP and LZM and liver SOD, AKP, and LZM in group D5 were significantly higher than those in the other groups. Thus, 100 fish/m2 was the optimal stocking density of M. salmoides at a size stage of 50.83∼130.13 g in the circulating water of land-based round ponds. [ABSTRACT FROM AUTHOR]

Recently, profitable Macrobrachium rosenbergii farming has developed rapidly in Asia. The occurrence of cyanobacterial blooms is one of the major environmental problems usually encountered in freshwater prawn farms. This study investigated the effects of pond water depth and aeration mode on phytoplankton communities in selected M. rosenbergii farming ponds in China. We adjusted pond water depth and aeration mode (pond water depth: 1.2 m or 1.8 m; method of aeration: surface or both surface and bottom) to compare and analyze phytoplankton community structure and characteristics between ecological (pond water depth: 1.8 m, both surface and bottom aeration) and traditional (pond water depth: 1.2 m, surface aeration) farming ponds. Water quality parameters were compared in six aquaculture systems, which were measured in situ or lab. The results showed that ecological culture suppressed Cyanophyta abundance and significantly increased the numbers of phytoplankton species leading to a 30.43–136.84% increase in the number of species for ecological ponds compared with that in traditional ponds. In all seasons, ecological culture tended to have decreased total nitrogen and ammonia nitrogen, and significantly lower total phosphorus and reactive phosphate compared with traditional ponds. In conclusion, ponds should maintain deeper water depth (1.8 m) and higher N/P ratio (>3) to promote phytoplankton diversity and suppress blooms; applying optimized culture may resolve planktonic algae problems in aquaculture ponds in Asia. [ABSTRACT FROM AUTHOR]

Water contamination, temperature imbalance, feed, space, and cost are key issues that traditional fish farming encounters. The aquaculture business still confronts obstacles such as the development of improved monitoring systems, the early detection of outbreaks, enormous mortality, and promoting sustainability, all of which are open problems that need to be solved. The goal of this study is to provide a machine learning (ML)-based aquaculture solution that boosts prawn growth and production in ponds. The study described a proposed framework that collects data using sensors, analyses it using a machine learning framework, and provides results like a preferred list of water quality (QOW) variables that affect prawn development and yield, as well as pond categorization into low, medium, and high prawn-producing ponds. In this study, we use eight distinct machine-learning classifiers to discover the driving elements that influence the development and yield of aquatic food products in ponds in terms of QOW variables, as well as three feature selection approaches to identify the aspects that have the largest impact on the pond's total harvest performance. To validate and obtain satisfying results, the suggested system was installed and tested. The average F score and accuracy when yield is employed as a harvest parameter are determined to be 0.85 and 0.78, respectively. The average merit ratings of temperature, dissolved oxygen, and salinity are significantly higher than those of the other QOW components. The temperature variations are greatest during the second, fourth, and seventh weeks. Temperature, salinity, and dissolved oxygen are the three QOW variables that have the largest influence on overall pond harvest performance, according to the data. Additionally, it has been discovered that a key QOW factor in separating high-yielding ponds from low-yielding ponds is the temperature change following stocking. [ABSTRACT FROM AUTHOR]

Animal welfare is an issue of increasing importance in global aquaculture. However, the incorporation of this issue into routine aquaculture operations is a challenge. A possible path to change this is the recognition, identification and addressing of the ecological, physiological, nutritional, behavioural and psychological needs of fish. The present study uses grass carp (Ctenopharyngodon idella), the world's most widely produced fish species, and earth ponds, the world's most widely used production system in fish farming worldwide, as the basis for developing indices to assess and monitor the welfare of farmed fish. The proposed indices were structured based on specific welfare indicators, reference values, individual weights and associated scores to address the Animal Welfare Five Freedoms and a Life Worth living concepts. Two types of indices were proposed: (1) partial welfare indices (PWIx), specific to each of the four observed/analysed freedoms; (2) general welfare index (GWI), which simultaneously summarizes the addressees' freedoms in a single variable. Both indices range from 0 (critical welfare impairment) to 1.0 (minimal risk of welfare impairment). The study was based on a comprehensive systematic review of the literature using the PRISMA method. The proposed indices were based on 10 environmental indicators, nine indicators for health, five for nutrition and four for behaviour. The PWIx can be used to determine how each category of indicators contributes to the GWI, which defines the level of fish farm welfare at a given point in time and which needs are affected or met during a production cycle. [ABSTRACT FROM AUTHOR]

Minerals are subjected to ore processing to turn them into usable and saleable raw materials. First of all, the ore is reduced to the smallest size with the crushing-grinding process, and after using water and chemical additives, according to the characteristics of the ore, useful minerals are taken, and unwanted minerals are stored in the tailings pools. Approximately, 26 million tons of mineral wastes were generated annually from ore processing facilities in Turkey. The construction of tailings pools, the stability of the tailing sludge, and the safety of dams are a burdensome issue faced by miners. In the ore plants, an average of 3 tons of water is used to enrich 1 ton of ore, and most of the wastewater cannot be removed by traditional methods, causing various economic, environmental, and stability problems. In this study, the dewatering of an iron ore tailing by applying different voltages by the electroosmosis method was investigated in the laboratory environment. By discharging the water of the iron ore tailings by the electroosmosis method, the solid content was increased from 43.01% to 87.63%. Thus, it has been observed that there will be a significant improvement in the geotechnical properties of the tailings' material. It has been estimated that electroosmotic dewatering rises with increasing the voltage gradient and the energy consumption varies in the range of 0.588–30.645 kWh/dry ton. The void ratio decreased from 5.58% to 0.23%. In the dewatering experiments, different parameters such as the amount of water discharged, density, void ratio, water content, and power consumed were measured or calculated and the relationships between them were discussed with graphics. In electroosmosis experiments, it has been observed that besides the voltage applied in the discharge of water, the mineralogy of the tailings has a significant effect. Since there are serious abrasions on the electrodes used in the experiments, alternative electrodes should be tried. [ABSTRACT FROM AUTHOR]

Efficient water budgeting for various species will help in establishing database for providing practical solutions to the aquaculture sector's water crisis. Hence, a 90‐day study was conducted to evaluate the requirement of water for culture of Penaeus vannamei in inland saline groundwater. The earthen grow‐out ponds (0.1 ha) were stocked with postlarvae of P. vannamei (2.50 ± 0.01 g) at three different stocking densities, that is 30/m2 (T1), 45/m2 (T2) and 60/m2 (T3) respectively. The total quantity of water supplied and evaporation and seepage losses were measured on a daily basis. The rainfall and surface runoff were measured in the event of rainfall. The water quality parameters were analysed once in 10 days and were found to be within the permissible limit. The mean total consumption of water for T1, T2 and T3 was 2093.33 ± 6.66, 2099.30 ± 3.33 and 2092.96 ± 5.77 m3 respectively. The survival and yield of P. vannamei in treatments T1, T2 and T3 were 80.49 ± 0.61%, 72.06 ± 0.74% and 68.70 ± 1.45%; and 283 ± 1.53, 322 ± 3.46 g and 311 ± 3.79 kg respectively. The consumptive water use index was significantly less (p > 0.05) in T2 (6.53 ± 0.07 m3/kg) followed by T3 (6.74 ± 0.08 m3/kg) and T1 (7.41 ± 0.04 m3/kg). The water productivity of P. vannamei was significantly higher (p < 0.05) in T2 (0.153 ± 0.002 kg/m3) followed by T3 (0.148 ± 0.002 kg/m3) and T1 (0.135 ± 0.001 kg/m3). Considering the total quantity of water used and the shrimp produced from the earthen grow‐out ponds using inland saline groundwater, a stocking density of 45/m2 and a water budget of 6.53 m3/kg production of shrimp could be recommended as optimum. [ABSTRACT FROM AUTHOR]

The interaction between fish and probiotics has been widely studied, whereas the interactions among meiofauna, probiotics and fish have yet to be explored. In September 2019–July 2020, the effects of a probiotic (Sanolife PRO‐W) on meiofaunal abundance, biomass and diversity, and the impact of these effects on Nile tilapia were studied. Two treatments were applied in earthen ponds: control (C) and probiotic‐treated (T). In spring–summer, a net was used to separate each pond into two areas with fish presence (O) or fish absence (I). Samples were randomly collected bimonthly and monthly from ponds in autumn–winter and spring–summer, respectively. Cladocera, Rotifera, Nematoda and Oligochaeta were dominant in the probiotic‐treated pond. The abundance, biomass and diversity of meiofauna did not differ between the ponds in autumn–winter. However, in spring–summer, meiofauna abundance differed in the following treatment pairs: CO vs. TO, CI vs. TI, CI vs. CO and TI vs. TO. Furthermore, biomass differed in CO vs. TO and CI vs. TI, whereas diversity differed in CI vs. TI and TI vs. TO. These results improve our understanding of positive fish–probiotic interactions; however, additional research is required to explore the relationships identified in these preliminary findings. [ABSTRACT FROM AUTHOR]

Establishing floating photovoltaic (FPV) systems on aquaculture ponds can reduce demand for land use and affects food and solar energy production. This study investigated the water quality of aquaculture ponds with and without simulated FPV systems (40% surface area shading) at three sites: Chupei, Lukang and Cigu. Results indicated the FPV‐covered ponds exhibited lower mean values in biochemical oxygen demand and plankton biomass but higher oxidation–reduction potential relative to the control ponds. The FPV‐covered ponds exhibited lower pH, water temperature and level of dissolved oxygen relative to the control ponds in Chupei and Lukang. The results suggested that the FPV shading effect potentially reduced phytoplankton growth. All FPV‐covered ponds exhibited 1.1, 1.2 and 1.4 times greater yields in giant freshwater prawn, tilapia and milkfish without any effect on the growth of cultured species. These results demonstrate the potential benefits and defects of combining aquaculture with FPV systems. [ABSTRACT FROM AUTHOR]

The aim of the study was to identify key factors of water environmental parameters affect shrimp productivities in the mixed mangrove‐shrimp system using multivariate approach. Water quality assessment was conducted at four mangroves stand ages (MAs) of 2–4, 5–7, 9–12 and >12 years old, with two water level (WLs) regimes in the ponds at 0–20 cm and 20–40 cm, and at every interval of 15‐day grow‐out cycle of shrimp in the systems based on the moon. Water quality in the study farms was within the appropriate range for shrimp growth. Mangrove ages affected alkalinity, pH, COD, N‐NO2, N‐NO3 and H2S, but did not influence the rest of water quality parameters. Shrimp productivity had moderate‐to‐fair positive correlation (rp = >0.36 and <0.5; and rp > 0.5) with N‐NH4, N‐NH3, water level on the platform and water level regimes management in the shrimp ponds respectively. The stepwise multiple regression model fitted very well with 19 independent variables (p = 0.0000; R2 = 0.63) and shrimp productivity. The equation of the fitted model is given as: Shrimp productivity = 18.4552 + 2.34394*DO ‐ 1.01044*Salinity ‐ 1.49646*H2S + 2.97012*Water level. [ABSTRACT FROM AUTHOR]

Microorganisms, as integral components of food webs, play key roles in regulating the aquatic environment in shrimp farming. However, the abundance and functional diversity of bacteria in shrimp aquaculture ponds and the factors shaping their distribution patterns remain largely unknown. We investigated the temporal and depth changes of the bacterial communities in water columns of shrimp ponds in the Min River estuary, southeastern China. Proteobacteria was the most dominant phylum throughout the aquaculture period. The differences in the pattern of variation in bacterial communities among three water column depths were minimal. As a potential pathogen, the genus Vibrio gradually increased in relative abundance from the initial to the final farming phase. Network analysis indicated that the degrees of species segregation were higher, and the average path lengths shorter, during the middle and final farming phases compared with the initial farming phase. This suggested that environmental stimuli are more efficient at reaching the whole network and are potentially more susceptible to external disturbance during the latter two phases. Anaerobic bacteria were most abundant during the middle and final farming phases. Salinity and chlorophyll a concentration were the variables most strongly correlated with the bacterial communities during all phases, and abiotic selection accounted for most of the total variation during the three farming phases. These findings contribute to a deeper understanding of the temporal changes in the composition and functional diversity of bacterial communities in coastal shrimp pond water columns and have implications for the effective and sustainable management of shrimp aquaculture systems. [ABSTRACT FROM AUTHOR]

A coal mine in Datong is an integrated mine. At present, there is goaf in the upper and lower part of the mining coal seam. There is a lot of ponding in the goaf, which has great potential safety hazards for production. In order to find out the scope and location of ponding in goaf, the comprehensive geophysical exploration method combining transient electromagnetic method and high-density resistivity method is used to carry out the research. Firstly, the time-base, turn-off time, receiving delay, current, superposition times, and other parameters of the instrument are tested on the surface of known goaf to obtain the best instrument parameters, and the parameters are used to verify the feasibility of the research scheme; then, the transient electromagnetic method is used for large-area exploration on the surface of the mine, the suspected goaf ponding area is found through comprehensive analysis, and the high-density resistivity exploration is arranged in the suspected goaf ponding area. According to the obtained results, the scope and location of the goaf ponding area are accurately located through comprehensive analysis. The results show that there are two goaf ponding areas in the exploration area, which are located above the 8# coal seam currently mined; the range and location of goaf ponding area can be accurately obtained by using the comprehensive geophysical method of high-density electrical method and transient electromagnetic method. This method can provide reference for mine water prevention and control in Datong area and has great practical significance to ensure coal mine safety production. [ABSTRACT FROM AUTHOR]

To evaluate the evolutionary processes guiding the formation of the tailings-water mixtures produced by the instantaneous collapse of tailings ponds and the influence of these on downstream facilities, a 2D simulation model with reasonable boundary and working conditions derived from actual engineering practice was built in this study, and the relationship between dam-break elevation and impact on downstream facilities was also analyzed to determine the relevant mechanism of influence. Computational results indicated that lowering the dam-break elevation caused the maximum velocity and flooding depth, along with the flooded area at monitoring points, to gradually increase. The occurrence times of maximum velocity and flooding depth were also gradually moved forward as the breaking elevation was reduced; this effect is directly related to the increase in the total potential energy at the lower break elevations. Further simulations of sand-prevent dams with different heights located downstream from a tailings pond were carried out to identify methods for mitigating the impact of dam failure. The results revealed that increasing the height of the sand-prevent dam reduced the production of tailings mixtures. Based on the results, the construction of a sand-prevent dam with a crest elevation equal to that of the starter dam was recommended. [ABSTRACT FROM AUTHOR]

This study aims to probe the potential adsorbent of the biochar produced from spent mushroom substrate (SMS), of which pyrolysis temperature is 400°C, in improving the qualities of sediment and water quality in aquaculture pond. In the first trial, the adsorption of biochars to the ammonia‐N and nitrite‐N in water was evaluated, and the results showed that the SMS‐derived biochars had the ability to adsorb ammonia‐N rather than nitrite‐N. Additionally, the adsorption capability of biochars to ammonia‐N decreased as ambient salinity was increased. The SMS‐derived biochars can also increase the pH of water. In view of the improvement of sediment, SMS‐derived biochars was able to increase sediment pH and decrease the levels of ammonia‐N and sulphite in sediments. In field trial, SMS‐derived biochars was applied to a red claw crayfish farming. As the SMS‐derived biochars had been thrown to the crayfish pond, pond conditions were improved because the pH of water and sediment increased, and the level of ammonia‐N in water decreased, and the levels of ammonia‐N and sulphide in sediment decreased. Therefore, the SMS‐derived biochars was considered great potential as sorbents to adsorb the toxic substances, such as ammonia‐N and sulphide in water and sediment. [ABSTRACT FROM AUTHOR]

Amylase‐producing bacteria could improve water quality contaminated by waste from feed residue and fish metabolism, thereby increasing the efficiency of aquaculture systems. The objective of this research was to screen and optimize fermentation conditions of a high amylase‐producing strain. Four amylase‐producing bacterial strains (named S458‐1, G05, H38 and B09) were isolated from a grass carp pond, and the strain S458‐1 showed the highest amylase‐producing ability, with 19.58 ± 0.38 mm hydrolysis circle diameter. The strain S458‐1 was identified as Bacillus cereus based on morphological identification, biochemical identification and 16S rDNA sequence analysis. The optimal culture medium formula included (in g/L) Ca2+ 0.8, Mg2+ 0.2, Mn2+ 0.4, Fe2+ 0.6, Al3+ 0.2, 1% soluble starch and 1% peptone. The optimal fermentation conditions were determined as initial pH 9, culture temperature 37°C, fermentation time of 60 hr and 2% inoculum. Under the optimal formula and condition, its enzyme activity increased from 32 U/ml to 173.01 U/ml, a 5.41‐fold increase. Surprisingly, our research found that the strain S458‐1 also had phosphorus degradation capabilities. Its phosphorus‐dissolving ability was both time‐ and concentration‐dependent. Thus, this study will make a contribution to the bacterial amylase based on the fermentation process and provide a theoretical basis for further research of aquatic probiotics. [ABSTRACT FROM AUTHOR]

The industrial aquaculture pond system has gradually replaced the use of traditional earthen pond, as it causes less pollution and is more economical. In this study, an industrial ecological purification recirculating aquaculture system consisting of the water source pond, high‐density culture ponds, a deposit pond, and ecological purification ponds for channel catfish cultivation was established. Twelve water samples from different ponds were sequenced, and the bacterial communities were analysed. The abundances of Cyanobacteria and Merismopedia varied in different functional ponds of the system. The water quality was stable after two months of cultivation at 1.89 ± 0.22 mg/L total nitrogen, 1.1 ± 0.08 mg/L NH4‐N and 0.43 ± 0.1 mg/L total phosphorus. The fish weight increased in a nearly linear manner, reaching 237.63 ± 23.8 per fish at day 120. An analysis of the environmental parameters, water quality and fish weight suggested that the system had an effective water purification process. Canonical correspondence analysis showed that the community was affected at the genus and phylum levels by different environmental parameters. We identified several dominant beneficial bacteria with nutrient removal abilities. Overall, our results demonstrated that the ecological purification recirculating aquaculture system had notable effects on water quality improvement and promoted changes in bacterial populations. These results provide important information on the microbial ecology of pond industrial eco‐aquaculture systems. [ABSTRACT FROM AUTHOR]

This study tested the effect of two diets differing in carbohydrate to lipid (CHO:LIP) ratio (4.7 vs. 19.5 g/g) on the contribution of natural food and the total fish production in tilapia ponds. Eight ponds, each divided into three equally sized compartments, were assigned to one of the two diets, which differed in CHO:LIP ratio but had the same digestible protein to digestible energy (DP:DE) ratio (15.5 and 15.6 g/MJ). Ponds were fed equal amounts of crude protein. Three feeding levels (no, low and high) were nested in each pond in a split plot design. Average body weight of fish at stocking was 90 g, and the duration of the experiment was 42 days. Increasing the CHO:LIP ratio had no impact on tilapia production. However, the feeding level influenced both biomass gain, specific growth rate and survival. The apparent digestibility coefficient (ADC) for fat and carbohydrate was influenced by dietary CHO:LIP ratio but ADC for energy was unaffected. Proximate analysis of fish body composition showed no effect of diet except for levels of ash. Diet had no effect on the organic matter composition of the faeces, and the contribution of natural food to fish nitrogen gain. Therefore, we postulate that changing the dietary non‐protein energy source from lipid to carbohydrate does not have any impact on tilapia culture in semi‐intensive ponds. [ABSTRACT FROM AUTHOR]

Seasonal variations can affect the concentration of trace elements, and the change in their concentrations can affect the natural productivity of freshwater aquaculture ponds. Hence, we studied the seasonal variations of the 12 pre‐selected trace elements (Co, Cu, Fe, Mn, Zn, Se, Ca, Mg, P, S, Al, Si) and their relationships with primary and secondary productivity in two aged ponds, stocked with three different life stages of marron (Cherax cainii), for a period of 1 year. Trace element analysis was performed by using (Agilent, ICP‐OES). Except Co and Se, all trace elements, and primary and secondary productivity were influenced by seasonal variation. The pond age significantly influenced the concentrations of some trace elements. On a seasonal basis, trace elements were positively correlated with the plankton abundance, species diversity, and wet and dry plankton weights. Seasonal variations and pond age affected the dissolved concentrations of trace elements and plankton productivity. [ABSTRACT FROM AUTHOR]

This study was aimed to investigate the effects of two probiotics, Bacillus cereus and Pediococcus acidilactici, on the water quality, growth performance, the survival ratio, economic benefits, immunohematology and bacterial flora in the intestine of whiteleg shrimp, Litopenaeus vannamei after 110 days. Nine earthen ponds (each one 1.2 hectare) were adjusted as three treatments including control (without adding bacteria), containing P. acidilactici probiotic (106 CFU/mL) and containing B. cereus probiotic (106 CFU/mL). The results showed that the adding B. cereus and P. acidilactici to the water pond positively decreased nitrate, ammonia and biochemical oxygen demand when compared with the control group (p <.05). Regarding growth performance, treating shrimp with B. cereus caused significantly higher weight gain (16.72 g) and survival ratio (94.50%) in comparison with control group (p <.05). Using these probiotics could increase shrimp production (27.30%, 18.42%) and net income (92.94%, 49.20%) as well. Respect to immunity, total hemocyte count (9.00), total protein (8.92 g/dl) and lysozyme activity (21.55 U/ml) in treated whiteleg shrimp with B. cereus were significantly higher than those untreated (p <.05). In conclusion, adding B. cereus (106 CFU/ml) to the earthen pond can be suggested in shrimp farm. [ABSTRACT FROM AUTHOR]

Fishponds are artificial yet dynamic environments. Microbes play a vital role in the conversion and metabolism of organic matter in aquaculture environments such as fishponds. Changes in bacterial community composition in three fishponds over a 5‐month period were investigated by sequencing the 16S rRNA gene through Illumina Miseq. A total of 2,195,879 sequences and 9,975 operational taxonomic units (OTUs) were obtained. Further analysis showed that the dominant phyla in three ponds were similar, including Proteobacteria, and Bacteroidetes. A comprehensive analysis of the diversity, redundancy analysis (RDA) and partial redundancy analysis (pRDA) showed a spatial‐temporal structural pattern in the bacterial communities. The bacterial community composition in the three fishponds was shaped more by spatial variation than by temporal variation. The effect of pond isolation was emphasized by the significant differences observed in the three fishponds. However, the temporal succession of bacterial communities in each pond exhibited a similar trend. Correlation analysis and RDA also indicated that temporal variation was significantly associated with TOC, TN and NO2−. This study would improve our understanding of the assembly mechanisms of a microbial structure in artificial pond ecosystems, and provide useful information for fishpond management. [ABSTRACT FROM AUTHOR]

In mountainous Northern Vietnam, traditional pond aquaculture is part of the integrated farming activity contributing to food safety and to income generation for small-scale farmers of ethnic minorities. Traditional pond management consists of a polyculture of macro-herbivorous grass carp with 3-5 other fish species that are cultured in small ponds with constant water flow through. The main limitations to production are species-specific mass mortalities of grass carp, a poor feed base especially for all species but grass carp, and poor water quality. In this study, we compared the traditional pond management to a semi-intensive pond management that was based on the traditional management system but included changes designed by researchers to increase fish production. The modifications consisted of water inflow control, supplemental fertilization and feeding, and a polyculture dominated by common carp. The changes in management significantly reduced the turbidity and increased oxygen supply, as well as the natural food base within the pond. These changes in pond management provide farmers with the possibility to improve their pond aquaculture scheme and overcome previous limitations. [ABSTRACT FROM AUTHOR]

This study was carried out in four regions in Southern Ghana with the objective of assessing the demographic profile of farmers and determining the profitability of the industry. A structured questionnaire was used to collect primary data from 74 pond and 13 pen farmers in the selected regions. The results showed that species mostly cultured were tilapia ( O. niloticus), catfish ( Clarias sp.), Heterotis sp. and snakehead ( Parachanna sp.). Descriptive analysis showed the ponds were generally larger than pens. More than 50% of the total farmers had between one and two ponds or pens. The average net returns were US$ 0.55 and US$ 0.42 m−2 for pond and pen culture respectively, making both systems profitable. On a regional basis, pond aquaculture was most profitable in the Western Region. From the results, both pond and pen aquaculture are presently a profitable venture in Ghana that will continue to attract more potential investors even in the next decade. Pond aquaculture was classified into small-, medium- and large-scale operations. Results indicated that small-scale operations were economically non-viable under the present situation, with large-scale operations being the most profitable. The main constraints affecting production were lack of capital, fish predators and poaching. [ABSTRACT FROM AUTHOR]

Production trials of threatened snakehead fish ( Channa striatus) were carried out under different stocking densities in earthen ponds of Bangladesh. The average weight and length of the fingerlings during stocking was 17.63 ± 1.23 g and 13.21 ± 0.52 cm. Fingerlings were stocked at 5000 ha−1 in treatment-1 (T1), 6250 ha−1 in treatment-2 (T2) and 7500 ha−1 in treatment-3 (T3) respectively. Fish in all the experimental ponds were fed with supplementary feed comprising of fish meal (30%) and mustard oilcake (70%) at the rate of 3-6% of estimated body weight two times per day. In addition, trash fish were supplied at the rate of 2-3% of the estimated biomass on each alternate day. In situ water quality parameters of the pond were within the suitable range for fish culture. The growth and survival of fingerlings were significantly higher in T1 than in T2 and T3. The food conversion ratio was significantly lower ( P<0.05) in T1 than in T2 and T3. The estimated gross and net production of fish was higher in T1, followed by T2 and T3. Overall, the highest growth, survival and production were obtained from T1. Therefore, it could be concluded that of 5000 fingerlings ha−1 is the most suitable stocking density for culturing C. striatus under a monoculture system in the earthen ponds for better production. [ABSTRACT FROM AUTHOR]

We evaluated the water characteristics and particle sedimentation in Macrobrachium amazonicum (Heller 1862) grow-out ponds supplied with a high inflow of nutrient-rich water. Prawns were subject to different stocking and harvesting strategies: upper-graded juveniles, lower-graded juveniles, non-graded juveniles+selective harvesting and traditional farming (non-grading juveniles and total harvest only). Dissolved oxygen, afternoon N-ammonia and N-nitrate and soluble orthophosphate were lower in the ponds in comparison with inflow water through the rearing cycle. Ponds stocked with the upper population fraction of graded prawns showed higher turbidity, total suspended solids and total Kjeldahl nitrogen than the remaining treatments. An increase in the chemical oxygen demand:biochemical oxygen demand ratio from inlet (4.9) to pond (7.1-8.0) waters indicated a non-readily biodegradable fraction enhancement in ponds. The sedimentation mean rate ranged from 0.08 to 0.16 mm day−1 and sediment contained >80% of organic matter. The major factors affecting pond ecosystem dynamic were the organic load (due to primary production and feed addition) and bioturbation caused by stocking larger animals. Data suggest that M. amazonicum grow-out in ponds subjected to a high inflow of nutrient-rich water produce changes in the water properties, huge accumulation of organic sediment at the pond bottom and non-readily biodegradable material in the water column. However, the water quality remains suitable for aquaculture purposes. Therefore, nutrient-rich waters, when available, may represent a source of unpaid nutrients, which may be incorporated into economically valued biomass if managed properly. [ABSTRACT FROM AUTHOR]

Annual sedimentation, re-suspension rates and contents of particulate organic carbon (POC), particulate organic nitrogen (PON) and total phosphorus (TP) in the sediment were investigated in two sea cucumber culture ponds at Rongcheng, Shandong Province, China. The results showed that the average flux of total particulate matter in the ponds was 22.1 g m d. The average re-suspension rate of the sediment in the ponds was 81.7%. The re-suspension rates in spring and autumn were higher than those in summer and winter. The mean contents of POC, PON and TP in the sediment of the ponds were 4.4, 0.5 and 0.6 (mg g), respectively, and the mean contents of Chlorophyll a (Chl a) and pheophytin in the sediment were 8.1 and 12.1 μg g respectively. The POC, PON and TP contents in the sediment of the ponds increased during the period of sea cucumber aestivation (summer) and hibernation (winter), while they decreased during the feeding periods. The organic matter accumulation rate and the contents of POC, PON, TP, Chl a and pheophytin in the sediment were even lower than those in the pond without sea cucumber ( P<0.05). The results demonstrated that sea cucumber culture can effectively stop nutrient accumulation at the bottom of the cucumber culture ponds. [ABSTRACT FROM AUTHOR]

Effects of supplemental feeding with cereals (rye, triticale, maize and the unsupplemental control group) on fat content in flesh of 3-year-old common carp ( Cyprinus carpio) were the subject of study carried out at four ponds (Czech Republic, Central Europe) during the growing season. The main result was that supplemental feeding with cereals to the same energetic level was associated with varying growth and fat content in the flesh of common carp. At the end of the experiment, the stock of fish supplementally fed with maize was found to have the highest fat content (112.7 ± 15.6 g kg−1), while the lowest value of fat content was found in the control group (56.8 ± 9.4 g kg−1). The carps supplementally fed with rye were found to have a higher fat content (90.1 ± 19.0) than those supplementally fed with triticale (84.3 ± 15.7 g kg−1). Established average fat content values (except for maize) were at the level that indicate a high sensory quality of carp flesh during the whole growing season. [ABSTRACT FROM AUTHOR]

This is the first controlled experiment to quantify the effect of introduced tilapia on indigenous species. This experiment was conducted in small earthen ponds (100 m2) to assess the impact of mixed-sex or all-male Nile tilapia ( Oreochromis niloticus) on small indigenous species (SIS) commonly found in south Asia, mola ( Amblypharyngodon mola), chela ( Chela cachius) and punti ( Puntius sophore). Ponds were fertilized, then stocked with 0.56 fish m−2 of water surface area in the mixed-sex and all-male tilapia treatments and 0.42 fish m−2 in the treatment without tilapia. No additional nutritional inputs were applied after stocking. Treatments were: mixed-sex tilapia with SIS, mono-sex male tilapia with SIS and SIS without tilapia (control). All treatments were stocked with 14 fish per species. All species reproduced during the 21-month culture duration. The number of recruits varied by species, Tilapia reproduced in greater numbers than SIS. Tilapia numbers at harvest were the highest (451 ± 25/100 m2) in the mixed-sex treatment compared with mola (221 ± 22/100 m2), chela (94 ± 8/100 m2) and punti (100 ± 7/100 m2). The number of mola was higher (399 ± 33/100 m2) in the all-male tilapia treatment. There was reduction in the number of mola and chela in the treatment containing mixed-sex tilapia. Gut content analysis combined with water sampling revealed that all fish species fed selectively. Significant interspecies dietary overlap was found between Nile tilapia and SIS and among SIS. Thus, there is potential for tilapia to compete with indigenous fish species when space and other resources are limiting, but a longer duration study with varying level of management is needed to determine how successfully tilapia competes with locally adapted SIS. [ABSTRACT FROM AUTHOR]

From 24 mating sets, 6300 fingerling of yellow perch ( Perca flavescens) were stocked into one pond and equal numbers of progeny from six representative sets out of the 24 were stocked into each of two other ponds. After communal rearing for 21 months, total length and body weight were assessed for n=300 fish in each of the three ponds and molecular pedigrees were performed for each sampled individual to assign the progeny back to the original parents. The overall average number of alleles per locus was A=16.4 and observed and expected heterozygosities were Ho=0.88 and He=0.77 respectively. The mean weight of random samples and the top 10% fast-growing fish from the pond with all the sets was significantly greater than those from either of the two replicate ponds with six crosses. For the two replicate ponds, no significant differences were found in family rankings and assignment of the top 10% fast-growing fish, indicating that families with superior growth performance in one pond also exhibited the same superior growth performance in the replicate pond. However, there were no significant correlations detected in family mean weights of the top 10% fish between any two of the three ponds. [ABSTRACT FROM AUTHOR]

A feeding trial was conducted to study the effect of dietary protein (DP) levels on the growth and digestive enzyme activities of different wild stocks of Macrobrachium rosenbergii juveniles. Wild juveniles of M. rosenbergii were collected from the west coast of India, Gujarat (G), Maharashtra (M) and from the east coast of India, Andhra Pradesh (A), and raised in culture ponds of 200 m2 at 1 juvenile m−2. All the animals were tagged individually with Elastomer tags of a particular colour assigned to their respective stock and acclimatized for 7 days before being released into the pond at a ratio of 70:65:65 (A:M:G). Each of the two feeds, the first with 27% DP, termed the suboptimum level (S), and the second 32% DP, termed the optimum level (O), was fed in duplicate ponds at 6% of the body mass for the first 30 days and 4% for the last 30 days. The average weight of stocked prawn, respectively, in O DP and S DP fed ponds was 0.90 ± 0.04 and 1.06 ± 0.08 g for the G stock, 0.80 ± 0.07 and 1.01 ± 0.1 g for the M stock and 3.06 ± 0.13 and 3.10 ± 0.23 g for the A stock. Both the protein level and the stock type had a significant ( P<0.05) effect on the weight gain% of the prawn. There was an approximate 95% change in weight gain with a DP change. Similarly, G and M stocks exhibited significantly higher ( P<0.05) growth rates of approximately 90% than the A stock, although no difference was noted between the G and the M stocks. However, for protein × stock (interaction) levels, there was no significant difference ( P>0.05) among the groups. Although insignificant, the survival rates among the different stocks varied from 56% to 77%. Optimum protein level showed a significant increase ( P<0.05) in the specific growth rate (SGR). Feed conversion ratio, feed efficiency ratio, protein efficiency ratio and net protein utilization were not affected either due to DP, stock type or their interaction. The O × A group exhibited the maximum variation in body weight. Digestive enzyme activities were similar in all the groups, but enzymes for phospho-monoesterase were significantly higher ( P<0.05) at O DP. Both the G and the M stock showed a significantly higher ( P<0.05) alkaline phosphatase activity while acid phosphatase activity was significantly higher ( P<0.05) in the M stock only. Overall, the G and M stocks showed higher growth responses compared with the A stock. [ABSTRACT FROM AUTHOR]

Seasonal variations in osmoregulatory and metabolic parameters were assessed in juvenile gilthead sea bream ( Sparus auratus) cultured in earthen ponds under a natural photoperiod and temperature. Specimens were sampled, and the plasma, gill, kidney and liver were collected during winter 2005 and 2006 (January), spring 2005 (April), summer 2005 (July) and autumn 2005 (October). Plasma osmoregulatory parameters showed higher values in summer, while metabolic parameters presented different patterns of variations. Gill Na+,K+-ATPase activity decreased significantly in winter, while gill metabolite levels showed different patterns of variations among seasons. The enzymatic activities tested did not present a clear pattern of variation [(glutamate dehydrogenase (EC 1.4.1.2) (GDH) and hexokinase (EC 2.7.1.11) (HK)] or significant differences along seasons [glucose 6-phosphate dehydrogenase (EC 1.1.1.49)]. Kidney Na+,K+-ATPase activity decreased during summer and autumn. Different patterns of variation were observed in kidney metabolite levels while all the enzymatic activities assessed [lactate dehydrogenase-oxidase (EC 1.1.1.27) (LDH-O), HK and GDH] presented the highest values during summer. In the liver, metabolite levels and enzymatic activities did not show significant variations or present clear patterns of variation along different seasons. These results indicated seasonal variations in the osmoregulatory and metabolic parameters of different organs (blood, gill, kidney and liver) in earthen pond-cultured gilthead sea bream ( S. auratus), which could be mainly attributed to seasonal changes in temperature. [ABSTRACT FROM AUTHOR]

Two topmouth gudgeon Pseudorasbora parva populations were studied in adjacent ponds in Northwest England to determine the influence of density on the expression of their life history traits. Initial introduction into one of these ponds had been in 2000, with establishment of an abundant population (density in March 2005: 6.1 ± 3.2 m−2). Their transfer into the adjacent pond only occurred during brief periods of seasonal connection; this population was of low abundance (density in March 2005: 0.6 ± 0.5 m−2) and was still colonising the pond at the time of sampling. In the low-density population, individuals were significantly faster growing, maturing earlier (generally in their first year of life) and more fecund at length and age (mean batch fecundity at 50 mm: 883 compared with 473 eggs). These traits were advantageous in maximising early life reproduction, facilitating their colonisation and population establishment, a process already completed in the high-density population. [ABSTRACT FROM AUTHOR]

Aquaculture of Spinibarbus denticulatus (Oshima, 1926), a fish species indigenous to North Vietnam and Eastern China, is constrained by lack of fingerlings for stocking ponds and cages. As these fish do not naturally breed in captivity, carp pituitary extract (CPE), luteinizing hormone-releasing hormone analogue (LHRHa) with domperidone (DOM) and human chorionic gonadotropin (HCG) were administered at various doses to induce ovulation. A first set of experiments evaluated the response to LHRHa (30, 40 and 50 μg kg−1) with or without DOM (10 mg kg−1), CPE (20, 30 and 40 mg kg−1) and HCG (3000, 4000 and 5000 IU kg−1). A second set of experiments evaluated the dose response to LHRHa (30, 35, 40 and 50 μg kg−1) primed with 6 mg kg−1 of CPE, and HCG (3000, 3500, 4000, 5000 IU kg−1) primed with 6 mg kg−1 of CPE. The treatment groups were compared with each other and the control (injected with 0.9% saline solution). Only 25% and 50% ovulation resulted when treated with LHRHa at 40 and 50 μg kg−1, whereas 100% ovulation was achieved with an addition of DOM to LHRHa. Both 30 and 40 mg kg−1 CPE induced 100% ovulation. However, HCG (4000 and 5000 IU kg−1) induced ovulation in only 33% of females. When primed with CPE, the minimum dose of LHRHa required was 35 μg kg−1 to achieve 70% ovulation. Priming HCG with CPE also resulted in 100% ovulation, and the minimum effective dose of HCG to induce ovulation was 3500 IU kg−1 with 60% ovulation. Fertilization and hatch rates observed in this study with different hormonal stimulation were high (80–93%). The results indicate that while the use of combined hormone strategy has no apparent advantage over a single hormone strategy, LHRHa+DOM (40 μg kg−1+10.0 mg kg−1) and CPE (30 mg kg−1) are most effective in consistently inducing ovulation and thus can be used for commercial hatchery production of S. denticulatus larvae. [ABSTRACT FROM AUTHOR]

An experiment was conducted for 3 months in 12 experimental ponds, each of 30 m2, with a view to develop a low-cost diet for monoculture of Macrobrachium rosenbergii in ponds. Three experimental diets (30% protein) were formulated using fish meal, meat and bone meal, mustard oilcake, sesame meal and rice bran in different combinations partially replacing fish meal by meat and bone meal and sesame meal and assigned to treatments T1, T2 and T3 respectively. A commercial golda feed (Starter-III) was assigned to T4 (reference diet). Each treatment had three replicates. Juveniles of M. rosenbergii (2.90±0.21 g) were stocked at the rate of 40 000 ha−1. Prawns were fed three times daily at the rate of 10% and 5% of their body weight at the beginning and for the last 2 months respectively. The ponds were provided with aeration during the night using air pumps. The ranges of water quality parameters recorded in different ponds were: temperature 28.9–32.5°C, dissolved oxygen 5.1–8.1 mg L−1 and pH 6.4–7.7. The results showed that the weight gain of prawns fed diet 1 was significantly higher ( P<0.05) than those fed diets 2 and 3, but was not significantly different from those fed diet 4 (reference diet). The feed conversion ratio (FCR) values of diets ranged between 2.21 and 2.96 with diets 1 and 4 showing significantly lower ( P<0.05) FCR values. The survivals (%) ranged between 68% and 78% with prawns fed diets 1 and 4 showing significantly higher survival. The production of prawn ranged between 921 and 1428 kg ha−1 and diet 1 resulted in a significantly high ( P<0.05) production. A simple economic analysis showed that diet 1 generated the maximum net profit of Tk 159 178 ha−1. The results of the study showed that a diet containing 20% fish meal, 10% meat and bone meal, 15% mustard oilcake, 15% sesame meal, 35% rice bran, 4% molasses and 1% vitamin–mineral premixes may be recommended to the farmers for monoculture of M. rosenbergii in ponds. [ABSTRACT FROM AUTHOR]

Sediment samples were collected from 42 catfish ( Clarias hybrid) ponds, 40 freshwater prawn ( Macrobrachium rosenbergii) ponds and 18 carp ( Puntius spp.) ponds in Thailand. Regression analysis revealed that pond age (1–30 years) was not a major factor influencing the physical and chemical composition of pond sediments. Sediment depth, F+S horizon thickness and bulk density of S horizon were greater ( P<0.05) in carp ponds than in catfish and prawn ponds. This occurred because sediment was removed from catfish and prawn ponds more frequently than from carp ponds. Total carbon, organic carbon and total nitrogen concentrations were greater ( P<0.05) in carp ponds than prawn and catfish ponds. Few ponds had sediment organic carbon concentrations above 3%, and carbon:nitrogen ratio values did not differ ( P>0.05) among ponds for the three species. Total phosphorus and other sediment phosphorus fractions increased in the order prawn ponds, carp ponds and catfish ponds. Sediment sulphur concentrations also increased in the same order. There were no differences in major or minor nutrient concentrations in sediment that would influence aquacultural production. Although there were significant correlations ( P<0.05) between various sediment quality variables, no single variable or group of variables would be useful in estimating sediment quality. Pond bottom management practices used by producers in Thailand included drying of pond bottoms between crops, liming, tilling and periodic sediment removal. These practices have maintained relatively good bottom quality. They should be continued in Thailand and adopted in other places. [ABSTRACT FROM AUTHOR]

A study was conducted to optimize stocking density of freshwater prawn, Macrobrachium rosenbergii, in carp polyculture for 3 months in 10 experimental ponds of 80 m2. Five stocking densities of prawn, 2500, 5000, 7500, 10 000 and 12 500 ha−1, were assigned to treatments T1, T2, T3, T4 and T5 respectively. The densities of catla, Catla catla, rohu, Labeo rohita and silver carp, Hypophthalmicthys molitrix, were 2500, 5000, and 2500 ha−1, respectively, in each treatment. Each treatment had two replicate ponds. The mean initial weights of prawn, catla, rohu and silver carp were 1.1±0.02, 8.28±0.1, 25.2±1.1 and 36.32±1.2 g respectively. A pelleted diet containing 30% protein was prepared using fish meal, meat and bone meal, mustard oilcake, rice bran, wheat bran and molasses, and was fed twice daily at a rate of 5% of fish biomass. Water quality parameters were measured fortnightly and the ranges of temperature, pH and dissolved oxygen were 27.5–1.3°C, 6.9–8.6 and 4.5–8.6 mg L−1 respectively. Feed conversion ratios ranged from 2.05 to 2.20 among the treatments. Per cent survival (%) of prawns ranged from 72% to 78%, while it varied from 80% to 93%, 90% to 95% and 90% to 92% for catla, rohu and silver carp respectively. The results showed that there were no significant differences among the weight gains of prawn and carp in different treatments. However, the overall total production of prawn and fish together was significantly ( P<0.05) higher in T3 and T4 compared with other treatments. The total production for 3 months ranged between 2618 and 2916 kg ha−1. The production of prawn was significantly higher (361.3 kg ha−1) in T5 with a highest stocking density of 12 500 prawn ha−1. Although there was no significant difference ( P>0.05) between the total production of prawn and fish together in T3 and T4, the highest net profit (Tk. 69 006 ha−1) was obtained in T4. Therefore, from the result of the study it may be concluded that a stocking ratio of 4:1:2:1 of prawn:catla:rohu:silver carp at a total density of 20 000 ha−1 may be recommended for prawn–carp polyculture in ponds. [ABSTRACT FROM AUTHOR]

To examine the role of humans in the non-native fish introductions, we measured the frequency of occurrence and density of non-native fishes in ponds (Epping Forest, Essex, England) that had been restored (drained of water and voided of fish or treated with rotenone) on a known date and into which no piscivorous or non-native fishes had subsequently been stocked intentionally. For each pond, the period of time since pond restoration, pond area, distance to nearest residential housing, distance to nearest footpath, distance to nearest water body or stream, and the proportion of pond vegetated were measured. The occurrence of both non-native and unexpected native fish species was non-random, and the number of ornamental varieties was found to increase as pond distance from the nearest road decreased. Variety richness of each of three categories of fish (non-native, goldfish Carassius auratus and native) was significantly correlated with at least two of the following variables: distance from nearest road, nearest footpath and nearest pond. The rate of non-native fish introductions (adjusted variety richness per year) could also be estimated from pond distance to the nearest road, being about 3.5 ornamental varieties introduced per year in ponds adjacent to roads, but the rate appears to be much greater in ponds that had recently (<1.5 years) undergone restoration. Implications for conservation and management, as well as the potential role of societal issues such as recreational activities, cultural and religious practices, are discussed. [ABSTRACT FROM AUTHOR]

A simulation model for the production of the Nile tilapia (Oreochromis niloticus niloticusL.) for mixed- or mono-sex culture and for poly-culture with the African catfish (Clarias gariepinusBurchell 1822) or African snakehead (Parachanna obscuraGünther 1861) is presented. The model is based on an exponential decay model used in population dynamics and follows an individual-based approach. The model consists of a tilapia sub-model representing population dynamics, growth and recruitment and a predator sub-model representing the predation process and population dynamics and growth of the used predator. The model was calibrated with data on mixed- or mono-sex culture of Nile tilapia and for poly-culture with the African catfish or African snakehead obtained in Congo Brazzaville and validated with similar data from the Philippines, Thailand and the Ivory Coast. The model visualized major underlying processes in tilapia farming and aspects for further improvement of the model; growth is one of the most sensitive input parameters and should be quantitatively related to feeding level and feed quality; length at first maturity and quantification of the recruitment of Nile tilapia has a relatively large influence and recruitment should be related to the length of the females; prey–predator relations are too coarse and should be more fine-tuned with the relation between prey size and predator size. Incorporation of these features would provide the basis of a model that can serve as a predictive and decision-making support tool. [ABSTRACT FROM AUTHOR]

Abstract The growth of two breeds of common carp, Cyprinus carpio L., was tested in ponds under the climatic conditions of South Bohemia. Třeboň scaly carp (TR) and Hungarian mirror carp (M2) were kept in both low and high stocking densities during the second growing season and then stocked together for communal testing during the third growing season. Before the communal testing, the mean initial weights of fish from low- and high-density stocks differed significantly (374.1 vs. 227.7 g for the TR breed and 766.7 vs. 317.3 g for the M2 breed respectively, P<0.01). After communal testing, mean weights of fish from low- and high-density stocks gained 761.8 vs. 543.8 g for the TR breed and 1339.7 vs. 706.7 g for the M2 breed respectively. These observed weights were also significantly different (P<0.01). However, the test of corrected weight gain, i.e. gain not related to the initial weight of fish, revealed insignificant differences (P>0.01) between the weight gains after correction, i.e. the effect of different initial weights was successfully eliminated. These results seem to confirm the applicability of this method for the assessment of growth of purebred common carp under the climatic conditions of Central European fish farms. [ABSTRACT FROM AUTHOR]

Abstract Chemical characteristics and P-fractionation of sediments from the Deroua fish culture farm (Beni Mellal, Morocco) were analysed in 1998 and 1999. The high concentrations of organic N and organic C in the sediments reflect the high productivity of phytoplankton in the lined ponds. Despite the fact that these ponds were not frequently fertilized, inorganic P was more important in the sediments. The P released from CaCO3 ≈P was the principal source of P for phytoplankton. The mineralization rate of organic C during the drying period was about 87 µg g-1 day-1 in the sediments. The mineralization rate of organic N seems to be less, compared with organic C. The experimental results indicate that the C:N ratio and texture of sediments could explain the immobilization of organic N. All forms of P remained almost unchanged after the drying period except for Fe(OOH)≈P. The ferric (oxy) hydroxides protect NaOHext -P from the bacterial lyses and stabilize therefore their concentration. The inorganic P represented about 88% of Total P in the sediments and may influence the mineralization rate of organic P. The growth of silver carp were reduced in presence of high concentrations of organic C in sediments (> 30 mg/g). Compounds toxic to fish such as Fe2+ , Mn2+ , H2 S and CH4 were then released in the water column. [ABSTRACT FROM AUTHOR]

Pond experiments with one treatment per pond are discussed for their sources of variability. Replication of treated ponds, randomization of treatment allocation to ponds and the importance of independence between ponds are emphasized for efficient estimation of both treatment and inherent pond differences. Appropriate models are given for the analysis of data for pond experiments with whole-pond treatments. Corresponding analyses of variance are given to illustrate the estimation of differences between treatments, between ponds and between fish within ponds. Appropriate significance tests for treatment effects are demonstrated to avoid pseudoreplication, the incorrect use of within-pond variation. Using a fertilizer experiment, simple graphical methods are presented for examining between- and within-pond variation to identify ponds with unusual data, and to determine adequacy of design and appropriate analyses. [ABSTRACT FROM AUTHOR]

In this study, one-cycle and multi-cycle culture systems for Artemia in seasonal salt ponds are compared. In one-cycle systems, Artewia is inoculated only once per season, while in multicycle systems ponds are drained and re-stocked several times per season. In Vietnam, three-cycle systems gave significantly higher cyst yields than did the one-cycle system. However, after two cycles, systems were not significantly different. Food limitation probably caused the steady decline in cyst yields, as observed in the one-cycle ponds. In these ponds, females have smaller broods (from the second cycle onwards) and during the last cycle the number of adult females is lower than in multi-cycle ponds. [ABSTRACT FROM AUTHOR]