Nicobar Archipelago Research Articles

Assessment of transboundary macro-litter on the remote island of Andaman and Nicobar: Unveiling the governing factors and risk assessment

The increasing occurrence of mismanaged plastic litter along India's coastline and the ominous challenges it poses to biodiversity and ecosystem health is a growing environmental concern. To address this issue, we comprehensively investigated the abundance, composition, and probable sources of marine litter on North Cinque Island, a remote uninhabited island in the Andaman and Nicobar archipelago, Bay of Bengal. This island is a designated wildlife sanctuary and serves as an important nesting site for Green, Hawksbill and Leatherback turtles. A total of 6227 litter items were enumerated, with an average concentration of 0.12 items/m2, representing 20 diverse litter types, with plastic dominating the litter composition (86 %). The cleanliness and environmental hazards of the coast due to the litter were assessed using different indices such as the Clean Coast Index (CCI), Plastic Accumulation Index (PAI), Hazardous Item Index (HII), and Clean Environment Index (CEI). CCI indicates the moderately clean-to-clean status of the surveyed sites. PAI points to low to moderate accumulation of plastic litter. HII of all five coasts fell in category II, suggesting a moderate abundance of hazardous items that can inflict injuries to the foraging turtle and their hatchlings. The CEI articulates the moderately clean to very clean status of the sites. Litter brand audit suggests a considerable amount of stranded litter on the coasts was transboundary and originated from six Indian Ocean Rim Countries (IORC), namely Thailand, Myanmar, Malaysia, Indonesia, Sri Lanka, and UAE. Joint solid waste management by the IORC is the need of the hour to avert litter accumulation on the pristine, remote islands.

Hydrogeology of southeastern coastal parts of Great Nicobar Island, India: development of an integrated conceptual model for a hitherto unexplored island in the Indian Ocean

The vulnerability of oceanic islands in the face of climate change, vis-a-vis human development, is a serious issue at present. The island of Great Nicobar in the Nicobar archipelago in the Indian Ocean will face major challenges owing to its impending development activities. The eastern coastal part of the island was investigated through exploratory drilling, geophysical investigations, and water-table monitoring. Field investigations show that coralline sand is the major groundwater repository and is commonly developed through dug wells. Exploratory drilling down to 100 m depth revealed that the underlying Tertiary consolidated aquifer is of limited potential and showed increased salinity with depth. Water is also present along the contacts of shale–sandstone. The mean seasonal fluctuations in the depth to the water table was 0.18 m. Geoelectrical sections identified promising fresh groundwater zones along the east coast, with freshwater-bearing semi-weathered coralline limestone and coralline sand having a resistivity of 146–622 ohm m. Based on generated data, a 3D model of the aquifer system was constructed. The observed soil infiltration rate was 0.3–0.5 cm h −1 . The specific capacity of the dug wells was c . 5 m 2 min −1 . The permeability of the phreatic aquifer was 5–11 m/day and the transmissivity was 0.11–0.2 m 2 min −1 . The optimum yield of the unconfined aquifer was 17–21 m 3 /day. The tidal influences on the aquifer system also added complexity to the island's hydrogeological dynamics. Despite the challenges of restricted access due to the presence of aboriginal tribes in the island, the present study provides the maiden set of hydrogeological data for the island, revealing the disposition of the aquifers, their properties and their spatio-temporal behaviour.

Archaic and Living Traditions: Ethnoarchaeology of Andaman and Nicobar Archipelago

The Andaman and Nicobar archipelago in the Bay of Bengal has been the home of three sects of people and cultures, namely, the natives, hybrids of convicts, and recent immigrants. The initial inhabitation of the islands is known through the study of shell middens and subsequent peopling by early ethnographic accounts and contemporary issue-based studies. The artifact-centric cultural inferences from such excavation reports, ethnographic accounts, material evidence, and living traditions are of immense value in understanding the cultural history of the archipelago. The cultural inferences derived from such studies under five categories—(a) settlements of the coast and the inland, (b) midden artifacts and native practices, (c) osseous trophies and wooden sculptures, (d) pottery and division of labor, and (e) seasons and preservation practices—are of ethnoarchaeological significance, despite the theoretical debate to consider the erstwhile ethnographic studies and museum collections as evidence for ethnoarchaeological interpretation.

First records of some coral reef-associated brachyuran crabs from the Nicobar archipelago, India

The coral reefs off the Andaman and Nicobar archipelagos harbour some of the world’s diverse reef-associated crustacean fauna, which have not been adequately surveyed. A recent faunal survey in the Andaman Sea on-board the Fishery Oceanographic Research Vessel Sagar Sampada (cruise number 388) revealed a rich diversity of coral reef-associated brachyuran crabs. The article reports four genera, Singhaplax Serène & Soh, 1976, Cavoportunus Nguyen & Ng, 2010, Cyrtocarcinus Ng & Chia, 1994 and Visayax Mendoza & Ng, 2008 occurring in Indian waters for the first time. Seven species namely Singhaplax ockelmanni (Serène, 1971), Urnalana angulata (Rathbun, 1911), Pseudolambrus confragosus (Calman, 1900), Cavoportunus dubius (Laurie, 1906), Cyrtocarcinus truncatus (Rathbun, 1906), Visayax osteodictyon Mendoza & Ng, 2008, and Xanthias joanneae Mendoza, 2013, are likewise reported for the first time from Indian waters.

Latitudinal variation in seagrass communities with special emphasis on post-tsunami status in the Andaman and Nicobar archipelago, India.

We studied spatial variation in seagrass communities in the Andaman and Nicobar archipelago (ANI), India using latitude as a surrogate variable. We classified the ANI into five latitudinally distinct island groups: North & Middle Andaman, Ritchie's archipelago, South Andaman, Little Andaman, and the Nicobar archipelago. We evaluated the Importance Value Index (IVI) for species to determine the ecologically dominant seagrasses within each Island group. Later, we related our findings to investigate the three decadal pre- and post-tsunami status of seagrass habitats in the ANI which were severely impacted by the Indian Ocean tsunami of 2004. Six of the 11 observed species, such as Halophila ovalis, Halophila beccarii, Halophila minor, Halodule pinifolia, Thalassia hemprichii, and Cymodocea rotundata, dominated the seagrass population among all island groups. Seagrass composition significantly varied across the five investigated latitudinal gradients. Seagrass communities in 'Ritchie's Archipelago and Nicobar' and 'South Andaman and Little Andaman' revealed the highest and lowest variation. Further, Ritchie's Archipelago and Nicobar had the highest species richness (n = 10), followed by North & Middle Andaman (n = 8), and the lowest in South and Little Andaman (n = 6). Despite similar species richness and composition, Nicobar contributed to the highest seagrass coverage compared to the lowest recorded in the Ritchie's Archipelago. Our observations on the re-colonization of disturbed areas by early successional and historical species suggest recovery of the seagrass population in the ANI post-disturbance. Lastly, co-variates associated with latitude as a surrogate warrant further investigation.

The benefits and challenges of citizen science for coastal wetlands management in Andaman and Nicobar archipelago—a review

The benefits and challenges of citizen science for coastal wetlands management in Andaman and Nicobar archipelago—a review

Evaluation of potential trace element contamination and ecological risks of beach sediments, Andaman and Nicobar Archipelago, India

This study emphasized the potential contamination level and ecological risk condition of the beach sediments in the Andaman and Nicobar archipelago. The mean concentration of acid -leachable trace metals (ALTMs) shows the following descending order: North Andaman sector: Pb > Zn > Ni > Co > Cr > Fe > Cu > Mn; Middle Andaman sector: Fe > Ni > Pb > Zn > Cr > Co > Mn > Cu; South Andaman sector: Fe > Ni > Pb > Zn > Cr > Co > Mn > Cu; Rutland Island sector: Ni > Fe > Pb > Zn > Co > Cr > Cu > Mn; Little Andaman sector: Ni > Pb > Zn > Co > Cr > Fe > Cu > Mn; Great Nicobar Island sector: Fe > Ni > Cr > Pb > Zn > Co > Mn > Cu. The enrichment factor shows the metal enrichment trend as follows: Pb > Ni > Cr > Cu > Mn > Zn. ALTM’s results reveal that Fe, Mn, Pb, and Cu are the most notable trace elements in the beach sediments. The geo-accumulation index of metals shows an unpolluted category for all the metals except Pb. The level of sediment contamination indicates the moderate to strong category. The sediment pollution index and ecological risk reveal that the sediment belongs to the natural category with low pollution risk. The concentration of metal in the beaches was less than the comparative studies and sediment quality guidelines (SQGs). Overall assessment studies on sediment accumulated trace metals and potential ecological studies suggest that the beach sediments of the study area were less contaminated and exposed to low risk.

Tropidonotus nicobarensis Sclater, 1891 is a junior synonym of Thamnophis saurita (Linnaeus, 1766) (Squamata: Serpentes: Natricinae).

Tropidonotus nicobarensis Sclater, 1891 is an enigmatic snake currently referred to the natricine genus Hebius Thompson, 1913. No specimens have been recorded since the original discovery of the name-bearing type in the late 19th century, which was allegedly collected on Kamorta Island in India's Nicobar Archipelago. Recently, a second observation of this species was reported from Havelock Island (Swarajdweep) in the nearby Andaman Archipelago. However, the snake in question is clearly conspecific with another natricine, Thamnophis saurita (Linnaeus, 1766), native to eastern North America. This discovery prompted us to examine the type specimen of Tropidonotus nicobarensis, which revealed that it too is conspecific with Thamnophis saurita. The provenance of the Tropidonotus nicobarensis type specimen and the Havelock Island snake are discussed, with the latter likely representing an introduced animal.

A review of the genus Bronchocela Kaup, 1827 (Reptilia: Agamidae) in the Nicobar Archipelago with the description of two new species

Species of the agamid genus Bronchocela Kaup, 1827 in the Andaman and Nicobar Islands are reassessed based on newly collected specimens from different parts of the Nicobar Archipelago. An assessment based on morphology and distribution of the identified groups reveal two new, unnamed populations, one allied to B. cristatella and the other allied to B. danieli. These two populations are described as new species, and Bronchocela cristatella is redescribed based on Sundaic specimens. The remaining species, B. danieli and B. rubrigularis are redescribed. Distributions of all of these four species are mapped and recommendations on their conservation status are suggested.

The Nicobarese tribes and their coastal fishing activities during the COVID-19 pandemic-related restrictions- preliminary findings.

We interviewed the Nicobarese tribal community (N = 95) of Car Nicobar Island situated in the Andaman and Nicobar archipelago, India to analyze the impact of COVID-19-related restrictions on their coastal fishing activities. Our surveys revealed a significant reduction (p < 0.001) in the average monthly income and fish catches during pre and post-COVID-19 scenarios. Constraints faced during the pandemic-related restrictions and the possible solutions to reinforce the fishing activities were highlighted for sustainable resource management in Car Nicobar Island.

First report of marine debris in Car Nicobar, a remote oceanic Island in the Nicobar archipelago, Bay of Bengal

This study forms the first record to systematically quantify and classify the marine debris from Car Nicobar Island. Car Nicobar is a small remotely located Island in the Nicobar archipelago that is largely inhabited by Nicobarese indigenous people for ages. Considering their remote location and lack of baseline information on marine debris, we surveyed ten beaches in Car Nicobar to study the prevalence of marine debris. A total of 1438 debris items were recorded from the surveys of which plastic debris was found dominant (83.72%). Among the plastics, nets/ropes (38.87%) were found to be dominant followed by plastic bags, plastic bottles, polypropylene woven bags, plastic cans, floaters, and plastic cups. The number of debris was found to be highest in Malacca Jetty (7.2 nos/m2) and least in Mus Jetty (1.28 nos/m2). Land-based debris items from recreational and shoreline activities constituted majorly (54.52%) followed by sea-based sources such as shipping, fishing, and dumping activities (45.48%). Hierarchical Cluster Analysis (HCA) revealed that Malacca Jetty exhibited a distinct pattern of debris accumulation. Kriging interpolation was applied to understand the possible prevalence of marine debris around the coast of Car Nicobar Island. Plastic debris belonging to nearby countries such as Indonesia, Thailand, Malaysia, Myanmar, etc. was also recorded in our surveys. Shipping-based debris could be a probable source of foreign debris due to the proximity of the Nicobar archipelago to the Strait of Malacca, being one of the busiest shipping routes in the world. The baseline information generated from this study could assist the decision-makers to initiate proactive measures toward effective management of marine debris on Car Nicobar Island.

First recorded outbreak of Paramphistomum cervi in Andaman local goats (Capra aegagrus hircus) from Bay island of India: A brief communication

This communication reports an outbreak of immature paramphistomiosis in Andaman local goats (Capra aegagrus hircus) along with report of mortality and gross as well as histopathological changes. During the month of September, 2021 there was report of 38.57% mortality in goats which was investigated in depth. Outbreak occurred at South Andaman district where goats were reared under semi intensive managerial system and allowed to graze in the morning in surrounding marshy land. The affected animals showed the symptoms of immature amphistomiasis; it was further confirmed on necropsy and identification of causative organism as Paramphistomum cervi based on its typical morphological features. Histopathological examination showed damaged structure of rumen with typical degenerative changes and initiation of necrotic changes of cells with infiltration of inflammatory cells. We report the outbreak of immature amphistomiasis for the first time from Andaman and Nicobar archipelago along with the causative agent.

New distributional record of Heterocera from Andaman and Nicobar Islands with six new additions to Indian Lepidoptera Fauna (Insecta: Lepidoptera)

This paper reports six species of Heterocera belonging to family Geometridae, Notodontidae, Euteliidae, and Noctuidae viz. Probithia imprimata (Walker, 1861), Ruttellerona pseudocessaria Holloway, 1994, Amraica solivagaria (Walker, 1866), Phalera sundana Holloway, 1982, Paectes psaliphora Hampson, 1912 and Iambia lyricalis Holloway, 1989. The species stated above have been collected from different islands of Andaman and Nicobar archipelago. Furthermore, the study reveals new contributions to India’s Lepidoptera fauna. Microphotographs of Adult genitalia along with species diagnosis, habitat, and the new distributional data from these islands are provided.

New distribution record of globally threatened Ocean Turf Grass Halophila beccarii Ascherson, 1871 from the North Andaman Islands highlights the importance of seagrass exploratory surveys

Halophila beccarii, listed as ‘Vulnerable’ on the IUCN Red List, aids in seagrass and mangrove succession, acts as a substrate stabilizer and provides feeding grounds for mega-herbivores like dugongs. This species was first recorded from the Andaman &amp; Nicobar Islands in 2015, and its distribution status within the archipelago remains under-investigated. We report a new distribution record of H. beccarii from the North Andamans and shed light on its inter-island distribution. H. beccarii was recorded from a mixed meadow comprising of Cymodocea rotundata (20.5 ± 28.8%, mean seagrass cover), Thalassia hemprichii (16.3 ± 23.3%, mean seagrass cover), and Halodule pinifolia (6.3 ± 12.1%, mean seagrass cover) at Pokkadera, North and Middle Andaman district. H. beccarii had the highest mean seagrass cover (30 ± 34.7%) and shoot density (103.5 ± 68.3 shoots/ m2) among sympatric seagrass species. We also recorded eight seagrass-associated macrofaunal groups (gastropods, bivalves, polychaetes, foraminiferans, nematodes, brachyurans, decapods and asteroids) from the infaunal and epibenthic micro-habitats within the meadow. Infaunal macrobenthos had a much higher density (73.5 ± 129.7 individuals/m2) than the epibenthic macrofauna (0.4 ± 1.5 individuals/m2), possibly influenced by the seagrass canopy structure and biomass. Overall, gastropods were the most dominant macrobenthic faunal group (overall mean 95.0 ± 106.1 individuals/m2). The present findings emphasize the need for more exploratory surveys to understand H. beccarii distribution in the Andaman &amp; Nicobar archipelago to identify priority conservation areas.

First report on the occurrence of Avicennia marina (Forssk.) Vierh. (Acanthaceae) in the Nicobar archipelago

The 2004 Sumatra-Andaman earthquake (9.2 Mw) and tsunami that followed it resulted in uplift and subsidence across the Andaman and Nicobar archipelago. This unusual natural event severely affected the mangrove and coastal ecosystems across the Andaman and Nicobar Islands. The tsunami and land drowning of 1.1-2.85 m resulted in considerable loss of mangrove habitats in the Nicobar archipelago. Meanwhile, the land drowning also created new intertidal habitats in the earlier terrestrial zones that are now providing suitable conditions for the colonization of mangroves. During the long-term monitoring of mangrove colonization in these new inter-tidal zones, we identified the first occurrence of the Avicennia marina (Forssk.) Vierh. in the Nicobar archipelago. The distribution of A. marina and the characteristics of its colonizing sites are discussed herein.

A new species of Tortanus (Atortus) Ohtsuka, 1992 (Copepoda, Calanoida, Tortanidae) from Great Nicobar Island, north-eastern Indian Ocean

A new planktonic copepod assigned to the subgenus Tortanus (Atortus) Ohtsuka, 1992 is described from Great Nicobar Island, Andaman and Nicobar archipelago. The new species Tortanus (Atortus) dhritiae sp. nov. belongs to the tropicus-group. The new species can be distinguished from all other species of the tropicus-group by the presence of a notch on the left lateral joining of fourth and fifth pedigerous somites, asymmetrical caudal rami with a rounded process originating from the anterior portion of the left ramus produced over to the right, and an elliptical shaped exopodal lobe of leg 5 with distolateral curved seta in female. In male, serrated ridge on the anterior one-third surface of segment XX of the right antennule, obtuse trapezoid-shaped right leg 5 coxa with triangle-shaped medial process, semi-circular basis with slight curve near base and crocodilian head-shaped medial process with small process distally and bearing one distal and one medial setae.

Characterization of the anopheline vector breeding habitats: Implications for elimination of malaria in tribal inhabited Car Nicobar Island.

Malaria is an important public health problem in Andaman & Nicobar archipelago. Among the three districts, Nicobar is the most endemic district where API is >2. In this district, the malaria incidence in Car Nicobar Tehsil has declined steadily over the past 10 years. A renewed initiative to consolidate this gain is being made with the ultimate objective of achieving zero indigenous transmission of malaria in Car Nicobar. So, the present study undertook a close environmental monitoring of water bodies for assessing changes in the risk potential of mosquito vector breeding habitats which can augment the elimination programme. The breeding habitats of anopheline mosquitoes were sampled in 16 areas of Car Nicobar Island for eight time periods during 2017-2020. Along with anophelines, various associated water parameters (n=60) were estimated, viz. physicochemical (n=13), and biological, which included culicine mosquito immatures, insect predators (n=5), phytoplanktons (n=31) and zooplanktons (n=10). In the 16 study sites, overall 1126 surface water stagnating bodies constituting 21 different habitat types were surveyed. Of these, 17 were positive for anopheline breeding. Water bodies from three villages were consistently found to be positive for anopheline breeding. However, early instars of anopheline larvae were more abundant compared to the late instars. Four anopheline species were recorded, including Anopheles sundaicus, A. barbirostris, A. insulaeflorum and A. subpictus, in which 48 per cent were A. sundaicus. Multivariable analysis indicated that anopheline density was significantly higher in permanent water bodies than in temporary habitats (P<0.05) (high risk of anophelines). The highest pH (≥8.2), dissolved solids (≥0.39) levels showed significantly (P<0.05) decreased larval densities (lower risk of breeding), adjusted with breeding sites and season. Nitrite levels increased (P=0.022) larval densities. The present study facilitated estimating the productive period of a larval habitat enabling target larval sources to reduce adult populations. Implementing larviciding strategy before monsoon season is presumably the most cost-effective strategy. The output can be utilized for environmental monitoring of mosquito breeding risk in other malaria endemic areas, particularly where medium/large water bodies are the predominant breeding sites for malaria vectors.

Policy framework and development strategy for freshwater aquaculture sector in the light of COVID-19 impact in Andaman and Nicobar archipelago, India

The present study was aimed at understanding the impact of COVID-19 pandemic related restrictions on the freshwater aquaculture sector of Andaman and Nicobar archipelago (ANI). We interviewed the freshwater fish farmers (N = 211) covering all the three districts (North and Middle, South Andaman, Nicobar district) of the archipelago. The results revealed the critical issues faced by the stakeholders such as fish seed unavailability, limitations in feeding, insufficient logistical support, movement related restrictions, lack of inputs, manpower shortages, etc. as the important constraints during lockdown. Our surveys also revealed that there was a significant reduction in the income of the farmers post COVID-19 outbreak (p < 0.001). Possible reform strategies that could promote the sector development and resilience were outlined to recover from the COVID-19 impacts. The study also highlights the significance of effective networking among the stakeholders and necessary preparedness measures to be undertaken by the fish farmers to deal with the exigencies. The study also recommends a policy framework to strengthen the planning and management of freshwater aquaculture sector towards the path of sustainability.

Mangrove recovery in the Nicobar archipelago after the 2004 tsunami and coastal subsidence

Mangrove recovery in the Nicobar archipelago after the 2004 tsunami and coastal subsidence

Co-Infection of Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV) and White Spot Syndrome Virus (WSSV) in the Wild Crustaceans of Andaman and Nicobar Archipelago, India.

The present study was intended to screen the wild crustaceans for co-infection with Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV) and White Spot Syndrome Virus (WSSV) in Andaman and Nicobar Archipelago, India. We screened a total of 607 shrimp and 110 crab samples using a specific polymerase chain reaction, and out of them, 82 shrimps (13.5%) and 5 (4.5%) crabs were found positive for co-infection of IHHNV and WSSV. A higher rate of co-infection was observed in Penaeus monodon and Scylla serrata than other shrimp and crab species. The nucleotide sequences of IHHNV and WSSV obtained from crab in this present study exhibited very high sequence identity with their counterparts retrieved from various countries. Histopathological analysis of the infected shrimp gill sections further confirmed the eosinophilic intra-nuclear cowdry type A inclusion bodies and basophilic intra-nuclear inclusion bodies characteristics of IHHNV and WSSV infections, respectively. The present study serves as the first report on co-infection of WSSV and IHHNV in Andaman and Nicobar Archipelago, India and accentuates the critical need for continuous monitoring of wild crustaceans and appropriate biosecurity measures for brackishwater aquaculture.