Pond Maintenance Research Articles

Risk Prediction Model for Tailings Ponds Based on EEMD-DA-LSTM Model

With the passage of time, the constant changes in relevant factors, and the daily maintenance of tailings ponds, the difficulty of tailings pond safety management is increasing day by day. In order to systematically improve the early warning ability for tailings pond dam break risk, the relationship between and influence of various related dam break risk factors of tailings ponds are utilised and the combination with dual attention is innovatively proposed. The risk prediction model for tailings ponds, EEMD-DA-LSTM, is improved. First, Pearson correlation coefficients are used to analyse the correlation between risk factors of tailings ponds. Then, the EEMD method is used to decompose the nonlinear displacement sequence, and the weights of input features are dynamically adjusted by double attention (DA). Finally, the LSTM network model is constructed to predict the displacement change. Taking valley-type tailings pond WKB-1 and mountainside tailings pond WKB-2 as examples, the dam break risk prediction models for tailings ponds are constructed based on three different models, the prediction results of different models are compared and analysed, and the prediction accuracy of the models is evaluated by three different evaluation criteria. The research results show that the integration of the EEMD-LSTM model with the DA model, that is, the EEMD-DA-LSTM model, has a better prediction effect for the dam break risk of tailings ponds WKB-1 and WKB-2 than other models through experimental verification. Therefore, the EEMD-DA-LSTM model is of great significance for preventing and resolving the safety risks of tailings ponds. It is valuable for practitioners in the mining industry and environmentally sustainable development.

Establishing a safe anesthesia concentration window for Nile tilapia (Oreochromis niloticus) (Linnaeus 1758) by monitoring cardiac activity in eugenol immersion baths

Nile tilapia, Oreochromis niloticus, is the most cultivated fish species in the world, due to its low cost, high growth rate, environmental adaptability, and resistance to disease and stress. Anesthetics for fish become necessary in management because they minimize mortality during transport and maintenance of ponds, one of the most used anesthetics is clove oil, which has eugenol as the major substance, representing 90–95 % of clove oil. The present study evaluates the effect of eugenol on cardiac activity in Oreochromis niloticus specimens and relates it to behavioral data to determine a concentration window for safe anesthesia. For the comportamental analysis, was used five treatments (50, 75, 100, 125, and 150 μL·L−1) were evaluated and for the eletrocardiographic test was used seven groups (Control, Vehicle, 50, 75, 100, 125, and 150 μL·L−1), n = 9/treatment, totaling 108 animals. Behavioral and electrocardiographic tests were performed on all treatments during induction and recovery. The results of the behavioral tests demonstrated the reversibility of the effects with recovery of the posture reflex, varying according to the concentration. The ECG results showed a slow recovery because, at concentrations above 100 μL·L−1, there was no full reversibility of the cardiac effects in the observed experiment time, which could cause greater changes in the tilapia hemodynamics, which led us to identify a window for safe anesthesia. Eugenol is an effective anesthetic in Nile tilapia juveniles when used in concentrations ranging from 50 to 100 μL·L−1, if there is a need for anesthetic deepening, doses above 100 μL·L−1, however, the animals must be monitored due to hemodynamic changes.

Management Strategy of Idola Bumdes Agrourism Village to Realize Improving the Community's Economy of Sambibulu, Taman, Sidoarjo

The economy is part of human life, and a source in living life. The government in Indonesia has launched various rural development programs. Some people are starting to realize the importance of a change, by utilizing the plantation land into agro-tourism. One of the places where plantation land is used as an agro-tourism idol for Bumdes is in Sambi Bulu, Taman, Sidoarjo. The focus of the research is, How is the plantation management process becoming a Bumdes idol agritourism in Sambi Bulu, Taman, Sidoarjo?, What is the role of the Bumdes idol agro-tourism in realizing an increase in the community's economy in Sambi Bulu, Taman, Sidoarjo?, The research objectives were to describe the process of managing plantations to become idol Bumdes agritourism in Sambi Bulu, Taman, Sidoarjo to describe the role of agrotourism idol Bumdes agrotourism to realize economic improvement in the community in Sambi Bulu, Taman, Sidoarjo. The research methodology is a qualitative approach and this type of research is descriptive qualitative. Data collection techniques using unstructured interviews, passive participatory observation and documentation. Data analysis using data reduction, data presentation and conclusions. The validity of the data in this study uses source triangulation. The results of this study are: the management process carried out is to make changes, make fishing ponds, planted commodities, care for plants (fertilizing irrigation and others), maintenance of fish ponds, making game rides. and planting suitable plants, as a place of study and tourism based on artificial open agriculture, The role of idol-owned agro-tourism in improving the rural economy is to provide job opportunities, communities around agro-tourism are given the freedom to sell in agro-tourism, provide counseling, transmit knowledge through various training -training. However, the existence of agro-tourism cannot increase the income of workers and the surrounding community.

SISTEM INFORMASI BUDIDAYA IKAN LELE DI BALAI BENIH IKAN (BBI) BUNGUS

The Bungus Fish Seed Center as an institution that produces catfish seeds has developed good cultivation techniques and management of catfish farming businesses. This study aims to examine catfish farming techniques and the application of information systems in the management of catfish farming at the Bungus Fish Seed Center. The research method used is a mixed research method by means of observation, interviews, and documentation. The results showed that the Bungus Fish Seed Center applied good cultivation techniques, such as managing water quality, selecting superior seeds, using good and correct feed, and good pond maintenance techniques. The Bungus Fish Seed Center also implements an information system in managing catfish farming, such as a real-time monitoring system for catfish production, a pond water quality monitoring system, a feed recording system, a production cost calculation system, and a planning and production system as well as financial reporting. From the results of the analysis and design of catfish farming information systems, it can be concluded that information systems can provide benefits for catfish farmers in managing catfish farming businesses more effectively and efficiently. Thus, catfish farming at the Bungus Fish Seed Center has implemented good cultivation techniques. So that it is expected to make a positive contribution in increasing the productivity and quality of catfish and the economy in Indonesia.

Technical Study of Sediment Pond Maintenance Scheduling ( Sediment pond) For Guard Quality Sand Wash PT. Gunung Source Fortune

PT. Gunung Sumber Rejeki is a subsidiary of PT. Agung Satrya Abadi which is located at Wonosunyo Village, Kec. Gempol, Kab. Pasuruan, Province. East Java. Gravel sand mining The sale value of natural products (sirtu) can be increased by processing and refining. The feed material is brought to the stone crusher and sand washing plant with the production of stone split 1 cm – 1 cm, 1 cm – 2 cm, 5 cm – 10 cm and sand wash with a silt content of less than 5%. In 1 cycle of pond maintenance, the feed material that can be processed is 1587.15 tons with a maintenance schedule every 6 days in all pond segments. Sludge impurities from the process washing sand flowed into pond one and experienced as much sedimentation 298.5 m 3 /6 days, pool two as much 313.98 m3 / 6 day, pool three as much 365.7 m3 / 6 day, and pool four as much 385.5 m3 / 6 day. Maintenance settling pond very need done because water in a settling pond reused for washing sand so that very influential on quality sand which in earn

Facilitating maintenance of stormwater ponds: comparison of analytical methods for determination of metal pollution

Stormwater ponds are widely used for controlling runoff quality through the sedimentation of particles and associated pollutants. Their maintenance requires regular removal and disposal of accumulated material. This necessitates an assessment of material hazardousness, including potential hazard due to its contamination by metals. Here we analyze 32 stormwater pond sediment samples from 17 facilities using several chemical analysis methods (total extraction, sequential extraction, diffusive gradients in thin-films DGT, and pore water extraction) in order to consider the complementarity and comparability of the different approaches. No clear relationship was found between analyses that have the potential to measure similar metal fractions (DGT and either fraction 1 of the sequential extraction (adsorbed and exchangeable metals and carbonates) or pore water concentrations). Loss on ignition (LOI) had a significant positive correlation with an indicator of the environmental risk developed in this paper (∑ranks) that incorporates different metals, speciations, and environmental endpoints. Large variations in metal levels were observed between ponds. As clustering was limited between the different analyses, a comprehensive analysis of different parameters is still needed to fully understand metal speciation and bioavailability.

Impacts of Dams on Freshwater Turtles: A Global Review to Identify Conservation Solutions

Background and Research Aims Dams impact freshwater ecosystems and biodiversity. Freshwater turtles are at direct and indirect risk due to changes caused by damming including the loss of terrestrial and aquatic nesting habitats, changes to food availability, and blocking movement. Effective management of these impacts requires robust evidence in order to gain an understanding of conservation solutions that work. Methods We reviewed the global scientific literature that evaluated the impact of dams on freshwater turtles, and carried out additional searches of literature published in seventeen languages for studies evaluating actions to mitigate dam impacts. Results The search produced 47 published articles documenting dam impacts on 30 freshwater turtle species from seven families (Chelidae, Chelydridae, Emydidae, Geoemydidae, Kinosternidae, Podocnemididae, and Trionychidae) in 13 countries. Few studies were found from Europe and Asia and none from Africa. Most studies were from temperate latitudes, where studies focused more on adults and less threatened species compared with tropical latitudes. More than half of the studies (57%, n = 27) suggested actions to help mitigate dam impacts. Yet, only five studies (three temperate and two tropical) documented the effect of interventions (dam removal, flow management, artificial pond maintenance and community-based action). Conclusion These findings demonstrate a serious lack of documented evidence evaluating mitigation actions for dam impacts on freshwater turtles. Implications for Conservation This lack of evidence reinforces the importance of strengthening and maintaining robust long-term studies needed to develop effective and adaptive conservation actions for this group of threatened vertebrates particularly in tropical regions.

Evaluation of Waste Stabilization Pond Efficiency and Its Effluent Water Quality: a Case Study of Kito Furdisa Campus, Jimma University, Southwest Ethiopia.

Waste stabilization pond (WSP) technology is one of the most promising wastewater treatment methods. In developing countries, including Ethiopia, only a small proportion of the wastewater is being treated. Discharge of untreated wastewater into receiving water bodies may lead to disruption of ecological integrity, economic, and public health risks. However, there is limited evidence on WSP efficiency and effluent water quality in Ethiopia. A laboratory-based cross-sectional study was conducted on 60 wastewater samples. A standard method of procedure was used to collect and analyze samples. SPSS version-24 was used for statistical analysis and a paired t-test was used to test for statistical significant differences. A statistically significant difference (p < 0.001) in the removal efficiency of BOD5 up to 75.3% (117 mg/L effluent) and COD up to 56.5% (457.5 mg/L effluent) was recorded. A statistically significant difference (p < 0.001) in the removal efficiency of TN up to 79% (17.4 mg/L effluent), TP up to 69.2% (4.8 mg/L effluent), and PO4−3 up to 71% (3.36 mg/L effluent) was recorded. Whereas, a statistically significant difference (p < 0.001) in the removal efficiency of total coliforms up to 99.99% (3.4 × 103 MPN/100 mL effluent) and fecal coliforms up to 94.3% (8.54 × 102 MPN/100 mL effluent) was recorded. The overall efficiency of the treatment plant was 73.5% and its water quality index of the effluent water quality of WSP was 30. The finding showed that the efficiency of the WSP was judged as satisfactory and the effluent water quality of WSP is unsuitable for the discharge into the environment. Therefore, to improve the efficiency of the WSP and to produce adequately treated water, it required adequate preliminary treatment, modification of the design, desludging of the pond, additional treatment, and frequent monitoring and maintenance of the pond.

Analysis of Erosion Management Based on GeoWEPP Spatial Modeling on Bauxite Mining Activities PT. XYZ in West Borneo

Bauxite ore open-pit mining activities are conducted in spread areas and increase the potential for water pollution, implying a need for good management. GeoWEPP is a spatial model that predicts the erosion magnitude and the location of sedimentation. This helps in erosion management and control, including constructing a settling pond. Therefore, the purpose of this study was to examine GeoWEPP based on land use, topographic and soil maps, as well as rainfall and temperature data. The results showed that 30 hills with a total area of 13 602.48 Ha obtained sediment of 150 186 m3/month and the amount of run off of 4 202 267 m3/month. Furthermore, GeoWEPP analysis on the planned mining block area obtained 30 outlet points to be used as the location for the settling pond construction. The optimistic and pessimistic cost of constructing the entire settling pond is Rp. 222 047 640 944 and Rp. 222 773 049 768, respectively. Additionally, the cost of settling pond maintenance at all outlet points during operation is Rp. 3 139 414 818. Planting cover crops in ex-mining areas is very effective in reducing erosion.

The effect of society participation, budget, and organization on the effectiveness of pond maintenance program in Kobalima District, Malaka Regency

Abstract: Purpose: The discussion of this research is Society Participation, Budget, and Organization on the Effectiveness of Pond Maintenance Program in Kobalima District, Malaka Regency. Research Methodology: This study uses quantitative research methods with sampling techniques in research using the Slovin formula and data analysis techniques using regression, namely looking for the effect of each independent variable on the dependent variable, and the instrument used in this study is intended to produce accurate data by using a Likert scale. Results: Each independent variable, namely society participation, budget, and organization, partially has a significant influence on the effectiveness of the pond maintenance program. Simultaneous society participation, budget, and organization also have a significant effect on the effectiveness of the pond maintenance program. Limitations: Research variables are complex and research results may change in the future. Contribution: Research findings can serve as a basis for evaluation and the basis for maintaining existing good performance in promoting an effective pond maintenance program. Keywords: 1. Budget 2. Organization 3. Participation

Local flow convergence, bed scour, and aquatic habitat formation during floods around wooden training structures placed on sand-gravel bars

Riverine ponds, which are formed and sustained through sediment erosion and deposition, are key habitats for enhancing biodiversity in river reaches. The objective of this study was to understand the roles of traditional river-training wooden structures called “seigyu” on the formation of ponds on nonvegetated bars. Here, the spatial and temporal patterns of the flow and bedform coupled with pond formations for several flood events were assessed. The surface flow patterns were monitored by an unmanned aerial vehicle (UAV) and evaluated by large-scale particle image velocimetry (LSPIV); the maximum flow velocities were 1.3 m s−1 and 1.9 m s−1 during floods when seigyu units were partially and fully submerged, respectively. Although the overall mean flow velocity was greater for the latter events, the spatial variation in flow velocity and dissipation rate of turbulent kinetic energy (TKE) around seigyu was greater for the former events. Such flow patterns affected both bed formation and ecological habitats; ponds were formed at locations beside and behind seigyu, where the flow converged and bed scouring occurred during floods. The frequency and size of ponds around seigyu increased in the early half of the season, and they decreased in the other half when floods were greater in magnitude, which suggests that the bed scouring effect of seigyu was greater in flood stages with partial than fully submergence. Although the bar ponds lack shade to temper the effects of incident light and atmospheric conditions, the ponds displayed smaller daily oscillations in temperature than did the main river, probably due to hyporheic water supply to the ponds. Because many aquatic species cannot tolerate extremely high temperatures in summer, the generation and maintenance of deeper ponds by scouring with sufficient water exchange with the hyporheic zone can be key to enhancing colonization by various aquatic species.

The impact of sustainable aquaculture technologies on the welfare of small-scale fish farming households in Myanmar

This study analyzed the determinants and potential impacts of the adoption of sustainable aquaculture (SA) technologies on the welfare of small-scale aquaculture (SSA) households in Myanmar using an endogenous switching regression model. Welfare is measured by fish productivity and fish income per cycle and Household Dietary Diversity Score. Our analysis revealed that distance to the sale-point, membership in farmers’ organizations, awareness of pond maintenance benefits, access to information through private extension services, and location were the main drivers behind adopting SA technologies. Results showed that adopting SA technologies increases welfare outcomes of SSA households; however, the non-adopters stand to benefit the most in terms of an increase in welfare outcomes if they adopt the technologies. Our research findings suggested that policies targeted at raising SSA households’ income and dietary diversity can be realized through interventions to raise farmer’s awareness, adoption, and technical know-how about the SA technologies.

APPLICATION OF ZERO WASTE TECHNOLOGY IN SOLID WASTE OF SHRIMP TAMBAK IN SRIMINOSARI VILLAGE, LABUAN MARINGGAI, LAMPUNG TIMUR

The application of zero waste technology in the handling of pond sludge is an alternative solution that can be done to overcome the problem of decreasing the productivity of shrimp ponds.This activity aims to provide guidance to shrimp farmers in the Sriminosari Village to apply zero waste technology in handling solid waste and processing it into a planting medium. The method of activity is carried out through technical approaches and guidance in the field. The activity target is a group of productive partners in the Sriminosari village. Partner groups gain an understanding of zero waste technology through guidance both theoretically and practically in the field.&#x0D; This activity was attended by 10 participants consisting of shrimp pond owners, Karang Taruna, and representatives from UKM Pemuda Sriminosari. The evaluation results show a very significant increase in understanding the concepts of zero waste (theoretically) in participants. Through technical guidance, a tool of a suction sludge with a capacity of 200 m3 per minute was successfully designed and equipped with 10 drums of sludge filter.&#x0D; Furthermore, the sludge waste has also been successfully processed into a media for planting. Based on the results, it can be concluded that there is an increase in the ability of partners in terms of implementing zero waste technology in handling solid waste in shrimp ponds. In addition, there is a new business opportunities related to shrimp pond maintenance services and businesses based on processing solid waste in shrimp ponds.

Acute Hepatopancreases Necrosis Diseases (AHPND) as Challenging Threat in Shrimp

White feces syndrome (WFS) is an emerging problem for penaeid shrimp farming industries in South East Asia countries. Outbreaks began in cultivated shrimp Penaeus (Penaeus) monodon, and Penaeus (Litopenaeus) vannamei and spread progressively worldwide, although the disease's cause was unknown. In 2011 a case definition for AHPND (as acute hepatopancreatic necrosis diseases) and white fecal syndrome (WFS) were reported. The presence of white feces floating on water and clinical symptoms include pale empty gut region, reduced growth, movable shell, and black discoloration. The pacific white shrimp, Litopenaeus vannamei, with the major shrimp cultivable species globally, is currently in danger by a severe disease- WFS, which causes serious losses worldwide. It has been confirmed that the causative agent of WFS/AHPND is a bacterium that is a pathogen - probably Vibrio parahaemolyticus. This bacterium currently reported has acquired plasmids that encode lethal binary toxins PirA/PirB causing rapid death of infected shrimp. Additionally, this plasmid acquired some virulence factor which is directly related to pathogenicity. Further rapid diagnostic tests for early detection of WFS/AHPND pathogens will promote the production of hatchery and pond maintenance and contribute to the long-term explication of the disease's various aspects.

Determinants of profitability in catfish farming in Ilorin West Local Government Area of Kwara State, Nigeria

This study analysed the profitability of catfish farming in Ilorin west Local Government Area of Kwara State. Multistage sampling technique was used to collect data from 120 catfish farmers using structured questionnaire. Data collected were analysed using descriptive statistics, Gross margin analysis and linear regression. Result shows that more than half (54.17%) of the catfish farmers were males while majority (63.34%) of the farmers were within the age group 31- 50 years. The mean age and household size of farmers in the study area were 38 years and 5 persons respectively. Most of the catfish farmers (45.83%) utilized concrete pond type while average fish pond size was 205 square metres. Major source of finance for farmers is from their personal savings. The gross margin analysis shows that gross margin for the catfish farmers was ₦22,013,583.1 while the average gross margin was ₦183,446.52 perproduction cycle indicating that catfish farming is profitable. The result of the linear regression reveals that pond maintenance, transportation and feed cost are negative and have significant effects on income generated from catfish business while pond size and education is positive and significant at 5%. Since catfish business is a profitable venture, the study recommends that the Nigerian government should use this as a means to empower unemployed youths and rural households to reduce poverty level as well as dependence on fish importation in the country.&#x0D; Keywords: Catfish farmers, Profitability, Production, Gross margin, Personal saving.

The technology of striped catfish broodstock (Pangasius hypophthalmus) in high-quality maintenance

Striped catfish (P. hypophthalmus) is a high economic value and is a determining factor at the hatchery stage. Quality catfish brooders that can produce superior seeds can be obtained through good handling. The purpose of this study is to gain knowledge in the maintenance techniques of catfish broodstock. The working methods used in the study is a descriptive method with primary and secondary data collection. Striped catfish broodstock uses a recirculation system which includes preparation of pond maintenance, broodstock maintenance, feed management, water quality management, broodstock selection, and spawning. The results of the average water quality parameters for 25 days are turbidity 17.85 cm, temperature 29.51°C, DO 4.23 mg/L, ammonium 0.005 mg/L, and pH 7.54. The average weight measurements in the first and second sampling are 3.11 kg and 3.13 kg, while the average length measurements in the first and second sampling are 55 cm and 56.05 cm. The growth rate in the maintenance of catfish broodstock for 21 days is 9.52 grams/day, and the specific growth rate is 0.028%. Catfish spawning uses a ratio of ten males and three females.

Why Do Beavers Leave Home? Lodge Abandonment in an Invasive Population in Patagonia

Research Highlights: Lodge abandonment by beavers is apparently a common phenomenon in Patagonia, but it is still poorly understood and we ignore what drives it. In relatively slow growth Nothofagus forests, resource depletion can impact abandonment while water availability may be a major driver in the semiarid steppe. Background and Objectives: North American beaver (Castor canadensis) was introduced in 1946 on the island of Tierra del Fuego (TDF) in southern Argentina. Since then, beavers have become a major disturbance affecting not only forest but also treeless steppe landscapes. Our goal was to determine the factors affecting lodge abandonment by beavers in two habitats of TDF: forest and steppe. Materials and Methods: A total of 47 lodges were surveyed between February and March from 2012 to 2014 in both habitat types, 22 in the forest and 25 in the steppe. To explain factors involved in lodge abandonment by beavers, we measured the following variables: water level variation, stream gradient, vegetation cover adjacent to shore and forest structure. Results: We recorded 24 abandonments events, with a similar proportion of lodges abandoned in both habitats. Our results revealed that lodge abandonment was mostly linked to water level fluctuations irrespective of habitat type. The water level at the entrances of the lodge generally decreased in abandoned lodges. Variables that characterize understory cover had some influence on lodge abandonment in the forest, and no effect in the steppe. Conclusions: Water level variation was associated with lodge abandonment in both habitats, and we found some evidence of resource depletion in the forest. However, we caution that changes in water level may be not only due to extrinsic factors but rather to beaver’s own activities or to a decay in pond maintenance following abandonment.

Use of aquaculture ponds by globally endangered red-crowned crane (Grus japonensis) during the wintering period in the Yancheng National Nature Reserve, a Ramsar wetland

Conversion of natural wetlands to artificial wetlands is a global phenomenon that leads to loss of natural habitats for waterbirds, while these alternative wetlands may buffer the adverse effects of natural wetlands loss by providing waterbirds with suitable habitats. Yancheng National Nature Reserve (YNNR), a Ramsar wetland in China, is the largest wintering area for the globally endangered red-crowned crane (Grus japonensis). A remarkable part of natural wetlands within the YNNR has been reclaimed into aquaculture ponds in recent decades. In order to better understand the utilization of aquaculture pond by cranes and identify beneficial management actions, we investigated the wintering crane occurrence in ponds and quantified pond characteristics as mainly influence factors from November to March in 2017–2018 and 2018–2019. A total of 198 ponds were measured (91 in 2017–2018 and 107 in 2018–2019), out of which 42 ponds were found to be used by 48 groups of cranes (16 in 2017–2018 and 32 in 2018–2019). Family groups with 2–4 individuals of cranes were mostly encountered (91.7%) of all the group types. Wintering crane abundance in the aquaculture ponds was higher in 2018–2019 (105 individuals) than that in 2017–2018 (59 individuals). Five factors including water depth, species abundance, species richness, structures and distance to road were identified to influence use of ponds by cranes. However, crane occurrence was significantly associated with only water depth. This study recognized aquaculture ponds as a potential habitat for red-crowned crane. Efforts should be channeled into the sustainable development and maintenance of aquaculture ponds. More specifically, we recommended appropriate management practices to benefit wintering cranes by sequential harvesting of aquaculture ponds, maintaining aquaculture ponds in the buffer zone and keeping the water at a low level.

Variability in phytoplankton community structure and influence on stabilization pond functioning

Density of phytoplankton in stabilization ponds influences treatment performance. The study hypothesized that the phytoplankton community structure varies according to local and temporal changes and consequently influences the treatment of the effluent. Phytoplankton community structure in facultative and maturation ponds in central Brazil was analyzed to provide guidance on system operation and maintenance. Further, species density, abundance, diversity, richness, dominance and beta diversity were measured. The efficiency of the treatment was evaluated based on Biochemical Oxygen Demand (BOD). Additionally, a Canonical Correspondence Analysis (CCA) was used to investigate how physical and chemical variables influenced the composition of the most abundant species in the dry and rainy seasons and the microalgae that were most related to the removal of BOD. One hundred and sixty-eight taxa were recorded, and the most abundant classes in both ponds were Chlorophyceae and Cyanophyceae (40% potentially toxic). The maturation pond had greater adaptability in the rainy season, while the facultative pond was more flexible in the dry season. The best period of growth varied among species. In both ponds, Chlorella minutissima was the one which most contributed to the optimization of the treatment. Thus, identifying phytoplankton species and relating them to water quality parameters and weather can help to understand the ecological dynamics of wastewater treatment and provide useful information for the operation and maintenance of stabilization ponds.

Association of Risk Factors and Management Issues on the Occurrence of Diseases in Carp Aquaculture in West Bengal, India

The risk factors, management issues and impacts of diseases in carp aquaculture in West Bengal were evaluated. The relative risk was calculated for 35 variables related to pond connection/establishment, pre-stocking, stocking, post-stocking management, hygiene and climate. Practices such as the use of rainwater, draining of pond water, pond bottom drying for > 20 days, liming, treatment of fish seeds before stocking, drying and disinfection of fishing nets and training in aquaculture were identified as sparing factors for infectious diseases. On the other hand, variables such as presence of wild fish in ponds, use of sewage water, intensification of culture, presence of more number of grow-out ponds in farms, presence/poor maintenance of nursery ponds, black pond bottom, sludge disposal on pond dyke, mortality of fish seeds during transportation, inclusion of Cirrhinus mrigala and Labeo bata as culturable species, and low temperature were identified as putative factors. These sparing and putative factors are the areas where the resource-poor farmers can attempt interventions with ease to prevent the diseases and to augment fish production. This calls for effective fish health management strategies and participation of all those involved in the development of carp aquaculture.