Southeast Bangladesh Research Articles

Experience of Continuous Ambulatory Peritoneal Dialysis In Remote Area of Southeast Bangladesh

Background: Chronic kidney disease (CKD) is a major public health problem that continues to increase in prevalence globally. The prevalence of chronic kidney disease is increasing day by day in low to middle income countries (LMICs). People living in LMICs have the highest need for renal replacement therapy (RRT) despite they have lowest access to various modalities of treatment. As continuous ambulatory peritoneal dialysis (CAPD) does not require advanced technologies, very much infrastructure, dialysis staff support, it should be an ideal form of RRT in LMICs, particularly for those living in remote areas. To authors knowledge there was scarcity of data regarding CAPD performance in remote area of Bangladesh. This study was aimed to report the characteristics and outcomes of CAPD in ESRD patients lived in least developed area of Bangladesh. Methods: This prospective study was conducted in Cox’sbazar Medical College Hospital, Cox’sbazar and Parkview hospital Ltd, Chattogram, Bangladesh. Data were collected by questionnaire from the patients of any age with end-stage renal disease (ESRD) who underwent CAPD in 2018–2021. The baseline characteristics, PD-related complication as well as patient and technique survivals were analyzed. Results: Out of 31 patients who underwent CAPD, 18 (58%) were male on the age range of 15–79 years. The mean follow-up duration was 18 months. Mortality was inversely related with the EF of echocardiography. The peritonitis rate was 0.48 episodes per patient per year. The 1, 3 and 4-year patient survival rates were 64.34% (95% CI = 52.5–81.5), 23.79% (95% CI = 17.9 – 57.4) and 3.22% (95% CI = 31.2–77.5) respectively. Conclusions: In this study, CAPD performance was poorer than usual reference. Cardiac compromised patient and inappropriate dwell might be the main contributing factors behind this scenario. The peritonitis rate was nearly similar to that of developed countries. CAPD was cost effective than HD in remote area. Some accessible measures may be taken to make CAPD a more acceptable RRT modality with improved outcomes in poor socioeconomic backgrounds area. J Dhaka Med Coll. 2023; 32(1) : 24-31

Geochemical characterization and reserve estimation of the economic heavy minerals of Sonadia Island, Bangladesh

The goal of the current study is to understand the elemental concentration, reserve assessment, mineralogical composition, and distribution of heavy minerals in the dune sands, foreshore, and backshore of Sonadia Island, Southeast Bangladesh. The study area yielded a number of drill hole composite sand samples that were used for density and magnetic separation of heavy minerals. These samples were then subjected to petrographic characterization, grain counting, mineralogical analyses using scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM–EDX), x-ray diffraction (XRD), and bulk sand geochemistry using X-ray fluorescence (XRF). The results of heavy liquid separation show that the total heavy mineral (THM) enrichments in foreshore sand (about 4.86%), backshore sand (about 9.03%), and dune sand (about 22.28%) are significantly higher. After characterizing the sand samples from Sonadia Island based on the abundance of each mineral species, the average content values relative to total economic heavy minerals (TEHM) were determined to be 38.14% ilmenite, 5.74% magnetite, 51.52% garnet, 1.01% zircon, 3.57% rutile, and 0.01% monazite. An SEM–EDX examination reveals that the elemental concentration of ZrO2 in zircon is 66.60%, while the average TiO2 content in rutile is ~ 95%, whereas TiO2 is 45% and the total Fe2O3 is 45.70% in ilmenite. Major phases including amphibole (tremolite) 45.9%, muscovite 15.6%, quartz 12.6%, garnet (almandine) 10.9%, dolomite 7.9%, ilmenite 4.1%, and kaolinite 1.3% are also identified by the XRD pattern. There are an estimated 19,794 tons of garnet in the foreshore sand, 47,324 tons in the backshore sand, and 276,868 tons in the dune sand within the reserve, making it the most prevalent heavy mineral. Ilmenite is the second most common heavy mineral, with quantities detected in the foreshore (15,016 tons), backshore (30,487 tons), and dune sand (215,092 tons).

The survival and growth of adult and juvenile hard clam Meretrix meretrix exposed to variable estuarine salinities in aquarium settings

Salinity fluctuations in estuaries can significantly impact marine organisms, leading to economic losses through mass mortalities of commercially important species. The effects of varying estuarine salinities on the survival, daily mortality, and growth of adult and juvenile hard clam Meretrix meretrix under controlled aquarium conditions were investigated. Adults (shell length ~45 mm) and juveniles (shell length ~30 mm) were collected from an 18 ppt estuarine habitat in Chowfaldondi, southeast Bangladesh, and exposed to six salinity levels (10, 15, 20, 25, 30, and 35 ppt) with three replications at ambient temperature. Adults were monitored for 51 days and juveniles for 23 days. Survival was significantly higher (≥80%) at 15–30 ppt for adults and 10–20 ppt for juveniles, with the lowest survival at 35 ppt. Analysis of co-variance showed that salinity had a greater effect on survival than the combined salinity*size model (p<0.05). While adult clams exhibited no mortality in first 15 days, juvenile mortality (~10%) began on day two across all salinities with a dose-dependent mortality exceeding 50–80% in 25–35 ppt. Adults were more tolerant to high salinities while juveniles to low salinities. Shell length and width did not vary significantly across salinities, likely due to insufficient plankton in the supplied seawater. This study has implications for potential site selection for coastal clam aquaculture along the Bay of Bengal. The sudden changes and combined effects of multi-stressors on bivalves can be assessed for better understanding how near future climate change can impact bivalve fishery and blue economy. Res. Agric. Livest. Fish. Vol. 11, No. 2, August 2024: 239-254

Accelerometer-Measured Physical Activity, Fitness and Indicators of Cardiometabolic Risk among Rural Adolescents: A Cross-Sectional Study at 15-Year Follow-up of the MINIMat Cohort.

Little is known about the relationship of physical activity (PA) and fitness with cardiometabolic risk among rural adolescents in low- and middle-income countries. Thus, we examined the associations of PA and fitness with selected cardiometabolic indicators along with potential gender-based differences in a birth cohort of rural adolescents from southeast Bangladesh. We utilized data from the 15-year follow-up of Maternal and Infant Nutrition Interventions in Matlab (MINIMat) cohort (n = 2253). Wrist-worn ActiGraph wGT3x-BT accelerometers were used to estimate sedentary time (ST) and PA. Fitness was assessed using: handgrip strength, standing long jump, and Chester Step Test. Anthropometric parameters, systolic blood pressure (SBP), and fasting lipid, insulin and glucose levels were measured. We calculated insulin resistance using the Homeostasis Model Assessment equation (HOMA-IR). Linear regression and isotemporal substitution models were fitted. The adolescents spent 64min/day (inter-quartile range: 50-81) in moderate-to-vigorous physical activity (MVPA). A 10-minute-per-day higher vigorous PA (VPA) was associated with: 4.9% (95% confidence interval (CI): 2.9-6.8%) lower waist circumference (WC), 3.2 mmHg (95% CI: 1.5-4.8) lower SBP, 10.4% (95% CI: 2.9-17.3%) lower TG, and 24.4% (95% CI: 11.3-34.9%) lower HOMA-IR. MVPA showed similar associations of notably smaller magnitude. Except for WC, the associations were more pronounced among the boys. Substituting ST with VPA of equal duration was associated with lower WC, SBP, triglyceride and HOMA-IR. Grip strength was favorably associated with all indicators, displaying considerably large effect sizes. Our findings indicated beneficial roles of PA- particularly VPA- and muscular fitness in shaping cardiometabolic profile in mid-adolescence. VPA and grip strength may represent potential targets for preventive strategies tailored to adolescents in resource-limited settings.

Climate change quadruples flood‐causing extreme monsoon rainfall events in Bangladesh and northeast India

Bangladesh and northeast India are the most densely populated regions in the world where severe floods as a result of extreme rainfall events kill hundreds of people and cause socio‐economic losses regularly. Owing to local high topography, the moisture‐carrying monsoon winds converge near southeast Bangladesh (SEB) and northeast Bangladesh and India (NEBI), which produces significant extreme rainfall events from May to October. Using observed data, we find an increasing trend of 1‐day extreme event (150 mmday) frequency during 1950–2021. The extreme rainfall events quadrupled over western Meghalaya (affecting NEBI) and coastal SEB during this period. Composite analysis indicates that warm Bay of Bengal sea‐surface temperature intensifies the lower tropospheric moisture transport and flux through the low‐level jet (LLJ) to inland, where mountain‐forced moisture converges and precipitates as rainfall during extreme events. To understand the role of climate change, we use high‐resolution downscaled models from Coupled Model Intercomparison Project phase 6 (CMIP6). We find that the monsoon extreme event increase is ongoing and the region of quadrupled events further extends over the NEBI and SEB in the future (2050–2079) compared with historical simulations (1950–1979). A quadrupling of the intense daily moisture transport episodes due to increased LLJ instability, a northward shift of LLJ, and increased moisture contribute to the increased future extreme events. This dynamic process causes moisture to be transported to the NEBI from the southern Bay of Bengal, and the local thermodynamic response to climate change contributes to the increased extreme rainfall events. The CMIP6 projection indicates that more devastating flood‐causing extreme rainfall events will become more frequent in the future.

Enhancing landslide risk reduction strategies in Southeast Bangladesh.

By integrating primary and secondary data, this study found that several political-economic aspects are major anthropogenic contributors to the recent increase in landslides in the region. The contributing factors included the following: policy and action plans to raise regional population; land management; illegal deforestation; plans to establish hydroelectricity in hilly areas; ownership of settlements; manipulation of water, gas and electricity supply to illegal settlements; commercial plantations; lack of risk governance; unplanned development activities; natural population rise; increased settlement along hill slopes. This study identified and discussed lessons learned from previous landslide disasters, the weakness of early warning systems and their dissemination and ways to improve evacuation, rescue, relief and risk reduction. Finally, this study formulated recommendations for the effective implementation of landslide risk reduction in southeast Bangladesh.

Morphological change assessment of a coastal island in SE Bangladesh reveal high accumulation rates

It is essential to comprehend various morphological aspects, change dynamics, and stressors on the coastal environment in both contemporary and historical contexts. This study examines the potential for morphological changes in land use, erosion-sedimentation patterns, shoreline changes, and sediment accumulation on Sonadia Island in Southeast Bangladesh. To evaluate the extraordinarily high sediment accumulation phenomenon, the researchers used toposheets, historical maps, numerous satellite images, and field work observations. The investigation revealed that the shoreline of the island is subject to regular and rapid modifications. The island’s area coverage was 1.65 km2 in 1779, but it has grown 21 times to 36 km2 in 2021. From 1972 to 2021, the current study looks at land-use/land-cover changes on Sonadia Island, including mangrove (12.15 to 20.22 km2), tidal mudflats (6.69 to 4.63 km2), salt/shrimp fields (0 to 3.33 km2), dune (1.30 to 3.33 km2), beach sands (5.07 to 4.57 km2), and man-made forest (0 to 1.06 km2), as well as spatial changes in land. Between 1972 and 2021, erosion and sedimentation reached 1.35 km2 and 14.09 km2, respectively, resulting in a depositional rate of 0.29 km2 per year and an erosional rate of 0.03 km2 per year. The high accumulation rates are linked to shoreline activities such as mixing and reworking fluvial systems, longshore currents, tidal activity, strong waves, and seasonal current circulation patterns.

Dietary patterns and indicators of cardiometabolic risk among rural adolescents: A cross-sectional study at 15-year follow-up of the MINIMat cohort.

Diet being a modifiable factor, its relationship with cardiometabolic risk is of public health interest. The vast majority of studies on associations of dietary patterns with cardiometabolic risk indicators among adolescents are from high-income countries and urban settings. We sought to describe dietary patterns and examine their associations with selected cardiometabolic risk indicators-waist circumference (WC), systolic blood pressure, fasting lipid profile and insulin resistance-along with its gender stratification among adolescents in a low-income, rural setting. This cross-sectional study utilized data from the 15-year follow-up of the Maternal and Infant Nutrition Interventions in Matlab (MINIMat) cohort in southeast Bangladesh. The children who were born as singletons to the mothers randomized in the MINIMat trial and had valid birth anthropometrics were eligible for the follow-up. We employed a single, qualitative 24-hour recall to assess diet. Dietary patterns were derived from simple K-means cluster analysis, and calculation of dietary diversity score (DDS) using a validated instrument. Anthropometric parameters and systolic blood pressure were recorded. Fasting plasma triglyceride, total cholesterol, low- and high-density lipoproteins, insulin and glucose levels were measured. We calculated insulin resistance using the Homeostasis Model Assessment equation (HOMA-IR). Three right-skewed outcome variables were natural log (Ln) transformed: WC, triglyceride and HOMA-IR. Omnibus and gender-specific multiple linear regression models were fitted. Among 2,253 adolescents (52.1% girls, 7.1% overweight/obese), we identified four diet clusters: Traditional, Fish-dominant, Meat-dominant, and High-variety. No significant associations were found between the clusters and indicators. On gender-stratification, triglyceride levels were lower among boys in the Fish-dominant (Ln-triglyceride βadjusted: -0.09; 95% confidence interval (CI): -0.15, -0.02) and Meat-dominant (Ln-triglyceride βadjusted: -0.08; 95% CI: -0.15, -0.004) clusters than among boys in the Traditional cluster. Compared to boys in the bottom quartile of DDS, boys in the top quartile had 2.1 mm of Hg (95% CI: 0.5, 3.6) higher systolic blood pressure and 1.9% (95% CI: 0.01-3.8%) higher WC. While statistically significant, the gender-specific differences in triglyceride, systolic blood pressure, and waist circumference across dietary patterns were small. Associations between dietary patterns and cardiometabolic risk indicators may require a time lag beyond mid-adolescence to manifest in a rural setting. Prospective studies are warranted to delineate the magnitude and direction of those associations.

How far westward? Revisiting the distribution of Arctonyx badgers in the westernmost global range

Abstract Bangladesh delimits the westernmost range of Arctonyx badgers, but their presence in the country is not completely understood. The whole of Bangladesh is reportedly home to the northern hog badger (A. albogularis); however, there is no valid record to date. The greater hog badger (Arctonyx collaris), its larger congener and a globally vulnerable mustelid, has three valid records. This work, between 2001 and 2021, traced 28 records (all of A. collaris: 20 from literature review and social media, 8 from camera-trapping) in Bangladesh including four rare cases of erythrism and seven conflict incidents. All but five were from mixed evergreen forests of southeast Bangladesh, the known A. collaris range. One record was from wet deciduous forests of northern Bangladesh (bordering Meghalaya, India), a region not previously marked as an A. collaris range. In 2021, from 4436 trap-nights of sampling, 17 notionally-independent events (all night-time) were obtained. This produced the first evidence of A. collaris in northeast Bangladesh, a region that borders the Tripura Hills, India (where it was first recorded in 2020) and belongs to the Indo-Burma biodiversity hotspot. The work proves the existence of relict populations whereas the absence of A. albogularis signifies a re-assessment of its westernmost distribution.

Assessment of benthic macroinvertebrates as potential bioindicators of anthropogenic disturbance in southeast Bangladesh coast.

Many human activities can greatly influence and alter the health of aquatic ecosystems. In this regard, the quantitative analysis of macroinvertebrates and their relationships with ecological variables is an effective method in environmental monitoring programs. Here, we used the benthic macroinvertebrate community as bioindicators for assessing anthropogenic impacts on coastal waters in southeast Bangladesh. Sediment samples were collected seasonally from three different sites influenced either by mangrove forests, aquaculture activity or sewage input. The indicator value index (IndVal) analysis revealed 23 species of benthic macroinvertebrates as potential bioindicators namely Enigmonia aenigmatica, Mactra chinensis and Pharella javanica of the class Bivalvia; Tubifex tubifex of the class Clitellata; Lithopoma brevispina, Bullia vittata, Pomacea maculata and Umbonium vestiarium of the class Gastropoda; Gammarus roeselii of the class Malacostraca; and Amphicteis gunneri, Amphitrite ornata, Aricidea simplex, Cirratulus cirratus, Heterospio catalinensis, Hypereteone foliosa, Lopadorrhynchus henseni, Neanthes chingrighattensis, Micronephthys oligobranchia, Nephtys hombergii, Nereis jacksoni, Nereis zonata, Polyodontes maxillosus and Stygocapitella subterranean of the class Polychaeta. Their composition across three sites varied significantly (P<0.05) due to influence of environmental conditions as inferred from redundancy analysis. Polychaeta, Gastropoda and Malacostraca were susceptible to sewage input, while Bivalvia and Clitellata were susceptible to aquaculture effluent. The results of this baseline study suggest that the identified benthic macroinvertebrate species can potentially be used to monitor anthropogenic disturbances in the marine environment.

Glucose lowering effect of wild banana cultivar of &lt;em&gt;Musa acuminata &lt;/em&gt;L. fruit peels from Bandarban, Bangladesh in Swiss albino mice

Diabetes is a debilitating disease, which has become a serious concern in Bangladesh. Earlier studies have shown that extracts of fruit skins of various cultivars of banana species can improve glucose tolerance in glucose-loaded mice. The objective of this study was to evaluate through oral glucose tolerance test (OGTT) of methanol extract of fruit peels of a wild cultivar of Musa acuminata, which can be found in southeast Bangladesh forests. In OGTT, ripe fruit skin methanolic extract of Musa acuminata (MEMA) showed a reduction by 0.04, 19.65, 19.80 and 26.84%, when administered per kg body weight in mice at doses of 50, 100, 200 and 400 mg, respectively. A standard glucose lowering drug, glibenclamide decreased blood glucose levels by 21.08 and 37.38% at doses of 2 and 10 mg. Overall, the findings indicate that MEMA can improve glucose tolerance and may be of potential use to diabetic patients.

Climate change perceptions, impacts and adaptation practices of fishers in southeast Bangladesh coast

PurposeThe small-scale artisanal fishers in coastal Bangladesh are comparatively more vulnerable to climate risks than any other communities in Bangladesh. Based on practicality, this paper aims to explain the local level climate change perception, its impact and adaptation strategies of the fisher in southeast coastal villages in Bangladesh.Design/methodology/approachTo achieve the above objective, this study used structural, semi-structured interviews and focus group discussion in two coastal communities, namely, at Salimpur in the Sitakund coast and Sarikait Sandwip Island, Bangladesh. It reviews and applies secondary data sources to compare and contrast the findings presented in this study.FindingsResults show that the fishers perceived an increase in temperature, frequency of tropical cyclones and an increase in sea level. They also perceived a decrease in monsoon rainfall. Such changes impact the decreasing amount of fish in the Bay of Bengal and the fishers’ livelihood options. Analysing seasonal calendar of fishing, findings suggest that fishers’ well-being is highly associated with the amount of fish yield, rather than climatic stress, certain non-climatic factors (such as the governmental rules, less profit, bank erosion and commercial fishing) also affected their livelihood. The major adaptation strategies undertaken include, but are not limited to, installation of tube well or rainwater harvesting plant for safe drinking water, raising plinth of the house to cope with inundation and use of solar panel/biogas for electricity.Originality/valueDespite experiencing social stress and extreme climatic events and disasters, the majority of the fishing community expressed that they would not change their profession in future. The research suggests implementing risk reduction strategies in the coastal region of Bangladesh that supports the small-scale fishers to sustain their livelihood despite climate change consequences.

Millions of Bangladeshi Children Missed Their Scheduled Vaccination Amidst COVID-19 Pandemic.

The Government of Bangladesh imposed a movement control order as a mass quarantine strategy to control the outbreak of coronavirus disease 2019 (COVID-19). Adherence to the home quarantine may put children at risk by missing routine vaccination. In this study, we investigated the impact of COVID-19 on child routine immunization in a rural area of Bangladesh and consider the broader implications. Data for this study comes from the Chakaria Health and Demographic Surveillance System (HDSS) of icddr,b with a population of 90,000 people residing in 16,000 households in 49 villages in a rural, coastal area of Southeast Bangladesh. We used an explanatory sequential mixed methods design which involved two phases between March 1, 2020, and May 31, 2020: first, we observed 258 outreach sessions of 86 EPI centers. We calculated the number of Expanded Program on Immunization (EPI) outreach sessions suspended and the number of children who missed their routine vaccination due to the COVID-19. We extrapolated the number of Bangladeshi children who missed their routine vaccination using Chakaria HDSS observations. Secondly, we conducted in-depth interviews to explain the quantitative results. The EPI outreach session (EOS) declined to 74.42% (95% CI 63.97–83.22), 10.45% (95% CI 5.00–18.94), and 3.45% (95% CI 1.00–9.75) from 2019 levels in March, April, and May 2020, respectively. By extrapolation, in Bangladesh, between March and May 2020, 3.2 million children missed their scheduled vaccination compared to 2019. Results from in-depth interviews showed that the unwillingness of villagers to hold EOS and the absenteeism of the vaccinators due to social distancing recommendations and lack of personal safety measures were the main reasons for the discontinuation of the EOS. Resuming EPI outreach sessions and introducing a special catch-up program is essential to prevent future outbreaks and deaths due to vaccine-preventable diseases in Bangladesh and the countries where children missed their routine vaccination due to COVID-19. This health system failure should be considered a factor in all future pandemic preparedness plans.

Ecological restoration through natural regeneration in Chunati Wildlife Sanctuary – a protected area of South-East Bangladesh

PurposeIn this paper, the authors show that ecological restoration potential through natural regeneration of degraded tropical rainforest is possible. This is significant because at present most of the tropical forest of the world, including of Bangladesh, are degraded.Design/methodology/approachRegeneration status of Chunati Wildlife Sanctuary (CWS) was assessed through stratified random sampling method using sample plots of 5 × 5 m in size covering 269 sample plots.FindingsA total of 3,256 regenerating seedlings/saplings of 105 species belonging to 35 families were recorded from CWS. From regenerating tree species, maximum (37.83) family importance value (FIV) index was found for Euphorbiaceae followed by Myrtaceae (18.03). Maximum importance value index (IVI) was found for Aporosa wallichii (21.62) followed by Grewia nervosa (16.41). Distribution of seedlings into different height classes of regenerating tree species was also calculated.Practical implicationsForest scientists are working to find out the best nature-based solution for ecological restoration of tropical rainforests to attain climate resilient ecosystem in a sustainable way. Tropical rain forest has huge plant diversity, and we find that ecological restoration is possible through natural regeneration from its rich soil seed bank. Natural regeneration is the best nature-based solution for sustainable management of the forest.Social implicationsThe authors believe that the findings presented in our paper will appeal to the forest and environmental scientists. The findings will allow readers to understand degraded tropical hill forest ecosystem and its management strategy.Originality/value The authors believe that this manuscript will give a clear picture about degraded tropical hill forest ecosystem and its genetic composition, diversity and soil seed bank status to apply appropriate management strategy.

Severity assessment of single-dose Oxford-AstraZeneca vaccinated individuals infected with severe acute respiratory syndrome coronavirus 2 in Southeast Bangladesh

Background and Aim: A vaccine program for coronavirus illness (coronavirus disease [COVID-19]) is currently underway in numerous regions of the world, including Bangladesh, but no health data on those who have been vaccinated are available at this time. The study aimed to investigate the health condition of people who had received their first dose of the Oxford- AstraZeneca vaccine and were infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Materials and Methods: To detect SARS-CoV-2, a standard virological approach, real-time reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR), was used. Several health indicators from vaccinated patients were collected using pre-structured questionnaires during the infection phase. Results: A total of 6146 suspicious samples were analyzed, and 1752 were found to be positive for SARS-CoV-2, with 200 people receiving the first dose of the COVID-19 vaccine. One hundred and sixty-five (82.5%) were not hospitalized among the vaccinated people, and 177 (88.5%) did not have any respiratory problems. Only 8% of patients required further oxygen support, and 199 (99.5%) did not require intensive care unit intervention. Overall, oxygen saturation was recorded at around 96.8% and respiratory difficulties did not extend more than 5 days during the infection period. Among the vaccinated COVID-19-positive people, 113 (56.5%) and 111 (55.5%) had typical physiological taste and smell. Surprisingly, 129 (64.5%) people had diverse comorbidities, with high blood pressure (27.9%) and diabetes (32 [24.8%]) being the most common. The major conclusion of the current study was that 199 (99.5%) of vaccinated patients survived in good health and tested negative for RT-qPCR. Conclusion: According to the findings of this study, administering the first dose of the Oxford-AstraZeneca vaccine considerably reduces health risks during the COVID-19 infection period.

Geometry of the Décollement Below Eastern Bangladesh and Implications for Seismic Hazard

AbstractEastern Bangladesh sits on the seismically active Chittagong‐Myanmar fold and thrust belt (CMFB), a north‐trending accretionary wedge on the eastern side of the India‐Eurasia collision. Earthquakes on the basal décollement and associated thrusts within the CMFB present a hazard to this densely populated region. In this study, we interpret 28 seismic reflection profiles from both published and unpublished sources to constrain the depth of the basal décollement. To convert profiles from the time domain to the depth domain, we integrate sonic log and seismic stacking velocity data to generate time‐velocity relationships for different parts of the CMFB. Our analysis reveals that the décollement is ∼9 km deep in northeast and southeast Bangladesh, but shallows to ∼5 km in east‐central Bangladesh. The décollement has an area of 7.25 × 104 km2 (∼150 × 450 km), making it capable of an Mw 8.5 earthquake. However, the warped geometry of this fault might act as a rupture barrier were a large earthquake to occur on the décollement. Our combined velocity and fault model lay the groundwork for future studies to address seismic segmentation, ground shaking, and rupture modeling in the CMFB. Finally, we use our compiled data set to analyze the evolution of fold kinematics in the CMFB. We observe that folding style and failure mode varies, from mainly ductile deformation in the foreland to mainly brittle in the hinterland. The dual‐failure modes within the CMFB support the hypothesis that a region with ductile deformation may still be capable of seismic behavior.

Landslide mitigation strategies in southeast Bangladesh: Lessons learned from the institutional responses

The paper examines how local-level institutions mitigate landslide hazards in southeast Bangladesh. In this context, sixteen sub-districts (Upazila) were selected as sample sites from the southeastern districts through disproportionate quota sampling for a sample survey. Forty-five officials were interviewed by using a semi-structured questionnaire at the local level. The study reveals two types of measures (i.e., structural and non-structural) that have been taken by local-level institutions under the National Plan of Disaster Management (NPDM) as there is no Landslide-specific Disaster Management Policy in southeast Bangladesh. The study explores that the structural measures (guide wall and retaining wall for slope stabilization, resettlement, small-scale plantation, etc.) are insufficient due to the financial constraints. The findings reveal that the emergency responses (eviction, temporary evacuation, dissemination of early warning, etc.) are adequate to reduce the landslide-induced causality; however, the non-structural measures (such as early warning system, housing facilities, community-based awareness-raising programs with more training and workshops, rehabilitation activities, etc.) need special attention to mitigate landslide hazards. The results also suggest that resettlement policy should consider the ethnic culture along with other regional factors of a diversified hilly environment. It also puts forward an institution-based solution, including a comprehensive official landslide database with sustainable hill management mechanisms. Such evidence epitomizes a significant foremost step in developing realistic mitigation strategies for landslide-prone areas with similar socio-economic, cultural, and regional settings like southeast Bangladesh.

China-Bangladesh Geopolitical Relations: A Study of Some Geostrategic and Geoeconomic Issues in the Context of the Bay of Bengal

Geopolitically, the Bay of Bengal is very important because it is connected with Andaman Sea and Malacca Straits. Moreover, the Bay of Bengal has direct links with South Asia and South East Asia including the Indian Ocean. Particularly, both China and India are very interested in the Bay of Bengal for mineral resources. Through the Bay of Bengal, China wants a direct connectivity between China and Indian Ocean through either South East Bangladesh or Rakhine state of Myanmar. This study has dealt with the importance of the Bay of Bengal in the light of China’s geopolitical desire, trade and investment, oil and gas, and regional connectivity. Many geopolitical issues of China and Bangladesh have been discussed in this study. The main objective of this study is to focus on strengthening the relationship between China and Bangladesh, so that these two neighboring countries can be beneficiaries through trade and investment, regional connectivity, expanding the exports and imports. And these two friendly countries can be also beneficiaries through constructing the deep seaports along the Eastern Coastal Zone of Bangladesh, particularly Southeast Cox’s Bazar. The findings of this study are that, the relationship Between China and Bangladesh in the light of the geopolitics and geo-economic issues is, of course, pivotal for both countries for trade and investment, and for economic cooperation and development. Methodologically it is a qualitative study, which is based on both primary and secondary data. Keywords: China, Bangladesh, Geopolitical Relations, Bay of Bengal

Investigating the Strength of the Indian Monsoons during Climate Extremes with Stable Isotope Records in Corals

The Indian monsoon affects the lives of over a billion inhabitants living in southern Asia via the hy-drological cycle. Agriculture on land and freshwater discharge into the ocean. This discharge and nutri-ent cycling are tied with the monsoon cycles that di-rectly impact society and the economy. Previous studies have demonstrated a strong connection be-tween the strength of the Indian monsoon and the cooling of the North Atlantic during climate ex-tremes, such as during the last glacial period 20,000 years ago, and the Little Ice Age (~1300-1870 A.D.). In our study, we compare the relative strength of the monsoon during two different climate states: the Lit-tle Ice Age (LIA) and the modern (2015) with proxy measurements obtained in surface corals from Saint Martin’s Island, Southeast Bangladesh. We used the oxygen-isotope 18O/16O ratio (δ18Oc) of coralline aragonite (CaCO3) to reconstruct changes in the δ18O of seawater (δ18Ow) attributed to freshening from monsoon rains. During both climate states, corals recorded large variations in δ18Oc (up to 2 parts per thousand or ‰). We attribute these changes, in part, to local salinity changes which are reflected by variability in δ18Ow from local riverine discharge. While our records only represent 5-year snapshots and may not be representative of the av-erage climate state, this data does not support that the monsoon was substantially weaker during the LIA compared to the modern. In this study, the coral records indicate subtle patterns of isotopic compo-sition as a function of precipitation and temperature variability, serving as a preliminary for further study through longer records lasting a century. Beyond this, it would better our understanding of interac-tions between extremes in temperature and climate systems.

Socio-ecological approach on the fishing and trade of rhino rays (Elasmobranchii: Rhinopristiformes) for their biological conservation in the Bay of Bengal, Bangladesh

Rhinopristioid rays are among the most globally threatened cartilaginous fishes, almost all of which are Critically Endangered. Fishery pressure and lack of knowledge, especially where these elasmobranch fish overlap their habitats off developing countries in the Indo-West Pacific, impede their biological conservation which in turns result in unnoticed population depletion. Rhino rays are an important component of the Bangladeshi artisanal fishery; however, an understanding of these fisheries and their trade is limited. Fishers and traders were interviewed between June 2018 and June 2019 in four areas of southeast Bangladesh to characterize rhino ray fishing, trade and fishers' perception of population trends. All interviewed fishers reported life-long rhino ray catch in sizable numbers and noted a steep decline in the catch over time, especially for Rhynchobatus spp. Seven species were documented- not only targeted by un-baited longlines but also by-caught in gillnets and set-bag nets. Unregulated and undocumented catch fuelled by substantial international trade to Myanmar on high-quality skin, meat and fins; and national usages of meat, liver, cartilages and intestines. Between 9000 and 33000 kg (avg. 23000 kg) of rhino rays were bought annually by each trader during 2015–2018. Southcentral shallow-water char (sand island) areas are perceived as essential habitats, hence providing important fishing grounds. The predominant threats are overexploitation by unselective gear use, bottom trawling, target catch, international trade and source of protein and income. Compliance with international trade control treaties or the Bangladeshi law was low, with most fishers (78%) unaware of specific regulation regarding rhino rays. It is crucial to adopt precautionary principles to prevent further rhino ray population declines. We propose a combination of actions rooted in sustainability and inclusiveness in this regard; e.g. a) trade mitigation, monitoring and enforcement, b) need for sustainable fisheries management regimes, c) need for habitat protection; finally, d) the importance of fishers’ inclusiveness in conservation decision making.