ArticleLiterature Review

Mangroves as unique but understudied traps for anthropogenic marine debris: A review of present information and the way forward

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Abstract

Marine debris and plastic pollution affect all coastal habitats, however coastal debris studies are predominantly performed on sandy beaches. Other coastal habitats, such as mangroves, remain understudied. Eighteen of the top twenty rivers that contribute the most plastic to the ocean are associated with mangroves, but very few of those forests were investigated in terms of plastic debris pollution. Here we discuss the results of the few available studies on macrodebris conducted in mangroves, which show that mangrove debris research is still in its early stages, with many areas of study to be further investigated. Indeed, the distinct structural complexity of mangroves increases their ability to trap debris from both terrestrial, freshwater and marine sources, resulting in impacts unique to the mangrove ecosystem. Our review highlights a significant lack in standardisation across the performed surveys. Here we suggest standardised guidelines for future integrated macrodebris and microplastic studies in mangroves to facilitate comparisons between studies. Such standardisation should prioritize the use of stratified random sampling, the measurement of the area covered by the debris and the abundance and type of macrodebris and microplastics found, in order to assess the ecological impact of macrodebris and its role as source of microplastics for adjacent ecosystems. We also advocate the use of standard categories across studies, based on those identified for surveying other coastal habitats. This review highlights an alarming knowledge gap in extent, sources and overall impacts of marine macrodebris, mainly constituted by plastic, on mangrove forests, which hinders policy making to address this issue. Standardised, reliable and extended research on this aspect of mangrove pollution is needed to manage and protect these endangered vegetated coastal ecosystems.

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... In recent decades, anthropogenic marine litter and plastics have become contaminants of emerging concern and a growing threat to mangrove ecosystems globally (Debrot et al., 2013;Luo et al., 2021). Structural complexities of the mangrove canopy and pneumatophores can trap and retain marine-borne debris from tidal currents and mismanaged waste from landward for a prolonged period (Luo et al., 2021;Martin et al., 2019). ...
... In recent decades, anthropogenic marine litter and plastics have become contaminants of emerging concern and a growing threat to mangrove ecosystems globally (Debrot et al., 2013;Luo et al., 2021). Structural complexities of the mangrove canopy and pneumatophores can trap and retain marine-borne debris from tidal currents and mismanaged waste from landward for a prolonged period (Luo et al., 2021;Martin et al., 2019). Trapped litter cover the mangrove branches and pneumatophores, prohibiting sunlight and disrupting photosynthesis. ...
... Marine litter, particularly plastics, poses a significant risk to mangrove species and mangrove-dwelling fauna by shedding, entanglement, and ingestion van Bijsterveldt et al., 2021), and the potential to incorporate into the food chain (Sarker et al., 2022). The accumulation of plastics in the mangrove ecosystems-aquatic-terrestrial transition zone has been raising particular concern as they accumulate at relatively high rates (Garcés-Ordóñez et al., 2019), highlighting mangroves as a potential trap for plastics from inland activities (Luo et al., 2021;Martin et al., 2019). Still, very few studies have investigated this issue in mangroves (Luo et al., 2021), and much remains unknown about the detrimental effect of anthropogenic litter on mangroves. ...
Article
Anthropogenic litter is a ubiquitous stressor in the global ocean and poses ominous threats to its biodiversity and ecosystem functioning. At the terrestrial-ocean interface, tropical mangrove forests are subject to substantial exposure to mismanaged litter from inland and marine sources. While the effects of litter in different marine ecosystems are well-documented, the possible ecological consequences on mangroves remain nascent. Here, we investigated anthropogenic litter concentration, composition, probable sources, and impact on coastal mangroves along the Central West coast of India. The mean concentration of trapped litter was measured 8.5 ± 1.9 items/m2 (ranged 1.4 ̶ 26.9 items/m2), and 10.6 ± 0.5 items/tree (ranged 0 ̶ 85 items/tree) on the mangrove floor and mangrove canopy, respectively. Plastic dominated 83.02 % of all litter deposited on the mangrove forest floor and 93.4 % of all entangled litter on mangrove canopy. Most litter comprised single-use plastic products across all surveyed locations. Mangrove floor cleanliness was assessed using several indices, such as Clean Coast Index, General Index, Hazardous Items Index, and Pollution Load Index, reiterating an inferior cleanliness status. The pollution load index indicates “Hazard level I" plastic pollution risk across the mangroves. Litter concentration differed markedly across all sites. However, a significantly higher concentration of stranded litter was detected in the densely populated urban agglomeration and rural areas with inadequate solid waste management. Probable sources of litter indicate land-based (local) and sea-originated (fishing). Supportive information on the transport and accumulation of marine litter is examined based on the National Centers for Environmental Prediction (NCEP) Climate Forecast System (CFS) model version 2 reanalysis of surface wind and current pattern across the Arabian Sea followed by MIKE simulated tide-induced coastal current. Mangrove pneumatophores and branches were found to be damaged by entangled plastics. Hence, determining litter quantum and their probable input source is pivotal in mitigating anthropogenic litter impact on mangrove ecosystems and fostering mangrove conservation. Overall, results envisage that stringent enforcement, implementation of an integrated solid waste management framework, and general behavioral change of the public are crucial to mitigate litter/plastic pollution.
... It is present in the water column, the seafloor, the sea surface and the coast, and so far its impact on 3726 species have been documented (Tekman et al., 2021). Yet despite the surge of studies, data is still skewed towards selected ecosystems and among the marine ecosystems mangroves are rarely studied for plastic occurrence, despite their ecological, societal and financial importance (Luo et al., 2021;Tekman et al., 2021). ...
... Few studies have quantified plastics in mangroves (Garcés-Ordóñez et al., 2019;Kesavan et al., 2021;Suyadi and Manullang, 2020;Paulus et al., 2020;Rahim et al., 2020;Bijsterveldt et al., 2020); they suggest that this ecosystem serves as a trap for plastic waste from land (Suyadi and Manullang, 2020) and sea (Martin et al., 2019). The mechanism of trapping plastics may vary based on the morphology of the stand (Luo et al., 2021). For Avicennia spp. ...
... As shown in this study, urban sites have more waste littered in the mangroves primarily because it has higher population density and more economic activities (Cordier et al., 2021;Jambeck et al., 2015). Aside from the social factors, differences in mangrove structure are likely to determine the inherent trapping potential of the ecosystem (Luo et al., 2021) and may explain why some sites have more plastics than others. Dense mangroves are reported to trap more plastics (Martin et al., 2019). ...
Article
The Philippines is identified as one of the major marine plastic litter polluters in the world with a discharge of approximately 0.75 million tons of marine plastic debris per year. However, the extent of the plastic problem is yet to be defined systematically because of limited research. Thus, this study aims to quantify plastic litter occurrence in mangrove areas as they function as sinks for plastic litter due to their inherent nature of trapping plastics. To define the extent of marine plastic pollution on an island scale, mangrove areas in 14 municipalities around Cebu Island were sampled, with 3 to 9 transects in each site depending on the length of coastline covered by mangroves. Sampling and characterization of both plastics and the mangrove ecosystem was performed in three locations along the transect - landward, middle, and seaward. A total of 4501 plastic items were sampled throughout the study sites with an average of 1.29 ± 0.67 items/m2 (18.07 ± 8.79 g/m2). The average distribution of plastic loads were 2.68 ± 1.9 items/m2 (38.52 ± 25.35 g/m2), 0.27 ± 0.10 items/m2 (6.65 ± 4.67 g/m2), and 0.94 ± 0.61 items/m2 (9.04 ± 4.28 g/m2) for the landward, middle, and seaward locations, respectively. The most frequent plastic types found were i) packaging, ii) plastic bags and iii) plastic fragments. The plastic loads and types suggest most plastic wastes trapped in mangroves come from the nearby communities. Fishing-related plastics originated from the sea and were transported across the mangrove breadth. The findings confirm mangroves are major traps of plastic litter that might adversely affect the marine ecosystem. The study underscores the urgent need for waste mitigation measures, including education, community engagement, infrastructure, technological solutions and supporting policies.
... Globally, the prevalence of anthropogenic debris polluting both terrestrial and aquatic habitats, composed mainly of plastic (Derraik, 2002;Serra-Gonçalves et al., 2019), raises increasing concerns for ecosystem health and functioning (Luo et al., 2021;Roman et al., 2020). An estimated 3.1 to 12.7 million tonnes of mismanaged plastic waste from coastal cities enters littoral ecosystems and the ocean annually, mainly via terrestrial waterways Lebreton and Andrady, 2019). ...
... Fortunately, there has been renewed optimism for the conservation of mangroves of Southeast Asia in recent years, as the rate of global mangrove loss has decreased and they still prove to host a diverse resident fauna compared to other parts of the world . However, assessing mangrove conservation status using only a simple metric of area loss/gain may obscure true mangrove ecosystem health and functionality by omitting vital indicators such as the presence of serious pollutants, including AMD, within the habitat and the food web Luo et al., 2021;Not et al., 2020). ...
... The presence of AMD poses numerous risks to mangrove habitats (Critchell et al., 2019;Green and Webber, 1996;Luo et al., 2021;Seeruttun et al., 2021). It can damage trees (Pranchai et al., 2019), smother roots (van Bijsterveldt et al., 2021), act as habitat for resident and immigrant fauna (Riascos et al., 2019) and create anoxic sediment conditions (Smith, 2012). ...
Article
The hotspots for mangrove diversity and plastic emissions from rivers overlap in Asia, however very few studies have investigated anthropogenic marine debris (AMD) pollution in these threatened coastal ecosystems. Despite Hong Kong's position at the mouth of the Pearl River, a major source of mismanaged waste in Asia, the mangroves in Hong Kong have never been extensively surveyed for AMD. Here we assessed the patterns of AMD abundance within 18 mangrove forests across Hong Kong surveying both their landward and seaward zones. We recorded and categorised, according to their material and potential uses, both the amount of debris items and area they covered, to better quantify its potential impact on the mangroves. Across Hong Kong mangroves, the average abundance of debris was 1.45 ± 0.38 (SE) items m⁻², with an average coverage of 6.05% ± 1.59%. Plastic formed a high proportion of AMD accounting for 70.31% by number of items and 49.71% by area covered, followed by glass/ceramics and wood/bamboo. Disposable food packaging, fishing gear and industrial and construction related waste were the major sources of AMD we documented. On average, we recorded about six times more debris items m⁻² at the landward sites than at the seaward one, but these abundances varied between the East and the West coastlines of Hong Kong. Our data confirms the hypothesis that landward areas of mangrove forests act as traps and retain marine borne debris, but they also suggest that direct dumping of waste from the land could represent a serious impact for these forests placed in between the land and the sea. More research is needed to ascertain the impact of land disposed debris on mangrove degradation, and this study strongly advocates for a cultural shift about the perception of these forests by the public.
... This situation has been recorded on the Hong Kong beaches after Typhoon Mangkhut (Lo et al., 2020), in the coastal waters of Turkey after severe floods (Gündogdu et al., 2018), and in the Sea of Japan with the 2011 Tsunami (Murray et al., 2018). In mangrove forests, marine litter transported by winds and water currents easily accumulates due to the height and structural complexity of mangrove aerial roots, which is why they are considered natural marine litter traps (Martin et al., 2019;Luo et al., 2021). ...
... Litter pollution was classified as low, medium, and high considering the characteristics described in Table 1. This classification of litter pollution was established according to expert criteria, prior knowledge of Colombia's mangroves (Garcés-Ordóñez and Vivas-Aguas, 2014), and considering the few previous reports of the average concentrations of marine litter in mangrove forests (Luo et al., 2021). ...
... Litter presence and accumulation in the mangroves of the Providencia and Santa Catalina islands increases the aspect of unhealthiness and deterioration of the ecosystem; it can also limit natural regeneration because it occupies soil areas interfering with the establishment and growth of mangrove propagules and seedlings (Luo et al., 2021). Litter was also accumulated in the channels, interfering with the water flow to the mangrove. ...
Article
Marine litter in mangroves comes mainly from poor waste management practices and its abundance is increased by natural catastrophes occurrence that affects coastal settlements, as occurred in November-2020, when two hurricanes (ETA and IOTA) destroyed homes and deposited litters in mangroves of the Providencia and Santa Catalina islands, in the Colombian Caribbean. This study aims to assess the litter pollution in mangrove forests of these islands after Hurricane IOTA. Litter pollution was high in mangroves near urban areas and low in mangroves with little urban influence. In three mangrove sectors with high pollution, litter densities of 0.4-1.4 items/m2 and masses of 0.1-1.2 kg/m-2 were determined; the majority were megalitter (sizes >1m). Plastics were the most abundant (>60%). Local community is aware of the litter pollution problem and their participation in scientific research and mangroves recovery is key to understanding the impacts of natural and anthropogenic events and for ecosystem conservation.
... Mangroves provide many important ecosystem services to coastal communities, but are nevertheless disappearing because of a multitude of man-made threats (Supplementary Text S2). Another threat has recently arisen with plastic pollution [29,30]. ...
... Mangroves seem to be especially impacted by plastic pollution because their complex aerial root systems give mangrove forests a high structural complexity which, in turn, creates a high trapping potential for marine debris [29,31] most of which is made up by plastics [32][33][34][35] (Figures 1, 2). The enhanced trapping ability was supported by the observation that debris density was positively related to tree density ( [33,36] but see [37][38][39]) and that mangroves and tidal marshes had higher plastic abundances than tidal flats and seagrass meadows [30]. ...
Full-text available
Article
Plastic pollution is now a worldwide phenomenon affecting all marine ecosystems, but some ecosystems and regions remain understudied. Here, we review the presence and impacts of macroplastics and microplastics for four such ecosystems: mangroves, seagrass meadows, the Arctic Ocean and the deep seafloor. Plastic production has grown steadily, and thus the impact on species and ecosystems has increased, too. The accumulated evidence also indicates that plastic pollution is an additional and increasing stressor to these already ecosystems and many of the species living in them. However, laboratory or field studies, which provide strong correlational or experimental evidence of ecological harm due to plastic pollution remain scarce or absent for these ecosystems. Based on these findings, we give some research recommendations for the future.
... Jambeck et al. reflected that the reported amount of floating plastic debris in the open ocean is 1−3 orders of magnitude lower than their estimates of the quantity of land-derived plastics entering the ocean, 28 and this difference may be accounted for by plastics retained in coastal habitats such as mangroves. 29 Additionally, mangrove forests are structurally more complex than open shores such as sandy beaches and therefore are inherently more efficient in trapping plastic debris and facilitating their deposition and fragmentation, 29,30 leading to mangroves becoming sinks of microplastics and ultimately nanoplastics. However, there is presently a lack of studies on the impacts of nanoplastics and the potential for them to be maternally transferred in marine invertebrates inhabiting coastal environments. ...
... Jambeck et al. reflected that the reported amount of floating plastic debris in the open ocean is 1−3 orders of magnitude lower than their estimates of the quantity of land-derived plastics entering the ocean, 28 and this difference may be accounted for by plastics retained in coastal habitats such as mangroves. 29 Additionally, mangrove forests are structurally more complex than open shores such as sandy beaches and therefore are inherently more efficient in trapping plastic debris and facilitating their deposition and fragmentation, 29,30 leading to mangroves becoming sinks of microplastics and ultimately nanoplastics. However, there is presently a lack of studies on the impacts of nanoplastics and the potential for them to be maternally transferred in marine invertebrates inhabiting coastal environments. ...
... En playa Blanca la abundancia fue de 0.02 microplásticos m -3 y en la de Manzanillo no se encontraron (Fig. 4A). En el agua costera La contaminación por microplásticos en las playas fue menor que en los manglares de Cispata, debido a que los mangles son más susceptibles a acumular basuras plásticas, porque sus raíces actúan como trampas (Deng et al. 2021;Luo et al. 2021;Ding et al. 2022). Las playas de Cispata son limpiadas frecuentemente por la comunidad. ...
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Article
Los microplásticos son contaminantes emergentes con una distribución global amplia y representan un riesgo para la biodiversidad y el sustento de comunidades humanas. Estas partículas son mayormente transportadas por los ríos desde el continente hacia los ecosistemas marino-costeros, en donde se acumulan y afectan su calidad ambiental. El objetivo de este estudio fue evaluar la contaminación por microplásticos en manglares y playas del área marina protegida de Cispata, Caribe colombiano. En mayo de 2018, se seleccionaron tres estaciones en los manglares y dos en las playas turísticas, en donde se muestrearon microplásticos en el agua superficial y sedimentos, los cuales se identificaron visualmente bajo el estereoscopio, se contaron para determinar su abundancia y se clasificaron según sus formas. La abundancia de microplásticos fue mayor en los manglares (de 13 a 123 ítems/m 3 de agua; de 72 a 1 668 ítems/m 2 o de 42 a 1 825 ítems/kg de sedimentos) en comparación con las playas (de 0 a 0.13 ítems/m 3 de agua; de 8 a 36 ítems/m 2 de sedimentos). En ambos ecosistemas, las películas, las espumas y los fragmentos fueron las formas más comunes, relacionándose con la deficiente gestión de residuos domésticos, del turismo y la pesca en la zona. Este estudio aporta al conocimiento sobre la distribución, la abundancia y las características de los microplásticos en manglares y playas de la región, para generar conciencia ambiental sobre sus riesgos y promover acciones que permitan prevenir y mitigar sus impactos negativos, especialmente, en las áreas marinas protegidas.
... Like sediment particles, MPs often undergo deposition/resuspension processes (Deng et al., 2021;Luo et al., 2021;Ouyang et al., 2022), resulting in MPs burial/removal from the sediment (Carmen et al., 2021;de Smit et al., 2021). The current study demonstrated that MPs abundance in the sediment was primarily determined by wave-induced sediment erosion rather than sediment accretion. ...
Article
Coastal sediments are considered as hotspots of microplastics (MPs), with substantial MPs stocks found in blue carbon habitats such as mangroves and tidal marshes, where wave-damping vegetation reduces sediment erosion and enhances accretion. Here, we examined the effects of such bio-geomorphic feedbacks in shaping MPs burial, through a year-round field study in a mangrove habitat along the coast of South China. The results revealed that MPs abundance decreased significantly with the increase of cumulative sediment erosion as the strength of bio-geomorphic feedbacks declined. More shapes and colors of MPs were found at locations with weaker waves and less sediment erosion, where the average particle size was also higher. Our findings highlight the importance of bio-geomorphic feedbacks in affecting both the abundance and characteristics of the buried MPs. Such knowledge extends our understanding of MPs transport and burial from the perspective of bio-geomorphology, which is essential to assess and predict MPs accumulation patterns as well as its impacts on ecosystem functioning of the blue carbon habitats.
... Mangroves help maintain water quality and clarity by filtering and trapping pollutants and sediments originating from land, as was observed in this study and also by other authors [10] [42] [43]. Lagoons in the study area, which had little mangrove stands, were highly polluted with plastics and silted. ...
... The anthropogenic marine debris (AMD) causes diverse types of ecological impacts in the environment, marine life, human health, and socio-economic wellbeing (Bravo et al., 2009;Thiel et al., 2011;Hidalgo-Ruz et al., 2018;Honorato-Zimmer et al., 2019;Gaibor et al., 2020;Olivelli et al., 2020). The AMD is present in different marine environments such as shorelines, estuaries, sea surface, ocean bottom and mangrove areas (Iñiguez et al., 2016;Luo et al., 2021). Marine debris is defined as everything persistent manufactured or processed solid material, disposed of, or neglected in a marine environment by different users deliberately or unintentionally. ...
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Article
Anthropogenic marine debris (AMD) is an environmental pollution that affects marine life, human health, wellbeing, and the economy. This marine litter can deposit in the coastlines, particularly on tidal zones and beaches. To pursue future mitigation strategies to reduce AMD is important to monitor the amount, type and frequency of litter being dumped on shores. This study presents the composition, temporal distribution, abundance and size of AMD on three sandy beaches from Guayas province, Ecuador. The field data was recollected from December 2018 to February 2020. A total of 12,362 items of AMD were collected with an abundance of 1.95 macro-litter items/m2. The composition of AMD was marked by the predominance of plastic items (91.8%), followed by wood and cloth (1.9%), while cigarettes were only present in village beaches. Our results suggest that sites with more AMD abundance are beaches nearby small coastal villages and fishing communities. Also, the AMD abundance is slightly higher at the beginning of the dry season than in the rainy season. Our findings indicate that it is necessary to implement concerted solid waste management measures and proactive environmental education programs to empower the local population, as well as investigate the anthropogenic sources and other variables influencing the AMD abundance coming onto sandy shores.
... Plastic pollution negatively impacts these marine habitats by mechanical and chemical means, and by altering microbial and macrofaunal communities and their associated traits. High macroplastic concentrations can smother and damage mangrove roots and cause leaf loss, decreasing tree survival and primary production, which in turn affect dependent aquatic ecologies, such as fish and shrimp nurseries (Luo et al., 2021;van Bijsterveldt et al., 2021). Additionally, entanglement by marine plastic waste, particularly fishing gear, can damage important habitat-forming organisms, such as coral reefs (Abu-Hilal and Al-Najjar, 2009;Chiappone et al., 2005;Gilardi et al., 2010;Valderrama Ballesteros et al., 2018). ...
Article
Southeast Asia is considered to have some of the highest levels of marine plastic pollution in the world. It is therefore vitally important to increase our understanding of the impacts and risks of plastic pollution to marine ecosystems and the essential services they provide to support the development of mitigation measures in the region. An interdisciplinary, international network of experts (Australia, Indonesia, Ireland, Malaysia, the Philippines, Singapore, Thailand, the United Kingdom, and Vietnam) set a research agenda for marine plastic pollution in the region, synthesizing current knowledge and highlighting areas for further research in Southeast Asia. Using an inductive method, 21 research questions emerged under five non-predefined key themes, grouping them according to which: (1) characterise marine plastic pollution in Southeast Asia; (2) explore its movement and fate across the region; (3) describe the biological and chemical modifications marine plastic pollution undergoes; (4) detail its environmental, social, and economic impacts; and, finally, (5) target regional policies and possible solutions. Questions relating to these research priority areas highlight the importance of better understanding the fate of marine plastic pollution, its degradation, and the impacts and risks it can generate across communities and different ecosystem services. Knowledge of these aspects will help support actions which currently suffer from transboundary problems, lack of responsibility, and inaction to tackle the issue from its point source in the region. Being profoundly affected by marine plastic pollution, Southeast Asian countries provide an opportunity to test the effectiveness of innovative and socially inclusive changes in marine plastic governance, as well as both high and low-tech solutions, which can offer insights and actionable models to the rest of the world.
... By the end of the 20 th century, mangrove area had declined by 35% globally, and continued to be lost at a rate of 1-3% per year through the 2000s [13,14]. Although deforestation of mangroves declined to 0.2-0.7% between 2000 and 2012, the synergistic interactions of natural and anthropogenic stressors has led to rapid and large-scale mangrove die-offs globally [15]. Tropical coral reefs are similarly important, harboring an estimated one third of all described marine species [16] and are also one of the most sensitive ecosystems to climate change [17]. ...
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Article
Marine ecosystems are structured by coexisting species occurring in adjacent or nested assemblages. Mangroves and corals are typically observed in adjacent assemblages (i.e., mangrove forests and coral reefs) but are increasingly reported in nested mangrove-coral assemblages with corals living within mangrove habitats. Here we define these nested assemblages as “coexisting mangrove-coral” (CMC) habitats and review the scientific literature to date to formalize a baseline understanding of these ecosystems and create a foundation for future studies. We identify 130 species of corals living within mangrove habitats across 12 locations spanning the Caribbean Sea, Red Sea, Indian Ocean, and South Pacific. We then provide the first description, to our knowledge, of a canopy CMC habitat type located in Bocas del Toro, Panama. This canopy CMC habitat is one of the most coral rich CMC habitats reported in the world, with 34 species of corals growing on and/or among submerged red mangrove aerial roots. Based on our literature review and field data, we identify biotic and abiotic characteristics common to CMC systems to create a classification framework of CMC habitat categories: (1) Lagoon, (2) Inlet, (3) Edge, and (4) Canopy. We then use the compiled data to create a GIS model to suggest where additional CMC habitats may occur globally. In a time where many ecosystems are at risk of disappearing, discovery and description of alternative habitats for species of critical concern are of utmost importance for their conservation and management.
... Most MPs sink to deeper layers of the water column [15] and accumulate in sediments [16]. Mangrove forests have been identified as a major sink of marine plastic pollution [17,18], which can effectively trap MPs through their root systems and sediment [19]. Numerous investigations concerning MP pollution in sediments along Thailand's coastal areas have been conducted, yet few existing studies on MP pollution in mangrove sediment have been conducted. ...
... The Indonesian government has targeted a national action plan to minimize marine plastic debris by 70% between 2018 and 2025, with a long-term ambition to achieve near-zero plastic pollution in Indonesia by 2040 [70]. This effort needs synergistic coordination between the central and local governments on strengthening law enforcement and real actions at the field level to deal with hazardous AMD, as well as international cooperation [71,72]. ...
Full-text available
Article
Mangroves are an important ecosystem that provides valuable social, economic, and environmental services. Indonesia has placed mangroves on its national priority agenda in an important effort to sustainably manage this ecosystem and achieve national climate commitments. However, mangrove management is faced with complex challenges encompassing social, ecological, and economic issues. In order to achieve the government’s commitments and targets regarding mangrove restoration and conservation, an in-depth study on and critical review of mangrove management in Indonesia was conducted herein. This work aimed to provide a comprehensive analysis of the challenges and strategic recommendations for sustainable mangrove management in Indonesia. SWOT analysis was carried out to understand the strengths, weaknesses, opportunities, and threats related to mangrove management in Indonesia. To address these gaps, we reviewed the existing policies, current rehabilitation practices, environmental challenges, and research and technology implementations in the field. We found that strategies on mangrove ecosystem protection, such as improving the function and value of mangrove forests, integrating mangrove ecosystem management, strengthening political commitments and law enforcement, involving all stakeholders (especially coastal communities), and advancing research and innovations, are crucial for sustainable mangrove management and to support the national blue carbon agenda. Keywords: mangroves; sustainable management; climate change; blue carbon; mangrove policy; restoration; rehabilitation
... The Indonesian government has targeted a national action plan to minimize marine plastic debris by 70% between 2018 and 2025, with a long-term ambition to achieve near-zero plastic pollution in Indonesia by 2040 [70]. This effort needs synergistic coordination between the central and local governments on strengthening law enforcement and real actions at the field level to deal with hazardous AMD, as well as international cooperation [71,72]. ...
... The Indonesian government has targeted a national action plan to minimize marine plastic debris by 70% between 2018 and 2025, with a long-term ambition to achieve near-zero plastic pollution in Indonesia by 2040 [70]. This effort needs synergistic coordination between the central and local governments on strengthening law enforcement and real actions at the field level to deal with hazardous AMD, as well as international cooperation [71,72]. ...
Full-text available
Article
Mangroves are an important ecosystem that provides valuable social, economic, and environmental services. Indonesia has placed mangroves on its national priority agenda in an important effort to sustainably manage this ecosystem and achieve national climate commitments. However, mangrove management is faced with complex challenges encompassing social, ecological , and economic issues. In order to achieve the government's commitments and targets regarding mangrove restoration and conservation, an in-depth study on and critical review of mangrove management in Indonesia was conducted herein. This work aimed to provide a comprehensive analysis of the challenges and strategic recommendations for sustainable mangrove management in Indone-sia. SWOT analysis was carried out to understand the strengths, weaknesses, opportunities, and threats related to mangrove management in Indonesia. To address these gaps, we reviewed the existing policies, current rehabilitation practices, environmental challenges, and research and technology implementations in the field. We found that strategies on mangrove ecosystem protection, such as improving the function and value of mangrove forests, integrating mangrove ecosystem management, strengthening political commitments and law enforcement, involving all stakehold-ers (especially coastal communities), and advancing research and innovations, are crucial for sustainable mangrove management and to support the national blue carbon agenda. Citation: Arifanti, V.B.; Sidik, F.; Mulyanto, B.; Susilowati, A.; Wahyuni, T.; Subarno; Yulianti; Yuniarti, N.; Aminah, A.; Suita, E.; et al. Challenges and Strategies for Sustainable Mangrove Management in Indonesia: A Review. Forests 2022, 13, 695. https://doi.org/10.3390/ f13050695 Academic Editors: Victor H.
... The Indonesian government has targeted a national action plan to minimize marine plastic debris by 70% between 2018 and 2025, with a long-term ambition to achieve near-zero plastic pollution in Indonesia by 2040 [70]. This effort needs synergistic coordination between the central and local governments on strengthening law enforcement and real actions at the field level to deal with hazardous AMD, as well as international cooperation [71,72]. ...
Full-text available
Article
Mangroves are an important ecosystem that provides valuable social, economic, and environmental services. Indonesia has placed mangroves on its national priority agenda in an important effort to sustainably manage this ecosystem and achieve national climate commitments. However, mangrove management is faced with complex challenges encompassing social, ecological , and economic issues. In order to achieve the government's commitments and targets regarding mangrove restoration and conservation, an in-depth study on and critical review of mangrove management in Indonesia was conducted herein. This work aimed to provide a comprehensive analysis of the challenges and strategic recommendations for sustainable mangrove management in Indone-sia. SWOT analysis was carried out to understand the strengths, weaknesses, opportunities, and threats related to mangrove management in Indonesia. To address these gaps, we reviewed the existing policies, current rehabilitation practices, environmental challenges, and research and technology implementations in the field. We found that strategies on mangrove ecosystem protection, such as improving the function and value of mangrove forests, integrating mangrove ecosystem management, strengthening political commitments and law enforcement, involving all stakehold-ers (especially coastal communities), and advancing research and innovations, are crucial for sustainable mangrove management and to support the national blue carbon agenda. Citation: Arifanti, V.B.; Sidik, F.; Mulyanto, B.; Susilowati, A.; Wahyuni, T.; Subarno; Yulianti; Yuniarti, N.; Aminah, A.; Suita, E.; et al. Challenges and Strategies for Sustainable Mangrove Management in Indonesia: A Review. Forests 2022, 13, 695. https://doi.org/10.3390/ f13050695 Academic Editors: Victor H.
... In CGSM, the highest number of microplastics per individual corresponds to C. undecimalis. According to CGSM fishermen, C. undecimalis is frequently found in waters close to the aquaculture infrastructures of the North CG zone and in mangroves, where plastic litter is highly abundant due to its proximity to urban centers and to the closeness of mangrove roots that retain this litter type Luo et al., 2020). However, a word of caution is needed here, as C. undecimalis is the species with the lowest number of individuals analyzed (five fish). ...
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Microplastics are emerging pollutants that have been found in different environmental matrices of marine and coastal ecosystems, where they can generate harmful ecological impacts. Little is known about the current state of microplastic pollution in fragile tropical lagoon ecosystems, such as Ciénaga Grande de Santa Marta (CGSM) in the Caribbean coast of Colombia. This study assesses microplastic pollution in surface waters and sediments, and the occurrence of microplastic ingestion in commercially important fish species from CGSM. In waters, microplastic abundances ranged from 0.0 to 0.3 items L-1 while in sediments they varied from 0.0 to 3.1 items kg-1. The most abundant types of microplastics are fibers and fragments, with polypropylene, polyethylene and high-density polyethylene as the most abundant polymers. Also, 100 (i.e. 21.1%) out of 474 individuals from nine fish species had microplastics in their digestive tracts. Microplastics present in water and sediments and in the digestive tract of the analyzed fish species have similar characteristics, also showing a moderate and statistically significant association. Microplastic abundances are higher near river mouths and in urban areas with a high density of fishing activities and aquaculture infrastructures, which are important sources of contaminants. Microplastic pollution in CGSM represents a threat to the lagoon ecosystem and to local people depending on artisanal fishing. Consequently, effective actions to reduce pollution and its socio-environmental impacts are urgently required.
... Mangroves are ecosystems generally found in the intertidal zones of the tropical and subtropical countries [1]. Mangrove species globally distinguish themselves from the other inland species by their ability to cope with some extreme conditions, notably an elevated level of salt, frequent tidal floods, saturated soils and wave effects [2]. ...
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Article
Mangroves are important coastal ecosystems, which deliver diverse and crucial services to humans. This study explored the diversity of mangrove ecosystem services, their associated threats as well as their contribution to livelihoods and wellbeing of coastal communities in the Mono Transboundary Biosphere Reserve (MTBR) located between Benin and Togo. Data were collected using the exploratory sequential mixed method. The approach included field reconnaissance, focus group discussions (n = 14), in-depth interviews (n = 17), household survey (n = 274) and direct observations. A total of 21 services and 7 associated threats were recorded in the entire reserve. Provisioning services were the most important service for mangroves in the reserve followed by supporting services, regulating services and cultural services. Change in water salinity, mangrove overharvesting and illegal, unreported and unregulated fishing were the three major threats to mangrove ecosystem services in the reserve. Most of the respondents indicated that the current flow of provisioning services, regulating services and cultural services does not sustain their wellbeing and livelihoods. However, the perception varied significantly across respondents’ gender, ethnical groups, educational background and country. Our study showed some similarities between the two countries but also highlighted important differences which can assist the sustainable management of mangroves in the MTBR.
... However, this important ecosystem faces pressure from coastal human activities (Fang et al., 2018). In recent years, it was found that waste plastics can be easily trapped by the roots, branches, or leaves of vegetation with the ebb and flow of tides (Huang et al., 2020b;Luo et al., 2020;Martin et al., 2019). Natural weathering (Galloway and Lewis, 2017) and ingestion by organisms (Dawson et al., 2018) split large plastics into smaller pieces. ...
Article
Microplastics (MP) in mangrove coasts are threating ecological health and seafood safety. However, quantitative evidence on the effects of different coastal human activities on microplastic accumulation in mangrove sediments is lacking, thereby impeding the policy development of evidence-based waste management. In this study, continuous geographical sampling (N = 50) was applied to collect sediments from the largest mangrove coast, namely the Leizhou Peninsula in China. Similar worldwide research data (16 mangrove coasts) were collected from the Science Citation Index Expanded (SCIE) database of the Web of Science. The connections between human drivers and microplastic accumulation were evaluated by spatial comparison, multi-correspondence analysis, and multiple differences analysis. The microplastic abundance fluctuated widely along the mangrove coasts (average value was 51.24, ranged from 6.40 to 255.57 items·kg⁻¹ dry weight; coefficient of variation = 97%) with a globally lower-middle concentration in sediments of the Leizhou Peninsula. Densely populated urban residents and the floating population of tourists largely contributed to the high abundance of microplastics in mangrove sediments, of which large-sized (1–5 mm) white foams were the dominant type. Although suburbs had less crowds, both onshore and offshore fishery production could cause high accumulation of microplastics in neighboring mangrove coasts, which were characterized by small-sized (<1 mm) fragments with fresh color. Small microplastics (80%) with fresh color (44%) were dominant. Weathering may break down more toxic particles in urban areas neighboring mangrove coasts. Larger mangrove patches could partly block ocean-based microplastics; however, coasts surrounded by more geographical barriers had intensified pollutant accumulation. It was suggested that foam packaging of commodities for urban residents and tourists in popular tourism areas should be reduced and restrictions of fishery waste plastics are needed along shores with mangroves, especially in coasts surrounded by more geographic barriers.
... 8 Plants in coastal wetlands can also trap plastics. 1 However, there is a paucity of information about the stocks of plastics in coastal wetlands and their effects on the associated fauna while this information is crucial in guiding effective waste management actions on plastic pollution. ...
... Suraj Prasannakumari Meera meerasuraj@gmail.com system of mangroves and directly suffocates the respiring roots (van Bijsterveldt et al. 2021;Luo et al. 2021). Mangrove areas have already become huge sinks of plastic waste entering the ecosystem either from marine or terrestrial sources (Deng et al. 2021). ...
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Article
Mangroves are one of the most productive ecosystems in the world harboring huge biological diversity. The prime ecological roles of mangroves are prevention of coastal erosion and shoreline protection. Mangroves face varying degrees of threats due to overexploitation, conversion of mangrove habitats for agriculture, settlement and industrial purposes, illegal encroachment, global warming, sea-level rise, El Nino, and pollution. Among them, microplastic (MP) pollution is a major concern threatening not only the mangroves per se but also the rich biodiversity that it shelters. In general, the microbial communities which are paramount to nutrient recycling and ecological dynamics undergo substantial changes upon MP exposure. If the MP pollution in the mangrove habitats continues unabated in the coming decades, there may be serious consequences on the already threatened mangrove ecosystems and the coastal communities. This review article attempts to consolidate MP pollution of mangrove wetlands, its impact on mangroves and associated microbiota, and the microbial solution for its remediation as a sustainable strategy.
... A focus on habitat quantity and efforts to reduce deforestation are welcome, but neglect the quality of remaining or rehabilitated patches . Areal loss is relatively straightforward to map and quantify, but stressors such as overutilization (Scales et al., 2018) and pollution (Deng et al., 2021;Luo et al., 2021) can lead to cryptic degradation (Dahdouh-Guebas et al., 2005) or habitat fragmentation of mangrove forests , without necessarily causing loss of extent. The effects of degradation are numerous, and in mangrove ecosystems may include changes in vegetation density, community composition, genetic diversity, the abundance and diversity of key faunal species, shifts in ecosystem functions, and losses of key ecosystem services (Cannicci et al., 2009;Bartolini et al., 2011;Penha-Lopes et al., 2011). ...
Article
The status and potential degradation of an ecosystem is often difficult to identify, quantify, and characterize. Multiple, concurrent drivers of degradation may interact and have cumulative and confounding effects, making mitigation and rehabilitation actions challenging to achieve. Ecosystem status assessments generally emphasize areal change (gains/losses) as a primary indicator; however, this over-simplifies complex ecosystem dynamics and ignores metrics that would better assess ecosystem quality. Consideration of multiple indicators is necessary to characterize and/or anticipate ecosystem degradation and appropriately identify factors causing changes. We utilize mangrove forests as a model system due to their distribution across a wide range of geographic settings, their position in the inherently dynamic coastal zone, and the multiple natural and anthropogenic pressures they face. We present a conceptual framework to: i) examine drivers of ecosystem degradation and characterize system status, and ii) delineate the roles of biogeographic and geomorphic variability, site history and typology, and references. A complementary workflow is proposed for implementing the conceptual framework. We demonstrate the universal applicability of our conceptual framework through a series of case studies that represent locations with differing drivers of degradation and biogeographic and geomorphic conditions. Our conceptual framework facilitates scientists, conservation practitioners, and other stakeholders in considering multiple aspects of ecosystems to better assess system status and holistically evaluate degradation. This is achieved by critically evaluating suitable comparisons and relevant elements in assessing a site to understand potential actions or the outcome of previously implemented management strategies.
... Challenges remain in the conversion of particle counts into estimates of mass needed to constrain models (Harris, 2020;Pabortsava and Lampitt, 2020); for the time being, nearly all results are reported ( Table 1) as numbers of particles kg − 1 (sediment) rather than mass. Mangroves and seagrass beds effectively trap plastic debris in their aerial root systems and sediments, respectively Y. Huang et al., 2020;Luo et al., 2021) but plastic mass accumulation rates have not been measured. Overall, there is no estimate available for the mass of plastic deposited in any of the main sedimentary sinks of the SCS (coastal, shelf or deep sea) and further research is needed to derive estimates for different regions and different environments. ...
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Article
The South China Sea (SCS) is recognised as a global hotspot for plastic pollution. We review available field studies and identify a significant lack of data needed to construct a simple mass balance box model for plastic pollution in the SCS. Fundamental information on plastic mass input, transfer and sink terms are simply not available. Also unknown are the rates of accumulation in different environments, the dispersal pathways of plastic particles of different density, the residence times of plastic in the water column and the rate at which macroplastics are transformed into microplastics in different environments. Filling these information gaps is critical for states to determine adequate response measures, including developing and tracking impact of policies to deal with the problem of plastic pollution in the SCS.
... Thus mangroves are estimated to have the greatest exposure to river-sourced plastic pollution of the four habitat types studied here. A number of studies have been published on the impact of plastic pollution on mangrove habitat, examples being papers by Cordeiro and Costa (2010), Costa et al. (2011), Smith (2012, Nor and Obbard (2014), Martin et al. (2020) and Luo et al. (2021). These studies document how mangrove roots and branches act as a sieve that retains large plastic objects, in amounts that exceed beaches where mangroves are absent. ...
Article
Marine litter is a global problem which poses an increasing threat to, ecosystem services, human health, safety and sustainable livelihoods. In order to better plan plastic pollution monitoring and clean-up activities, and to develop policies and programmes to deter and mitigate plastic pollution, information is urgently needed on the different types of coastal ecosystems that are impacted by land-sourced plastic inputs, especially those located in proximity to river mouths where plastic waste is discharged into the ocean. We overlayed the most current existing information on the input of plastic to the sea from land-based sources with maps of coastal environments and ecosystems. We found an inverse relationship exists between coastal geomorphic type, plastic trapping efficiency and the mass of plastic received. River-dominated coasts comprise only 0.87% of the global coast and yet they receive 52% of plastic pollution delivered by fluvial systems. Tide-dominated coasts receive 29.9% of river-borne plastic pollution and this is also where mangrove and salt marsh habitats are most common. Wave-dominated coasts receive 11.6% of river-borne plastic pollution and this is where seagrass habitat is most common. Finally, rocky shores comprise 72.5% of the global coast, containing fjords and coral reefs, while only receiving 6.4% of river-borne plastic pollution. Mangroves are the most proximal to river-borne plastic pollution point sources of the four habitat types studied here; 54.0% of mangrove habitat is within 20 km of a river that discharges more than 1 tonne/yr of plastic pollution into the ocean. For seagrass, salt marsh and coral reefs the figures are 24.1%, 22.7% and 16.5%, respectively. The findings allow us to better understand the environmental fate of plastic pollution, to advance numerical models and to guide managers and decision-makers on the most appropriate responses and actions needed to monitor and reduce plastic pollution.
Article
Currently, information on microplastics (MPs) weathering characteristics and ecological functions driven by MPs-associated microbes in mangrove ecosystems remains unclear, especially in the degraded areas. Herein, we compared the weathering characteristics of MPs in both undegraded and degraded mangrove sediments, and then explored the potential interactions between their weathering characteristics and microbially-driven functions. After 70 days of incubation, different MPs (including polyethylene PE, polystyrene PS, and polylactic acid PLA) were strongly weathered in mangrove sediments, with significant erosion features. Interestingly, more obvious weathering characteristics were found for MPs in the undegraded mangrove sediments. O/C ratio value of MPs in the undegraded sediments was 2.3-3.0 times greater than that in the degraded ones. Besides, mangrove degradation reduced network complexity among MPs-associated microorganisms and affected their metabolic activities. Bacteria involved in carbon cycle process enriched on nondegradable MPs, whereas abundant bacteria responsible for sulphur cycle were observed on PLA-MPs. Moreover, these relevant bacteria were more abundant on MPs in the undegraded mangrove sediments. Mangrove degradation could directly and indirectly affect MPs weathering process and microbially-driven functions through regulating sediment properties and MPs-associated microbes. During weathering, contact angle and roughness of MPs were key factors influencing the colonisation of hydrocarbon degradation bacteria on MPs.
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Coastal lagoons are transitional environments between continental and marine aquatic systems. Globally, coastal lagoons are of great ecological and socioeconomic importance as providers of valuable ecosystem services. However, these fragile environments are subject to several human pressures, including pollution by microplastics (MPs). The aim of this review was to identify and summarize advances in MP pollution research in coastal lagoons across the world. We consider peer-reviewed publications on this topic published in English and Spanish between 2000 and April 21, 2022, available in Scopus and Google Scholar. We found 57 publications with data on MP abundances and their characteristics in 50 coastal lagoons from around the world, 58% of which have some environmental protection status. The number of publications on this type of pollution in lagoons has increased significantly since 2019. Methodological differences amongst studies of MPs in coastal lagoons were nevertheless a limiting factor for wide-ranging comparisons. Most studies (77%) were conducted in single environmental compartments, and integration was limited, hampering current understanding of MP dynamics in such lagoons. MPs were more abundant in lagoons with highly populated shores and watersheds, which support intensive human activities. On the contrary, lagoons in natural protected areas had lower abundances of MPs, mostly in sediments and organisms. Fiber/filament and fragment shapes, and polyethylene, polyester, and polypropylene polymers were predominant. MPs had accumulated in certain areas of coastal lagoons, or had been exported to the sea, depending on the influence of seasonal weather, hydrodynamics, anthropogenic pressures, and typology of MPs. It is advised that future research on MP pollution in coastal lagoons should focus on methodological aspects, assessment/monitoring of pollution itself, MP dynamics and impacts, and prevention measures as part of a sound environmental management.
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Over the past decades, mangrove ecosystem has been polluted by plastic debris and microplastics (MPs) due to anthropogenic activities. Yet, little information is available on the composition and functional diversity of microbial communities on the surface of MPs in this ecosystem. The present study aims to investigate the bacterial communities growing on the surface of polyethylene microplastics (PE-MPs) in water, surface sediments and at the water-sediment interface (WSI) of mangrove ecosystems. Obtained results showed distinct variations in the taxonomic composition of bacterial communities among water, surface sediments and PE-MPs exposed to the different sites in mangrove ecosystems. For PE-MPs deployed to water, the dominant phyla were Proteobacteria and Bacteroidetes, accounting for 89.2% of the total abundance, while a relatively high proportion of Proteobacteria (85.6±8.4%) was found for PE-MPs in sediments. For PE-MPs at the WSI, the top five phyla were Proteobacteria, Bacteroidetes, Planctomycetes, Actinobacteria and Firmicutes. Relatively abundant microorganisms on PE-MPs at the WSI were mainly due to tidal ebb and flood increasing interactions of sediment bacteria and PE-MPs. Functional annotation of prokaryotic taxa (FAPROTAX) analysis demonstrated that the ecological functions of microbial communities inhabiting PE-MPs were exposure site-dependent. Bacteria living on PE-MPs in water and at the WSI mainly participated in carbon and nitrogen cycle process, whereas PE-MPs in sediments enriched bacteria responsible for sulphur cycle. These results presented here highlight the importance of the exposure sites to MPs-associated bacteria in mangrove ecosystems.
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Technical Report
A new report commissioned by WWF provides the most comprehensive account to date of the extent to which plastic pollution is affecting the global ocean, the impacts it’s having on marine species and ecosystems, and how these trends are likely to develop in future. The report by researchers from the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI) reveals a serious and rapidly worsening situation that demands immediate and concerted international action: ● Today almost every species group in the ocean has encountered plastic pollution, with scientists observing negative effects in almost 90% of assessed species. ● Not only has plastic pollution entered the marine food web, it is significantly affecting the productivity of some of the world’s most important marine ecosystems like coral reefs and mangroves. ● Several key global regions – including areas in the Mediterranean, the East China and Yellow Seas and Arctic sea ice – have already exceeded plastic pollution thresholds beyond which significant ecological risks can occur, and several more regions are expected to follow suit in the coming years. ● If all plastic pollution inputs stopped today, marine microplastic levels would still more than double by 2050 – and some scenarios project a 50-fold increase by 2100.
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Plastic ingestion has been widely investigated to understand its adverse harms on fauna, but the role of fauna itself in plastic fragmentation has been rarely addressed. Here, we review and discuss the available experimental results on the role of terrestrial and aquatic macrofauna in plastic biofragmentation and degradation. Recent studies have shown how biting, chewing, and stomach contractions of organisms shatter ingested plastic along their digestive tracts. Gut microbial communities can play a role in biodegradation and their composition can shift according to the type of plastic ingested. Shifts in molecular weights, chemical bond forming and breaking, and changes in thermal modification detected in the plastic debris present in the faeces also suggest active biodegradation. A few studies have also shown interactions other than ingestion, such as burrowing, may actively or passively promote physical plastic fragmentation by fauna. We suggest that further investigations into the role of fauna in physical fragmentation and chemical degradation linked to active ingestion and gut associated microbiota metabolism, respectively, should be conducted to better evaluate the impact of these mechanisms on the release of micro- and nano-plastic in the environment. Knowledge on macrofauna other than marine invertebrates and terrestrial soil dwelling invertebrates is particularly lacking, as well as focus on broader types of plastic polymers.
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The SEAFLOWER Biosphere Reserve (SBR) is the largest Marine Protected Area in the Caribbean Sea and the second largest in Latin America. Marine protected areas are under pressure from various stressors, one of the most important issues being pollution by marine litter, especially plastic. In this study our aim is to establish the distribution pattern and potential sources of solid waste in the different marine/coastal ecosystems of the islands of Providencia and Santa Catalina (SBR), as well as assess any interconnections between these ecosystems. At the same time, the distribution characteristics of marine litter in the different compartments facilitated a more dynamic understanding of the load of marine litter supplied by the islands, both locally and externally. We observed that certain ecosystems, principally back-beach vegetation and mangroves, act as crucial marine litter accumulation zones. Mangroves are important hotspots for plastic accumulation, with densities above eight items/m² (minimum 8.38 and maximum 10.38 items/m²), while back-beach vegetation (minimum 1.43 and maximum 7.03 items/m²) also removes and stores a portion of the marine litter that arrives on the beaches. Tourist beaches for recreational activities have a low density of marine litter (minimum 0.01 and maximum 0.72 items/m²) due to regular clean-ups, whereas around non-tourist beaches, there is a greater variety of sources and accumulation (minimum 0.31 and maximum 5.41 items/m²). The low density of marine litter found on corals around the island (0–0.02 items/m²) indicates that there is still no significant marine litter stream to the coral reefs. Identifying contamination levels in terms of marine litter and possible flows between ecosystems is critical for adopting management and reduction strategies for such residues.
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This research studied the types and quantity of marine debris in mangrove forests at Bangpu Recreation Center, Muang Samut Prakarn District, Samut Prakan Province. Marine debris was collected from 9 quadrats of 3x3 meters each. Then, all debris was classified by producing activity and source according to the International Coastal Cleanup (ICC) protocol. Sampling debris was collected twice in August 2019 and in April 2020. The result showed that food wrappers and plastic bags were the types of marine debris found the most. The most abundant debris-producing activity was the shoreline and recreational (90.77-96.42%). The most found marine debris was the plastic bags (75.40-90.30%). The amount of stock and a daily flow of marine debris in August 2019 was higher than in April 2020 (p<0.05). The stock of marine debris quantity was 2.06 and 0.44 items/m 2 , respectively. While the amount of daily flow marine debris was 1. 38 and 0. 36 items/ m 2 , a high abundance of marine debris was found near the shoreline. This research provided the framework for future research in this area and the guidelines for prevention, resolving, and reduce the impact arising from the marine debris problems in the future.
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Micro-(nano-)plastics have become emerging contaminants worldwide in recent years. However, there has not been a critical review on their fate and potential risk in intertidal zones with different geological conditions. Thus, this review provides a comprehensive analysis of the roles of intertidal zones in accumulation or transportation of microplastics, involving convergence, migration, plastiglomerate, and ingestion effects. It is found that microplastics (MPs) are likely to be stranded in mudflats but be transported across the sandy beaches according to their intrinsic and external conditions. Meanwhile, MPs could also form the contamination of plastiglomerate and act as vectors for contaminants, even pathogens, in rocky and biological beaches. Thus, MPs together with nanoplastics (NPs) could potentially threaten the ecosystems of the intertidal zone by their ingestion and translocation. In view of the upsurge of personal protective equipment (PPE) during COVID-19, the occurrence of discarded PPE in the intertidal zones has also been summarized and discussed. Despite that the amount of discarded PPE is relatively smaller than other MPs, the pollution caused by these wastes could increase the possibility for pathogen-attached MPs becoming the source for spreading disease among wildlife and humans. It will be of vital importance for understanding the roles of intertidal zone in influencing the fate and ecotoxicity of the MPs. Moreover, the in-depth discussion on fate of the PPE in each kinds of intertidal zones can be conducive to drawing more attentions on plastic concerns in COVID-19 pandemic and achieving environmental sustainability.
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Accumulation of microplastics (MPs) data on a global scale is key to supporting plastic waste management for protecting ecosystems. To respond this call, a sampling campaign was conducted in the summer and winter seasons of 2018 to collect beach and mangrove sediment samples from 32 sites along the coastline of South China. The MPs concentrations in the intertidal zone along the coast of South China were comparable to those in other regions around the world. Polystyrene foams and fibers were the most abundant debris in the 0.2–5 mm and 0.02–2 mm MPs, respectively. Principal component and correlation analyses indicated that the abundances of MPs were related to wind direction, wastewater discharge amount, and tourist and fishing activities. Risk assessments suggested that potential ecological risks induced by MPs on beaches and mangrove forest along the coast of South China should not be overlooked.
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Significance Global mangrove deforestation and degradation drive the loss of the associated invertebrate fauna vital to ecosystem services. The functional diversity and resilience of this fauna has not been assessed. We show that even small mangrove patches host functionally diverse faunal assemblages and can act as biodiversity reservoirs. However, globally, functional redundancy of mangrove invertebrates (i.e., the average number of species performing a similar functional role in an assemblage) is extremely low, except in Southeast Asia. Thus, even a modest local loss of invertebrate diversity will have significant negative consequences for mangrove functionality and resilience. Current approaches to assess threats to mangroves heavily rely on loss in areal extent, but our results suggest that loss of function may be more vulnerable.
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The South China Sea (SCS) is recognised as a global hotspot for plastic pollution. We review available field studies and identify a significant lack of data needed to construct a simple mass balance box model for plastic pollution in the SCS. Fundamental information on plastic mass input, transfer and sink terms are simply not available. Also unknown are the rates of accumulation in different environments, the dispersal pathways of plastic particles of different density, the residence times of plastic in the water column and the rate at which macroplastics are transformed into microplastics in different environments. Filling these information gaps is critical for states to determine adequate response measures, including developing and tracking impact of policies to deal with the problem of plastic pollution in the SCS.
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Mangrove forests are important ecosystems in the coastal intertidal zone, but China’s mangroves have experienced a large reduction in area from the 1950s, and the remaining mangrove forests are exhibiting increased fragmentation. A detailed mangrove dataset of China is crucial for mangrove ecosystem management and protection, but the fragmented mangrove patches are hardly mapped by medium resolution satellite imagery. To overcome these difficulties, we presented a fine-scale mangrove map for 2018 using the 2-meter resolution Gaofen-1 and Ziyuan-3 satellite imagery together with field data. We employed a hybrid method of object-based image analysis (OBIA), interpreter editing, and field surveying for mangrove mapping. The field survey route reached 9500 km, and 2650 patches were verified during the field work. Accuracy assessment by confusion matrix showed that the kappa coefficient reached 0.98, indicating a highly thematic accuracy of the mangrove dataset. Results showed the total area of mangrove forest in China for 2018 was 25,683.88 hectares, and approximately 91% of mangroves were found in the three provinces of Guangdong, Guangxi, and Hainan. About 64% of mangroves were distributed in or near the nature reserves established by national or local governments, which indicated that China’s mangroves were well protected in recent years. The new fine-scale mangrove dataset was freely shared together with this paper, and it can be used by local authorities and research groups for mangrove management and ecological planning.
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Sequestration of plastics in sediments is considered the ultimate sink of marine plastic pollution that would justify unexpectedly low loads found in surface waters. Here, we demonstrate that mangroves, generally supporting high sediment accretion rates, efficiently sequester plastics in their sediments. To this end, we extracted micro- plastics from dated sediment cores of the Red Sea and Arabian Gulf mangrove (Avicennia marina) forests along the Saudi Arabian coast. We found that microplastics <0.5 mm dominated in mangrove sediments, helping ex- plain their scarcity, in surface waters. We estimate that 50 ± 30 and 110 ± 80 metric tons of plastic may have been buried since the 1930s in mangrove sediments across the Red Sea and the Arabian Gulf, respectively. We observed an exponential increase in the plastic burial rate (8.5 ± 1.2% year−1) since the 1950s in line with the global plastic production increase, confirming mangrove sediments as long-term sinks for plastics.
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Knowledge on anthropogenic marine debris (AMD) distribution and accumulation dynamics in mangroves is limited. To address this shortfall, abundance, sorting, and diversity parameters of AMD were evaluated in Penang’s urban and peri-urban mangroves. Debris were counted and classified across transects parallel to the coastline at progressively higher water marks. Plastic percentages make most of the AMD across all sites. More AMD were retained in the urban sites, consistent with larger population density. Diversity of debris was consistent with land use and livelihood of the population in each area. The greatest differences in abundance, diversity, and evenness were recorded between the lower intertidal zones and the remaining inner transects consistent with sorting towards the coastal edge in favour of plastic items. Differences across transects and sites suggested: 1) the main body of the mangrove efficiently retained debris with little sorting; and 2) debris deposited closer to the edge are increasingly sorted and lost to the water body in favour of smaller plastic items. The findings show that mangroves are vulnerable to accumulation and retention of potentially harmful debris, with evidence of a less efficient retention and selective sorting of materials back to the water body closer to their coastal edges.
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A mess of plastic It is not clear what strategies will be most effective in mitigating harm from the global problem of plastic pollution. Borrelle et al. and Lau et al. discuss possible solutions and their impacts. Both groups found that substantial reductions in plastic-waste generation can be made in the coming decades with immediate, concerted, and vigorous action, but even in the best case scenario, huge quantities of plastic will still accumulate in the environment. Science , this issue p. 1515 , p. 1455
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The crisis facing the world’s oceans from plastics is well documented, yet there is little knowledge of the perspectives, experiences and options of the coastal communities facing overwhelming quantities of plastics on their beaches and in their fishing waters. In emerging economies such as those in the Coral Triangle, the communities affected are among the poorest of their countries. To understand the consequences of ocean plastic pollution in coastal regions, through the eyes of local people, this study examines the knowledge, use, disposal and local consequences of single use plastics in remote island communities in two archipelagos of southern Sulawesi, Indonesia. Using mixed methods—a survey of plastic literacy and behaviour, household interviews about purchasing and disposal, and focus group discussions to generate shared mental models—we identify a complex set of factors contributing to extensive plastic leakage into the marine environment. The rising standard of living has allowed people in low resource, remote communities to buy more single-use plastic items than they could before. Meanwhile complex geography and minimal collection services make waste management a difficult issue, and leave the communities themselves to shoulder the impacts of the ocean plastic crisis. Although plastic literacy is low, there is little the coastal communities can do unless presented with better choice architecture both on the supply side and in disposal options. Our results suggest that for such coastal communities improved waste disposal is urgent. Responsible supply chains and non-plastic alternatives are needed. Producers and manufacturers can no longer focus only on low-cost packaged products, without taking responsibility for the outcomes. Without access to biodegradable, environmentally friendly products, and a circular plastic system, coastal communities and surrounding marine ecosystems will continue to be inundated in plastic waste.
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Global mangrove loss has been attributed primarily to human activity. Anthropogenic loss hotspots across Southeast Asia and around the world have characterized the ecosystem as highly threatened, though natural processes such as erosion can also play a significant role in forest vulnerability. However, the extent of human and natural threats has not been fully quantified at the global scale. Here, using a Random Forest‐based analysis of over one million Landsat images, we present the first 30‐meter resolution global maps of the drivers of mangrove loss from 2000‐2016, capturing both human‐driven and natural stressors. We estimate that 62% of global losses between 2000‐2016 resulted from land‐use change, primarily through conversion to aquaculture and agriculture. Up to 80% of these human‐driven losses occurred within six Southeast Asian nations, reflecting the regional emphasis on enhancing aquaculture for export to support economic development. Both anthropogenic and natural losses declined between 2000‐2016, though slower declines in natural loss caused an increase in their relative contribution to total global loss area. We attribute the decline in anthropogenic losses to the regionally‐dependent combination of increased emphasis on conservation efforts and a lack of remaining mangroves viable for conversion. While efforts to restore and protect mangroves appear to be effective over decadal time scales, the emergence of natural drivers of loss presents an immediate challenge for coastal adaptation. We anticipate that our results will inform decision making within conservation and restoration initiatives by providing a locally‐relevant understanding of the causes of mangrove loss.
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Pollution of coastal and marine environments by mismanaged anthropogenic debris is a global threat requiring complex, multilateral solutions and mitigation strategies. International efforts to catalogue and quantify the density, extent and nature of mismanaged waste have not yet assessed the heterogeneity of debris between nearby areas. Better understanding of how debris types and density can be used as a proxy between regions and between land and seafloor habitats at a global scale can aid in developing cost effective and representative debris monitoring systems. Using volunteer collected clean-up and survey data, we compared the proportion and density of both total debris and specific items across 19,428 coastal land and seafloor sites from International Coastal Clean-ups and Dive Against Debris surveys, from 86 countries between 2011 and 2018. We show that although some items common on land are also common on the seafloor, there is an overall global mismatch between debris types and densities on land and the seafloor from nearby areas. Correlations in land/seafloor debris type/density occurred primarily for items which entangle and/or sink, including fishing line, plastic bags, glass and polyethylene terephthalate (PET) bottles. Minimal similarity between land and seafloor surveys occurs for items which float or degrade. We suggest that to accurately evaluate local debris density, land and seafloor surveys are required to gain a holistic understanding. When detailed information on debris type, relative concentration, and likely source and transport are assessed, more cost effective and efficient policy interventions can be designed and implemented from local through to global scales.
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Coastal flood risks are rising rapidly. We provide high resolution estimates of the economic value of mangroves forests for flood risk reduction every 20 km worldwide. We develop a probabilistic, process-based valuation of the effects of mangroves on averting damages to people and property. We couple spatially-explicit 2-D hydrodynamic analyses with economic models, and find that mangroves provide flood protection benefits exceeding $US 65 billion per year. If mangroves were lost, 15 million more people would be flooded annually across the world. Some of the nations that receive the greatest economic benefits include the USA, China, India and Mexico. Vietnam, India and Bangladesh receive the greatest benefits in terms of people protected. Many (>45) 20-km coastal stretches particularly those near cities receive more than $US 250 million annually in flood protection benefits from mangroves. These results demonstrate the value of mangroves as natural coastal defenses at global, national and local scales, which can inform incentives for mangrove conservation and restoration in development, climate adaptation, disaster risk reduction and insurance.
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Mangrove forests are found along the shorelines of more than 100 countries, and provide a wide range of ecosystem services that support the livelihoods and wellbeing of tens of millions of people. Despite their importance, loss of global mangrove area has been so substantial that twelve years ago academics warned of “a world without mangroves” [1]. This seminal work highlighted the large historical loss of mangroves, suggesting that they had declined faster than almost any other ecosystem, including coral reefs and tropical rainforests. The authors predicted that if nothing was done, the world could be deprived of mangroves and their ecosystem services by the end of this century. Such rates of mangrove loss reflect a broader global environmental crisis, with intergovernmental groups such as the International Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) recently predicting the catastrophic loss and degradation of ecosystems globally [2]. However, we report that compared with other ecosystems, the global loss rate of mangrove forests is now less alarming than previously suggested [3]. This gives cause for conservative optimism among broader projections of environmental decline.
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As marine plastic debris is primarily sourced from terrestrial input, coastal environments are particularly affected by deposition. Because of their pneumatophores, mangroves have been recognized for their importance in confining plastic waste. Crabs are a dominant component of the mangrove ecosystem and play a critical role in maintaining healthy and resilient mangrove forests. Therefore, the presence of debris fragmented from waste, in their habitat is a potential threat. However, the potential ingestion of microplastic pieces by mangrove crabs has not yet been investigated. Here, we quantified microparticles found in the cardiac stomachs and gill chambers of four species of crabs. All specimens collected had anthropogenic microparticles present either via their digestive or respiratory systems. We observed significant variability in the abundance and types of anthropogenic microparticles across sites and species. Interspecific differences appear to be explained by their particular feeding habits, with less selective species ingesting more particles.
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Marine debris is distributed worldwide and constitutes an increasing threat to our environment. The exponential increase of plastic debris raises numerous concerns and has led to an intensification in plastic monitoring and research. However, global spatial and temporal patterns and knowledge gaps in debris distribution, both on land and at sea, are relatively poorly understood, mainly due to a lack of comprehensive datasets. Here we critically review the quality of the available information on beach plastic debris worldwide to highlight where the most urgent actions are required, and to promote the standardization of reporting metrics and sampling methods among researchers. From a total of 174 studies evaluated, 27.0% reported marine debris densities in metrics that were not comparable. Some studies failed to report basic parameters, such as the date of the sampling (9.8%) or the size of the collected debris (19.5%). Our findings show that current research regarding beach debris requires significant improvement and standardization and would benefit from the adoption of a common reporting framework to promote consensus within the scientific community
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Intertidal mangrove forests are a dynamic ecosystem experiencing rapid changes in extent and habitat quality over geological history, today and into the future. Climate and sea level have drastically altered mangrove distribution since their appearance in the geological record ∼75 million years ago (Mya), through to the Holocene. In contrast, contemporary mangrove dynamics are driven primarily by anthropogenic threats, including pollution, overextraction, and conversion to aquaculture and agriculture. Deforestation rates have declined in the past decade, but the future of mangroves is uncertain; new deforestation frontiers are opening, particularly in Southeast Asia and West Africa, despite international conservation policies and ambitious global targets for rehabilitation. In addition, geological and climatic processes such as sea-level rise that were important over geological history will continue to influence global mangrove distribution in the future. Recommendations are given to reframe mangrove conservation, with a view to improving the state of mangroves in the future. Expected final online publication date for the Annual Review of Environment and Resources, Volume 44 is October 17, 2019. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Marine litter pollution has become a complex global problem, because of the negative ecological and socioeconomic impacts as well as the human health risks that it represents. In Colombia, mangroves are affected by inadequate solid waste management, which results in litter accumulation. Additionally, the information related to this problem is limited avoiding the development of prevention and reduction strategies. For the first time, pollution by marine litter and microplastics were evaluated in mangrove soils of the Ciénaga Grande de Santa Marta, where 540 ± 137 and 31 ± 23 items/ha of marine litter were determined in mangroves near and away from populated centers respectively. Plastics represented between 73 and 96% of litter, and microplastic quantity oscillated between 31 and 2,863 items/kg finding the highest concentrations in mangroves near to the population. This study contributes to the knowledge of the marine litter problem in mangroves of the Colombian Caribbean, becoming a help for their conservation.
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The use of mangroves as a travel and tourism destination has not received much attention, but provides a high-value, low impact use of these important ecosystems. This work quantifies and maps the distribution of mangrove visitation at global scales using keyword searches on user-generated content of the popular travel website, TripAdvisor. It further explores the use of user-generated content to uncover information about facilities, activities and wildlife in mangrove tourism locations world-wide. Some 3945 mangrove “attractions” are identified in 93 countries and territories. Boating is the most widespread activity, recorded in 82% of English-language sites. Birdlife is recorded by visitors in 28% of sites, with manatees/dugongs and crocodiles/alligators also widely reported. It is likely that mangrove tourism attracts tens to hundreds of millions of visitors annually and is a multi-billion dollar industry.
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Human population density within 100 km of the sea is approximately three times higher than the global average. People in this zone are concentrated in coastal cities that are hubs for transport and trade – which transform the marine environment. Here, we review the impacts of three interacting drivers of marine urbanization (resource exploitation, pollution pathways and ocean sprawl) and discuss key characteristics that are symptomatic of urban marine ecosystems. Current evidence suggests these systems comprise spatially heterogeneous mosaics with respect to artificial structures, pollutants and community composition, while also undergoing biotic homogenization over time. Urban marine ecosystem dynamics are often influenced by several commonly observed patterns and processes, including the loss of foundation species, changes in biodiversity and productivity, and the establishment of novel assemblages, ruderal species and synanthropes. Further, we discuss potential urban acclimatization and adaptation among marine taxa, interactive effects of climate change and marine urbanization, and ecological engineering strategies for enhancing urban marine ecosystems. By assimilating research findings across disparate disciplines, we aim to build the groundwork for urban marine ecology – a nascent field; we also discuss research challenges and future directions for this new field as it advances and matures. Ultimately, all sides of coastal city design: architecture, urban planning, and civil and municipal engineering, will need to prioritize the marine environment if negative effects of urbanization are to be minimized. In particular, planning strategies that account for the interactive effects of urban drivers and accommodate complex system dynamics could enhance the ecological and human functions of future urban marine ecosystems. This article is protected by copyright. All rights reserved.
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Mangrove forests, through pneumatophores, are filters that retain large floating plastic objects and therefore constitute a sink of marine plastic pollution.
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In 2015, the China State Council in its 13th Five-Year Plan for Economic and Social Development strategically initiated the Guangdong-Hong Kong-Macau Greater Bay Area, with emphasis on strengthening its role in economic development and its powerful synergy with the all-important The Belt and Road Initiative (BRI) in the country and globally. The Greater Bay Area is a unique mega city region situated at the Pearl River Delta, covering the 11 [9 mainland cities +2 special administrative regions (Hong Kong and Macau)] cities. However, few studies examined the bay area under a unique institutional and economic context. This study aims to examine regional integration and spatial connection that affect the growth and success of the megacity region using network analysis. Particularly, it analyzed the centrality of human movements, traffic flow and railway network through visualization of the results from Tencent (QQ) Location Big Data, railway service and census data. The study reveals that the vital contributor to the formation and success of the Greater Bay Area is its rapid growth of transport infrastructure and capacities, particularly high-speed railway, promoting free flowing of the key factors. Strong spatial and transport connection critically harness regional integration and boosting viable development of the Greater Bay Area. Guangzhou-Shenzhen-Hong Kong has shaped a triangle structure. The findings provide planning recommendation and policy implications for city planners and policy makers for regional governance and cooperation in mainland China, Hong Kong and worldwide.
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This study presents a new global baseline of mangrove extent for 2010 and has been released as the first output of the Global Mangrove Watch (GMW) initiative. This is the first study to apply a globally consistent and automated method for mapping mangroves, identifying a global extent of 137,600 km 2 . The overall accuracy for mangrove extent was 94.0% with a 99% likelihood that the true value is between 93.6–94.5%, using 53,878 accuracy points across 20 sites distributed globally. Using the geographic regions of the Ramsar Convention on Wetlands, Asia has the highest proportion of mangroves with 38.7% of the global total, while Latin America and the Caribbean have 20.3%, Africa has 20.0%, Oceania has 11.9%, North America has 8.4% and the European Overseas Territories have 0.7%. The methodology developed is primarily based on the classification of ALOS PALSAR and Landsat sensor data, where a habitat mask was first generated, within which the classification of mangrove was undertaken using the Extremely Randomized Trees classifier. This new globally consistent baseline will also form the basis of a mangrove monitoring system using JAXA JERS-1 SAR, ALOS PALSAR and ALOS-2 PALSAR-2 radar data to assess mangrove change from 1996 to the present. However, when using the product, users should note that a minimum mapping unit of 1 ha is recommended and that the error increases in regions of disturbance and where narrow strips or smaller fragmented areas of mangroves are present. Artefacts due to cloud cover and the Landsat-7 SLC-off error are also present in some areas, particularly regions of West Africa due to the lack of Landsat-5 data and persistence cloud cover. In the future, consideration will be given to the production of a new global baseline based on 10 m Sentinel-2 composites
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Marine Debris is one of the spotlight issues of the world. The existence of marine debris can disrupt the ecosystem. Marine Debris carried by the current to coastal areas and accumulated along the coast. The study area of this research was on the coastline of TundaIsland, which located between Ban-ten and Lampung Provinces. These two provinces are part of two major islands of Indonesia, Java and Sumatra Island which have a high density of population. Household needs produce every day directly proportional to the population. This study is to record what types of garbage contained along the coast. There are 8 stations used in this study using International Coastal Cleanup (ICC) form with an area of 100 m2 collection at each station. From 800m2 area coverage, 1,234 items collected with 47 kg weight of debris and the density 0.072 kg/m2 with abundance 0.75 items/m2. This result suggests that household needs give the big proportion of debris such as Food wrapper, cigarettes butts, and foam pieces. In addition, the study indicates that there is a strong relation between human activities and spreading of debris.
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Coastal zones constitute one of the most heavily populated and developed land zones in the world. Despite the utility and economic benefits that coasts provide, there is no reliable global-scale assessment of historical shoreline change trends. Here, via the use of freely available optical satellite images captured since 1984, in conjunction with sophisticated image interrogation and analysis methods, we present a global-scale assessment of the occurrence of sandy beaches and rates of shoreline change therein. Applying pixel-based supervised classification, we found that 31% of the world's ice-free shoreline are sandy. The application of an automated shoreline detection method to the sandy shorelines thus identified resulted in a global dataset of shoreline change rates for the 33 year period 1984-2016. Analysis of the satellite derived shoreline data indicates that 24% of the world's sandy beaches are eroding at rates exceeding 0.5 m/yr, while 28% are accreting and 48% are stable. The majority of the sandy shorelines in marine protected areas are eroding, raising cause for serious concern.
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Plastics have outgrown most man-made materials and have long been under environmental scrutiny. However, robust global information, particularly about their end-of-life fate, is lacking. By identifying and synthesizing dispersed data on production, use, and end-of-life management of polymer resins, synthetic fibers, and additives, we present the first global analysis of all mass-produced plastics ever manufactured. We estimate that 8300 million metric tons (Mt) as of virgin plastics have been produced to date. As of 2015, approximately 6300 Mt of plastic waste had been generated, around 9% of which had been recycled, 12% was incinerated, and 79% was accumulated in landfills or the natural environment. If current production and waste management trends continue, roughly 12,000 Mt of plastic waste will be in landfills or in the natural environment by 2050.
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Plastics in the marine environment have become a major concern because of their persistence at sea, and adverse consequences to marine life and potentially human health. Implementing mitigation strategies requires an understanding and quantification of marine plastic sources, taking spatial and temporal variability into account. Here we present a global model of plastic inputs from rivers into oceans based on waste management, population density and hydrological information. Our model is calibrated against measurements available in the literature. We estimate that between 1.15 and 2.41 million tonnes of plastic waste currently enters the ocean every year from rivers, with over 74% of emissions occurring between May and October. The top 20 polluting rivers, mostly located in Asia, account for 67% of the global total. The findings of this study provide baseline data for ocean plastic mass balance exercises, and assist in prioritizing future plastic debris monitoring and mitigation strategies.
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Marine debris is a burgeoning global issue with economic, ecological and aesthetic impacts. While there are many studies now addressing this topic, the influence of urbanisation factors such as local population density, stormwater drains and roads on the distribution of coastal litter remains poorly understood. To address this knowledge gap, we carried out standardized surveys at 224 transect surveys at 67 sites in two estuaries and along the open coast in Tasmania, Australia. We explored the relative support for three hypotheses regarding the sources of the debris; direct deposition by beachgoers, transport from surrounding areas via storm water drains and coastal runoff, and onshore transport from the marine system. We found strong support for all three mechanisms, however, onshore transport from the marine reservoir was the most important mechanism. Overall, the three models together explained 45.8 percent of the variation in our observations. Our results also suggest that most debris released into the marine environment is deposited locally, which may be the answer to where all the missing plastic is in the ocean. Furthermore, local interventions are likely to be most effective in reducing land-based inputs into the ocean.
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Crab burrowing activity impacts several important biogeochemical processes within mangrove forests. Burrow morphology has been shown to be variable between brachyuran families, hence the community structure and composition of burrowing crabs may have the potential to impact ecosystems differently. By increasing belowground surface area, volume and bacterial microhabitats, large and complex burrows may differ from smaller and simpler burrows in their impact to nutrient and organic matter distribution. The central aim of this work was to provide a detailed quantification of the scale to which different mangrove crab families impact Hong Kong mangrove ecosystem through their burrowing activities. To achieve this goal, we recorded burrow densities and described specie-specific burrow morphology, through casts and 3D scans, of eight crab species belonging to four families, across three mangrove forests. Where present, the large and complex burrows of Parasesarma bidens (Sesarmidae) increased the total below ground air-sediment surface area per m² by ~190% and accounted for ~1.9% of excavated volume per m³ of mangrove sediment. On average, the burrows of Metaplax spp. (Varunidae) increased the surface area by ~55%, while the ocypodid and dotillid species accounted for a 10–25% increase across sites. Due to its densities and the complexity of its burrows, P. bidens showed to exert a wide impact on Hong Kong mangrove ecosystems unrivalled by other species. By incorporating species-specific burrow characteristics and actual burrow densities, we were able to accurately estimate the differential bioengineering role of the dominant mangrove crab species. Due to the functional role of crab bioengineering, our estimates are critical to assess Hong Kong mangrove ecosystem functioning and health.
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Plastic pollution in mangroves located in small islands was not well documented. This study found that mangrove ecosystem in small island was polluted by plastic debris (mainly film: 63% and fiber: 31%). Density of plastic debris in mangrove area was ranging from 10 ± 4 items m-2 to 230 ± 75 items m-2, mean density was 92 ± 28 items m-2. Landward was the most polluted zone mangrove (mean density: 155 ± 58 items m-2) or about 61% of plastic debris was distributed in this zone. This is corresponds to the sources of plastic waste was from land such as households and markets. Mean density of plastic debris was significantly correlated with mangrove health (r2 = 0.59, p = 0.00). This indicated that plastic debris negatively affected mangrove ecosystem directly and indirectly. Effective land-based plastic waste management and actions such as regular beach cleanup are essential to reduce plastic pollution and to ensure mangrove conservation.
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Mangroves are critical nursery habitats for fish and invertebrates, providing livelihoods for many coastal communities. Despite their importance, there is currently no estimate of the number of fishers engaged in mangrove associated fisheries, nor of the fishing intensity associated with mangroves at a global scale. We address these gaps by developing a global model of mangrove associated fisher numbers and mangrove fishing intensity. To develop the model, we undertook a three-round Delphi process with mangrove fisheries experts to identify the key drivers of mangrove fishing intensity. We then developed a conceptual model of intensity of mangrove fishing using those factors identified both as being important and for which appropriate global data could be found or developed. These factors were non-urban population, distance to market, distance to mangroves and other fishing grounds, and storm events. By projecting this conceptual model using geospatial datasets, we were able to estimate the number and distribution of mangrove associated fishers and the intensity of fishing in mangroves. We estimate there are 4.1 million mangrove associated fishers globally, with the highest number of mangrove fishers found in Indonesia, India, Bangladesh, Myanmar, and Brazil. Mangrove fishing intensity was greatest throughout Asia, and to a lesser extent West and Central Africa, and Central and South America.
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Over the last decade, microplastics (MPs, plastic particles <5 mm) as emerging contaminants have received a great deal of international attention, not only because of their continuous accumulation in both marine and terrestrial environment, but also due to their serious threats posed to the environment. Voluminous studies regarding sources, distribution characterization, and fate of MPs in the different environmental compartments (e.g., marine, freshwater, wastewater, and soil) have been reported since 2004, whereas MPs pollution in unique marine ecosystems (e.g., coastal mangrove habitat) receives little scientific attention. Mangrove ecosystem, an important buffer between the land and the sea, has been identified as a potential sink of MPs caused by both marine and land-based activities. Moreover, the source and distribution characteristics of MPs in this ecosystem are significantly different from other coastal habitats, mainly owing to its unique features of high productivity and biomass. With the impetus to provide a more integrated view of MPs pollution in mangrove habitats, a literature review was conducted based on the existing studies related to this topic. This is the first review to present the current state of MPs pollution in mangrove ecosystems, specially including (i) the possible sources of MPs in mangrove areas and their pathways entering into this habitat; (ii) MPs pollution in the different mangrove compartments (including surface seawater, sediments, and biotas); and (iii) factors influencing MPs distribution in mangrove areas. Toward that end, the research gaps are proposed to guide for future research priorities.
Article
Tourism is an important socioeconomic activity in coastal communities, which deteriorates marine-coastal ecosystem quality when poorly managed, increasing litter pollution on beaches during the main tourist seasons. This study aims to assess the tourism impact on litter pollution on eleven Santa Marta beaches, Colombian Caribbean. During high and low tourist seasons, people on the beaches were counted, macrolitter and micro-plastics were sampled, and perception surveys about litter on beaches were conducted. During the high tourist season, the number of people and macrolitter pollution increased, compared to the low tourist season. Plastics accounted for 30%-77% of macrolitter and microplastics ranged from 1 to 355 items/m 2. Respondents identified tourism as a main litter source and plastics as the most common litter type. All assessed beaches are impacted by tourism causing litter pollution, therefore, stronger controls, educational, and awareness strategies are needed to reduce litter pollution and prevent ecological and socioeconomic impacts.
Article
Mismanaged plastic waste is transported via rivers or city drains into the ocean where it accumulates in coastal sediments, ocean gyres and the deep ocean. Plastic harms marine biota and may ultimately return to humans via the food chain. Private initiatives proposing to collect plastic from the sea and rivers have gained widespread attention, especially in the media. However, few of these methods are proven concepts and it remains unclear how effective they are. Here we estimate the amount of plastic in the global surface ocean to assess the long-term legacy of plastic mass production, calculate the time required to clean up the oceans with river barriers and clean up devices, and explore the fate of collected plastic waste. We find that the projected impact of both single and multiple clean up devices is very modest. A significant reduction of plastic debris in the ocean can be only achieved with collection at rivers or with a combination of river barriers and clean up devices. We also show that the incineration and production of plastic has a significant long-term effect on the global atmospheric carbon budget. We conclude that a combination of reduced plastic emissions and reinforced collection is the only way to rid the ocean of plastic waste.
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Microplastic pollution is a global phenomenon. This is the first time in recent decades that quantitative and qualitative evidence from bibliometrics and Altmetric has been used to conduct an in-depth statistical analysis of global microplastics research knowledge and demonstrate research progress, trends and hotspots. We comprehensively searched the Web of Science Core Collection scientific database from its inception(1986) to September 21, 2019. The study shown that the number of papers on microplastics has increased significantly since 2011. Worldwide, researchers in the field come mostly from Western Europe, mainly spread in the UK, Netherlands and Belgium. With the exception of China, the contribution of developing countries was very limited. Moreover, this study systematically elaborated the hotspots in this field (ecological toxicity and human health risks). The results shown that research on marine systems and marine plankton is still dominant. Since human beings are the ultimate consumers of the food web, microplastics may have potential effects on the human respiratory system and gastrointestinal tract. Towards that end, some topics and perspectives are noted that could indicate the current scientific hotspots and guide future research directions.
Article
Wetlands provide a wide range of ecosystem services, and so their conservation and wise use are receiving increasingly greater attention globally. China has a wealth of wetland ecosystems that are well known as hot spots of biological diversity. China has experienced a serious loss of wetlands owing to rapid urbanisation, population growth and industrialisation. Some of the major threats and challenges to wetlands are related to habitat degradation, loss of biodiversity and weaknesses in their protection and management. In this paper we review the distribution of wetlands in China and discuss the key factors that degrade these wetlands. We further discuss management strategies and make recommendations to strengthen the network of wetlands in China.
Article
Hydrodynamic factors have always been considered as the predominant factors determining the transportation of suspended particulate matter in tidal flats. However, whether such factors also affect the transportation of microplastics (MPs) in mangrove forests remains largely unknown. In our study, the extent to which the two most critical hydrodynamic factors (tidal range and current velocity) impact the distribution of MPs in mangrove sediments was evaluated. In the different zones of the mangrove forest, strong linear relationships were observed between the tidal current velocity and MPs content during both the flood and ebb tide periods (p = 0.002, R² > 0.837). Similarly, in the same mangrove forest, the MPs content significantly differed, and a general increasing trend was found from the seaward boundary (ranging from 80 ± 16 item/kg to 1020 ± 89 item/kg) to the landward boundary (ranging from 520 ± 32 to 6040 ± 114 item/kg). The MPs growth rates showed obvious linear relationships with the tidal current velocity (p < 0.005, R² > 0.905), but there were no relationships with the tidal range (p = 0.717). The results of this work highlight that tidal current velocity and tidal range should be taken into account when exploring the mechanisms of MPs distributions in mangrove ecosystems.
Article
Mangroves are a unique and important type of coastal wetlands in the tropical and subtropical zones worldwide. The abundance and spatial distribution of microplastics in the mangrove sediments however are still poorly understood. The present study aimed to illustrate the characteristics, abundance and spatial distribution of microplastics in different mangrove sediments along the south-eastern coastal zones of China. Microplastic samples (roughly 10-20 kg fresh sediments at each site) taken from 21 sampling sites showed various shapes, colors, composition, sizes, surface morphology, abundance and strong spatial heterogeneity. Five different shapes of microplastics with a variety of colors were detected in the mangrove sediments, among which foams (74.6%) and fibers (14.0%) were the dominant types. The polymer composition of the microplastics identified based on the FT-IR and μ-FTIR covered polystyrene (75.2%), polypropylene (11.7%), rayon (4.6%), polyester (3.4%), polyethylene (2.8%) and acrylic (2.4%). The observed microplastics with a size range of less than 2 mm made up 58.6% of the total microplastic particles. The microplastics had various surface morphologies, exhibiting complicated weathered surfaces. The abundance of microplastics showed a substantial variation among the sampling sites, ranging from 8.3 to 5738.3 items kg-1 (dry sediment). Altogether, our study provides a better understanding of microplastic pollution status and prevention policy-making of mangrove habitats in China.
Article
Along the Upper Gulf of Thailand, coastal fences and breakwaters have been constructed using bamboo since 2005. Despite their potential benefits, bamboo structures disintegrate within seven years releasing floating debris which severely damages mangrove tree stems. The aim of the study was to investigate whether such stem damage resulted in the decline of Avicennia spp. stands along the Upper Gulf of Thailand. Tree health assessments were conducted to assess the probability of crown dieback in damaged and undamaged trees. Satellite-derived time-series of vegetation indices were used to detect long-term forest decline. In contrast to the unaffected landward mangroves, seaward mangroves were unable to recover from insect-induced defoliation events after the collapse of a nearby fence. Furthermore, there was a significantly higher probability that damaged trees showed signs of moderate-to-severe crown dieback. It is recommended that bamboo fences be secured by replacing individual stems before they become detached.
Article
Marine plastic waste has become an ever-increasing environmental threat in the world's ocean largely due to their unique properties and ubiquitous occurrence. They include diverse forms of land- and ocean-based sources of plastics and are estimated to account for up to 85% of marine debris worldwide. As secondary pollutants, marine microplastic particles (<5mm) are derived from pellet loss and degradation of macroplastics. Up to now, several reports have proposed negative impacts of both macro-sized and micro-sized plastics on marine biota. As one of the rapidly growing economies, China is the topmost contributor of plastic waste in the world. China's massive impact on the plastic levels of the ocean are a definite cause of concern and is developing multiple economic, environmental and biological complications. The research of plastics impact on coastal environments in China is only incipient. Here we review the available information on plastic waste, their impacts on marine biota and human health, and Chinese government policies and management initiatives. Although Chinese coastal environments (surface water, coastal sediments, water column) are affected by microplastics pollution, both from land-based and sea-based activities, their impacts on marine biota remain to be elucidated. Though national-level policies are modern and well suited for minimizing the impacts of plastic pollution, there is hardly any legislation for containment of microplastic pollution. Our objective is to review and summarize the information about the occurrence, impacts, and management of plastic pollution in the Chinese coastal environments in order to comprehend their widespread repercussions.
Article
Polymer science is one of the most revolutionary research areas of the last century, instigated by the discovery of Bakelite, the first synthetic plastic. Plastic, once a revolutionary material, has gradually become a global environmental threat with ubiquitous distribution. The term ‘microplastics’ coined in 2004, is used to describe the smaller plastic particles recorded, however there is still no all-inclusive definition that accurately encompasses all criteria that could potentially describe what a microplastic is. Here, the authors focus on the currently reported methods for describing and identifying microplastics and propose a new definition that incorporates all the important descriptive properties of microplastics. This definition not only focuses on size and origin, but also considers physical and chemical defining properties. While this manuscript may promote debate, it aims to reach a consensus on a definition for microplastics which can be useful for research, reporting and legislative purposes.
Article
Over the last decades, plastic debris has been identified and quantified in the marine environment. Coastal and riverine input have been recognized as sources of plastic debris, whereas oceanic gyres and sediments are understood to be sinks. However, we have a limited understanding of the fate of plastic debris in the nearshore environment. To investigate the movement and distribution of plastic debris in the nearshore environment, we collected samples at three distinct locations: below the high tide line, the turbulent zone created by the combination of breaking wave and backflush (defined as the boundary), and the outer nearshore. We estimated the abundance and physical characteristics (e.g. density, hardness, etc.) of macroplastic and microplastics. Four times and 15 times more macroplastics and microplastics are observed, respectively, at the boundary than in the outer nearshore waters, which suggests an accumulation driven by the physical properties of the plastic particles such as density, buoyancy and surface area. We further report that highly energetic conditions characteristic of the boundary area promote the long-term suspension and/or degradation of low density, highly buoyant or large surface area plastic debris, leading to their preferential accumulation at the boundary. Contrastingly, denser and low surface area plastic pieces were transported to the outer nearshore. These results emphasize the role of selective plastic movement at the nearshore driven by physical properties, but also by the combined effects of several hydrodynamics forces like wave action, wind or tide in the resuspension, as well as degradation and transport of plastic debris out of the nearshore environment. A higher abundance of plastic litter has been found in the breaking wave area of nearshore marine environments. This is attributed to wave dynamics responsible for selective transport of plastic litter based on their physical characteristics.
Article
Interest in the biodegradation of microplastics is due to their ubiquitous distribution, availability, high persistence in the environment and deleterious impact on marine biota. The present study evaluates the growth response and mechanism of polypropylene (PP) degradation by Bacillus sp. strain 27 and Rhodococcus sp. strain 36 isolated from mangrove sediments upon exposure to PP microplastics. Both bacteria strains were able to utilise PP microplastic for growth as confirmed by the reduction of the polymer mass. The weight loss was 6.4% by Rhodococcus sp. strain 36 and 4.0% by Bacillus sp. strain 27 after 40 days of incubation. PP biodegradation was further confirmed using Fourier-transform infrared spectroscopy and scanning electron microscopy analyses , which revealed structural and morphological changes in the PP microplastics with microbial treatment. These analyses showed that the isolates can colonise, modify and utilise PP microplastics as carbon source.