Andaman And Nicobar Research Articles

New and Interesting Plant Records from Andaman-Nicobar Islands, India

Six species are reported as new records for the Andaman-Nicobar Islands. The occurrence of two species which were recorded earlier from these islands based on literature are confirmed by the recent collections

Climatic Trends in Temperature, Relative Humidity, and Wind Speed Over Indian Landmass and Isle in Andaman Nicobar and Lakshadweep During 1981–2021

Climatic Trends in Temperature, Relative Humidity, and Wind Speed Over Indian Landmass and Isle in Andaman Nicobar and Lakshadweep During 1981–2021

3D Local Earthquake Tomography of the Andaman–Nicobar Subduction Zone Using Ocean-Bottom Seismometer Data

ABSTRACT The Andaman–Nicobar (A–N) subduction zone is one of the most seismically active subduction zones of the world where the Indian plate subducts beneath the Burmese–Sunda plate. Imaging the subducting Indian plate (SIP) geometry in this region is important to understand the subduction process, earthquake genesis, and associated seismic hazards. Therefore, we imaged the SIP for the first time using local earthquake data recorded from a network of nine ocean-bottom seismometers and six surface seismic stations. We inverted 2819 P and 2171 S phases picked from 410 local earthquakes recorded between December 2013 and May 2014 to obtain the tomographic images in the A–N region. The images show high-VP and VP/VS anomalies linked to colder and thicker SIP in the A–N region. We also observed seismic signatures of strong structural heterogeneity all along the SIP. The low-velocity anomaly at 60–100 km depth beneath the Andaman back-arc spreading center indicates mantle upwelling. Likewise, low-VP anomalies beneath the active volcano Barren Island indicate production of arc magmas by slab dehydration and corner flow in the mantle wedge.

A Novel and Efficient Spatio-Temporal Clustering Algorithm to Discover Patterns in Indian Earthquake Data

The seismic activity in India, including the Himalayas, the North-East region, and the Andaman-Nicobar Islands, is prominently displayed on the seismic map. It is important to analyze the specific characteristics of seismic events on the Indian sub-continent. This research paper introduces a new algorithm for data analysis using a partitioning technique that mines clustering patterns. The algorithm generates clusters of spatial and spatio-temporal data by distributing the data into spatial bins or buckets, identifying neighboring bins, and minimizing distance calculations. Furthermore, the selection of centroids is based on the density of data in the spatial region, utilizing a random selection method. It requires minimal parameter settings, enhancing its efficiency and practicality for analyzing large-scale spatio-temporal datasets. We validate the algorithm's efficacy through experiments conducted on the Indian earthquake spatio-temporal dataset, demonstrating its ability to detect spatio-temporal patterns and identify earthquake-prone regions.The conducted experiments reveal a correlation between the frequency of earthquake events and the number of clusters formed, indicating that regions with a higher occurrence of earthquakes exhibit a greater clustering tendency, signifying their susceptibility to seismic activity. The results imply promising clustering quality, with Silhouette index in the range of 0.88 to 0.93.

CHINA REACTIONS TOWARDS INDIA’S MILITARY MODERNIZATION AT ANDAMAN AND NICOBAR ISLANDS

This research studies the factors that lead to India's military modernisation in Andaman and Nicobar Islands (ANI). The research focuses on the geostrategic elements of the ANI and the contemporary Sino-Indian relationship. This research has three objectives namely 1) to study the factors that led to India's military modernization, 2) to examine the impact of India's military modernisation on China and 3) to analyse the China's reaction to it. The theory of realism was applied to support the argument of Sino-Indian relations, as both countries have a particular interest in the Indian Ocean Region (IOR). This research uses a qualitative technique that is based on secondary data references from credible sources, both printed and online. This research findings that the Andaman and Nicobar archipelagos consist of 572 islands and islets chain stretched from the southern tip of Myanmar to the north-western tip of Sumatra is India’s potential fortress of defence in the Bay of Bengal. Since 2001, the Indian government has established a tri-service Andaman and Nicobar Command (ANC) at Port Blair to protect its sovereignty in the Indian Ocean. India announced the massive weapon procurement plan forecast for a 15 years period (2012-2027), followed by establishment of the Island Development Agency (IDA) in 2017 in effort to shift the archipelago from a merely military base into an active economic hub. This gained reaction from China as it sees India is projecting supremacy over its backyard, creating a possible “security chain” that would supresses China besides the existing “Malacca’s Dilemma”. This research concludes Andaman and Nicobar has a great potential in the future due to its location between two major seas, the South China Sea (SCS) and the Indian Ocean. Its proximity to the Straits of Malacca (SOM) gives leverage over one of the world’s busiest trade chokepoints.

Life history traits of cycad blue butterfly, Luthrodes pandava Horsfield (Lepidoptera: Lycaenidae) on cycad hosts in an Island ecosystem

AbstractThe life history traits (egg, larva, and pupa stage) of the Lycaenidae butterfly, Luthrodes pandava Horsfield (Lepidoptera: Lycaenidae) observed and trapped on cycad plants are described from the Andaman and Nicobar Islands (ANI), India. The diversity of cycad host plants offered as larval food influences fecundity and conservation status. Zamia furfuracea is recorded for the first time as a cycad host plant and seasonal polyphenism in the ANI, India.

Exploration of Mangroves Associated Microbes for Bioactive Metabolites

Mangroves are woody plants found growing at transition zones between land and sea in tropic and sub-tropical regions. They arehighly adapted morphologically and physiologically to survive in extreme environments. Mangroves are found worldwide in theirdistribution, with 110 species that belong to 20 different families. In India, mangrove forests are mostly found on the Andaman andNicobar Islands and the West and East Coast. Mangroves have enormous ecological, commercial and biological significance. They arealso regarded as hotspots for microbes because of their rich microbial diversity. Various types of microorganisms like bacteria, fungi,microalgae and macroalgae are abundant in mangrove ecosystems. More recently, fungal endophytes associated with mangroveshave added to their microbial diversity. Many mangrove plants are used as ethno-medicine in traditional health care. Mangroves arealso used as antimicrobial and antiviral agents. Fungal endophytes -colonizing medicinal plants are reported to produce importantbioactive metabolites. These endophytes are believed to produce same and more biologically active metabolites as compared to theirrespective hosts. Many fungal endophytes isolated from mangrove species have produced some important biological active metaboliteslike triterpenes, indole triterpenes, isocoumarin and marinamide. Therefore, the study of fungal endophytes associated with medicinalmangroves may give rise to important endophytic strains that might produce novel and new bioactive metabolites of pharmaceutical,industrial and agricultural importance. Due to the alarming rate of depletion of mangrove genetic resources across the world, it is highlyneeded to explore fungal endophytes associated with mangroves for the inventorisation of new metabolites.

High spatial resolution marine gravity trend determined from multisatellite altimeter data over Bay of Bengal

SUMMARY Mass redistribution in the Earth system induce variations of the Earth's gravity field. Now, the time-varying gravity models from the Gravity Recovery and Climate Experiment (GRACE) mission can only estimate the large-scale gravity changes, so the high-resolution marine gravity trend (MGT) model is urgently required to detect small-scale Earth's mass migration. The sea level change is a significant response to marine gravity field change. Here, we propose to estimate the high-resolution MGT using the sea level trend (SLT). Firstly, the SLT model caused by marine mass change (MMC) on 5′ × 5′ grids covering the Bay of Bengal (BOB) is established based on multisatellite altimetry data and EN4 quality-controlled ocean data, named BOB_MMC_SLT. Then, the marine mass trend (MMT) is calculated using the BOB_MMC_SLT. The spherical harmonic function (SHF) method is applied to estimate MGT using the MMT, and this MGT model on 5′ × 5′ grids, named BOB_SHF_MGT, is used to study marine gravity changes and their associated geophysical processes. The results show that, the MGT mean of BOB_SHF_MGT is about 0.14 μGal yr−1, which indicates that marine gravity in BOB is rising. The earthquakes mainly occur in the southeastern BOB where MGT is obviously rising, which may be related to the increased density of the Burma Plate due to the subduction of the India Plate and the Australia Plate. BOB_SHF_MGT shows that the marine gravity rise rate is increasing from the 85°E ridge to Andaman–Nicobar ridge, with a maximum at the location where the India Plate subducts to the Burma Plate. The MGT model based on altimetry data constructed by SHF method is important for the study of small-scale mass migration near the subduction boundaries.

Seagrass ecosystem adjacent to mangroves store higher amount of organic carbon of Andaman and Nicobar Islands, Andaman Sea

This study quantified the organic carbon (Corg) stocks in Thalassia hemprichii meadows that are (i) adjacent to mangroves (MG), and (ii) without mangroves (WMG), in tropical Andaman and Nicobar Islands (ANI) of India. In the top 10 cm of the sediment, Corg content was 1.8-fold higher at the MG sites than the WMG sites. The total Corg stocks (sediment + biomass) in the 144 ha of seagrass meadows at MG sites (988.74 ± 138.77 Mg C) was 1.9-fold higher than in 148 ha of WMG sites. Protection and management of T. hemprichii meadows of ANI can lead to emission avoidance of around 5447.33 (MG; 3595.12 + WMG: 1852.21) tons of CO2. The social cost of the carbon stocks in these T. hemprichii meadows is around US$ 0.30 and 0.16 million at the MG and WMG sites, respectively, showcasing the importance of ANI's seagrass ecosystems as nature-based solutions for climate change mitigation.

Lactation stages modulate the hematological, serum biochemical, and endocrinological profiles and oxidative stress markers in crossbred cows under tropical humid island ecosystem of Andaman and Nicobar Islands

The present study was designed to assess the interrelationship between hematological, serum biochemical, and endocrinological profiles and oxidative stress markers and lactational stages in crossbred (CB) dairy cows of Andaman and Nicobar Islands (ANI). Healthy (n = 6) CB cows (50-62.50% exotic inheritance; Holstein Friesian × Andaman local) of 4th parity with age of 7-9years and body weight of 350-400kg were selected from Cattle Breeding Farm, ICAR-Central Island Agricultural Research Institute (ICAR-CIARI), Port Blair, ANI. These experimental cows were synchronized with Ovsynch protocol, and parturition was planned to happen in the month of May-June. Lactation was allowed for 305days. Hematological profiles, serum biochemical profiles, oxidative stress markers and endocrinological profiles were measured at a 15-day interval from day 07 to 305 of lactation (after 6days of colostrum). The lactation period was divided into first (day 07 to 90), second (day 91 to 180), and third (day 181 to 305) stage of lactation. Average daily milk yield (L) did not vary among the stages of lactations; however, first (8.56 ± 1.26) and second (9.79 ± 0.87) stages had higher milk yield compared to third (7.93 ± 0.79) stage of lactation. Hematological profiles did not vary among the stages of lactation; however, these values were within the range of bovine species at lactation. Serum glucose, triglyceride, total cholesterol, total protein, globulin, and blood urea nitrogen (BUN) increased (P < 0.05) and albumin and creatinine decreased (P < 0.05) gradually as lactation stages advanced. Activity of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) and concentration of calcium, phosphorous, and magnesium were nearly similar among the stages of lactation. Similarly, triiodothyronine (T3), and thyroxine (T4) increased and prolactin and cortisol decreased (P < 0.05) gradually as stages of lactation advanced. Total antioxidant capacity (TAC) increased and malondialdehyde (MDA) decreased (P < 0.05) as lactation stages advanced. The results of the present study indicated that the lactating CB cows suffered nutritional stress (deficiency of protein, carbohydrate, lipids, and minerals), physiological stress (higher cortisol), oxidative stress (higher MDA and deficiency of total antioxidant capacity), and hormonal imbalance (higher prolactin and cortisol and deficiency of thyroid hormones) during the early stages of lactation. Thus, the first and second stages are more stressful events compared to the third stage of lactation in the CB cows in ANI. Therefore, regular monitoring of blood components and accordingly suitable feeding strategies with balanced nutrients and minerals, supplementation of suitable antioxidants, and appropriate management practices need to be implemented to mitigate these stresses and to prevent metabolic disorders with maximum milk production during different stages of lactation in CB cows under humid tropical island ecosystem of Andaman and Nicobar Islands.

Flaxseed oil modulates testicular biometrics, hormone, libido, antioxidant and semen profiles in endangered Teressa goat of Andaman and Nicobar Islands

Teressa goat is a unique goat breed in Andaman and Nicobar Islands (ANI) of India. Effects of Flaxseed oil (FSO) supplementation in body weight (BW), scrotal circumference (SC), testicular volume (TV) and testicular weight (TW), endocrinological profiles, sex behavioural profiles (SBPs), oxidative stress markers and semen production and its quality profiles in rainy and dry summer season were studied in Teressa goat. Male goats (n=12) of 3-4 years old were equally divided into control and treated groups. Treated animals received 25mL FSO per day. Oral drenching of FSO was done in the morning before feeding the concentrate ration. Body weight, scrotal circumference, TV and TW were measured in bucks of FSO treated and untreated during rainy and dry summer seasons. Blood follicle stimulating hormone (FSH), luteinizing hormone (LH), testosterone, thyroid stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), cortisol and prolactin, total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and malondialdehyde (MDA) were measured in bucks of FSO treated and untreated during rainy and dry summer seasons. Libido score (LS), mating ability score (MAS) and sex behavioural score (SBS) were estimated at time of semen collection in bucks of FSO treated and untreated during rainy and dry summer seasons. Semen samples (n=100; 50 semen samples from each season; each 25 semen samples from control and treatment groups per season) were collected and analysed for semen quality profiles. One-way ANOVA (control rainy, control dry, treated rainy and treated dry) revealed that BW, SC, TV and TW, FSH, LH, testosterone, TSH, T3 and T4 were higher (P<0.05) and cortisol and prolactin were lower (P<0.05) in FSO treated bucks of rainy season followed by untreated bucks of rainy season, FSO treated bucks of dry summer season and were lower (P<0.05) in untreated bucks of dry summer season. Similarly, TAC, CAT, SOD and GSH, LS, MAS and SBS, and volume, pH, sperm concentration, mass activity, total motility (TM), viability, acrosomal integrity (AcI), plasma membrane integrity (PMI) and nuclear integrity (NI) were higher (P<0.05) and MDA and TSA were lower (P<0.05) in FSO treated bucks of rainy season followed by FSO treated bucks of dry summer season, untreated bucks of rainy season and were lower (P<0.05) in untreated bucks of dry summer season. The results of the present study indicated that the breeding bucks suffered physiological stress (higher cortisol), oxidative stress (higher MDA and deficiency of antioxidants), hormonal imbalance (higher prolactin and cortisol and deficiency of gonadotropins, gonadal hormone and thyroid hormones) and infertility due to poor libido and poor semen production and its quality profiles during dry summer season. Thus, dry summer was more stressful season compared to rainy season for the goat bucks. FSO supplementation mitigated these stresses and improved the scrotal and testicular biometrics, libido, antioxidants, hormones and semen quality profiles in Teressa goat bucks. The current study concluded that FSO effectively improved the hormones, libido, antioxidant profiles, and scrotal and testicular biometrics with cascading beneficial effects on semen quality profiles in Teressa goat bucks under humid tropical island ecosystem of Andaman and Nicobar Islands.

Cross section of genetic diversity in mainland and insular populations of Costus speciosus (Koen ex. Retz.) Sm. using SPAR markers reveal patterns linked to allopolyploidy and biogeography

Costus speciosus (Koen ex. Retz.) Sm. is a major source of diosgenin, used for the commercial synthesis of cortisone, sex hormones and contraceptives. The genetic diversity analysis in wild populations of C. speciosus from 3 biogeographic regions viz., Western Ghats (WG), Eastern Ghats (EG) and Andaman and Nicobar Islands (AN) were done using 2 different Single Primer Amplification Reaction (SPAR) methods. A total of 70 accessions spanning these regions were used in the present study. The assay yielded a total of 314 amplicons of which 268 were polymorphic, exhibiting 85.35% of polymorphism. The prevalence of high rate of genetic differentiation (mean Gst = 0.90) and low gene flow (mean Nm= 0.06) are the main attributes of the observed low diversity in these populations. The accessions clustered broadly under 2 major groups corresponding to the three biogeographic zones with insular populations diverse from the mainland. This was further resolved by AMOVA analysis. C. speciosus is found to exist in different cytotypes exhibiting allopolyploidy. The differences in distribution and genetic fitness of the population from EG and WG may be attributed to the allopolyploid nature of the taxa. In the present study, Island populations comprise very low heterozygosity (Ht = 0.10) suggesting that the rate of fixation is more in these populations. Similarly, the rate of gene flow was almost absent (Nm = 0.02). The higher levels of genetic similarity (0.99) may be due to an increase in fixation of the genes resulting from allopolyploidy. This is the first study on comparative genetic diversity of C. speciosus using SPAR markers.

Evaluation of Osmotolerant Potential of Halomonas sulfidaeris MV-19 Isolated from a Mud Volcano.

Salinity is one of the major challenges for cultivation of crops in a sustainable way because it severely affects plant growth and yield. Keeping this challenge in view, in the current study, a salt-tolerant Halomonas MV-19 was isolated from an extreme niche of mud volcano of Andaman Nicobar Island, India and identified on the basis of standard morphological, biochemical, and physiological tests and identified as Halomonas sulfidaeris strain MV-19 by 16S rRNA gene sequencing. The bacterium can grow on nutrient agar and nutrient broth supplemented with 3.5M (≥ 20%) sodium chloride (NaCl). Sugar utilization assay revealed that H. sulfidaeris MV-19 utilizes only three sugars (dextrose, fructose, and mannose) from among twenty four tested sugars. The best growth of H. sulfidaeris MV-19 was observed in nutrient broth supplemented with 8% NaCl. When the broth was supplemented with dextrose, fructose, and mannose, the H. sulfidaeris MV-19 grew maximally in nutrient broth supplemented with 8% NaCl and 5% fructose. This strain produced exopolysaccharides (EPS) in nutrient broth supplemented with 8% NaCl and sugars (dextrose, fructose, and mannose). The EPS production was increased by 350% (three and half time) after addition of 5% fructose in nutrient broth compare with the EPS production in nutrient broth without supplemented with sugars. H. sulfidaeris MV-19 strain can produce EPS, which can help aggregate soil particle and reduced osmotic potential in soil, thus, be useful in alleviation of salinity stress in different crops cultivated in saline soils. The findings of the current investigation are expected to contribute towards effective abiotic stress management.

Analysis of trawl-net operation and major fish landings at Andaman and Nicobar Islands, India

Trawl-net is an important fishing gear in Andaman and Nicobar Islands (ANIs) India since three decades with minimum number(n=10) of boats meeting the daily fish consumption of Islanders with minimum costs. A study was carried out between 2014 to 2018 to investigate the major fish landings of Trawl-net in the ANIs coast. The trawl-net landing is occurring only from Junglighat fish landing centre(FLC) which is having loading and unloading facilities in ANIs. The total number of FLC visits, fishing-trips, operations and fish-landing of trawl-net recorded during this period were 692(n), 533(n), 7561(n) and 691(tonnes) respectively. The maximum fishing-trips(149) and fishing-operations(2086) occurred during the year 2018 and minimum of same (87 and 1218) occurred during 2015. Similarly, the maximum(170.51tonnes) and minimum (109.33 tonnes) of fish landings were observed during the year 2014 and 2015 respectively with an average of 138.21±10.54tonnes/year. The contribution of trawl-net landing amongst other gears was 17.8% including fin-fishes(598.7tonnes) and shell-fishes(115.34tonnes) during the study period. The trawl-net operation was occurring at very few fishing grounds(n=14) in ANIs and the maximum fish catch occurred in the Coast of Havelock Island (26.7%). Totally 52 genera of fishes were recorded in trawl-net landings under 37 families in which Leiognathidae was found more dominant(21.38%). Altogether 21 Trawl-net validations were conducted at each PFZ and Non- PFZ during the period. The fishes captured at PFZ 3288kg with an average of 156.6±13.5 kg/operation and at Non-PFZ 1237kg with an average of 58.9±5.3kg/operation. The minimum range of fish cost in the market was maintaining in this Island due to the trawl-net landings, in-spite of there was controversy of non-selective fish catch and by-catch in trawl-net fishing.

Influence of breed, production system and fecundity on serum antioxidant profiles of goats reared in the tropical Island conditions

The present study assessed the physiological antioxidant status of goats reared under the humid tropical island ecosystem of the Andaman and Nicobar Islands (ANI). From 2019 to 2020, 25 multiparous non-pregnant does with three to six kidding records maintained in the organized farm of Central Island Agricultural Institute (CIARI) and farmer’s field flocks from South Andaman district were selected for the study. Antioxidant markers such as total antioxidant capacity (TAC), superoxide dismutase (SOD), TG (Total glutathione) and catalase (CAT) were analyzed in blood serum with respect to rearing systems, breeds and level of fecundity. Correlation analyses of all dependent variables were performed using Pearson’s correlation. The endogenous antioxidant systems, viz. CAT, TG and SOD was non-significant with respect to rearing systems, breeds and fecundity. Similarly, TAC was non-significant among the breeds and with fecundity; however, semi-intensively managed goats showed significantly higher values than goats under the extensive condition. Correlation analysis showed that CAT was positively correlated with SOD and negatively correlated with TAC. TG showed no correlation with any of the studied antioxidants. Regression analysis of CAT as dependent variable and SOD and TAC as independent variables showed significance. It is concluded that values of antioxidant in the study can be considered as a baseline data for the ALG and other goat breeds of Andaman and Nicobar Islands and other islands or topographies with similar ecosystems for further studies.

Neglected Maritime Terrain in the Bay of Bengal: An Examination of the Future of the Andaman and Nicobar Islands

The Andaman and Nicobar Islands (ANI) are some of the most neglected maritime terrain in the world despite their proximity to one of the busiest maritime chokepoints on Earth. Strategic competition in the Bay of Bengal and around the Strait of Malacca necessitates that U.S. strategy carefully considers the implications of having a U.S. presence on the ANI. The United States has the capacity to assist in international law enforcement of illegal, unreported, unregulated (IUU) fishing and piracy as well as ensure the security of international shipping through the Strait of Malacca. The possibility of bilateral exercises that introduce concepts such as expeditionary advanced base operations (EABO) and the use of the U.S. Coast Guard in multiple capacities are real possibilities as well. Perhaps most importantly, the United States can partner with India to leverage China’s Malacca Dilemma and constantly threaten a blockade of Chinese shipping through the Strait of Malacca in a potential conflict. China also aspires to alleviate its Malacca Dilemma.

Assessment of seawater ingress in the coastal aquifers of south Andaman Island, India

Seawater ingress is a widespread environmental issue posing threat to the fresh groundwater reserves of the coastal aquifers of Andaman and Nicobar Islands (ANI) particularly after the great Indian Ocean Tsunami 2004, and the comprehensive investigations of seawater ingress in this region are relatively uncommon. In this context, the spatial distribution and vertical movement of seawater ingress in the coastal and catchment areas were mapped using geo-spatial techniques and the extensive geoelectrical resistivity surveys (96 vertical electric soundings (VES) and profiling) along and across the identified and affected coastlines. The geoelectrical surveys unravels very low resistivity formations (≤10 Ω m) at varying depths interpreted as the lateral and vertical intrusion of seawater. The hydro-chemical and other physical analyses of groundwater samples reveal critical concentrations of the different major elements and other physical parameters like TDS, pH as well the EC above its permissible limit for drinking water standards. The integrated approach allows to delineate the site specific hydrogeological setting including the saline/fresh aquifer geometry (transition zone) and stratigraphic−geomorphological reconstruction of coastal aquifers. Further, various assessment parameters including very low formation resistivity, surface manifestation of salt tolerant plants, high chloride concentration, low formation factor and high ionic strength were employed to infer the various levels of contamination. The present study show that impact of seawater intrusion is intense in sedimentary formations than Ophiolite suite and needs site specific mitigation measure to prevent further deterioration of aquifer health.

Effect of hydrodynamic conditions on seagrass ecosystems during Cyclone Lehar in the South Andaman Islands, India

The physical disturbances of hydrodynamic conditions in shaping the seagrass meadows were studied in the vicinity of seagrass meadows over the south of Port Blair in the Andaman and Nicobar Islands (ANI) during the lifetime of Cyclone Lehar using spatial and temporal metrological - oceanic parameters and in-situ measurements. A cyclonic depression formed on 23 November 2013 over the west coast of the Malay Peninsula and then transformed into a severe cyclone named Lehar on 25th November 2013. It made its first landfall south of Port Blair in the ANI and caused extensive damage to life and properties. The present study made an attempt to investigate the hydrodynamic condition and their impact on the seagrass meadows during the lifetime of the cyclone. The results revealed that the floristic composition of seagrass species such as Thalassia hemperichii, Halodule pinnifolia and Halodule uninervis was badly damaged due to the effect of the high gradient of velocities in the vertical direction, turbulence, high energetic waves, and storm surge. Approximately 32.4% of the seagrass meadows were uprooted in Haddo Bay and 68% in Sesostris Bay of the South Andaman Islands. A year after the cyclone passage (December 2014), 13% (∼0.70 ha) of the seagrass meadow in Haddo Bay and 44.5% (∼0.30 ha) of the seagrass in Sesostris Bay had recovered. This study emphasises that the morphometric features of the most dominant species, T. hemperichii, were regulated by the physical hydrodynamic mechanisms and led to substantial destruction in the study sites. This study is very useful to understand the impact of hydrodynamic conditions on seagrass ecosystems during a cyclone and brings attention to the real-time monitoring of seagrass ecosystems. Monitoring of the seagrass ecosystem can be further improved by predicting the behavioural dynamics of the marine ecosystem under the various scenarios of extreme weather conditions using high-resolution numerical models. It also helps to determine the appropriate management policy during extreme natural events.

Documentation of gill net operation and major fish landings at Andaman Islands, India, during 2014 - 2018

Three decades before, the gillnet was the major gear in Andaman and Nicobar Islands(ANI), India, because of the less expensive and simple method of operation with non-motorised small dinghies or without craft. Earlier, the gillnet landing was 39% of the total landings and a further report said 27%, which indicated the decrease in gillnet landings. The present study was carried out from 2014 to 2018 at four main fish landing centers (FLCs) Junglighat, Dignabad, Guptapara and Wandoor of ANI to investigate the present status of major gillnet landings. Altogether 1097 visits were carried out at all FLCs and 63.1% of visits occurred at Junglighat. The total landings of all FLCs were 3880.6 tons, of which 98.6% were recorded at Junglighat. The total gillnet landings were 330.4tons, of which Driftnet covered 82.1%, followed by bottom plastic(9.8%) and bottom nylon(8%) gillnets. Significant landings (P&lt;0.0001) of Scombridae family were recorded through Drift gillnet (182.47tons) compared to other families. The family of Carangidae(7.71tons) and Clupeidae(16.54tons) were recorded dominantly through bottom plastic and bottom nylon gillnets, respectively. The gillnetters explored 31 fishing grounds in the South, Middle, North and Little Andamans sectors. The significant (P&lt;0.0001) fish catch was recorded from the South Andaman sector. A total of 17 validation experiments carried out in each Potential Fishing Zone (PFZ) and Non-PFZ by using PFZ advisories indicated a significant(P&lt;0.0001) catch from PFZ(3.5:1). There was a decline of 18.5% in the landings of gillnet than earlier studies. It is suggested that the fishermen may follow the PFZ forecast for a better catch. The gillnet fishing to be promoted to under-exploited pelagic fishes of these islands will benefit the gillnetters.

A baseline study of meso and microplastic predominance in pristine beach sediment of the Indian tropical island ecosystem

The global presence and prevalence of microplastic have moved microplastic from an emerging pollutant to a persistent contaminant. Microplastic prevails in almost all spheres of the environment viz. terrestrial, marine and atmosphere the globe abundantly. The prevalence and toxic effects on marine organisms have been studied around the world but the studies are limited to the coastal regime of the Andaman and Nicobar Islands (ANI). This study aims to record microplastic prevalence on the tourist beaches of Port Blair, ANI. Three coastal stations namely Cove beach, Quarry beach and Wandoor beach were examined in detail in this regard. Microplastics in the form of lines, fragments, pellets, foams and fibres were found at the sampled sites. Wandoor beach recorded the highest microplastic particles ranging from 105–475 particles kg−1 of sediment with the mean value of 249.82 ± 105.78 particles kg−1. Quarry beach near the municipal waste dumpsite showed the lowest of 72.5–222.5 particles kg−1 with a mean value of 135.625 ± 62.83 particles kg−1. The polymeric forms found were High-density polyethylene (HDPE), polystyrene (PS), polypropylene (PP) and polyethylene terephthalate (PET). This study revealed microplastic input from municipal dump waste near the beach. Fourier Transform Infrared spectroscopy (FTIR) revealed the presence of a new type of polymer namely plasta zinc in the beach sediment, which possibly could be a nanoplastic. Its presence reveals the biological enzymatic degradation of microplastic occurring in the marine environment. Further investigations are required to determine the factors influencing the prevalence of microplastic, its toxic effects on marine habitat and microplastic degradation mechanisms in the marine habitat.