Temporal and spatial variability of beach litter in Mangaluru, India

Tide of change: Urgency of a national marine litter policy in India

The rise of plastics in the 20th century revolutionized modern life but inadvertently exacerbated the marine litter crisis. The proliferation of wastes such as single-use plastics has escalated pollution along the coastline, demanding coordinated, decisive, and unified action. While the absence of specific national marine litter policies is concerning, there is growing recognition of urgency to address this issue. A group of experts and stakeholders was involved through a multi-staged workshop to assess the generated information based on scientific evidence and formulate a framework for the National Marine Litter Policy (NMLP). This paper proposes policy options (4 targets & 20 strategies) to address marine litter pollution, especially plastics, and aims to elucidate the urgency and significance of implementing an NMLP as a comprehensive strategy to combat plastics pollution. Implementing dedicated policies and action plans tailored to the unique challenges faced by each country is a vital step towards sustainable oceans.

Spatiotemporal variations in marine macro-litter pollution along the shoreline of Koh Mun Nai, an uninhabited island in the Gulf of Thailand

Despite a recent ambitious plan to improve waste management in Thailand, few studies have monitored the impact of these policies on beached marine litter. Here, we assessed weekly the amounts and composition of stranded macro-litter (≥2.5 cm) on five beaches from an uninhabited island in Thailand during one year. A total of 24,407 items (391.86 kg) yielded a mean abundance of 3.18 ± 11.39 items m-2 (52.75 ± 204.68 g m-2), with plastic being the most abundant marine litter (48% of the total number). The overall Clean Coast Index (30.1) classified the beaches as 'extremely dirty', with a Plastic Abundance Index of 9.8 ('very high abundance' of plastics). When assessing the seasonal rates of accumulation, we found a higher flux pre-monsoon (0.05 items m-2 d-1; 0.66 g m-2 d-1) than post-monsoon (0.01 items m-2 d-1; 0.35 g m-2 d-1). Using modeling of the local hydrodynamic conditions, we explored the potential sources of the pollution, and surprisingly found that the closest river appeared not to be the source. Our results denote that the distribution and typology of marine litter were representatives of household and fishing activities, which in turn highlights the need for better regional litter management measures.

Marine litter weight estimation from UAV imagery: Three potential methodologies to advance macrolitter reports

In the context of marine litter monitoring, reporting the weight of beached litter can contribute to a better understanding of pollution sources and support clean-up activities. However, the litter scaling task requires considerable effort and specific equipment. This experimental study proposes and evaluates three methods to estimate beached litter weight from aerial images, employing different levels of litter categorization. The most promising approach (accuracy of 80 %) combined the outcomes of manual image screening with a generalized litter mean weight (14 g) derived from studies in the literature. Although the other two methods returned values of the same magnitude as the ground-truth, they were found less feasible for the aim. This study represents the first attempt to assess marine litter weight using remote sensing technology. Considering the exploratory nature of this study, further research is needed to enhance the reliability and robustness of the methods.

Increasing risk of invasions by organisms on marine debris in the Southeast coast of India

Increasing amount of anthropogenic litter in the marine environment has provided an enormous number of substrates for a wide range of marine organisms, thus serving as a potential vector for the transport of fouling organisms. Here, we examined the fouling organisms on different types of stranded litter (plastic, glass, rubber, foam sponge, cloth, metal and wood) on eight beaches along the southeast coast of India. In total, 17 encrusting species belonging to seven phyla (Arthropoda, Bryozoa, Mollusca, Annelida, Cnidaria, Chlorophyta and Foraminifera) were identified on 367 items, with one invasive species, the mussel Mytella strigata, detected. The most common species associated with marine litter were the cosmopolitan bryozoans Jellyella tuberculata (%O = 31.64 %) and J. eburnea (28.61 %), the barnacle species Lepas anserifera (29.97 %), Amphibalanus amphitrite (22.34 %) and Amphibalanus sp. (14.16 %), and the oyster species Saccostrea cucullata (13.62 %) and Magallana bilineata (5.44 %). We also reported the first records on stranded litter of four species: the gastropod species Pirenella cingulata and Umbonium vestiarium, the foraminiferan Ammonia beccarii, and the oyster M. bilineata. This study is thus the first documentation of marine litter as a vector for species dispersal in India, where the production and consumption of plastic rank among the highest in the world. We also highlight the increasing risk of invasions by non-indigenous organisms attached to debris along the southeast coast of India. Comprehensive monitoring efforts are thus needed to elucidate the type of vectors responsible for the arrival of invasive species in this region. Raising awareness and promoting education are vital components in fostering sustainable solutions to combat plastic pollution in the country and globally.

Anthropogenic marine litter: An approach to environmental quality for India's southeastern Arabian Sea coast

Anthropogenic marine litter (AML), mainly plastic, is a global concern that is persistent and widespread. To prevent and mitigate this threat, we need to understand the magnitude and source of AML. There is limited knowledge about AML pollution on the Indian Coast. In this context, the present study examined the distribution, abundance, typology, and beach quality based on AML along 22 beaches on the southeastern coast of the Arabian Sea. A total of 4911 AML items were classified into 9 categories, weighing 16.79 kg, and retrieved from a total area of 8000 m². The mean abundance and weight of AML in the current study were 0.45 ± 0.34 items/m² and 1.53 ± 0.92 g/m², respectively. Thottapally showed the most abundant AML among the studied beaches with 0.96 items/m², followed by Azheekkal with 0.73 items/m². Plastic, being the most common item, accounts for 77.6 % of all items and has a mean density of 0.35 items/m² comprising hard plastic (22 %), thermocol (13 %), food wrappers (7 %), cigarette butts (7 %), plastic rope (6 %), and plastic cutlery (6 %). Hazardous anthropogenic litter (HAL) was maximum at Thottapally (17.71 %; 85 out of 480 items collected). Based on the cleanliness of beaches, they are graded "moderately clean" (63 %) by the General Index (GI), "clean" (54 %), and "moderately clean" (40 %) as calculated by the Clean Coast Index (CCI). Hazardous Anthropogenic Beach Litter Index (HABLI) classifies 72 % of beaches as "moderately safe", while the Environmental Status Index (ESI) rates 68 % of beaches as "mediocre". Besides, model simulations demonstrated the pathways of AML propagation, which correlate to the littoral and coastal current flow patterns over the region. Land-based activities were the crucial factors influencing AML distribution. The study highlighted the need for effective regional litter management strategies, policy instruments for the litter impact pathways, economic, regulatory, and behavioural management tools, which were also discussed.

Changes in Sources and Composition of Beach Waste in Coastal Cities around the Bohai Sea of China during the Tourist Peak and Off-Peak Seasons

Beach waste is an important pollutant in the Bohai Sea and coastal cities around the Bohai Sea and has raised many social and environmental concerns in China. The semi-closed characteristics of the Bohai Sea, the well-developed tourism, the special industrial structure and residents' living habits endow the beach waste around Bohai sea with a unique character that should be explored. This study investigated changes in the sources and composition of beach waste in coastal cities around the Bohai Sea of China during the tourist peak and off-peak seasons. Beach waste from twenty beaches in thirteen coastal cities around the Bohai Sea was sampled and analyzed in March and August 2021, respectively. The results showed that beach waste around the Bohai Sea was characterized by large quantities and small weights and was greatly affected by human coastal activities. The sources and composition of beach waste from different coasts and different seasons varied, whereas the overall trend was consistent. In terms of composition, beach waste in both the tourist peak season and off-peak season was mainly composed of plastics, fabrics and paper, which accounted for more than 70% of the total in weight. Meanwhile, the proportion of plastics in the total quantity of beach waste was greatest (maximum of up to 71%) and exhibited seasonal fluctuations, trending higher in the tourist peak season than in the off-peak season. In contrast, trends in the proportion of paper and fabrics in the total quantity and total weight of beach waste were relatively stable in different seasons. In terms of sources, beach waste mainly derived from human coastal activities, the proportion of which in the total quantity of beach waste in the tourist peak season reached 70.55% and was 11% higher than that in the tourist off-peak season. Shipping/fishing activities were the second largest source of beach waste, and their proportion in the total quantity of beach waste in the tourist peak season was 5% lower than that in the tourist off-peak season, as the tourist peak season around the Bohai Sea coincides exactly with the fishing moratorium. The quantity of smoking-related waste only accounted for 9.35% and 7.73% of beach waste in the tourist peak and off-peak seasons, respectively. The special semi-enclosed structure of the Bohai gulf, surrounded by land on three sides, aggravated the accumulation of beach waste on the coast. Source reduction and classified recovery, collaborative management of marine waste and beach waste, and joint prevention and control mechanisms of three provinces (Liaoning, Hebei and Shandong) and one municipality (Tianjin) were suggested for comprehensive management of beach waste in coastal cities around the Bohai Sea of China. This study provided valuable information for beach waste management in coastal cities around the Bohai Sea of China.

Assessment of national beach litter composition, sources, and management along the Indian coast - a citizen science approach

The present study evaluates the Pan-India beach litter density (items/m²), weight (kg/m²), composition (%), and probable sources based on the citizen science approach. A total of 33 beaches in 2019 and 30 beaches in 2021 were studied. Based on density, the national beach litter average was 0.475± 0.51 and 0.3 ± 0.4 items/m² in 2019 and 2021, respectively. Plastic was the dominant litter type (65 % in 2019; 74 % in 2021) and Single-Use Plastics (SUPs) were predominant. Based on Clean-Coast Index, six beaches in 2019 and three beaches in 2021 are classified as "extremely dirty". The principal (∼60 %) sources of litter were tourism and public littering. Improving solid waste management, stringent implementation of environmental legislation, leveraging the polluter pays principle, monitoring the effectiveness of SUPs ban, generating awareness, and beach clean-up at regular intervals by engaging the public, educational, and non-governmental organizations will improve and sustain the cleanliness of beaches.

Sources and management of marine litter pollution along the Bay of Bengal coast of Bangladesh

Marine debris is often detected everywhere in the oceans after it enters the marine ecosystems from various sources. Marine litter pollution is a major threat to the marine ecosystem in Bangladesh. A preliminary study was conducted to identify the sources of marine litter (plastics, foamed plastic, clothes, glass, ceramic, metals, paper, and cardboard) along the Bay of Bengal coast. From the observations, the range of abundance of the collected marine litter was 0.14-0.58 items/m². From the ten sampling sites, the highest amount of marine litter was observed for aluminium cans (3500), followed by plastic bottles (3200). The spatial distribution pattern indicated that all the study areas had beach litter of all types of materials. The present investigation showed that plastics were the dominating pollutants in the marine ecosystem in Bangladesh. The clean-coast index (CCI) value indicated that the Cox's Bazar coast was clean to dirty class. The abundance, distribution, and pollution of marine litter along the coastal belts pose a potential threat to the entire ecosystem. This study will help come up with ways to manage and get rid of marine litter along the coast in an effective way.

Baseline marine litter abundance and distribution on Saint Martin Island, Bay of Bengal, Bangladesh

Baseline marine litter abundance and distribution on Saint Martin Island, Bay of Bengal, were assessed. Seventy-two transects (100-150 m) along 12 km of coastline were surveyed for litter items every two weeks for two months. The most abundant items were polythene bags, food wrappers, plastic bottles/caps, straws, styrofoam, plastic cups, plastic fragments, fishing nets, clothes, and rubber buoys. Tourism, local markets, hotels, domestic waste, and fishing activities were primary sources of marine litter. According to the mean clean coast index (CCI), all transects were clean, of which 11.3 % and 14.1 % of sandy beaches and rocky shores with sandy beaches were reported dirty, respectively. Northern Saint Martin Island comprised sandy beaches (2.8 %) and was extremely dirty. In addition, plastic abundance index (PAI) analysis showed that 24 % of sites, out of 72 sites, were under "very high abundance", 33 % were "high abundance", 33 % showed "moderate abundance", and 4 % were classified as "low abundance". Establishing baseline results of marine litter abundance and distribution on Saint Martin Island may help improve island conservation and mitigation strategies (e.g., improved waste management, beach cleaning activities to raise public awareness, local government litter reduction policies, and increase local pro-environmental behavioral change).

Spatio-temporal variation and seasonal dynamics of stranded beach anthropogenic debris on Indonesian beach from the results of nationwide monitoring

The first stranded macrodebris study on a national scale in Indonesia was conducted on 18 beaches from February 2018 to December 2019. The average weight and abundance of beach debris were higher between October and February (rainy season). The highest stranded macrodebris was located in Ambon, Manado, Takalar, and Padang. Plastic (46.38 %) was the most prevalent type of debris across all macrodebris categories, with single-use plastics such as plastic sachets, plastic bags, and plastic bottles being the dominant macroplastic debris (64.64 %). Based on CCI, HII, and BGI, 18 beaches are "moderately clean," with few hazardous items observed, and "Good." This anthropogenic macrodebris is thought to be more localized (55 %) than transboundary macrodebris. Litter control and environmental quality of this Indonesian coastal region should be improved through a proactive and flexible approach. Finally, extensive stranded beach debris monitoring is recommended to better understand the distribution of macrodebris in the region.

Personal protective equipment (PPE) pollution driven by the COVID-19 pandemic in coastal environment, Southeast Coast of India

The rise in the use of single-use plastics and personal protective equipment (PPE) has increased plastic waste in the marine environment. In this study, we surveyed the presence of PPE (face masks and gloves) discharged in 6 beaches along the coast of India. A total of 496 PPE were counted with an average density of 1.08 × 10^-3 PPE m^-2. The PPE density found was comparable to previous studies. Face masks were the most recorded type of PPE (98.39%), with gloves accounting for only 1.61% of the total. However, a significant reduction in the appearance of PPE was recorded on all six beaches, likely due to the increase in vaccination rates. The most contaminated places were the beaches with recreational activities + fishing. It has been noticed that the lack of awareness of environmental pollution and the negligence of the population and the mismanagement of municipal waste are the main causes of beach pollution by PPE. This study confirms the potential threat of PPE to terrestrial and aquatic organisms of multiple taxa in India, but further studies are needed to quantify the impact of this type of waste on marine animals.

Macro marine litter survey of sandy beaches along the Cox's Bazar Coast of Bay of Bengal, Bangladesh: Land-based sources of solid litter pollution

Macro-sized marine litter (>2.5 cm) was collected, characterized, and enumerated along the Cox's Bazar Coast, Bangladesh. Marine litter abundance was converted to density (number of items/m²). Beach cleanliness was evaluated using the clean-coast index (CCI). Plastic polythene bags were the most abundant litter items, followed by plastic cups. Total marine litter abundance was 54,401 ± 184 items. Major sources of marine litter were from tourism, fishery and residential activities. Of 10 sites surveyed, two were classified as dirty, two were moderate, four were clean and two were very clean using the CCI. Marine litter pollution along the Cox's Bazar Coast represents a potential threat to coastal and marine environments. This baseline study will help to establish mitigation strategies that are urgently required to reduce marine litter pollution along the Cox's Bazar Coast.

Spatio-temporal assessment of COVID-19 lockdown impact on beach litter status and composition in Goa, India

The study aimed to understand beach litter status at some of the world-famous beaches of Goa, West India, to comprehend the impact of the Covid-19 lockdown. We characterize litter in six categories (Nylon+Rubber, Plastics, Footwear, Glass, Metal, and Thermocol) for eight sampled beaches in the north and south Goa. All beaches show increased glass and decreased plastics (significant litter) during the lockdown period compared to the unlock period that marked the high tourist inflow. Beaches were classified and graded with colour codes using litter density exhibit light blue-green colour coding during the lockdown or unlock period, suggests clean maintenance. The Miramar beach located in the heart of the capital city showed relatively more litter density (yellow code) due to the combination of local people and tourist inflow. Morjim, Palolem, Velsao were littered the least during both periods.

Qualitative and Quantitative Beach Cleanliness Assessment to Support Marine Litter Management in Tropical Destinations

In addition to its ecological and recreational relevance, beach cleanliness is also one of the five most important aspects (i.e., the “Big Five”) for beach visitors around the world. Nonetheless, few efforts have been carried out to guide the sound management of this rising issue. This paper presents a quantitative and qualitative method to assess the level of beach cleanliness, in order to allow managers to focus their attention on the environmental management of the most frequent and relevant types of litter in tropical areas. In a first step, a survey on users’ perception was applied to 361 beachgoers in eight beaches in Colombia to identify the most relevant types of beach litter and the weighting factors to obtain quantitative calculations. In a second step, the thirteen categories of litter identified were analyzed in relation to beach cleanliness, origin of litter, and environmental impact, to define its individual weighting importance. Some categories were also selected according to particularities of tropical countries, such as the presence of abundant natural vegetation debris and gross polystyrene items, largely transported by rivers in great quantities. In a third step, the method was then tested at eight beaches in the Caribbean coast of Colombia through a period of four months, during which 192 transect samplings were carried out. The qualitative module of the proposed technique, named Beach Litter Assessment Technique—Qualitative and Quantitative (BLAT-QQ), identified the main types of beach litter and the quantitative module gave an overview on the state of beach cleanliness. The method is demonstrated to be quick and effective in diagnosing beach cleanliness, providing a simple instrument to carry out sound environmental management actions in coastal destinations.

Distribution and characterization of microplastics in beach sediments from Karnataka (India) coastal environments

The presence of microplastic particles from five different beach locations (Arabian Sea coast) in the Indian state of Karnataka was assessed. The sieving and density separation method was modified to enhance the yield of microplastics. Three different techniques were used to characterize isolated microplastics, such as optical fluorescence microscopy, Raman spectroscopy, and FESEM-EDX. Microplastic concentrations ranged from 264 ± 62 n/kg to 1002 ± 174 n/kg of dry sand in beach sediments, and the average abundance of the five beaches was 664 ± 114 n/kg. The majority of the microplastics were fragmented, <1 mm in size, white and transparent in color. FESEM images of microplastics show the roughness, cracks, mechanical and oxidative weathering, indicating their continuous exposure in the environment. EDX spectra provide the presence of various elements on the microplastic surface.

A comprehensive review on assessment of plastic debris in aquatic environment and its prevalence in fishes and other aquatic animals in India

The presence of meso, macro, and microplastics (MPs) in aquatic environments has raised concerns due to their potential risks to aquatic as well as human life. Though plastics are considered to be inert in nature, MPs with toxic additives and accumulated contaminants have harmful ecological effects. Reports of absorption of MPs by internal tissues and toxicity in vital organs such as lung cells, liver, and brain cells have proved its serious health hazards. The study of plastic debris in the aquatic environment deserves special attention due to its ecotoxicological impact. This review presents a detailed account of the assessment of plastic debris in marine as well as freshwater environments. The formation of MPs and their sources, sampling, isolation, identification and characterization methods adopted, and the prevalence of MPs in aquatic life are discussed. To the best of our knowledge, the present article is a first-ever comprehensive review covering the entire of India. Our review finds that, so far, very few studies have been carried out, and there is a paucity of information, especially on the prevalence of plastic debris in the freshwater environment, fish, and other aquatic animals in India. While major studies have been done at various coastal locations in the southern part of India and a few studies in the rest of India, south-eastern states remain neglected. Toxicological studies on various life forms, including humans, are lacking. The present review also fills the gap in our knowledge of the various locations studied across India and can guide future research.

Spatiotemporal variations in anthropogenic marine litter pollution along the northeast beaches of India

Marine litter is widely distributed in marine environments and has been a severe concern worldwide, due to the disposal of waste from diverse sources. The severity of this threat has garnered increasing attention in India over the last decade, but the full consequences of this pollution are yet to be quantified. To estimate the spatiotemporal distribution, composition and beach quality of marine litter pollution, 17 beaches along the Hooghly estuary, a part of the Gangetic delta was studied. Marine litter was collected from 100 m long transects during two seasons (monsoon and post-monsoon). The OSPAR monitoring standard was applied to the 16,597 litter items collected, then grouped under 6 types and 44 categories. In terms of number, litter abundance was higher during monsoon (1.10 ± 0.39 items/m²) than that of post-monsoon (0.86 ± 0.32 items/m²). Most of the beaches were categorized as low cleanliness as computed by the general index and clean coast index and the good for the pellet pollution index. Hazardous litter constituted 6.5% of the total collected litter items. The model prediction revealed that the influence of high discharge from Hooghly, Rasulpur and Subarnarekha River carried enormous anthropogenic litter to the northeast beaches. The litter flux decreases with an increase in distance from the shore, and act as a sink to the sea-floor. The results denote that the distribution and typology of marine litter were representatives of household, tourism and fishing, which in turn highlights the need for better regional litter management measures. Suggested management practices include source reduction, mitigation, management of beach environment and change in littering behaviour through environmental education.

Fouling organisms in marine litter (rafting on abiogenic substrates): A global review of literature

One of the underestimated consequences of marine litter presence on marine environment is the transportation of fouling species on detritus - a process known as rafting. We undertook a review of articles concerning rafting published between 1970 and 2020 to identify patterns and potential areas of study that could contribute to directing future research. We observed in 53 publications an increase in rafting studies from the 1990s but fewer studies have been undertaken in the Southern Atlantic. The main fouling organisms were algae, barnacles, bryozoans, mollusks and polychaetes. The transport of those organisms over time and distances, and the volumes of material transported, have been very irregular, reflecting oceanic movements and detritus generating events acting at local, regional, or trans-oceanic scales. No standardized methodologies for collecting marine litter and identifying and quantifying their fouling were observed, but are suggested in this review, to allow more accurate future comparisons among different studies.

Message in a bottle: Open source technology to track the movement of plastic pollution

Rivers worldwide are now acting as major transport pathways for plastic pollution and discharge large quantities of waste into the ocean. Previous oceanographic modelling and current drifter data have been used to predict the movement and accumulation of plastic pollution in the marine environment, but our understanding of the transport and fate through riparian systems is still largely unknown. Here we undertook a proof of concept study by applying open source tracking technology (both GPS (Global Positing System) cellular networks and satellite technology), which have been successfully used in many animal movement studies, to track the movements of individual plastic litter items (500 ml PET (polyethylene terephthalate) drinks bottles) through the Ganges River system (known as the Ganga in India and the Padma and Meghna in Bangladesh, hereafter known as the Ganges) and the Bay of Bengal. Deployed tags were successfully tracked through the Ganges river system and into the Bay of Bengal marine system. The "bottle tags" were designed and built (e.g. shape, size, buoyancy) to replicate true movement patterns of a plastic bottle. The maximum distance tracked to date is 2845 km over a period of 94 days. We discuss lessons learnt from the development of these plastic litter tags, and outline how the potential widespread use of this open source technology has the ability to significantly increase understanding of the location of accumulation areas and the timing of large inputs of plastic pollution into the aquatic system. Furthermore, "bottle tags" may act as a powerful tool for stimulating social behaviour change, informing science-based policy, and as valuable educational outreach tools for public awareness.

Marine plastic litter in certain trawl grounds along the peninsular coasts of India

Non-biodegradable marine debris such as derelict fishing gears and their parts, polythene covers, carry bags, synthetic packaging materials etc., cause serious damages to the benthic ecosystem including the marine biota. We report here the monthly variation in the marine plastic litter (MPL) and its relative percentage to the quantity of fish caught from the trawling grounds off Cochin, Ratnagiri, Mumbai and Veraval along the west coast as well as Visakhapatnam from the east coast of India. The mean values of MPL from the fishing grounds registered the maximum of 55.2 ± 16.52 kg/km² off Veraval and the minimum of 2.11 ± 0.55 kg/km² off Visakhapatnam, registering a national average of 10.95 ± 3.05 kg/km². The relative percentage of MPL over the fish catch remained highest (3.83%) at Veraval and lowest from Visakhapatnam (0.33%) while, the national average was 1.89 ± 0.28. Monsoon season registered maximum MPL in the fishing grounds of all the coastal regions we studied. Depth of the trawling grounds also influenced the quantity of MPL that 20 m depth registered quantity (24.25 ± 9.16 kg/km²) and the overall mean at 10 m and 40 m depth zone are significantly different from that of 20 m. The database created through this study are discussed in the light of increasing deleterious effects of plastic pollution in the active fishing areas in coastal region and the urgent need to save the sea for sustainable use of its resources.