Sugata Hazra

Application of a ‘bio-engineering’ technique to protect Ghoramara Island (Bay of Bengal) from severe erosion

Ghoramara Island is located ca. 150 km south of Kolkata, Bay of Bengal, India, in the Sundarban Delta complex. This sparsely populated island is suffering from severe coastal erosion and areal reduction for the last three decades, which results in the loss of major areas on the northwest coast. Both numerous households and a significant area of agricultural land and coastal stretches for fish drying have been lost. This has rendered thousands of people homeless as ‘environmental refugess’. In the present paper an attempt is made to study the erosion and accretion process through time series analysis using a GIS technique. Also, a study of remedial measures to protect the island using a ‘bio-engineering’ technique is reported in this paper. It has been shown that, in the absence of protection measures, the eastern shore will merge with the Indian mainland during the next 25 years, while the western part will be completely washed off.

Automatic shoreline detection and future prediction: A case study on Puri Coast, Bay of Bengal, India

Abstract Shoreline prediction models have the capability of integrating geoinformatics within them. The present study is conducted on the 142 km-long coastline of Puri district, India. It aims to analyze the change in coastline due to erosion/accretion and provide best estimate of future shoreline positions based on past shorelines. A simple mathematical model, End Point Rate (EPR), has been used to calculate the rate of change of shoreline and its future positions, based on empirical observations. The erosional/accretional scenario has also been analysed by delineating the shoreline from Landsat imageries of 1972, 2001 and 2010. It is found that the northern part of Puri, in the vicinity of Kushabhadra estuary and Chandrabhaga beach undergo high rates of erosion. Based on the delineated shoreline, the short term (2015) and long term (2025) shoreline positions have been predicted.

Estimating aboveground biomass in Avicennia marina plantation in Indian Sundarbans using high-resolution satellite data

Abstract Mangroves are active carbon sequesters playing a crucial role in coastal ecosystems. In the present study, aboveground biomass (AGB) was estimated in a 5-year-old Avicennia marina plantation (approximate area ≈ 190     ha ) of Indian Sundarbans using high-resolution satellite data in order to assess its carbon sequestration potential. The reflectance values of each band of LISS IV satellite data and the vegetation indices, viz., normalized difference vegetation index (NDVI), optimized soil adjusted vegetation index (OSAVI), and transformed difference vegetation index (TDVI), derived from the satellite data, were correlated with the AGB. OSAVI showed the strongest positive linear relationship with the AGB and hence carbon content of the stand. OSAVI was found to predict the AGB to a great extent ( r 2 = 0.72 ) as it is known to nullify the background soil reflectance effect added to vegetation reflectance. The total AGB of the entire plantation was estimated to be 236 metric tons having a carbon stock of 54.9 metric tons, sequestered within a time span of 5 years. Integration of this technique for monitoring and management of young mangrove plantations will give time and cost effective results.

siRNA-nanoparticle conjugate in gene silencing: A future cure to deadly diseases?

Alzheimers, cancer, acquired immune deficiency syndrome (AIDS) are considered to be some of the most deadly diseases of the 21st century on account of their severity and rapid increase in the number of affected population and with scarce cases of recovery, they still remain a troubling paradox. Specifically, with millions of cancer patients worldwide and lack of proper cure for the same, understanding the deadly disease at the molecular level and planning a therapeutic strategy in the same line is the need of the hour. Further, the potential threat of prevalence and escalation of Alzheimers and HIV (human immunodeficiency virus) infection by more than three times as of recent past, needs a medical breakthrough to arrive at a meaningful solution to tackle the present day scenario. It is evident that these diseases initiate and propagate based on certain genes and their expression which needs to be silenced by the help of small interfering RNA (siRNA) by at least 70%. For short term silencing of the protein coding genes, siRNA is the most appropriate tool. Hence, the present communication explores the possibility for treatment and cure of a plethora of deadly diseases, e.g., cancer, including Alzheimers and AIDS to some extent, emphatically at the molecular level, using the current trend of RNAi (RNA interference) delivery via a wide variety of nanoparticles.

A comparison of CO2 dynamics and air-water fluxes in a river-dominated estuary and a mangrove-dominated marine estuary

The fugacity of CO2 [fCO2 (water)] and air-water CO2 flux were compared between a river-dominated anthropogenically disturbed open estuary, the Hugli and a comparatively pristine mangrove dominated semi-closed marine estuary, the Matla on the east coast of India. Annual mean salinity of the Hugli Estuary (≈ 7.1) was much less compared to the Matla Estuary (≈ 20.0). All the stations of the Hugli Estuary were highly supersaturated with CO2 (annual mean ~ 2200 µatm) whereas, the Matla was marginally oversaturated (annual mean ~ 530 µatm). During the post-monsoon season, the outer station of the Matla Estuary was under saturated with respect to CO2 and acted as a sink. The annual mean CO2 emission from the Hugli Estuary (32.4 mol C m-2 yr-1) was 14 times higher than the Matla Estuary (2.3 mol C m-2 yr-1). CO2 efflux rate from the Hugli Estuary has increased drastically in the last decade, which is attributed to increased runoff from the river-dominated estuary.

Sense of fold asymmetry in single-phase and superposed folding

The sense of asymmetry of folds depends upon the sense of shear strain parallel to the enveloping surface. In bulk pure shear, S folds develop by a layer-parallel shortening combined with a sinistral shear strain along the enveloping surface when this surface rotates clockwise in progressive deformation. In layers which shorten but rotate anticlockwise, Z folds form under a dextral shear strain. In simple shear the sense of layer-parallel shear strain is the same as that for bulk simple shear, provided the layering is at a low angle to the direction of shearing. If this angle is large (> 45°) the sense of layer-parallel instantaneous shear strain is opposite to that of bulk simple shear. The sense of asymmetry of the folds can therefore change in the course of progressive simple shear. During refolding of early asymmetric folds (F1) the pattern of S- and Z-shaped F1 folds on two limbs of F2 will depend upon several factors, e.g. the initial sense of asymmetry, the initial angle between the F1 and F2 axes, and the mechanism of F2 folding. The different types of fold asymmetry in type 1, type 2 and type 3 fold interference have been considered. In ductile shear zones where the F1 hinge lines are deformed to hairpin bends over F2 folds, the sense of asymmetry of F1 parasitic folds on adjoining limbs of F2 may be either the same or opposite. In the latter case the pattern of fold asymmetry may be similar or opposite to that of congruous parasitic folds. There may be an association of congruous and incongruous patterns when parasitic folds of different generations are present. This association may be of different types but usually two generations of parasitic folds can be distinguished from their asymmetry and other geometrical characters.

Characterizing the multi-risk with respect to plausible natural hazards in the Balasore coast, Odisha, India: a multi-criteria analysis (MCA) appraisal

Coastal zones are often prone to several natural hazards, and where the coastal zone has high population density and infrastructural assets, these hazards can render severe loss to both life and properties. The present paper reports a comprehensive assessment of the multi-hazard and multi-risk (keeping in view the population and assets exposed to multi-hazards) in the Balasore coast, situated in the state of Odisha, India, facing the Bay of Bengal immediately to its east. In most of the multi-hazard and multi-risk assessments, the importance of any one hazard in relation to others is often determined arbitrarily. To overcome this limitation, this work presents a multi-criteria analysis implemented on six hazards, namely coastal erosion, storm surge, sea level rise, coastal flooding, tsunami, and earthquake. The respective hazards were ranked according to their relative weight computed by pair-wise comparison, and the overall multi-hazard map of the coast was prepared using weighted overlay technique in GIS environment. In order to assess the exposure, population density and urban assets of the study area were also mapped. Finally, the population and urban density data were overlain on the multi-hazard map in order to derive the final map portraying the multi-risk of the Balasore coast. Coastal erosion and storm surge inundation are the two most substantial natural hazards that regularly affect this coast. It is also observed that hazard from the perspective of coastal erosion is spatially concentrated along the central part of the coast, while in the southern part, the effect of storm surge is higher. The area in and around Chandipur, which is situated in the central portion of the Balasore coast, has been found to have the highest multi-risk, which also happens to be a popular tourist destination.

Trends of sea level in the Bay of Bengal using altimetry and other complementary techniques

Abstract In the present study, the different components of sea level (sea surface height, halosteric height, and thermosteric height) were estimated in the Bay of Bengal during 1993–2010 (Altimeter) and 2004–2010 (GRACE, Argo and Altimeter). The altimetry-based sea level (sea surface height) data showed a generally positive trend of sea level rise during 1993–2010 in the Bay of Bengal. The thermal expansion of ocean volume and discharge of water mass into the bay may be responsible for such changes. The temporal pattern of sea level variation derived from altimeter observations was compared with ocean mass and steric signals derived from GRACE and Argo data. It was observed that the sum of steric sea level and the ocean mass components has a positive trend of 6.26 ± 1.29 mm/yr, which was in conformity with the total sea level rise of 4.36 ± 1.45 mm/yr estimated from altimeter data, within a 95 percent confidence interval, during 2004–2010.

BLACKSPOTTED CROAKER, Protonibea diacanthus (Lacepède, 1802): A NEW DIMENSION TO THE FISHING PATTERN IN WEST BENGAL, INDIA

Blackspotted Croaker ( Protonibea diacanthus ) is one of the most commer- cially important croakers which migrate along West Bengal coast during winter season. This paper deals with the importance of the species along with its market value and the cause of its popularity in West Bengal. This species is gaining prime importance among the fishermen due to the high market price of its swim bladder. The dried swim bladders are sold in local markets for Rs. 40,000-50,000 per kg. There is a risk factor involved as the fishermen do not get the catch at a time and, moreover, they often lose common pelagic fishes due to the usage of larger mesh nets. In spite of this risk, a shift from pelagic to demersal fishing across the northern Bay of Bengal marks an important emerging trend of winter fishing in this area.

Biology and fisheries of Hilsa shad in Bay of Bengal

Hilsa (Tenualosa ilisha) or river shad is an anadromous fish species widely distributed in the North Indian Ocean, mainly in the Bay of Bengal (BoB). Hilsa is the national fish of Bangladesh and it contributes 10% of the total fish production of the country, with a market value of