Nutrients and chlorophyll-a in the northern Bay of Bengal: the need for focused research on Bangladesh’s shelf.
Nutrients and chlorophyll-a (chl-a) are critical to understanding marine ecosystem, yet in situ data on Bangladesh’s continental shelf remained sparse compared to offshore Bay of Bengal (BoB). This study addresses this gap by measuring chl-a and nutrients, including nitrate (NO₃⁻-N), nitrite (NO₂⁻-N), phosphate (PO₄³⁻), ammonia (NH₃-N) and silica (SiO₂) across the eastern continental shelf of Bangladesh. These observations were compared with data from the Copernicus Marine Environment Monitoring Service (CMEMS) and relevant literature. Shelf in situ data varied as nutrients (mg l-1): nitrate: 1.8-5.3; nitrite: 0.002-0.008, phosphate: 0.02-0.12, ammonia: 0.42-5.2, silica: 0.5-3.0 and chl-a: 0.426 – 10.119 mg m-3. Trend observed in the order: nitrate > ammonia
> silica > phosphate > nitrite. Nitrite and phosphate, characterized by relatively low concentrations, can act as limiting nutrients in this region. Weak correlations were observed between chl-a and most nutrients, with a moderate negative correlationbetween chl-a and silica (r = - 0.46) and a moderate positive correlation between nitrate and ammonia (r = 0.334). The concentrations of all in situ measured parameters weresignificantly higher than CMEMS-derived estimates, specifically adjacent to the coast. This underscores the need for a comprehensive, multi-seasonal investigation of the northern BoB’s continental shelf particularly focusing on measuring the riverine flux of these measured parameters into the BoB. These datasets are crucial for validating
remote sensing observations and improving estimates in this understudied region.
Tide driven currents and Nutrient Distribution in the Naf River, Southeastern Coast of Bangladesh Utilizing Coupled Hydrodynamic and Ecological Model
A coupled hydrodynamic and ecological configuration was developed using the MIKE 3 model and its Ecolab module to simulate the tide-driven currents, surface elevation, components of the flow and water quality of the Naf estuary, along the southeastern coast of Bangladesh. The present study particularly focuses on the analysis of the local e tidal characteristics and properties of water quality, such as biological oxygen demand (BOD), dissolved oxygen (DO) and nutrients, nitrate and phosphate) within the modeled domain. Water samples were retrieved from six different stations, spanning from (i) the mouth of Naf River, (ii) Shahparir Dwip jetty ghat, (iii) Near Jaliapara, (iv) Sabrang, (v) Teknaf and (vi) Kewari ghat Teknaf. The comparison of Model data with in-situ records showed a satisfactory agreement between the two datasets The highest surface elevation was found at 1.28 m in Kewari ghat and Teknaf because of the narrow area interested by the greatest value of high tide, while the highest current speed was 1.20 m/s in Shahparir Dwip jetty ghat area and lowest 0.0598 m/s in the river upstream area during low tide. Values of BOD close to 1.12 mg/L were found in Teknaf due to sewage and boat waste dumping from the surrounding towns. The DO concentration was as high as 5.89 mg/L in the downstream area. The highest nitrate concentration was equal to 1.58 mg/L in the upstream area of Kewari ghat and the highest phosphate concentration was 1.64 mg/L in the Sabrang area. The water-quality degrading components like nitrate (standard value 0.03-3.0 mg/L) and phosphate (standard value 0.1- 1.0 mg/L) were within acceptable ranges, suggesting that the Naf estuary conditions are suitable for the productivity of aquatic flora, fauna, and for a healthy estuarine environment.
Read morePlanktonic abundance and diversity in an upstream area of the northeastern Bay of Bengal: Rabnabad channel, Patuakhali, Bangladesh
The Rabnabad channel, serving as the navigational route for the Payra Sea Port, is a significant upstream region in southern Patuakhali, Bangladesh. The channel holds significant economic value, supporting diverse aquatic resources and providing livelihoods for thousands of fishermen, yet it has been largely overlooked in ecosystem studies. Given its significance, the first initiative to study the planktonic community was carried out with the purpose of discussing the abundance and diversity. Field sampling and data collection were conducted in January 2021. A total of 30 phytoplankton species, belonging to 7 classes: Bacilariophyceae, Chlorophyceae, Coscinidiscophyceae, Cyanophyceae, Dynophyceae, Fragilariophyceae, Zygnematophyceae, and 7 zooplankton species across three classes: Branchiopoda, Copepoda, and Monogononta were identified. Among these, Coscinodiscophyceae (37%) was the most abundant phytoplankton class, while Branchiopoda (83%) dominated the zooplankton community. The highest phytoplankton and zooplankton abundances (48,101 cells L-1 and 12,643 cells L-1) were recorded in the upstream station, whereas lower abundances were observed at the estuary mouth where the channel meets the northern Bay of Bengal (BoB). Physicochemical parameters, including temperature (T), salinity (PSU), pH, dissolved oxygen (DO), and total dissolved solids (TDS), were also measured and found to have association with the planktonic distribution. TDS and salinity had a clear increasing trend from upstream to downstream stations, whereas plankton abundance showed a decreasing trend in the same direction. The species identified, along with the associated physicochemical data will provide a baseline for understanding the planktonic ecosystem of the Rabnabad channel. This will serve as a valuable reference to identify knowledge gap, and guide broader investigations into the ecosystem of the area throughout the seasons.
Read moreDevelopment of A Python Code for Propeller Design Calculation And The Procedure of Additive Manufacturing of Propeller
Python is one of the prominent programming languages in today’s computing. This research aims to delineate the coding methodology employed to calculate a B-series propeller geometry data. First, geometry data is calculated and stored in an excel sheet. Subsequently, 2D section data of propeller blade is produced. Finally, the 2D data is converted into 3D co-ordinates in global X, Y, Z system. Such a program enables the user to compute, analyze, change and visualize the 3D section view of a propeller. In the realm of contemporary manufacturing techniques, additive
manufacturing emerges as a highly prospective method. This paper aims to provide a structured method of the additive manufacturing process for a marine propeller. The propeller data produced from 'PropCad 2010' serves as the source data for creating 3D surfaces in 'SolidWorks 2017'. 'Ultimaker Cura 5.4.0' is thereupon utilized to generate G-code, which can be used to 3D print an entire propeller. The plausibility of the procedure was put to test through 3D printing a scaled plastic propeller. This paper ventures to present an introductory, step-by-step guide for manufacturing a marine propeller using this novel approach.
Payra Port: Challenges of Sedimentation and the Way Forward
The Payra port was established in 2013 on the bank of Rabnabad Channel with an aspiration not only to sustain the saturated country‟s seaborne trade and shipping but also to establish a Dhaka-Payra economic corridor for development, power generation, and sustainability. As an initial step, the port authority implemented capital and maintenance dredging of Rabnabad channel between August 2022 and April 2024 and vessels of drafts over 10 meters had started entering the port. However, the channel depth significantly reduces due to high sedimentation. The primary objective of this study is to analyze the annual sedimentation volume of Rabnabad channel for various depths and recommend a realistic approach for channel maintenance with a view to optimizing the dredging cost and assess the sustainability of the port. The study mainly adopted quantitative approach. The analysis indicated that, the main challenge of the
port is the excessive sedimentation along the channel. The paper concluded that Payra port has potentials to emerge as 3rd economic corridor of Bangladesh. However, it requires strong commitment and a judicial funding of Government to give confidence to the investors and port operators that the desired depth of the access channel would be maintained for a long term.
Blue Swimming Crab: A New Entrapped Resource for Bangladesh Blue Economy
The Bay of Bengal is one of the major habitats of blue swimming crabs (BSC) in the world, although commercial catching of it is currently restricted by the government of Bangladesh. However, it has a high demand but the present status and availability of the BSC is not well emphasized. Therefore, the study was designed based on the physical survey of the fishing communities and the fish landing centers covering the coastal belts of the country. Based on the survey, the approximate total volume of BSC by-catch was 14,150 ton/year and a small portion (approx. less than 5% only, i.e., approx. 707.50 ton/year) of this total catch was carried out by the fishermen to the landing ports for sell. The rest of the volume caught (approx. more than 95%, i.e., approx. 13,442.50 ton/year) was thrown away back to the Bay of Bengal. The current price in the market was very low, around 10-20 BDT/kg. Mainly it was caught as a by-catch, not being the regular catch. Currently, limited uses of the BSC by-catch include seafood item in local restaurants and as a low-price raw material for fish/poultry feed industries. As such, this volume of BSC by-catch made a considerable amount of post-harvest losses to our economy as a waste. In addition, the thrown back of the dead BSC by-catch in the sea water also imposed a threat to the marine environment which also demanded for proper attention of the concerned authorities. Thus, instead of allowing it to be a waste or a low value item, following the current practices of our neighboring and ASEAN countries, this wasted or low value BSC by-catch from the Bay of Bengal can be turned into an export earning resource and hence enhanced the growth of our blue economy, as it has high demand in the international market.
Read moreHydrodynamic Analysis and Selection of Airfoil for Efficient Hydrokinetic Turbine Design
Hydrokinetic turbines harness the energy of moving water in rivers, canals and artificial currents without requiring dams. The most critical aspect of maximizing power production is optimizing rotor design, which includes selecting the ideal hydrofoil. The performance of hydrokinetic turbines is determined by the lift-to-drag ratio of the selected foils, with high lift forces at low flow rates being essential for blade design. In this study, the hydrodynamic characteristics of ten different high-lift airfoils were analyzed through Structural Analysis Software QBlade (XFOIL Analysis), by measuring lift and drag coefficients and their ratios to identify the most appropriate airfoils for enhancing hydrokinetic turbine efficiency. The selected airfoils include several commonly used in wind turbines, as the operational principles of wind turbine and hydrokinetic turbine are similar. Due to water's higher Reynolds number (Rn) and broader angle of attack (AoA), a wide range of Rn and AoA were considered. The results show that NACA 4412, S1223 and FX74 offered superior lift coefficients, but FX74 and E421 surpassed other airfoils due to their higher lift-to-drag ratios, achieving 243.01 and 242.22 respectively at Rn 5,000,000, making them highly efficient for water energy harnessing. Symmetrical airfoils showed lower lift and glide ratios, making them less efficient than cambered profiles.
Read moreNumerical Investigation of Hydrodynamic Performance of a Symmetric Aerofoil in Openwater
Symmetric aerofoils are crucial components in marine and aerospace engineering, particularly in applications like ship rudders and submarine fins. This study presents numerical investigation of hydrodynamic characteristics of a 2D symmetric aerofoil (NACA 0012) surface for a series of different angle of attacks (0° - 20°) with various combinations of flow velocities in open water. The pressure distribution and lift-drag characteristics at the mentioned angle of attacks for ideal ship speed 3 m/s to 8 m/s has been accounted based on CFD simulations. Simulations were performed using ANSYS Fluent with Spalart-Almaras turbulence model and numerical validation was performed with NASA’s experimental data for the same aerofoil. The results indicated that the maximum lift-to-drag ratio occurred at an 8 m/s flow speed and a stall angle of 17.5°. The analysis of pressure distributions indicated within each tested velocity that there were considerable changes experienced over the chord length, particularly in higher flow speed conditions. The findings provide essential insight for design and optimization of marine applications i.e., ship rudder, submarine fins etc. highlighting potential for improved efficiency and maneuverability in ships
Read moreTowards Marine Environmental Sustainability of St. Martin Marine Protected Area: The 3P Model Perspective
St. Martin – a recently declared Marine Protected Area (MPA) is faced with environmental challenges due to acts of negligence on the part of its coastal inhabitants, as well as the ongoing influx of tourists. Those and the resultant effects of overexploitation of marine living and non-living resources, destructive fishing practices, climatic impacts, and rapid population growth exacerbated by policy gaps threaten the marine ecology of St. Martin MPA. It is projected that such anthropogenic pressure fueled by climatic impacts is set to degrade its marine environment to an irreversible and unsustainable state. In addition, rapid population growth along with poverty and lack of alternative livelihoods for the islanders also undermines its sustaining capacity through higher consumption of natural resources. This research paper, through the prism of sustainability, focuses on exploring the environmental security threats and vulnerabilities of the St. Martin MPA. In doing so, it examines the conceptual underpinnings of the ‘3P’ Model that is deemed particularly relevant for the MPA, wherein the synergy between the pillars namely ‘policy’, ‘people’ and ‘preservation’ could optimally enhance marine environmental sustainability amidst the challenges faced in relation to blue growth. It further attempts to pave the way of the ‘3P Model’ to be implemented in the St. Martin MPA for reasons of sustainability. In doing so, the paper advocates measures towards marine environmental sustainability of St. Martin MPA taking lessons from global best practices.
Read moreExploring Bangladeshi Maritime Stakeholders' Perceptions of Maritime Autonomous Surface Ships Integration
Humanity has experienced and undergone three distinctive industrial revolutions since the dawn of civilization. The emergence of autonomous technology and automation ushered in a new era of industrialization called the Fourth Industrial Revolution and the shipping industry will be significantly impacted by the rapid advancements of automation and autonomous technology. The shipping sector is gradually transitioning from human-operated conventional shipping to the autonomous shipping concept. IMO was the first to adopt the term MASS (Maritime Autonomous Surface Ship) and is currently working towards the development of a 2028-scheduled mandatory goal-based MASS Code. Several developing maritime nations, including Norway, Finland, Japan, Korea, and China, have undertaken extensive research on this topic and demonstrated multiple autonomous vessel trials. Despite being a maritime nation and possessing a glorious maritime history, Bangladesh has yet to make any significant contributions to the autonomous shipping sector. Against this backdrop, this study delves into the case of Bangladesh, investigating the global development, and its stakeholder's perception of integrating MASS into its maritime landscape. A mixed methods approach (a combination of qualitative and quantitative methodologies) is utilized to examine the perceptions of Bangladeshi maritime stakeholders regarding the implementation of autonomous vessels. The findings contribute to a comprehensive understanding of MASS in Bangladesh's maritime domain.
Read moreQuantifying the Effects of Blue Carbon Storage Considering Coastal Landscape Change in Hatiya and Manpura Islands of Bangladesh: A Remote Sensing Approach
Over the last three decades, the coastal landscapes of Hatiya and Manpura islands in Bangladesh have experienced significant changes, resulting in notable variations in carbon storage both temporally and spatially. This study utilized seven sets of remotesensing images from the Landsat Satellite website, capturing data from both premonsoon and post-monsoon seasons, to analyze coastal landscape changes (CLC). Spatiotemporal variations in land use and land cover (LULC) classifications were assessed, alongside changes in carbon storage using the carbon-stock-assessment modules of the integrated valuation ecosystem services and tradeoffs (InVEST) model. The results were mapped using ArcGIS 10.7. The findings conceded that agricultural land, vegetation, and built-up areas increased over the study period, while water bodies decreased. Vegetation and water bodies accounted for the highest carbon storage and sequestration, followed by agricultural areas, bare soil, low-lying areas, built-up regions, and sandy soils. Hatiya Island demonstrated higher carbon capture than Manpura Island, with the study area collectively storing 6,822.95 Mg/hm² of carbon over the three decades. The results underscore the need for ecological interventions to enhance species’ well-being and maintain ecosystem health. The study highlights critical implications for strategic land-use planning, the adjustment of ecosystem carbon cycles, and informed policy development to address ongoing environmental changes.
Read moreImplementing Zero Dumping in Maritime Sectors of Bangladesh: Environmental Law Perspectives
While up-to 90% of world's goods are transported through the sea, shipping industry is leaving its mark on nature too. Dumping from the ships has become a concern for world community since 1950 and London Convention and Protocol is the result of the idea of sustainable shipping, for best of both worlds. But no basin country of Bay of Bengal, including Bangladesh signed any of those and didn’t take strong position against the dumping. As a result, environmental degradation, imbalance in eco system, introduction of hazardous substance, extinction of species has been noticed in this region. It should be our prime concern to adopt strict laws against dumping in the sea and set the goal of “zero dumping” gradually. The concept of Zero dumping is promising, but hard to achieve and it may take years to implement it. This paper explores the current legal framework governing marine pollution, both national and international, particularly the practice of dumping waste, and advocates for the implementation of a "Zero Dumping" policy in the maritime sector of Bangladesh. It highlights the probable challenges Bangladesh may face to adopt Zero dumping by analyzing socio-economic condition of the country. By analyzing international conventions, existing Bangladeshi laws, and environmental policies and challenges of implementation of Zero dumping, this research aims to provide a comprehensive plan to create legal instruments on mitigating marine pollution. Furthermore, it highlights the importance of sustainable maritime practices to ensure the protection of marine
biodiversity and align with global environmental goals.
Application of GIS and Remote Sensing for Sustainable Fisheries Management in the Bay of Bengal: A Habitat Mapping Approach
The Bay of Bengal’s fisheries are under considerable pressure from overfishing and environmental degradation, threatening long-term sustainability. This study applies Geographic Information Systems (GIS) and remote sensing to map critical fish habitats, identify Potential Fishing Zones (PFZs), and assess species abundance. Satellite data from MODIS and Sentinel-3 provided insights into sea surface temperature (SST) and chlorophyll-a concentrations, crucial for understanding fishery productivity. Analysis focused on four key fishing grounds—Swatch of No Ground, Middle Ground, South Patches, and South of South Patches—within Bangladesh’s Exclusive Economic Zone (EEZ), which covers over 118,000 square kilometers of marine area. The study revealed that the South and South of South Patches, with depths up to 80 meters, have the highest species richness. Notably, SST in these regions ranged from 24°C to 28°C, and chlorophyll-a concentrations varied from 0 to 5 mg/m³. Yearly fish abundance trends from 2005 to 2021 showed a significant increase in Hilsa production from 277,123 metric tons (MT) in 2005 to 566,593 MT in 2021, a rise of over 100%. The findings underline the importance of habitat mapping for improving management strategies and reducing overfishing. This study also highlights the critical role of remote sensing and GIS in identifying optimal fishing zones, supporting Bangladesh’s efforts toward sustainable fisheries management and marine conservation.
Read moreInter-comparison of chlorophyll-a and associated physiochemical parameters in the three Marine Protected Areas of Bangladesh utilizing remote sensing datasets
The Sustainable Development Goals (SDGs) mandate that Marine Protected Areas (MPAs) occupy 10% of each marine area's Exclusive Economic Zone (EEZ). Four
MPAs that cover 8.25% of Bangladesh's EEZ have been declared, yet research on the efficacy and health of these areas is still pending. It is vital to evaluate crucial factors including nutrients, water quality, human impact, and chlorophyll-a (Chl-a) to guarantee that these MPAs are successfully protecting marine ecosystems. The increase or decrease in Chl-a concentration and other physicochemical parameters correlate with greater or lesser transportation through river water. Our observations exploit that there is slight decrease of the Chl-a concentration at Nijhum Dwip MPA and increasing in both Swatch of No Ground (SoNG) and St. Martin MPA. St. Martin MPA’s concentration level of Chl-a and nutrients is distinct from that of other places because of the island's relatively low exposure to freshwater flow. High probability of decreasing Chl-a concentration occurs for turbid water or high rate of sedimentation in Nijhum Dwip MPA. Even the water velocity and upwelling of the nutrient-rich water increases the concentration of the region, especially the SoNG MPA. It’s preferable to say that there are some driving forces such as water current, wind stress, temperature, saline layer, and mixed layers that are likely to be responsible for the variation in these MPA regions. Distinction between the regions for depth, turbidity, freshwater influx, and seasonal variability.
Phytochemical, nutritional, cytotoxic, and antimicrobial profiling of Ulva lactuca collected from the Bay of Bengal, Cox Bazar
Global interest in seaweeds has grown, and Bangladesh is emerging as a seaweed growing powerhouse. Research on the identification of phytochemical bioactive
compounds, as well as their antioxidant, cytotoxicity, and antimicrobial activities, represents a significant area of interest that may not have been thoroughly explored in Bangladesh. This study emphasizes the importance of seaweeds by investigating the phytochemicals, cytotoxic properties, antibacterial activity, and proximate profiles derived from the methanolic extracts of the green seaweed, Ulva lactuca, sourced from Nuniachara, Cox’s Bazar, Bangladesh. Phytochemical screening revealed the presence of phenolics, tannins, flavonoids, steroids, and terpenoids in the collected seaweed sample. The brine shrimp lethality assay (BSLA) demonstrated a cytotoxic effect of the methanolic extracts, with a significant LC50 calculated showing mild cytotoxicity. Furthermore, Salmonella sp, and E. coli exhibited a higher zone of inhibition compared to other bacterial species employed in the study indicating a greater antibacterial activity of these two species. The proximate quantitative test indicated that the seaweed comprises 10.17% protein, 62.66% carbohydrate, 0.54% total fat, 5.47% fibre, 16.50% ash, and 10.13% moisture. The analysis also revealed that vitamin A was not present, whereas the concentration of vitamin B12 was measured at 97 μg/100g. Notably, heavy
metals such as lead (Pb) arsenic (As) and cadmium (Cd) were below detectable level in U. lactuca , while the amount of Zn was 2.28 ppm. Ulva lactuca from the Bay of Bengal, cox’bazar could be a potential candidate to further explore as a source of novel bioactive compounds.