Nicobar Archipelago Research Articles

Assessing forest canopy closure in a geospatial medium to address management concerns for tropical islands—Southeast Asia

The present study outlines an approach to classify forest density and to estimate canopy closure of the forest of the Andaman and Nicobar archipelago. The vector layers generated for the study area using satellite data was validated with the field knowledge of the surveyed ground control points. The methodology adopted in this present analysis is three-tiered. First, the density stratification into five zones using visual interpretation for the complete archipelago. In the second step, we identified two island groups from the Andaman to investigate and compare the forest strata density. The third and final step involved more of a localised phytosociological module that focused on the North Andaman Islands. The results based on the analysis of the high-resolution satellite data show that more than 75% of the mangroves are under high- to very high-density canopy class. The framework developed would serve as a significant measure to forest health and evaluate management concerns whilst addressing issues such as gap identification, conservation prioritisation and disaster management--principally to the post-tsunami assessment and analysis.

Genetic variability of diurnally sub-periodic Wuchereria bancrofti in Nicobarese tribe of Nicobar group of Islands, Andaman and Nicobar Islands, India

Sub-periodic form of Wuchereria bancrofti occurs in several well-isolated islands of Nicobar group of islands of Andaman Nicobar archipelago, India, presenting an interesting situation to study the genetic variability of its population. Microfilariae collected from 40 microfilaria (mf) carriers residing in eight locations on five islands (five carriers from each locality) were studied for genetic variability by generating random-amplified polymorphic DNA profiles. Phylognetic analysis of the profiles revealed a considerable genetic variability among parasite populations of different islands. The Nei's gene diversity between populations of 40 individual mf carriers ranged from 0.0218 to 0.2400. It was highest (0.24) among the parasite populations of Car Nicobar island and lowest (0.0218) among those of Payuha area of Camorta island and Teressa island. The dendrogram constructed exhibited four distinct clusters, which are geographically localized, and the gene flow between them appears to be influenced by human migration pattern.

Assessment of Tsunami Impact on Fish Eggs and Larvae along Parangipettai Coast (Southeast Coast of India)

The tsunami on 26th December, 2004 caused extensive damage to coastal communities and affected many marine ecosystem in southern regions of India and Andaman and Nicobar islands affecting 2,260 km of coastline. The most affected regions were the state of Tamil nadu and the Andaman and Nicobar archipelago. The present research analysis the impact of tsunami on finfish eggs and larvae and its distribution patterns. It deals how the tsunami impinges directly on ichthyoplankton ecology. After the tsunami effect, the eggs and larvae samples were collected and compared with previous year data of the same month (January 2004 and January 2005). We selected five stations, 0.5 1,3,5 and 10 km distance from the shoreline. During the present study a total of 1067 eggs and 285 larvae belonging to 29 families and 57 species were sorted and identified. The pre and post tsunami collection shows the significant variation on eggs and larvae distribution. During pre tsunami and zooplankton biomass was highly correlated with ichtyoplankton density with all the five station significant at 1 % level (p-value <0.01) but there is no correlation observed in the post tsunami samples.

Shaping Security in India's Maritime East: Role of Andaman & Nicobar

Complex and amorphous threats confront India's security environment in its maritime East. India has very high stakes in the Bay of Bengal and its adjoining seas. The confluence of vital sea lines makes this region one of great strategic relevance to other powers as well. This translates into both challenges and opportunities for India. The Andaman & Nicobar archipelago had long been perceived as India's key vulnerability due to its remote location and a history of some of its islands 'slipping away' from the Indian dominion. Such wariness may be unfounded in the present times. Appropriate measures have been taken to strengthen its defence. The island chain can now play a greater role towards securing India's vital interests in the East beyond merely protecting itself. To achieve this, India needs to adopt a two-fold approach — first, augment its intrinsic capabilities, and second, actively engage its maritime neighbours.

Homegardens of Andaman and Nicobar, India

The study reports the influence of biophysical and socio-cultural factors on composition, diversity and distribution of plant species in the homegardens of the Andaman and Nicobar archipelago of India. The study also examines component interactions and productivity of the system. Four hundred and thirty homegardens were surveyed from six islands, four from Andaman (South Andaman, North Andaman, Middle Andaman and Little Andaman) and two from Nicobar district (Car Nicobar and Nancowry). In Nicobar, an aboriginal tribe, the Nicobari, predominates. The Nicobaries are Christians. However, people from different parts of the Indian subcontinent were rehabilitated in the Andamans in the mid twentieth century. A mixed culture prevails in South Andaman, but in the other Andaman islands either Bengali or Tamil culture predominates. Biophysically, South Andaman is hilly whereas Nicobar is flat. The other islands lie in between the two extremes. All are similar climatically. Twelve to thirty-four plant species were encountered in the homegardens that were planted, cared for and harvested. These plants categorized as palm, fruit, spice and forest trees, formed a three-storey structure in Andaman and a two-storey structure in Nicobar’s homegardens. The floristic similarity between the homegardens of the Andamans was 82–92%. However, it was only 12–18% between the homegardens of Andaman and Nicobar. Compared to Nicobar, species richness was greater in the homegardens of the Andamans. However, diversity was higher and evenness lower in the homegardens of Nicobar. All plant species in the homegardens of Nicobar are spontaneous in regeneration. For the Andamans, the proportion of spice trees was higher in the homegardens of South Andaman, mango and citrus in North Andaman, and pineapple and vegetables in Little Andaman. High plant diversity in these homegardens serves subsistence needs and provides income to most of the households as well. Net income in the homegardens of Andaman was 6.9 times higher compared to that in the homegardens of Nicobar.

Molecular insights into the origins of the Shompen, a declining population of the Nicobar archipelago

The Shompen, one of the most isolated and poorly understood contemporary hunter-gatherer populations, inhabit Great Nicobar Island, the southernmost island of the Nicobar archipelago. Morphological imprints in the Shompen were interpreted to favour a mixed Indo-Chinese, Malay, Negrito and Dravidian origin. Analyses of the mitochondrial, Y-chromosomal and autosomal gene pool of contemporary Shompen have revealed low diversity, illustrating a founder effect in the island population. Mitochondrial sequence analyses revealed the presence of two haplogroups of R lineage: B5a, and a newly defined clade, R12. Y-chromosomal analyses demonstrated the occurrence of a single lineage found predominantly in Austro-Asiatic speakers across Asia. With the different types of genetic markers analysed, the Shompen exhibit varying levels of genetic relatedness with the Nicobarese, and Austro-Asiatic speakers of mainland India and Southeast Asia. These genetic analyses provide evidence that the Shompen, an offshoot of the Nicobarese, are descendants of Mesolithic hunter-gatherers of Southeast Asian origin, deriving from at least two source populations.

Intensity Distribution from the 2004 M 9.0 Sumatra-Andaman Earthquake

The epicenter of the Mw 9.0 Sumatra-Andaman earthquake on 26 December 2004 at 00:58 UTC occurred near the northwestern end of Sumatra and ruptured northward along the Andaman and Nicobar Archipelago (Figure 1). The principal rupture had a duration of more than 10 minutes (Park et al., 2005) and was perceptible to a distance of 3,300 km westward and 2,600 km northward. The largest accelerations were perceived near the epicenter, but high intensities were also perceived along the archipelago with diminishing intensity northward. Presented here are 206 intensity reports interpreted in terms of EMS-98 (Grunthal, 1998), a scale with similarities to the MSK and Modified Mercalli Intensity scales but designed to take into account modern building practices. The data are culled from primary accounts, newspaper reports, and responses to an online intensity questionnaire (http://asc-india.org/menu/felt.htm). Insofar as additional epicentral data will be forthcoming in the next several months, the data are presented with a minimum of interpretation. Figure 1. Map showing the region of the rupture and its aftershocks (black dots). The location of the December mainshock is shown by a star. It is believed that the main rupture propagated to close to Port Blair. This study focuses on evidence for shaking intensity resulting from the earthquake, ignoring damage due to the tsunami, landslides, or liquefaction. Preliminary ground-based tsunami surveys are available (Borrero, 2005; NICEE, 2005); these provide some information about shaking intensities as well but are spatially limited. First-hand accounts of the disaster and damage reports that appeared in Web logs, conventional newspapers, and Web sites are evaluated along with 48 felt reports sent via the Internet by eyewitnesses in India. Multiple felt reports were received from places such as Bhubaneswar, Chennai, and Port Blair. The highest assigned intensity of 9 EMS was reported from Lameureum, on the northwest coast …

A “4R” environmental model for Andaman and Nicobar

Efforts to protect the fragile ecosystem of the Andaman and Nicobar archipelago show measurable results and encourage Welcomgroup to adopt environment-friendly policies.

Environmental quality assessment of Port Blair in Andaman islands

The Andman and Nicobar archipelago comprises of about 556 small and big islands covering an area of 8493 sq. kms in the Bay of Bengal. The very remoteness of these islands from the mainland has preserved their pristine environment and spectacular natural beauty. The Andman and Nicobar Administration is going for major developmental projects to cope with the increasing needs of the people, which ultimately results in significant changes in environmental quality. This paper describes the existing environmental quality around Port Blair city, which will give baseline scenario to assess the environmental impacts due to developments in the future.In order to monitor the air quality of the region, sampling stations were selected based on the locations of various industries and domestic activities. Suspended Particulate Matter (SPM), Sulphur dioxide (SO2) and Nitrogen Oxides (NOx) were monitored for a period of one month during winter season. In addition, micrometeorological data, viz. wind speed and direction were also recorded and analysed to obtain the representative meteorological scenario of the air basin. The monitored values of ambient air quality was found to be within the NAAQ standards of India.Similarly, noise levels were also measured at various locations viz., residential areas, commercial centres, villages, stone quarry sites and construction sites. Noise levels were found to exceed the standards at stone quarry, construction sites and other locations.Water quality studies were carried out with respect to surface and ground water. The various physico- chemical and bacteriological parameters were analysed. It was observed that the physico-chemical parameters of surface and ground water lie within the standards stipulated for Indian subcontinent except for heavy metals which exceed the limits in ground water samples. Bacteriological analysis of sea water and ground water indicate that they are contaminated with faecal matters. Further, the ground water can be used for drinking purposes only after adequate treatment.