A new hotspot of macro-litter in the Rutland Island, South Andaman, India: menace from IORC

Supralittoral zones of 13 sandy beaches of remote Rutland Island were divided into three zones to identify the litter contamination, its source, pathway of plastic transport to determine the level of macro-litter contamination, and its impact on coastal biota. Owing to the floral and faunal diversity, apart of the study area is protected under Mahatma Gandhi Marine National Park (MGMNP). The supralittoral zones of each sandy beach (between low-tide and high-tide line) were individually calculated from 2021 Landsat-8 satellite imagery before conducting the field survey. The total area of the surveyed beaches was 0.52 km2 (5,20,020.79 m2), and 317,565 litters representing 27 distinct litter types were enumerated. Two beaches in Zone-II and six in Zone-III were clean; however, all five in Zone-I were very dirty. The highest litter density (1.03 items/m2) was observed in Photo Nallah 1 and Photo Nallah 2, whereas the lowest (0.09 items/m2) was observed in Jahaji Beach. According to the Clean Coast Index (CCI), Jahaji Beach (Zone-III) is the very cleanest beach (1.74) while other beaches of Zone-II and Zone-III are clean. The findings of the Plastic Abundance Index (PAI) indicate that Zone-II and Zone-III beaches have a low abundance of plastics (< 1), while two beaches of Zone-I, viz., Katla Dera and Dhani Nallah, exhibited a moderate abundance of plastics (< 4) while a high abundance of plastics (< 8) was observed in the rest of three beaches of the same zone. The primary contributor of litter on Rutland’s beaches was plastic polymers (60–99%), which were presumed to originate from the Indian Ocean Rim Countries (IORC). A collective litter management initiative by the IORC is essential in preventing littering on remote islands.


Introduction
Globally, 60 to 99 million tons of litter is disposed into the environment each year and a predictive assessment articulates that the quantity is likely to increase threefold by 2060 (Lebreton and Andrady 2019). The marine litter was Responsible Editor: V.V.S.S. Sarma * Venkatesan Shiva Shankar shivashankarvj@gmail.com 1 3 classified into macro-(> 2.5 cm to 1 m), meso-(5 mm to 2.5 cm), and micro-plastics (< 5 mm) based on their size. Macro-litter was further categorized based on its origin as land-derived or oceanic (Galgani et al. 2015;GESAMP 2020). Land-derived litter is associated with agricultural, industrial, and recreational activities. In contrast, oceanderived litter is typically associated with commercial shipping, fisheries, and recreational boating. Globally,192 coastal countries are predicted to create 275 million metric tonnes of plastic garbage, with large volumes (4.8-12.7 million metric tonnes) entering marine systems by both landderived and oceanic origin (Cheshire et al. 2009;Jambeck et al. 2016). A voluminous quantity of these plastics enters marine systems since 40% of the global population (80 persons/km 2 ) live within 100 km of the coastlines, posing a severe threat to marine faunal diversity (Gall and Thompson 2015;Galgani et al. 2015;Cavalcante et al. 2020). Consequently, mid-ocean garbage patches, plastic deposition on remote islands, entanglement, plastic ingestion, and mortality of marine animals have increased globally (Miralles et al. 2018;Rodríguez-Díaz et al. 2020;Kaviarasan et al. 2020).
Multiple factors influence the prevalence of litter on beaches, including the location and topography of the beach, the existence of rivers and streams, floods, and winds (Ryan et al. 2018). Supralittoral zones of sandy beaches are often assumed to be significant sinks for floating litter, and their occurrence may be detrimental to biotic communities, and turtle nesting sites (Nelms et al. 2016).
Once plastic litter reaches the vast expanse of the ocean, it may either be deposited on the adjacent coast or carried long distances (due to its low density) by the wind and current patterns. Plastic litter may get stranded on open ocean islands during this transport, and secluded island systems may serve as a prospective basin (Lavers and Bond 2017;Lebreton et al. 2018;Kaviarasan et al. 2020). The Indian Ocean (IO) has several remote islands. Among these, the Andaman and Nicobar Islands (ANIs) are a territorial extension on the east coast of India remotely situated in the North-Eastern Indian Ocean in the Bay of Bengal (BoB); it hosts a dynamic and vibrant bio-diversity hotspot (FSI 2019). The Rutland Island is located in the southern region of South Andaman and is encompassed by Mahatma Gandhi Marine National Park (MGMNP), turtle nesting grounds, the largest saltwater crocodile congregation, and endemic Andaman water monitor lizards. Investigations of macrolitters in ANIs suggest a paucity of comprehensive studies on unmanaged marine macro-litters in Rutland Island (Dharani et al. 2003;Mohan and Dhivya 2013;Kaladharan et al. 2017;Kaviarasan and James 2017;Goswami et al. 2020Goswami et al. , 2021Krishnakumar et al. 2020;Patchaiyappan et al. 2020;Saravanan et al. 2021). This study intends to (1) provide a snapshot of the presence of foreign plastics from Indian Ocean Rim Countries (IORC) on 13 supralittoral zones of sandy beaches of Rutland island, (2) count and categorize litters, and (3) assess the status of supralittoral zones of sandy beaches using Clean Coast Index (CCI) and Plastic Abundance Index (PAI). The finding of this investigation would provide first-hand information to promulgate a global litter management strategy for conserving pristine beaches in Rutland and adjacent islands.

Rutland Island
R u t l a n d I s l a n d ( 1 1°2 0 ′ 0 0 ″ N -1 1°3 2 ′ 0 0 ″ N , 92°34′00″E-92°43′00″E) is one of the largest of the labyrinth group of islands in the southern region of the Andaman, separated by Duncan Passage from Little Andaman Island (Fig. 1). The island's total geographic area is about 120 km 2 , with a shoreline of approximately 71 km. The study area has an estimated population of 347 people (Census 2011), with the primary occupations being farming and fishing. The study area is characterized by a tropical, hot, and humid climate with 3074.3 mm of rainfall on average per year. Besides, Rutland Island often encounters heavy gales, storms, and cyclones, unlike the rest of ANIs (Goswami et al. 2020). The South-West Monsoon (SWM) brings substantial rainfall (76.35%) from May to September, followed by a short (22%) North-East Monsoon (NEM) from October to December, and a dry spell during the Pre-Monsoon (PM) between January and April (1.64%).
The study area receives minimum rainfall during the Pre-Monsoon as well. The wind speed would be 5 knots/h in good weather conditions. However, during cyclonic storms, the wind speeds may exceed 120 to 130 knots/h. The average annual relative humidity and air temperatures range are about 81% and 23.9 to 30.2 °C, respectively. Rutland Island experiences strong tidal currents ranging from 0.543 m/s (August) to 0.0109 m/s (April) due to the complex hydrological condition (https:// marine. coper nicus. eu). The study area also experiences semidiurnal tides (12 h and 20 min), with mean wave heights of 1.90 m and 0.5 m during spring and neap tides, respectively. The tidal currents flow north to south during ebb tide and vice versa during flood tide. Due to the channels between the Labyrinth Islands and cumulative effects of tidal range, strong surface currents are generated between (1) Rutland-Cinque Island (Manners Strait), (2) Twins Island-Jahaji Beach (Rutland), and (3) Labyrinth Islands, South Andaman-Rutland (Mac Pherson Strait). As a result, the coastal waters around the study area are always turbulent.
The study area is a habitat for diverse fauna and an area of high biological productivity. Coral reefs, mangroves, sandy beaches, rocky shores, tropical evergreen forests, littoral forests, and deciduous forests exist within the study area. It also includes Mahatma Gandhi Marine National Park, established in 1983 to conserve varied fringing coral reef habitats and sea turtle nesting sites. The study area is the nesting and breeding ground of saltwater crocodiles (Crocodylus porous) and the endemic Andaman water monitor lizard (Varanus salvator andamanesis). These two reptiles were commonly sighted in the study area and across the South Andaman Islands (Sivaperuman 2015;Samarasinghe et al. 2020). Five of the 13 beaches, viz., Bakra Balu, Dhani Nallah, Jahaji, Photo Nallah 1, and Photo Nallah 2, are the turtle nesting sites for four species (Department of Environment and Forest of ANIs and Andrews 2000). These four species, viz., Green turtle (Chelonia mydas), Leatherback turtle (Dermochelys coriacea), Hawkbill turtle (Eretmochelys imbricata), and Olive Ridley turtle (Lepidochelys olivacea), exhibit foraging nesting at the aforementioned beaches (Fig. 1). The ANI's Department of Environment and Forest protects Jahaji Beach because of the massive foraging nesting activity. The profile and utility of the 13 beaches are shown in the supplementary table.

Sampling strategies and macro-litter survey
A macro-litter survey (2.5 cm to 1 m) was carried out on supralittoral zones of 13 sandy beaches on Rutland Island between February 2020 and March 2021. Three zones were established for the supralittoral zones of 13 sandy beaches based on monsoonal currents. Katla Dera, Photo Nallah 1, Photo Nallah 2, Dhani Nallah, and Bakra Balu were all located in Zone-I. Zone-II included two beaches, Pharsa Dera and Machi Dera. Niranjan Balu, Kichad Nallah, Hathi Level, Kumda Nallah, Bada Khari, and Jahaji were all included in Zone-III. The survey was conducted only under favorable weather conditions. The results were expressed as items per meter square for better understanding and comparison with earlier findings in India and worldwide. During the study period, a five-member reconnaissance team organized an orientation visit to each beach for planning the litter survey. Later, five members examined beaches with a coast length of less than 1 km in a day. On the other hand, a 15-member team inspected the beaches with more than a 1-km coastline in 3 to 5 days. The litter was classified (country-wise) based on the examination of the label to determine the manufacturing address or packing region on the field, followed by a snapshot of it to reduce ambiguity. Further, label snapshots were reviewed using applications like Google Search Engine, Google Lens, and Google Translate to determine the country of origin. According to UNEP/ IOC, the litter was then counted, categorized, and classified into six main groups (plastic, foam plastic, glass and ceramics, rubbers, cloths, and others) (Marine Conservation Society 2002; Cheshire et al. 2009).

Typology of macro-litter
Several distinct litter types were distinguished according to material types and origin: plastics such as polyethylene terephthalate (PET) (beverage bottles), packed drinking water plastic bottles, plastic buoys, foam buoys, engine oil jerry cans, polyvinyl chloride (PVC) (toys and pipes), and fishing gears (ropes, nets, lures). The minor debris was the tube lights, incandescent bulbs, liquor glass bottles, medicine glass bottles, cigarette lighters, toys, footwear, and toothbrushes. All litter items were counted individually.
The output of the indices was derived using the raster calculator option. The false color composite (FCC) of NDTI, MNDWI, and NDWI on RED, GREEN, and BLUE planes enables the easy discrimination of sandy beaches. The results obtained from the indices were re-projected to UTM Zone 46N. Thereafter, a polygon encompassing low-tide and high-tide lines was digitized. The supralittoral zones of 13 sandy beaches were individually enumerated using calculate geometry option. All the processes and calculations were carried out using ArcMap 10.5 software.

Clean Coast Index
The data was compiled to assess the tidiness of the beach using the CCI (Alkalay et al. 2007).
"Total plastic things" was substituted for "total litter items" in the calculation, which was slightly altered. In order to prevent the value of the resulting index from falling between 0 and 1, the multiplier K = 20 was used (Portman and Brennan 2017). The CCI has established the following criteria: (1) 0-2: very clean-no litter observed, (2) 2-5: clean-no litter is witnessed over a large area, (3) 5-10: moderate-a few pieces of litter detected, (4) 10-20: dirtymuch debris seen, and (5) 20 + : extremely dirty-most availability of litters on the beach.

Plastic Accumulation Index
The Plastic Abundance Index (PAI) was used as the second index (Buitrago et al. 2021). It calculates the existing relationship between the amount of plastic and the total amount of litter items collected to determine the plastic abundance on a beach. Following is the formula used to calculate the PAI for each of the 13 surveyed beaches.
where PAI is the number of plastic items per square meter based on the existing plastic association between the total amount of plastic and log 10 of all marine litter items collected along the sampling area. The PAI classifies beaches into five categories based on their plastic presence: (1) zero: very low abundance, (2) 0.1 to 1: low abundance, (3) 1.1 to 4: moderate abundance, (4) 4.1 to 8: high abundance, and (5) > 8: a very high abundance of plastics on the beach.

Statistical analysis
The Bray-Curtis similarity index was evaluated to determine the similarity between sampling sites along the coast. The unweighted pair group method with arithmetic mean (UPGMA) was used to show the clustering associations between locations depending on the categories of marine debris. UPGMA and similarity index were employed using PAST3 software (Hammer et al. 2001;Rakib et al. 2022a). Principal Component Analysis (PCA) was used to transform from data tables into smaller datasets for better visualization and analysis (Liu et al. 2003;Rakib et al. 2022b). PCA was carried using Primer 6 software.

Abundance and composition of macro-litter
Macro-litter was counted on supralittoral zones of 13 sandy beaches on Rutland Island, covering 0.52 km 2 (520,020.79 m 2 ) and totaling 317,565 litter items. The litter density in Zone-III and Zone-II ranged between 0.09 items/m 2 (Jahaji) and 0.18 items/m 2 (Machi Dera), respectively. The litter density in Zone-I ranged from 0.87 items/m 2 (Katla Dera) to 1.03 items/m 2 (Photo Nallah 1 and Photo Nallah 2). Twenty-seven different types of macro-litter belonging to UNEP-recommended categories were identified in the surveyed beaches (Table 1). Macro-litter enumerated were predominantly plastic bottles, plastic buoy, foam buoy, engine oil jerry can, polyvinyl chloride (PVC) (toys and pipes), and fishing gears (ropes, nets, lures). Tube lights, incandescent bulbs, liquor glass bottles, and medication glass bottles were the minor litter. Cigarette lighters, toys, footwear, and toothbrushes were also recorded during the survey. It was observed that plastic bottles (1 lt and > 1 lt) were found lavishly on all studied beaches. Bada Khari (79.04%) and Kumda Nallah (71.37%) showed the highest number of 1-lt plastic water bottles (Table 1). Collinpur and Carbyn's Cove Beaches in South Andaman also showed a dominant prevalence of water bottles (Mohan and Dhivya 2013; Kaviarasan and James 2017), respectively. The sitewise distribution of plastics and non-plastics demonstrated the ubiquitous presence of plastic litter as an inadvertent contaminant in Rutland Island (Fig. 2a). Diverse types of low-density plastics that are buoyant were escorted by oceanic currents (Morales-Caselles et al. 2021), which were lavishly encountered in all the Zones (I to III) (Fig. 2b).
The massive amount of litter recorded was unlikely to be produced by the 347 inhabitants from the study area.
In light of the above, it is possible to infer that these litters originated in the neighboring countries and peninsular India as confirmed by the labels on the encountered macro-litters (Fig. 3). Several studies conducted on remote islands worldwide corroborate the prevalence of plastics (Pieper et al. 2015;Lavers and Bond 2017;Ryan et al. 2018;Ríos et al. 2018;Kaviarasan et al. 2020;Krishnakumar et al. 2020;Patchaiyappan et al. 2020;Goswami et al. 2020Goswami et al. , 2021. According to Kaladharan et al. (2017), the ANIs confront 47% of plastic litter compared to the national average of 14% in India. When compared to other coastal states in mainland India, Lakshadweep has a similar condition as ANIs (Kaladharan et al. 2017). A study by Dharani et al. (2003) indicates that considerable quantum of plastic litter originates from IORC and ship discards in ANIs.
Public, fishing, and shipping are the primary sources of macro-litter in Rutland Island (Fig. 4a). The results coherent the impact of the public utility litter, which was invariably present in all three zones. A similar impact was observed in Lakshadweep Islands (Kaviarasan et al. 2020). Zone-I and Zone-II are active fishing sites; due to the remoteness and absence of collection facilities, debris buildup was remarkably higher in these zones (Table 1). Although the fishing potential in Zone-I is higher than in Zone-II, adverse weather conditions, strong oceanic currents, and most importantly, the grave threat by the saltwater crocodile restrict fishing activity in Zone-I. Since Zone-III is a protected area under the MGMNP, fishing activities are prohibited and punishable. Therefore, it is reasonable to presume that the fishing debris washed ashore from a different distant destination through the oceanic currents.
The PAI is a vital tool for assessing the quantum of plastics among other litter. The PAI results (Table 1) articulate that the plastics are least abundant (< 1) on the beaches of Zone-II (Machi Dera and Pharsa Dera) and Zone-III (Niranjan Balu, Kichad Nallah, Hathi Level, Kumda Nallah, Bada Khari, and Jahaji Beach). Plastics were found in moderate abundance (< 4) on two beaches in Zone-I via Katla Dera and Dhani Nallah. While rest of the three in the same Zone-I exhibited high abundance (< 8) of plastics ( Fig. 4b and Table 1).

Statistical inferences
The findings of the present study were fortified statistically. The dendrogram generated by clustering analysis revelaed two distinct groups. The first assembly comprises Zone-II and Zone-III due to a relativley lower plastic percentage than the other location. Sub-clustering was observed within the first assemblage owing to the differential presences of marine litter. Except Jhaji Beach (very clean) in Zone-II, all of the beaches in Zone-II and Zone-III are clean. The second cluster assembly was Zone-I, where all the beaches were very dirty with the exception of Katla Dera Beach, which was dirty (Fig. 5).
The distribution patterns of marine litter were examined using PCA because the quantities of the various plastic types varied between collection sites. In Fig. 6, biplot-graphic depictions of factor loadings in different components (components 1 and 2) are shown. The first two principal components represent 97.114% of the total variance. The PCA showed that the variables contributing to component 1 were 68.82%, whereas variables contributing to component 2 were 28.29%. The PCA of the 27 variables of the various forms of marine litter from the study area shows a clear distinction by distributions. The findings showed that various sampling locations were dominated by various categories of marine litter, but invaraiably all the sampled 13 stations were dominated plastics.

Factors influencing litter arrival
The ANIs and other remote island systems serve as prospective catchment areas for ubiquitous marine anthropogenic litter in the open ocean (Krishnakumar et al. 2020;Patchaiyappan et al. 2020;Goswami et al. 2020Goswami et al. , 2021. Litter entering the marine environment, viz., riverine discharge, is unlikely due to the study area's pristine condition and small population. The small human occupancy on the island would not have generated the massive amount of litter that ended up in the island's streams ultimately reaching the sea or the beaches. On the contrary, the inhabitants of the island scavenge the beaches for various plastic litters in good condition for reusing it in their life. Therefore, multiple pathways such as strong winds, diurnal tides, oceanic currents, and storms are the significant introducing vectors from the adjacent countries into the study area (Dharani et al. 2003;Patchaiyappan et al. 2020;Krishnakumar et al. 2020). The landfall of foreign-origin litter was emplaced (2-m width) all along the foreshore berms (highest high-tide line). The text and language were used as the key to identify the country of origin based on the encountered labeling (Fig. 3).
Zone-I exhibited diversified litter from nine countries, including Sri Lanka, Maldives, UAE, Somalia, Indonesia, Malaysia, Thailand, Myanmar, and Bangladesh. These highly diversified litters are indicative of the movement of South West Monsoon Currents (SMC) and North East Monsoon Currents (NMC) via the Duncan strait, which connects Rutland and Little Andaman (Fig. 1). On the other hand, Zone-II encountered diversified litter from Indonesia, Malaysia, Thailand, Myanmar, and Bangladesh. In contrast, macro-debris from Sri Lanka, the Maldives, the UAE, and Somalia are encountered in Zone-III (Fig. 7). The stratification of Indian Ocean Rim Countries (IORC) macro-debris in Zone-II and Zone-III can be attributed to the predominance of NMC and SMC. Apart from the IORC, macro-debris from India's eastern and western coastal regions were also encountered.
The West Indian Coast Current (WICC) carries litter from Western Indian coastal states such as Gujarat, Maharashtra, Goa, Karnataka, Kerala, and Kanyakumari along with the litters from west Asian countries; these particles tend to follow a similar path. They move southeastward into the Arabian Sea, then into the BoB, and then eastward following the Equatorial Counter Current, depending on monsoon currents in the North Indian Ocean (Shankar et al. 2002;Tomczak and Godfrey 2003;Chassignet et al. 2021). Further, unmanaged macro-plastic debris mobilized by the East Indian Coast Current (EICC) from south east Asian countries apart from the eastern coastal states of India (Tamil Nadu, Andhra Pradesh, Odisha, and West Bengal) are directly flushed into the Andaman Sea reaching the Zone-I and Zone-II by the NMC.
The BoB is most likely to be a hotspot of macro-litter due to the multiple-scale recirculation gyre and vast input of land-based plastic litter (Li et al. 2021). Besides, the SMC and NMC play a vital role in the emplacement of plastic litter from the IORC in the BoB (Mheen et al. 2020). Apart from oceanic currents, the northern Indian Ocean is wellknown for heavy passenger and commercial ships sailing from a variety of locations. As a result, shipping is likely a source of trash in the research area (Smith et al. 2018;Ryan et al. 2018Ryan et al. , 2020Ryan et al. , 2021. The quantity of plastics produced, used, and unmanaged debris are a good indicator of a country's socioeconomic status (Hardesty et al. 2017 MMT/year) (Jambeck et al. 2016). The IORC collective litter management initiative would pave the way for litter prevention on remote islands.

Adverse impact on animals and adjacent ecosystems
The camouflaging green, blue, and whitish transparent fishing gears will cause turtle (Fig. 8a) and saltwater crocodile (Fig. 8b) entanglement. Turtles may accidentally consume marco-plactics laden with lush growth of macro-algae (Di Beneditto and Awabdi 2014). Furthermore, turtles mistake transparent floating debris for prey and consume it directly, resulting in death. The abandoned fishing gear may cause physical damage to corals (Fig. 8c) and associated species of the coral reef ecosystem (Wilcox et al. 2013;Stelfoxet al. 2016;Ballesteros et al. 2018). The mangroves are likely to deteriorate as a result of plastic litter.
The beached plastic litter ( Fig. 8d and e) may enhance the soil's permeability while reducing the thermal diffusivity of the turtle nesting ground, resulting in all-male hatchlings (Nelms et al. 2016). Similarly, lower temperature due to the presence of plastic litter in the nesting ground of saltwater crocodile would result in all female (Lang and Andrews 1994). A recent assessment on the impact of marine litter on sandy beach fauna reveals that invertebrates and vertebrates are entangled and trapped by beached macro-plastics, and also shown an increase in unfavorable interactions with seals and sea turtles (Costa et al. 2022). Changes in the nesting and feeding habits of local and migratory creatures demonstrated as typical early warning indicators of the effects of marine litter. It is worth noting the outstanding conservation efforts of the South Andaman forest division, which every October, before the commencement of the nesting season, conducts extensive surface beach cleanup initiatives at Jahaji Beach in Rutland (Figs. 8f and 9).

Suggestion for transboundary litter pollution management for IORC
Preventive and corrective measures can be used to manage beach litter. A comprehensive solid waste management system, which includes efficient segregation at sources, collection, and recycling, is essential for the better management of litter, particularly plastics. Based on the investigation that the majority of plastic litter, particularly water bottles, Fig. 4 a Major sources of macro-litters in three different zones of Rutland Island and b spatial distribution of Clean Coast Index and Plastic Abundance Index at different sites in Rutland Island originates from various nations, it is a time to improve strict legal enforcement, monitoring of marine litter, awareness campaigns, and frequent cleanup operations with the assistance of civil society organizations and international collaborations among IORC nations. Hatzonikolakis et al. (2022) and Katsanevakis et al. (2020) also suggested several recommendations for the transboundary plastic pollution for the Mediterranean and other European Seas, which can be adopted for IORC with regional importance as similar to Regional Marine Litter Action Plan (RMLA) for South Asian Seas Region (Bangladesh, India, Maldives, Pakistan, Sri Lanka).

Conclusion
Macro-litter studies on remote islands could be essential for gaining insight into ocean-sourced litter on the coast and clarifying doubts about the missing plastics from the ocean. Although the study area is a part of MGMNP and has Beach. e Fishing gears washed ashore at Katla Dera Beach. f Debris pile after beach cleaning at Jahaji and Bangladesh, apart from India's mainland. The Indian Ocean Rim Countries shall collaborate to implement an effective litter management program to minimize plastic littering. The forest department of the Andaman and Nicobar Administration made an effort to clean the selected beach (Jahaji) annually before the start of turtle nesting season. It is recommended that beaches identified as dirty, such as Bakra Balu, Dhani Nallah, Photo Nallah 1, and Photo Nallah 2, should be cleaned regularly since they also serve as the nesting ground for sea turtles. The accumulating litter on the aforementioned beaches may result in the loss of nesting grounds. The present study establishes a new avenue for future research endeavors in Rutland such as (1) the quantification of micro-plastics in various locations; (2) the impact of beach-buried plastics on the sex ratio of turtles, saltwater crocodiles, and Andaman water monitor lizard; (3) bio-accumulation of micro-plastics by various life forms; and (4) seasonal monitoring and modeling study for source and fate of marine litter in this region.

Acknowledgements
The authors express gratitude to all the staffs and mazdoors of Mangultan Forest Range, South Andaman Forest Division for extending their support throughout the investigation.
Author contribution V. Shiva Shankar and Neelam Purti: field work, design of framework of methodology, mapping, and drafting of manuscript.
Neelam Purti: supervision of field work, compilation of field data, and photography. R. Sivasankar: language editing, fine-tuning, and review of the manuscript.
T. Kaviarasan: data compilation, analysis, and fine-tuning the manuscript.
T. R. Satyakeerthy and Sunil Jacob: collection of literature and marking the vital information's relevant to the manuscript.
Data availability All the data and materials are presented as tables and figures.

Declarations
Ethical approval 1) This material is the authors' own original work, which has not been previously published elsewhere.
2) The paper is not currently being considered for publication elsewhere.
3) The paper reflects the authors' own research and analysis in a truthful and complete manner. 4) The paper properly credits the meaningful contributions of co-authors and co-researchers. 5) The results are appropriately placed in the context of prior and existing research. 6) All sources used are properly disclosed (correct citation). Literally copying of text must be indicated as such by using quotation marks and giving proper reference. 7) All authors have been personally and actively involved in substantial work leading to the paper, and will take public responsibility for its content. 8) The manuscript was checked for plagiarism as well.

Consent to participate
The results from the present research were originally generated from the fieldwork in the study area by the first and second authors. No data from any other sources/individuals/organization were used in the present research.

Consent for publication
All the authors actively participated in the present research activity. Those extended the support are been acknowledged.

Competing interests
The authors declare no competing interests.