Tilapia lake virus (TiLV), a negative sense RNA virus with a 10 segment genome, is an emerging threat to tilapia aquaculture worldwide, with outbreaks causing over 90% mortality reported on several ...continents since 2014. Following a severe tilapia mortality event in July 2017, we confirmed the presence of TiLV in Bangladesh and obtained the near-complete genome of this isolate, BD-2017. Phylogenetic analysis of the concatenated 10 segment coding regions placed BD-2017 in a clade with the two isolates from Thailand, separate from the Israeli and South American isolates. However, phylogenetic analysis of individual segments gave conflicting results, sometimes clustering BD-2017 with one of the Israeli isolates, and splitting pairs of isolates from the same region. By comparing patterns of topological difference among segments of quartets of isolates, we showed that TiLV likely has a history of reassortment. Segments 5 and 6, in particular, appear to have undergone a relatively recent reassortment event involving Ecuador isolate EC-2012 and Israel isolate Til-4-2011. The phylogeny of TiLV isolates therefore depends on the segment sequenced. Our findings illustrate the need to exercise caution when using phylogenetic analysis to infer geographic origin and track the movement of TiLV, and we recommend using whole genomes wherever possible.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
•An estimate of COVID-related single-use plastic usage and waste in Bangladesh is provided.•The potential impact of single-use face masks on plastic pollution in the aquatic environment of Bangladesh ...is considered.•The concomitant increase in aquatic macro and microplastic waste is placed into the context of the importance of aquaculture to Bangladesh.•An observational field study reveals an abundance of plastics in and around aquaculture ponds.•Recommendations are made and discussed to mitigate against this emerging threat.
In Bangladesh, as with many countries, the spread of COVID-19 made the wearing of single-use face masks, a non-pharmaceutical intervention to reduce viral transmission, surge in popularity amongst the general population. Consequently, irresponsible discarding of used masks into the environment, and mismanagement of the waste they produce, is potentially placing a large pollution burden on aquatic ecosystems in the country. Slow degradation of mask-derived polypropylene and polyethylene fibres creates large reservoirs of microplastic pollutants and these have acute and chronic effects on aquatic organism physiology. Using literature reviews, extrapolation of published data, and field observations, we present an emerging issue of pollution from COVID-19 personal protective equipment such as face masks in Bangladesh. We have estimated the volume of waste generated and document the potential consequences of its improper disposal, and subsequent degradation, in aquaculture ponds within country. In a field survey of 30 ponds in the Muktagacha upazilla, 76.7% were found to have plastics in contact with the water, or within 1m of the pond, and there was an average of 63 pieces of macro-plastic pollution per 5m2. This included floating discarded face masks. Bangladesh has a rich freshwater and marine resource which it depends upon for export trade, nutrition of the population, and jobs. To mitigate potential acute and chronic impacts on aquaculture and the environment, recommendations are made that, if adopted, would reduce entry of microplastics into the aquatic environments via face mask waste mismanagement.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•ANCs in pangasius and tilapia, fish feed, pond sediments and water were analysed comprehensively.•Residual ANCs except heavy metals were not found in farmed pangasius and tilapia ...flesh.•Residual toxic heavy metals lead and chromium in fish were above the permissible limit.•Heavy metals sourced primarily from fish feed with secondary sources such as groundwater.•Lead and chromium concentrations in fish flesh pose potential carcinogenic risks to human health.
Intensive feeding and the use of drugs and other chemicals for enhancing yield characterised commercial pangasius and tilapia aquaculture in Bangladesh. The residual presence of prohibited antibacterial substances, nitrofuran metabolites and other chemicals (ANCs) in fish, and their effect on public health are a concern for consumers. This study collected samples from 15 pangasius and 15 tilapia ponds to assess the contamination of ANCs, including pesticides, dyes and heavy metals in fish flesh, and heavy metals in feed, sediments and water. Antibacterial substances, nitrofuran metabolites and dyes in fish flesh were detected using LC–MS/MS. Organochlorine pesticides and heavy metals were detected applying GC–MS and AAS, respectively. We found very low residue of the most ANCs in pangasius and tilapia flesh, however, both species contained heavy metals, particularly lead (Pb) and chromium (Cr). The level of metal contamination was affected by the age of the pond; the highest concentration of Pb was in pangasius from old ponds (> 10 years), and the highest concentration of Cr was found in pangasius from new ponds (< 10 years), and tilapia from old ponds. The feed sampled in this study, particularly the commercial pellet and farm-made feed, were highly contaminated with heavy metals. Pond water and sediments were contaminated by heavy metals; fish, water and sediment samples from older ponds had higher concentrations of heavy metals. The concentration of these heavy metals in fish flesh above regulatory limits poses potential risks to human health. To ensure the production of safe fish for human consumption, commercial aquaculture in Bangladesh requires a functional regulatory framework.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Intensive aquaculture generates large deposits of N and P in pond sediments.•Commercial dairy production in Bangladesh is constrained by lack of green fodder.•Field trials producing fodder using ...pond sediments as fertilizer show encouraging results.•Fodder grass yielded better net returns and cost benefit ratios than rice.•Nutrient recycling from pond sediments for fodder grass production has potential to contribute to sustainable intensification.
Intensive aquaculture systems (e.g. pangasius farming) make important contributions to food security in developing countries, including Bangladesh, but are associated with a variety of negative environmental impacts, including the discharge of nutrient rich sediments into local ecosystems. The present study consists of laboratory based analysis of the nutrient content of pangasius pond sediments (PPS), a trial of the efficacy of reuse of PPS as fertilizer to produce para grass as a green fodder for dairy cattle, and a comparative assessment of the economic viability of para grass production in rice fields using PPS to support small-scale dairy farming operations, thereby removing a major constraint to the growth of commercial dairy production in Bangladesh. PPS had significantly higher levels of organic carbon, nitrogen, phosphorous, potassium and sulfur than rice plot soil, and was a highly effective fertilizer for para grass cultivation. Production of green fodder for dairy cows using PPS yielded a higher rate of return than rice production. The indirect integration of aquaculture with agriculture through the reuse of PPS as fertilizer for green fodder production has significant potential to contribute to sustainable intensification and nutrition security goals, by improving the efficiency of nutrient use in aquaculture, reducing local environmental impacts associated with sediment disposal, and increasing the production of micronutrient rich milk.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•IMTA consisting of fish, snail and water spinach was tested to assess the potentials of increasing pond productivity.•The total biomass yield from IMTA increased significantly.•The higher biomass ...yield in IMTA was due to synergistic interactions among fish, snail and water spinach.•Good water quality with higher biomass yield suggests further potentials to increase pond productivity in IMTA system.
An experimental study was carried out for a period of six months to assess the potential of integrated multi-trophic aquaculture (IMTA) in earthen freshwater ponds. Nine earthen ponds (40 m2 each) were randomly assigned to three treatments in triplicate. Carps and stinging catfish; carps, stinging catfish, and snails; and carps, stinging catfish, snails, and water spinach as IMTA, were assigned to T1, T2, and T3, respectively. The stocking densities were: carps: 20,000 fingerlings ha−1 at a ratio of 3: 1: 2: 2 for catla: silver carp: rohu: mrigal; stinging catfish: 24,700 fingerlings ha−1 in cage-in-pond for all treatments; and snails: 62 kg ha−1 in T2 and T3. The carps were fed with supplementary feed, a mixture of rice bran and wheat bran (1: 1) at the rate of 3–5% of fish biomass; the stinging catfish with commercial feed for the first 45 days, and snail-mixed pelleted feed for the rest of the experimental period, at the rate of 5–25% of body weight. The highest survival, particularly of silver carp, mrigal, and stinging catfish was found in T3, i.e., in IMTA ponds. The weight gain of silver carp, rohu, and stinging catfish was the highest in IMTA ponds. The highest yields of the carps and stinging catfish in cage-in-ponds were obtained in IMTA ponds. The production of snails and water spinach in IMTA ponds contributed to the biomitigation process of organic and inorganic waste, keeping the water quality within suitable conditions for fish culture.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Shrimp farming is fundamental to the national economy of Bangladesh, particularly through earning foreign currency. The nationwide lockdown and international cargo restriction jeopardized the sector ...and breaking its marketing chain. Assessing the degree of farming socio-economic peril from COVID-19 and suggesting early coping strategies and long-term mitigation measures are pressing to build resilience for this food production sector. To collect survey data, two key-informant face-to-face surveys with 51 shrimp farmers and 62 consumers in southwest Bangladesh were accomplished. As national lockdowns restricted access to export markets and movements within the country, farm incomes decreased against rising production costs. To compensate, farmers reduced their workforce (29.4%), but even with the sale of co-cultured finfish still suffered from large drops in revenue (42.8% average profit reduction). Furthermore, we present evidence that shrimp farmers should consider diversification of aquaculture product type as co-culture of additional shrimp species was a poor mitigation strategy against large market price fluctuations. Product price reductions were passed on to the consumer, who enjoyed falling product prices including more expensive shrimp products, but the markup for nearly all aquaculture products increased. The current jeopardy and consequences of shrimp farming future are discussed, including coping strategies to help policymakers in building resilience against future uncertainties.
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CEKLJ, DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The article presents the summary of a dataset related to the risks factors of white spot disease (WSD) of farmed shrimp (Penaeus monodon) in Khulna, Bagerhat and Satkhira districts of Bangladesh. ...This dataset was developed following two consecutive steps. In the first step, participatory rural appraisal tools were applied to get the conceptual framework for data collection regarding lists of farmers and the variables of the risk factors of WSD. In the second step, sampling of farmers, google featured questionnaire development, and mobile phone-assisted survey were carried out. The total surveyed farms were 233 consisting of 21 and 212 semi-intensive and extensive farms, respectively. The data were collected in the form of continuous, nominal and binary variables disaggregated by saline zones. The dataset contains some basic socio-economic data of shrimp farmers, farm characteristics, environmental attributes and disease history of shrimp farms. The dataset also has GPS coordinates of all the surveyed farms individually which are very useful for spatial analysis. In total, the dataset in MS Excel has 46 variables and attached as the supplementary material with this article.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Participatory epidemiologists have emphasized that farmers have rich and detailed knowledge about the diseases of the animals they rear and the risk factors responsible for the diseases. Based on ...this conception a step-wise method where collegial participation of researchers and farmers was followed to gather qualitative and quantitative information to identify the possible risk factors of white spot disease (WSD) of shrimp. This proposed method consists of two phases: participatory phase that includes sampling of relevant farmers and identifying possible risk factors; and conducting survey and data analysis phase that includes mobile phone-assisted survey and statistical analysis. The advantages compared to traditional survey methods are that this method: i) brings researchers and shrimp farmers together in a participatory platform in identifying various risk factors associated with WSD, which is not possible by researcher-only surveys; ii) feeds the data of risk factors/variables to the mobile-phone assisted survey, in order to enhance the data quality through direct participation by the farmers and using mobile phones for data entry; and iii) supports multivariate statistical analysis, which is highly effective in identifying the relationships between potential risk factors and WSD in shrimp. Farm operator, the type of fertilizer used, water source (direct natural), presence or absence of a reservoir, and frequency of water exchange were the significant variables/risk factors found from the multivariate analysis most likely to be associated with WSD prevalence. Analysis of the collected data reveals that the major constraining variables identified by this participatory study were related to water management measures. Therefore, the WSD affected shrimp farmers do not need any expensive inputs from outside their communities but can solve the problem of WSD participatory manner with other stakeholders. A participatory model, as we proposed based on the results indicates that, DoF as the key stakeholder can play a leading role for organizing cluster of farmers and identify other stakeholders to solve the problems of WSD.
•Societal and technological headway posed challenges in survey-based data collection.•High quality data collection ensured following step-wise mixed mode method.•Data of WSD risk factors in shrimp farming were collected for method validation.•Data were statistically analyzed to get prevention strategies of WSD.•Strategies were framed in farming community through cluster-based participatory model.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study evaluates changes in fish species diversity over time in Hakaluki Haor, an ecologically critical wetland in Bangladesh, and the factors affecting this diversity. Fish species diversity ...data were collected from fishers using participatory rural appraisal tools and the change in the fish species diversity was determined using Shannon-Wiener, Margalef's Richness and Pielou's Evenness indices. Principal component analysis (PCA) was conducted with a dataset of 150 fishers survey to characterize the major factors responsible for the reduction of fish species diversity. Out of 63 fish species, 83% of them were under the available category in 2008 which decreased to 51% in 2018. Fish species diversity indices for all 12 taxonomic orders in 2008 declined remarkably in 2018. The first PCA (climatic change) responsible for the reduced fish species diversity explained 24.05% of the variance and consisted of erratic rainfall (positive correlation coefficient 0.680), heavy rainfall (−0.544), temperature fluctuation (0.561), and beel siltation (0.503). The second PCA was anthropogenic activity, including the use of harmful fishing gear (0.702), application of urea to harvest fish (0.673), drying beels annually (0.531), and overfishing (0.513). Finally, the third PCA was loaded with the fishermen age (0.719), education (−0.767), and fishing experience (0.695) of the fishers. Deepening of beels could enhance dry season water availability and shelter the fish. Imposing fisheries regulations to reduce human activities is inevitable to sustain haor fisheries.
Haor; Fish species diversity; Fishers; Principal component analysis; Climate change; Anthropogenic activity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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