The silent threat of plastics along the coastal frontiers of Bangladesh: Are we concerned enough?

Globally plastic pollution is posing a significant threat to the health and integrity of coastal ecosystems. This study aimed to provide a comprehensive overview of plastic pollution in the coastal areas of Bangladesh by examining land-based macroplastic distribution, exploring microplastic (MP) contamination in the coastal aquatic ecosystem and enhancing our understanding of the potential risks associated with MP contamination. Citizen science based monitoring approach using the android application was applied to understand the land-based plastic pollution in the coastal area of Bangladesh. From December 2022 to December 2023, a total of about 3600 photographs of plastic items from 215 citizen scientists were received from the coastal area of Bangladesh covering 580 km long coast line. Polymer Hazard Index (PHI) and Pollution Load Index (PLI) were also calculated to understand the risk of plastic pollution in sediment, water, aquatic organism, dried fish and sea salt. A total of 43 land-based plastic items reported from the coastal area of Bangladesh. Among these plastic items single use items contributed 58.2 % while disposable plastic items contributed 41.8 %. A strong spatial variability in the distribution of these plastic items was observed. PHI and PLI values suggested hazard category-I for MP contamination in sediment, sea salt, water, commercial fishery resources and dry fish. This study highlighted that coastal land area, sea salt, dried fish, water, sediment and organisms are contaminated with plastics which might have the potential threats to human health. Findings from this study will serve as reference data and also baseline for future research to combat the plastic pollution.

Towards net zero: A technological review on the potential of space-based solar power and wireless power transmission.

The global need for energy is increasing at a high rate and is expected to double or increase by 50%, according to some studies, in 30 years. As a result, it is essential to look into alternative methods of producing power. Solar photovoltaic (PV) power plants utilize the sun's clean energy, but they're not always dependable since they depend on weather patterns and requires vast amount of land. Space-based solar power (SBSP) has emerged as the potential solution to this issue. SBSP can provide 24/7 baseload carbon-free electricity with power density over 10 times greater than terrestrial alternatives while requiring far less land. Solar power is collected and converted in space to be sent back to Earth via Microwave or laser wirelessly and used as electricity. However, harnessing its full potential necessitates tackling substantial technological obstacles in wireless power transmission across extensive distances in order to efficiently send power to receivers on the ground. When it comes to achieving a net-zero goal, the SBSP is becoming more viable option. This paper presents a review of wireless power transmission systems and an overview of SBSP as a comprehensive system. To introduce the state-of-the-art information, the properties of the system and modern SBSP models along with application and spillover effects with regard to different sectors was examined. The challenges and risks are discussed to address the key barriers for successful project implementation. The technological obstacles stem from the fact that although most of the technology is already available none are actually efficient enough for deployment so with, private enterprises entering space race and more efficient system, the cost of the entire system that prevented this notion from happening is also decreasing. With incremental advances in key areas and sustained investment, SBSP integrated with other renewable could contribute significantly to cross-sector decarbonization.

Antimicrobial resistance and virulence profiling of Staphylococcus pseudintermedius isolated from cats, Bangladesh.

Staphylococcus pseudintermedius is a significant bacterial pathogen that frequently colonizes different body sites and mucous membranes of pets. The objectives of the cross-sectional study were to estimate the prevalence, antimicrobial resistance pattern, and detection of diverse resistance as well as virulence genes of S. pseudintermedius in cats. A standard bacteriological method, species-specific gene and different antimicrobial resistance as well as virulence genes were confirmed by PCR assay. A total of 233 swab samples were collected from different body sites of 102 cats, among them 146 swabs from 73 healthy cats, and 87 from 29 diseased cats. Overall, prevalence of S. pseudintermedius in cats was 12.01%, while dermatitis and otitis affected cats were 26.08% and 33.33%, respectively. The highest antimicrobial resistance was observed against penicillin (96.42%) followed by streptomycin (85.71%) and erythromycin (78.57%). Moreover, 89.28% of S. pseudintermedius isolates exhibit multi-drug resistance (MDR) (≥ 3 classes' antimicrobial resistant). In addition, 17.86% isolates harbored the mecA gene; thus, were classified as methicillin-resistant S. pseudintermedius (MRSP). Furthermore, the erythromycin resistance genes ermA and ermB were harbored by 25% and 10.71% of isolates, while 42.86% and 17.86% of isolates carried tetK and tetL (tetracycline resistance) genes, respectively. In virulence profiling, 32.14% (sea) and 10.71% (seb) of isolates were found positive for enterotoxin genes, whereas, the toxic shock syndrome toxin-1 (tst-1) gene and the Panton-Valentine leukocidin gene (pvl) were detected in 25% and 14.29% of isolates, respectively. To our knowledge, this is the first report of cats in Bangladesh for MDR S. pseudintermedius, MRSP, and their virulence profiling.

Digital twin: Data exploration, architecture, implementation and future.

A Digital Twin (DT) is a digital copy or virtual representation of an object, process, service, or system in the real world. It was first introduced to the world by the National Aeronautics and Space Administration (NASA) through its Apollo Mission in the '60s. It can successfully design a virtual object from its physical counterpart. However, the main function of a digital twin system is to provide a bidirectional data flow between the physical and the virtual entity so that it can continuously upgrade the physical counterpart. It is a state-of-the-art iterative method for creating an autonomous system. Data is the brain or building block of any digital twin system. The articles that are found online cover an individual field or two at a time regarding data analysis technology. There are no overall studies found regarding this manner online. The purpose of this study is to provide an overview of the data level in the digital twin system, and it involves the data at various phases. This paper will provide a comparative study among all the fields in which digital twins have been applied in recent years. Digital twin works with a vast amount of data, which needs to be organized, stored, linked, and put together, which is also a motive of our study. Data is essential for building virtual models, making cyber-physical connections, and running intelligent operations. The current development status and the challenges present in the different phases of digital twin data analysis have been discussed. This paper also outlines how DT is used in different fields, like manufacturing, urban planning, agriculture, medicine, robotics, and the military/aviation industry, and shows a data structure based on every sector using recent review papers. Finally, we attempted to give a horizontal comparison based on the features of the data across various fields, to extract the commonalities and uniqueness of the data in different sectors, and to shed light on the challenges at the current level as well as the limitations and future of DT from a data standpoint.

Supercapatteries as Hybrid Electrochemical Energy Storage Devices: Current Status and Future Prospects.

Among electrochemical energy storage (EES) technologies, rechargeable batteries (RBs) and supercapacitors (SCs) are the two most desired candidates for powering a range of electrical and electronic devices. The RB operates on Faradaic processes, whereas the underlying mechanisms of SCs vary, as non-Faradaic in electrical double-layer capacitors (EDLCs), Faradaic at the surface of the electrodes in pseudo-capacitors (PCs), and a combination of both non-Faradaic and Faradaic in hybrid supercapacitors (HSCs). EDLCs offer high power density but low energy density. HSCs take advantage of the Faradaic process without compromising their capacitive nature. Unlike batteries, supercapacitors provide high power density and numerous charge-discharge cycles; however, their energy density lags that of batteries. Supercapatteries, a generic term that refers to hybrid EES devices that combine the merits of EDLCs and RBs, have emerged, bridging the gap between SCs and RBs. There are numerous articles and reviews on EES, and many of those articles have emphasized various aspects of HSCs and supercapatteries. However, there are no recent reviews that dealt with supercapatteries in general. Here, we review recently published critically selected articles on supercapatteries. The review discusses different EES devices and how supercapatteries are different from others. Also discussed are properties, design strategies, and future perspectives on supercapatteries.

An integrated coastal ecosystem monitoring strategy: Pilot case in Naf-Saint Martin Peninsula, Bangladesh.

Rapid population growth creating an excessive pressure on the marine environment and thus monitoring of marine ecosystem is essential. However, due to high technical and financial involvement, monitoring of coastal ecosystem is always challenging in developing countries. This study aims to develop an integrated coastal ecosystem monitoring system that combines scientific sampling, numerical model simulation and citizen science observations to monitor the coastal ecosystem of Bangladesh. This concept of integrated monitoring approach was piloted from January 2022 to April 2023 at the South East coastal zone of Bangladesh. Scientific sampling and numerical model simulations were performed for temperature and salinity data collection. Citizen science approach was employed to collect data on environmental conditions, fisheries, plankton, other marine resources, and plastic pollution. Numerical model simulations and citizen scientists observations of temperature and salinity showed good agreement with the scientifically collected data. In addition, citizen scientists observations on fisheries, plankton, other marine resources and plastic pollution were also in line with the existing database and previous studies. The proposed integrated monitoring approach presents a viable technique, creating a new avenue for coastal and marine ecosystem monitoring where infrastructural facilities are limited.

A review on self-healing featured soft robotics.

Soft robots are becoming more popular because they can solve issues stiff robots cannot. Soft component and system design have seen several innovations recently. Next-generation robot-human interactions will depend on soft robotics. Soft material technologies integrate safety at the material level, speeding its integration with biological systems. Soft robotic systems must be as resilient as biological systems in unexpected, uncontrolled situations. Self-healing materials, especially polymeric and elastomeric ones, are widely studied. Since most currently under-development soft robotic systems are composed of polymeric or elastomeric materials, this finding may provide immediate assistance to the community developing soft robots. Self-healing and damage-resilient systems are making their way into actuators, structures, and sensors, even if soft robotics remains in its infancy. In the future, self-repairing soft robotic systems composed of polymers might save both money and the environment. Over the last decade, academics and businesses have grown interested in soft robotics. Despite several literature evaluations of the soft robotics subject, there seems to be a lack of systematic research on its intellectual structure and development despite the rising number of articles. This article gives an in-depth overview of the existing knowledge base on damage resistance and self-healing materials' fundamental structure and classifications. Current uses, problems with future implementation, and solutions to those problems are all included in this overview. Also discussed are potential applications and future directions for self-repairing soft robots.

Evaluating the long-term geomorphic process in-relation to hydrodynamics in the central coastal zone of Bangladesh.

The central coast of Bangladesh is dynamic for its geographical location, hydrodynamic characteristics and residual flow. The research employed the Digital Shoreline Analysis System (DSAS), an ArcGIS extension tool, to conduct a historical trend analysis of shoreline. The study demonstrates that the central coast is eroding to the north and accreting to the south. The highest accretion value was found as 195.42 m/year, whereas the maximum value of erosion was estimated as -185.83 m/year, according to End Point Rate (EPR). The Linear Regression Rate (LRR) indicates that the average rate of erosion and accretion are -17.77 m/year and 17.88 m/year, respectively. Meanwhile, using Weighted Linear Regression (WLR), 0.48% of all transects demonstrated statistically significant erosion, while 0.43% showed statistically significant accretion. During the wet season, heavy river discharge leads to a low salt level in the ocean. Ocean currents hit central coast of Bangladesh from east to west, affecting the majority of the islands in the Meghna Estuary in the dry season. Changes in current directions can be seen during the wet seasons. Southern central coast areas are hit by south-east currents that split in two directions. The Sandwip Channel has a flow of 10,000 to 15,000 m³ s-1 northward. The Tetulia River, Shahbazpur Channel, and Hatia-Sandwip flow southward at rates ranging from 3000 to 17,000 m³ s-1, 14,000 to 60,000 m³ s-1, and 7000 to 39,000 m³ s-1, respectively. In the Meghna Estuary, the combined forces result in a counter-clockwise residual circulation, with the northward flow in the Sandwip channel and southbound flow in the Hatia and Shahbazpur channels. As a result of hydrodynamic, ocean currents, and residual flow, the Central Coast of Bangladesh is continually changing in appearance.

Intrinsic Properties of GO/RGO Bilayer Electrodes Dictate Their Inter-/Intralayer Intractability to Modulate Their Capacitance Performance.

The demand for high-capacity energy storage along with high power output and faster charging has made supercapacitors a key area of energy research. The charge storage capacity of capacitors is largely dependent on the electrode materials utilized. To that end, graphene oxide (GO) and reduced GO (RGO) have been extensively employed for preparing supercapacitors. However, to date, no study has reported utilizing a GO/RGO bilayer electrode material for supercapacitor application. Herein, we report the synthesis of GO/RGO bilayer electrodes on fluorine-doped tin oxide (FTO) conducting substrates with four different combinations, namely, RGO-RGO, RGO-GO, GO-RGO, and GO-GO. Electrochemical capacitance analysis based on a symmetrical electrode configuration revealed that FTO-GO-RGO electrodes had the best areal capacitance performance. However, the highest specific areal capacitance (27.85 mF/cm2) for both symmetric/asymmetric configurations was achieved with FTO-GO-RGO as the anode and FTO-GO-GO as the cathode. The heterogeneous capacitance performance of the GO/RGO bilayer systems was analyzed based on structural characterization and computational simulation methods. Based on our analysis, we identified that inter-/intralayer molecular interaction of the GO/RGO bilayer sheets through the confinement pressure effect might have prompted their unique physicochemical properties. This work highlights the importance of probing multilayer GO/RGO electrode fabrication methods for preparation of high-capacity supercapacitors through fine-tuning their structural and molecular properties.

The ecological impact of plastic pollution in a changing climate.

Assessing three interlinked issues, plastic pollution, climate change and biodiversity loss separately can overlook potential interactions that may lead to positive or negative impacts on global ecosystem processes. Recent studies suggest that threatened species and ecosystems are vulnerable to both plastic pollution and climate change stressors. Here we consider the connectivity and state of knowledge between these three environmental issues with a focus on the Global South. Nine out of top ten Long-Term Climate Risk Index (CRI) (2000-2019) ranked countries are located within the Global South, yet research is focused in the Global North. A literature search for the top ten Long-Term Climate Risk Index (CRI) (2000-2019) ranked countries matched a total of 2416 (3.3% of global publications) search results on climate change, with 56 (4% of the global publications) on plastic pollution, and seven (7.7% of the global publications) on both climate change and plastic pollution. There is a strong correlation between the Global South and high biodiversity hotspots, high food insecurity and low environmental performance. Using Bangladesh as a case study, we show the erosion rates and sea level rise scenarios that will increase ocean-bound plastic pollution and impact high biodiversity areas. Poverty alleviation and promoting renewable energy and green practices can significantly reduce the stress on the environment. We recommend that these connected planetary threats can be best addressed through a holistic and collaborative approach to research, a focus on the Global South, and an ambitious policy agenda.

Trophic transfer of microplastics in the aquatic ecosystem of Sundarbans mangrove forest, Bangladesh.

Globally microplastics (MPs) contaminations have been widely reported across the large number of organisms in the marine ecosystem. Consequently, trophic transfer of MPs inferred to occur across the organisms of marine food webs. However, scientific evidence on trophic transfer of MPs across the marine organisms is very limited. Therefore, this study aimed to understand the transfer of MPs across the trophic levels in the marine ecosystem. We sampled individuals of different species of primary consumers, secondary consumers, tertiary consumers and quaternary consumers from the aquatic ecosystem of Sundarbans mangrove forest from June 2021 to December 2021. This study found that marine organisms in the aquatic ecosystem of Sundarbans mangrove forest are contaminated with MPs. The abundance of MPs in collected samples varied between 0.56 ±â€¯0.25 items/individual and 6.06 ±â€¯1.20 items/individual. Maximum MPs was recorded as 5.5 ±â€¯1.21 items/individual in predators followed by 5.1 ±â€¯0.85, 4.5 ±â€¯0.39, 1.2 ±â€¯0.26, 1.1 ±â€¯0.28 and 1.01 ±â€¯0.25 in filter feeders, browsers, deposit feeders, selective planktivores and variable feeders, respectively. Maximum MPs abundance was encountered in quaternary consumers (4.17 items/individual) followed by tertiary consumers (3.17 items/individual), secondary consumers (2.74 items/individual) and primary consumers (0.56 items/individual). We found that MPs abundance increases with the increase of trophic levels (R2 = 0.64, p < 0.001) which indicates that transfer of MPs across different trophic levels and also showed the evidence of biomagnification of MPs in successive trophic levels. Our study is the first report of trophic transfer of MPs in sub-tropical mangrove ecosystem and will serve as a guideline to understand the MPs pollution in the coastal ecosystem of Bangladesh.

Seaweeds for the sustainable blue economy development: A study from the south east coast of Bangladesh.

Bangladesh is a maritime country with an area of 118000 km2 which supports a large number of commercially important species. Currently seaweeds are considered as important component of blue economy development in Bangladesh and farming is practiced at small scale level (Hypnea spp, Caulerpha reacemosa, Gelidium sp. are cultured). For the expansion of the seaweed farming in Bangladesh, a complete understanding of social and economic status of current farmers is important. However, information on socio-economic status of seaweed industry in Bangladesh is very limited. Therefore, this study aimed to understand existing culture methods and their cost, marketing channel and problems with seaweed farming in south east coast of Bangladesh. We used questionnaire survey and focus group discussions to collect data from seaweed farmers, researchers, local community and entrepreneurs. The study found that farmers are currently practicing long-line and horizontal net methods for the seaweed farming in the south east coastal region. The study also found that these culture methods are economically profitable. Seaweeds are currently sold locally and a proper value chain for seaweed marketing is still missing. Existing seaweed farmers are facing the problems related to insufficient credits for starting seaweed farming, lack of proper guidelines for farming and processing of harvested seaweed. This study suggests that for industrial level expansion of seaweed production in Bangladesh a proper value chain, development of seaweed derived products, farm monitoring systems, smooth seed supply and information hubs are required.

Ecological risk evaluation in bottom-surface sediments and sub-surface water in the subtropical Meghna estuarine system.

Assessment of elemental contamination is emerging research in the present world. Metals are hazardous to the environment and people's health when metals concentration might exceed the tolerable level. In this research, 12 elements (i.e., Mn, Ni, Cu, Zn, As, Se, Sr, Co, Pb, Fe, Rb, and Ti) were assessed using the energy dispersive X-ray fluorescence (EDXRF) method in water and sediment samples in four (4) different spawning grounds of Tenualosha ilisha at the confluence of the Meghna River in Bangladesh. A comparative analysis was performed for the first time among four sampling spots, i.e., Chandpur, Bhola, Sandwip, and Hatiya, assessed all possible risk indices-it is a unique thing. Several risk indices were solved to determine the degree of sediment pollution for all 12 elements, e.g., degree of contamination (Cd):6.5-7.01, the modified degree of contamination (mCd): approximately 0.7, the pollution load index (PLI): 0.45-0.51, etc. where all the indices' results showed low or baseline levels of pollution. According to the enrichment factor (EF) computation, slight enrichment of examined metals except Pb and Zn was found. In addition to these, the ecological risk factor (Er) found in the following order (pollution level: low): Cu > Pb > Zn among the four stations. Moreover, a spatial incline of metal accumulation was observed among the four spots: Bhola < Sandwip < Hatiya < Chandpur based on the risk index (RI) set value. However, a strong positive correlation (p < 0.05) between Ca and Fe, Ti and Fe, Ti and Mn, Mn and Fe, Fe and Sr were observed while Ca, and Co were strongly negatively correlated (r = minus (-)0.60, p < 0.05). The cluster analysis was performed and got an asymmetrical cluster among the sampling stations. This study recommends assessing the heavy metal concentration in biological samples, particularly in Hilsha fish.

Highly efficient, heat dissipating, stretchable organic light-emitting diodes based on a MoO3/Au/MoO3 electrode with encapsulation.

Stretchable organic light-emitting diodes are ubiquitous in the rapidly developing wearable display technology. However, low efficiency and poor mechanical stability inhibit their commercial applications owing to the restrictions generated by strain. Here, we demonstrate the exceptional performance of a transparent (molybdenum-trioxide/gold/molybdenum-trioxide) electrode for buckled, twistable, and geometrically stretchable organic light-emitting diodes under 2-dimensional random area strain with invariant color coordinates. The devices are fabricated on a thin optical-adhesive/elastomer with a small mechanical bending strain and water-proofed by optical-adhesive encapsulation in a sandwiched structure. The heat dissipation mechanism of the thin optical-adhesive substrate, thin elastomer-based devices or silicon dioxide nanoparticles reduces triplet-triplet annihilation, providing consistent performance at high exciton density, compared with thick elastomer and a glass substrate. The performance is enhanced by the nanoparticles in the optical-adhesive for light out-coupling and improved heat dissipation. A high current efficiency of ~82.4 cd/A and an external quantum efficiency of ~22.3% are achieved with minimum efficiency roll-off.

Riverine plastic pollution from fisheries: Insights from the Ganges River system.

Abandoned, lost or otherwise discarded fishing gear represents a substantial proportion of global marine plastic pollution and can cause significant environmental and socio-economic impacts. Yet little is known about its presence in, and implications for, freshwater ecosystems or its downstream contribution to plastic pollution in the ocean. This study documents fishing gear-related debris in one of the world's largest plastic pollution contributing river catchments, the Ganges. Riverbank surveys conducted along the length of the river, from the coast in Bangladesh to the Himalaya in India, show that derelict fishing gear density increases with proximity to the sea. Fishing nets were the main gear type by volume and all samples examined for polymer type were plastic. Illegal gear types and restricted net mesh sizes were also recorded. Socio-economic surveys of fisher communities explored the behavioural drivers of plastic waste input from one of the world's largest inland fisheries and revealed short gear lifespans and high turnover rates, lack of appropriate end-of-life gear disposal methods and ineffective fisheries regulations. A biodiversity threat assessment identified the air-breathing aquatic vertebrate species most at risk of entanglement in, and impacts from, derelict fishing gear; namely species of threatened freshwater turtle and otter, and the endangered Ganges river dolphin. This research demonstrates a need for targeted and practical interventions to limit the input of fisheries-related plastic pollution to this major river system and ultimately, the global ocean. The approach used in this study could be replicated to examine the inputs, socio-economic drivers and ecological impacts of this previously uncharacterised but important source of plastic pollution in other major rivers worldwide.

Plastic pollution in aquatic systems in Bangladesh: A review of current knowledge.

Rivers play a crucial role in transporting land-based plastic waste to the ocean, with the Ganges reported as the second largest contributing river of plastic pollution globally. To better quantify global plastic pollution transport and effectively reduce the sources and risks imposed, a clear understanding of the origin, transport, fate, and effects of riverine plastic debris is important. In this review paper, we discuss the current state of knowledge of plastic pollution in aquatic systems in Bangladesh and evaluate existing research gaps. Bangladesh has been recognized as an internationally significant nation in the plastic pollution crisis, but this paper identifies a major disconnect in knowledge, understanding and capacity to understand and address this critical environmental and public health issue. Here, we review all available scientific publications on plastic pollution in the freshwater and marine environment in Bangladesh and identify key research themes. A total of 24 studies relevant to plastic pollution were published from 2006 to 2019, of which 18 were selected for this study under the authors' criteria. Nine focused on plastic pollution in the marine environment, eight focused on plastic waste generation and management and only one focused on the freshwater environment. We compared our findings with three other countries in the Global South with comparable per capita gross domestic product (GDP) and mismanaged waste, namely Cambodia, Kenya, and Tanzania, revealing similar knowledge gaps. This lack of research demonstrates a need for further work to monitor and model riverine plastic transport and examine the implications for aquatic organisms. This will facilitate the formulation of national management strategies aimed at addressing plastic pollution.

Seasonal variations of trace metals from water and sediment samples in the northern Bay of Bengal.

We aimed to determine the temporal variation of trace metals concentrations in surface water and surface sediment samples at Kutubdia Channel, Bangladesh. Trace metals of samples were detected using energy dispersive X-ray fluorescence (Energy-dispersive X-ray spectroscopy) method. The lowest concentration of metals was found in water samples during post-monsoon season and the highest during pre-monsoon season (Cu: 0.030 ± 0.001 µg/L in pre-monsoon and 0.026 ± 0.002 µg/L in post-monsoon, Zn: 0.087 ± 0.003 µg/L in pre-monsoon and 0.073 ± 0.002 µg/L in post-monsoon, Fe: 0.080 ± 0.001 µg/L in pre-monsoon and 0.055 ± 0.001 µg/L in post-monsoon). In contrast, metal concentration in surface sediment samples were higher in post-monsoon than in pre-monsoon season i.e. Cr 11 mg/kg in pre-monsoon and 12 mg/kg in post-monsoon, Mn 571 mg/kg in pre-monsoon and 606 mg/kg in post-monsoon, As (8 mg/kg in pre-monsoon and 10 mg/kg in post-monsoon, Pb (22 mg/kg in pre-monsoon and 24 mg/kg in post-monsoon, and Fe 2317 mg/kg in pre-monsoon and 2435 mg/kg in post-monsoon. We found a spatial gradient of high to medium to low in trace metal concentration from river to river mouth to offshore area. Considering the sources of metals, land erosion by waves and tidal action, an influx of water and sediment from the surrounding rivers, agricultural waste, industrial effluent and sewage are the most likely sources of metal pollution in the study area. We conclude that proper management strategies should be adopted to control the pollution and conserve the ecosystem health.

Primary productivity connects hilsa fishery in the Bay of Bengal.

Tropical hilsa shad (Tenualosa ilisha) contributes significantly to the society and economy of Bangladesh, India and Myanmar, but little is known about their habitats across the life cycle and their relationship with environmental drivers. This study describes spatial and temporal variability of productivity in the Bay of Bengal (BoB) relating to hilsa fishery. Decadal data on net primary productivity, nutrients (i.e. nitrate, phosphate and silicate) and zooplankton were collected from Aqua MODIS, world ocean database and COPEPOD respectively with spatial resolution 1°×1°. Moreover, monthly abundance of phytoplankton, hilsa catch and long-term catch dynamics were analyzed to determine the associations between variables. The present study was extended over 3.568 million km2 area, of which 0.131-0.213 million km2 area characterized as the most productive with net primary production of >2,000 mg C/m2/day, 0.373-0.861 million km2 area as moderately productive with 500-2,000 mg C/m2/day, and 2.517-3.040 million km2 area as the least productive with <500 mg C/m2/day which were consistent with field verification data. In case of nutrients, the Ganges-Brahmaputra-Meghna (GBM) delta was rich in nitrate and phosphate than that of the Ayeyarwady delta, while silicate concentration persisted high all over the northern BoB including the deltas. A peak abundance of phytoplankton was observed in GBM delta during the months of August-November, when ~80% of total hilsa are harvested in Bangladesh annually. Variations in seasonal productivity linked with nutrients and phytoplankton abundance are important factors for predicting hilsa habitat and their migration patterns in the deltaic regions and shelf waters of BoB. These results can be useful in forecasting potential responses of the hilsa in BoB ecosystem to changing global ocean productivity.

Microplastic contamination in Penaeid shrimp from the Northern Bay of Bengal.

Microplastic pollution has received increased attention recently due to potential threat to marine biota and human health. This study reports microplastic (MP) content in brown shrimp (Metapenaeus monocerous) and tiger shrimp (Penaeus monodon) inhabiting in the shallow and offshore waters of the Northern Bay of Bengal, Bangladesh. Gastrointestinal tract (GT) of shrimps (n = 150) were examined for MPs following alkali digestion, microscopic observation and chemical analysis by micro-Fourier Transformed Infrared Spectroscope (µFTIR). A total of 33 and 39 MP items were found in P. monodon and M. monocerous, averaging 3.40 ±â€¯1.23 and 3.87 ±â€¯1.05 items/g GT, respectively. Among various shapes, types and colours of MP, filament (57-58%), fiber (32-57%) and black (48-51%) were dominant amongst the various particles identified. Tiger shrimp had high numbers (23 items) of larger size fractions of MPs (1-5 mm) but brown shrimp had high numbers (15 items) of smaller MPs (250-500 µm), and µ-FTIR data confirmed 13 particles of polyamide-6 and 6 particles of rayon polymers. These results provide a baseline of MP contamination in seafood from Bangladesh that should be useful for future monitoring efforts.