Species-specific microplastic enrichment characteristics of scleractinian corals from reef environment: Insights from an in-situ study at the Xisha Islands

Distribution characteristics and transport pathways of soil microplastics in coral reef islands with different developmental stages and human activities

Microplastics have attracted substantial attention on remote coral sand islands owing to their delicate ecosystems. However, the distribution, transport pathways, and control mechanisms of soil microplastics on these islands are yet to be elucidated. The coral reef islands of China's Xisha Archipelago in the South China Sea are at varying stages of development and experience differing levels of human activity, rendering them an ideal location to investigate the environmental characteristics of microplastics. This study conducted a comparative analysis of the distribution characteristics of microplastics in surface soils and beach sands, which were collected from coral cays and islands. We further analyzed the potential impacts of plant cover, geomorphology, soil environmental factors and human activities on accumulation and transport of microplastics. The results show that their abundance varies from 1068 to 1616 particles/kg on the different reef islands. Total organic carbon and dissolved organic carbon in the soils exert a significant influence on the accumulation of microplastics. The abundance of microplastics in the exposed areas showed an increasing trend with the degree of island development, and the human activities have a significant impact on the distribution of microplastics across the islands. Analysis of the microplastic abundance at different locations of the atoll reveals that ocean currents and monsoons are the primary drivers of microplastic accumulation on the coral reef islands. This study provides a scientific basis for the management of microplastic pollution and environmental conservation on remote islands.

Sources, Status, and Potential Risks of Microplastics in Marine Organisms of the Bohai Sea: A Systematic Review

This study focused on microplastic pollution in the Bohai Sea, employing bibliometric analysis and meta-integration methods to systematically analyze its pollution characteristics and ecological risks. The results indicated that microplastics primarily originated from land-based inputs (62%) and marine activities (23%). Microplastic concentrations in the Bohai Sea's coastal areas were significantly higher than in deep waters, and the abundance of microplastics in aquaculture sediments was three to five times that in non-aquaculture areas. Bioaccumulation demonstrated a significant trophic magnification effect, with top predators containing much higher microplastic concentrations than plankton. The combined toxicity of microplastics and pollutants severely impacted key species, leading to a 92% decrease in Chinese shrimp populations and a significant reduction in benthic biodiversity. To address this issue, a "four-in-one" prevention and control system was proposed, encompassing source reduction, intelligent monitoring, targeted treatment, and regional collaboration, with measures including policy, technological innovation, and ecological restoration. This aims to provide scientific evidence for Bohai Sea ecological security management and offer a reference for microplastic management in globally semi-enclosed seas.

Microplastic pollution in stony coral skeletons and tissues: A case study of accumulation and interrelationship in South Penghu Marine National Park, Taiwan Strait

Microplastics (MPs) pose a growing threat to coral reef ecosystems worldwide. However, data on MP contamination in coral reefs remain limited, hampering accurate ecological risk assessment. This study investigated MP contamination in coral reefs at South Penghu Marine National Park, analyzing 40 samples from 31 coral species. The average MP abundance was 0.32 ± 0.32 MPs/g wet weight, and the mean MP abundance in the coral tissues (0.26 ± 0.26 MPs/g ww) was significantly higher than that in the coral skeleton (0.08 ± 0.10 MPs/g ww). Most MPs were small (<1 mm: >60 %), fibrous (99.7 %), and primarily composed of rayon (59.8 %) and polyester (27.5 %). Significant correlations were found among MP abundance in whole corals, coral tissues, and coral skeletons. The correlation equation established in this study, linking coral skeleton, tissue, and whole corals, can facilitate a more comprehensive understanding of MP pollution level and its associated risks in coral reef environments. Notably, monofilament overgrowth was observed, highlighting the impact of nearby fisheries and recreational activities on MP contamination. These findings provide valuable field-based data on MP pollution levels and the associated risks to corals and offer a novel tool for assessing MP accumulation and potential risks in coral ecosystems.

Bisphenol A leachate from polystyrene microplastics has species-specific impacts on scleractinian corals

Plastic waste causes pervasive environmental contamination and can result in the release of harmful chemical leachates into marine ecosystems, especially as they fragment to smaller microplastics (<5 mm). The toxicity of commonly found polystyrene (PS) microplastics and associated bisphenol A (BPA) leachate to framework-building corals Pocillopora damicornis and Dipsastraea pallida was assessed through exposure experiments. Intermittent exposure over 14-days to 1) virgin PS, 2) preformulated PS with bound BPA (BPA-PS) and 3) leached BPA-PS (L-BPA-PS; simulating early stages of weathering) showed that microplastics void of leachable BPA had minimal effect on either coral species. However, BPA leachate had negative effects on the maximal photochemical yield (Fv/Fm) and tissue composition of P. damicornis fragments (e.g., decreased chlorophyll and protein compared to controls). Conversely, BPA leachate did not compromise tissues of D. pallida fragments. These results reveal that exposure to chemicals leaching out of microplastics can drive negative effects of microplastic exposure distinct from physical mechanisms due to ingestion alone, and that effects are species specific.

Microplastic pollution in tropical coral reef ecosystems from the coastal South China Sea and their impacts on corals in situ

Coral reefs possess extremely high ecological value in tropical and subtropical waters worldwide. Microplastics as emerging and pervasive pollutants pose a great threat to the health of coral ecosystems. However, in situ studies on microplastics pollution and its impacts in coral ecosystems globally are limited. The occurrence characteristics of microplastics in the environment mediums and reef-dwelling organisms were investigated in coral reef areas from the southern Hainan Island, and the impacts of microplastics on corals in situ were evaluated in this study. Average microplastics abundance was 9.48 items L-1 in seawater, 190.00 items kg-1 in sediment, 0.36 items g-1 in coral, 1.50 items g-1 in shellfish, 0.48 items g-1 in fish gill, and 1.71 items g-1 in fish gastrointestinal tract. The prevalent microplastics in the above samples were characterized as being less than 1000 µm in size, fibrous, and transparent, with predominant polymer types as polyethylene terephthalate, polypropylene, polyethylene, and rayon. The microplastic enrichment capacity of different corals varied (Pocillopora > Acropora > Sinularia). Notably, microplastics were more abundant on the surface of corals compared to their interiors, with distinct characteristics observed, including larger-sized (>500 µm) and fiber-shaped polyethylene terephthalate microplastics on the surface and smaller-sized (20-200 µm) fragmented polyethylene microplastics within coral interiors. Furthermore, the investigation showed species-specific impacts of microplastics on corals in situ, including photosynthetic activity of photosymbionts and antioxidant and immune activities of corals. Furthermore, the ecological risks of microplastics were minor across most environmental media in the studied areas, with exceptions in the bottom seawater and surface sediment of YLW, which exhibited extreme and medium risk levels, respectively. Coral risk levels were generally medium, except for dangerous levels in DDH and high levels in LHT. The potential sources of microplastics in the marginal reefs of southern Hainan Island were primarily tourism, residential, and fishing activities.

Possible sink of missing ocean plastic: Accumulation patterns in reef-building corals in the Gulf of Thailand

Individual coral polyps contain three distinct components-the surface mucus layer, tissue, and skeleton; each component may exhibit varying extent of microplastic (MP) accumulation and serve as a short- or long-term repository for these pollutants. However, the literature on MP accumulation in wild corals, particularly with respect to the different components, is limited. In this study, we investigated the adhesion and accumulation of MPs in four coral species, including both large (Lobophyllia sp. and Platygyra sinensis) and small (Pocillopora cf. damicornis and Porites lutea) polyp corals collected from Si Chang Island in the upper Gulf of Thailand. The results revealed that MP accumulation varied significantly among the four coral species and their components. Specifically, P. cf. damicornis exhibited the highest degree of accumulation (2.28 ± 0.34 particles g-1 w.w.) [Tukey's honestly significant difference (HSD) test, p < 0.05], particularly in their skeleton (52.63 %) and with a notable presence of high-density MPs (Fisher's extract test, p < 0.05). The most common MP morphotype was fragment, accounting for 75.29 % of the total MPs found in the coral. Notably, the majority of MPs were black, white, or blue, accounting for 36.20 %, 15.52 %, and 11.49 % of the samples, respectively. The predominant size range of MP particles was 101-200 μm. Nylon, polyacetylene, and polyethylene terephthalate (PET) were the prevalent polymer types, accounting for 20.11 %, 14.37 %, and 9.77 % of the identified samples, respectively. In the large polyp corals, while MP shapes, colors, and sizes exhibited consistent patterns, remarkable differences were noted in the polymer types across the three components. The findings of this study improve the understanding of MP accumulation and its fate in coral reef ecosystems, underscoring the need for further investigation into MP-accumulation patterns in reef-building corals worldwide.

Low incidence of microplastics in coral reefs of Kāne'ohe Bay, Hawai'i, USA

This study investigated microplastic and other micro-debris pollution in sediment, seawater, sea cucumbers, and corals from fringing and patch reefs in Kāne'ohe Bay, O'ahu, Hawai'i, USA. Microplastic pollution in Kāne'ohe Bay Bay was low compared to other tropical coral reefs. Microplastics were detected in sediments (29 %), sea cucumbers (9 %), and coral (0-2 %) samples but were not quantifiable. Seawater had quantifiable microplastic (< 0.5 mm) and macroplastic (> 0.5 mm) pollution, with mean concentrations ranging from 0.0061 to 0.081 particles m-3. Most particles detected in seawater samples were larger, floating plastic debris consisting mostly of polyethylene, polypropylene fragments, and fibers. Across the other matrices, the most detected particles were polyester, polypropylene, and cotton fibers. These results provide baseline data for this important coral reef ecosystem, and further monitoring is recommended to understand the seasonal and long-term trends in microplastic pollution and its potential future impacts.

Microplastic pollution status in the coral reef ecosystems on the Southern and Western coasts of Sri Lanka during the Southwest monsoon

We investigated the microplastics (MP) abundance, characteristics and pollution severity in the six coral reef ecosystems along the southern and western coasts of Sri Lanka during the southwest monsoon. The small blue-coloured fibres dominated within coral reefs and reef environments. The average coral, surface water and surface sediment MP concentration were 806.64 ± 93.72 particles kg-1ww, 23.42 ± 5.01 particles m-3, and 54.11 ± 8.04 particles kg-1dw, respectively. Coral MP concentration was significantly correlated with surface water (r = 0.65) and surface sediments (r = 0.59) indicating that the reef environment was the source of coral MP enrichment. Coral MP concentration was spatially different (p < 0.05) which may likely be due to the changes in winds, waves, coral biology and plastic sources. MP Pollution Load Index indicated that low MP contamination hazard. Since the presence of MP often deteriorates coral's health, further investigations are necessary to understand the MP's effects on the health of coral reef ecosystems.

A conceptual approach for an innovative marine animal forest apparatus that facilitates carbon sequestration and biodiversity enhancement

Climate change, mainly caused by the indiscriminate usage of fossil fuels, is an urgent global challenge which endangers lives and livelihood of billions of people, the integrity of environmental well-being and the composition and functioning of terrestrial/marine ecosystems alike. To address this pressing concern, climate mitigation and adaptation solutions that target "carbon neutrality by 2050" becomes a crucial global mission. Yet, numerous emerged broad solutions that support biological approaches, such as tree planting, are less stable under enhanced climate change impacts (e.g., forests go on fire). Targeting to achieve the Paris Agreement goals, a wide range of blue carbon sequestering (BCS) approaches have been suggested, since they may contribute considerably to carbon neutrality. Unfortunately, most biological solutions, neglect the employment of marine animal-forests. Here I discuss the potential significance of a novel approach for marine animal forests' BCS, converting the commonly used coral nursery tool into a carbon sequestering floating reef device, a modular device that may accommodate carbon and biodiversity credits.

Microplastics in remote coral reef environments of the Xisha Islands in the South China Sea: Source, accumulation and potential risk

Microplastics (MPs) are of great concern to coral health, particularly enhanced biotoxicity of small microplastics (< 100 µm) (SMPs). However, their fate and harm to remote coral reef ecosystems remain poorly elucidated. This work systematically investigated the distributions and features of MPs and SMPs in sediments from 13 islands/reefs of the Xisha Islands, the South China Sea for comprehensively deciphering their accumulation, sources and risk to coral reef ecosystems. The results show that both MPs (average, 682 items/kg) and SMPs (average, 375 items/kg) exhibit heterogeneous distributions, with accumulation within atolls and dispersion across fringing islands, which controlled by human activities and hydrodynamic conditions. Cluster analysis for the first time reveals a pronounced difference in their compositions between the southern and northern Xisha Islands and resultant distinct sources, i.e., MPs in the north part were leaked mainly from local domestic sewage and fishing waste, while in the south part were probably derived from industrial effluents from adjacent countries. Our ecological risk assessment suggests that the ecosystem within the Yongle Atoll is exposed to a high-risk of MPs pollution. The novel results and proposed framework facilitate to effectively manage and control MPs and accordingly preserve a fragile biosphere in remote coral reefs.

Assessing Microplastics and Nanoparticles in the Surface Seawater of Venice Lagoon-Part I: Methodology of Research

Microplastics (MPs) and nanoplastics (NPs) both represent significant concerns in environmental sciences. This paper aims to develop a convenient and efficient methodology for the detection and measurement of MPs and nanoparticles from surface seawater and to apply it to the water samples collected from the UNESCO site of Venice and its lagoon, more precisely in the Venice-Lido Port Inlet, Grand Canal under Rialto Bridge, and Saint Marc basin. In this study, MPs were analyzed through optical microscopy for their relative abundance and characterized based on their color, shape, and size classes, while the concentration and the mean of nanoparticles were estimated via the Nanoparticle Tracking Analysis technique. Bulk seawater sampling, combined with filtration through a cascade of stainless-steel sieves and subsequent digestion, facilitates the detection of MPs of relatively small sizes (size classes distribution: >1 mm, 1000-250 μm, 250-125 μm, 125-90 μm, and 90-32 μm), similar to the size of MPs ingested by marine invertebrates and fishes. A protocol for minimizing interference from non-plastic nanoparticles through evaporation, digestion, and filtration processes was proposed to enrich the sample for NPs. The findings contribute to the understanding of the extent and characteristics of MPs and nanoparticle pollution in the Venice Lagoon seawater, highlighting the potential environmental risks associated with these pollutants and the need for coordinated approaches to mitigate them. This article is based on scientific research carried out within the framework of the H2020 In-No-Plastic-Innovative approaches towards prevention, removal and reuse of marine plastic litter project (G.A. ID no. 101000612).

Microplastics inhibit the growth of endosymbiotic Symbiodinium tridacnidorum by altering photosynthesis and bacterial community

Microplastics, ubiquitous anthropogenic marine pollutants, represent potential threats to coral-Symbiodiniaceae relationships in global reef ecosystems. However, the mechanism underlying the impacts of polystyrene microplastics (PS-MPs) on Symbiodiniaceae remains poorly understood. In this study, the cytological, physiological, and microbial responses of Symbiodinium tridacnidorum, a representative Symbiodiniaceae species, to varying concentrations of PS-MPs (0, 5, 50, 100, and 200 mg L-1) were investigated. The results revealed that microplastic exposure inhibited cell division, resulting in reduced cell density compared to control group. Furthermore, algal photosynthetic activity, as indicated by chlorophyll content, Fv/Fm, and net photosynthetic rate, declined with increasing microplastic concentration up to 50 mg L-1. Notably, elevated levels of microplastics (100 and 200 mg L-1) prompted a significant increase in cell size in S. tridacnidorum. Transmission electron microscopy and fluorescence microscopy indicated that hetero-aggregation was formed between high levels of PS-MPs and algal cells, ultimately causing damage to S. tridacnidorum. Moreover, the impact of PS-MPs exposure on the bacterial community associated with S. tridacnidorum was investigated. The results showed a reduction in alpha diversity of the bacterial community in groups exposed to 50, 100, and 200 mg L-1 of microplastics compared to those treated with 0 and 5 mg L-1. Additionally, the relative abundance of Marinobacter, Marivita, and Filomicrobium significantly increased, while Algiphilus and norank Nannocystaceae declined after microplastic exposure. These findings suggest that MPs can inhibit the growth of S. tridacnidorum and alter the associated bacterial community, posing a potential serious threat to coral symbiosis involving S. tridacnidorum.

Selective enrichment of bacteria and antibiotic resistance genes in microplastic biofilms and their potential hazards in coral reef ecosystems

Microplastics become hotspots for bacteria to trigger a series of ecological effects, but few studies have focused on the potential impacts of microplastic biofilms in coral reef ecosystems. Here, we measured the bacterial communities and antibiotic resistance genes (ARGs) in the seawater and microplastic biofilms. Results showed that microbial biofilms were formed on the surface of microplastics. The alpha diversity of the bacterial community in the microplastic biofilms was lower than that in the seawater, and the bacterial communities were distinct between the two. Further analysis revealed that several bacteria in the microplastic biofilms carried ARGs, and the proportion of which was correlated to the concentration of antibiotics in the seawater. Specifically, Vibrio was positively correlated to sul1 in the microplastic biofilms under higher concentrations of sulfonamides. Pathway analysis reflected significant overrepresentation of human disease related pathways in the bacterial community of microplastic biofilms. These results suggest that the microplastic biofilms could selectively enrich bacteria from the reef environments, causing the development of ARGs under antibiotic driving. This may pose a serious threat to coral reef ecosystems and human health. Our study provides new insights into the ecological impacts of microplastic biofilms in coral reef ecosystems.

Microplastic trapping efficiency and hydrodynamics in model coral reefs: A physical experimental investigation

Coastal ecosystems, such as coral reefs, are vulnerable to microplastic pollution input from proximal riverine and shoreline sources. However, deposition, retention, and transport processes are largely unevaluated, especially in relation to hydrodynamics. For the first time, we experimentally investigate the retention of biofilmed microplastic by branching 3D printed corals (staghorn coral Acropora genus) under various unidirectional flows (U = {0.15, 0.20, 0.25, 0.30} ms-1) and canopy densities (15 and 48 corals m-2). These variables are found to drive trapping efficiency, with 79-98% of microplastics retained in coral canopies across the experimental duration at high flow velocities (U = 0.25-0.30 ms-1), compared to 10-13% for the bare bed, with denser canopies retaining only 15% more microplastics than the sparse canopy at highest flow conditions (U = 0.30 ms-1). Three fundamental trapping mechanisms were identified: (a) particle interception, (b) settlement on branches or within coral, and (c) accumulation in the downstream wake region of the coral. Corresponding hydrodynamics reveal that microplastic retention and spatial distribution is modulated by the energy-dissipative effects of corals due to flow-structure interactions reducing in-canopy velocities and generating localised turbulence. The wider ecological implications for coral systems are discussed in light of the findings, particularly in terms of concentrations and locations of plastic accumulation.

Do coral reefs act as sinks for microplastics?

Microplastic (MP) pollution has been detected in coral reefs, raising concerns regarding its global impact. Although they cover a small portion (<1%) of the total area of the world's oceans, coral reefs are geological and biological structures that trap MPs and disproportionately enhance their accumulation. In this review, we attempted to understand how coral reefs act as short- and long-term sinks for MPs. We describe five characteristics that lead to the enrichment of microplastics in coral reefs: 1) adhesion on reef-building corals at distinct depths; 2) ingestion by reef organisms (e.g., suspension feeders, such as sponges, ascidians, and corals), bioconcentration, and formation of short-term (i.e., years to decades) biological sinks for MPs; 3) formation of long-term (i.e., centuries) MP sinks in coral skeletons and unconsolidated subsurface sediments; 4) reduction of sediment resuspension and seafloor turbulent kinetic energy by complex marine forest architecture that reduces bottom shear stress, facilitates the retention, and deposition of small (<0.5 mm) and high-density floating MPs; and 5) diagenesis of Anthropocene sedimentary rocks containing MPs. We estimate that reef processes may remove more than 10% of floating MPs in shallow tropical waters yearly. Statistical results show that microplastic abundance for reef-building corals are higher than values found in reef sediments and especially in seawater. Moreover, pellets, films, foams and mainly fragments and fibers have been found. These field-based data support our hypothesis of sinks in the reef sediments and organisms. We highlight the role of these seascapes in the interception of MPs as traps and sinks in reef sediments, biota, and carbonate frameworks. As coral reefs are prone to MP accumulation and can become pollution hotspots, global initiatives are necessary to conserve these rich ecosystems and prevent rapidly increasing plastic pollution.

Unveiling the hidden threat of microplastics to coral reefs in remote South Atlantic islands

The widespread presence of marine microplastics (< 5 mm) is a significant concern, as it may harm marine biodiversity and ocean ecosystems. Corals' capacity to ingest microplastics has emerged as a significant threat to reef ecosystems, owing to the detrimental physiological and ecological effects it can trigger. The extent of the impact of microplastics on Brazilian corals remains unclear and this study aimed to investigate its distribution and characteristics in four coral species: Favia gravida, Mussismilia hispida, Montastrea cavernosa, and Siderastrea stellata, found in the Trindade and Martim Vaz Islands - the most isolated archipelago of Brazil, located about 1200 km (680 miles) east of the coast. This study aims to reveal the extent of microplastic distribution in the coral reef environment, assess the amount of microplastics in different coral species, and compare each species' capacity to adhere and accumulate microplastics. A high concentration of ingested and adhered microplastics was detected in all coral species evaluated in the present study. No significant differences were observed in the sampling points which indicates that although the sampling points are located at different distances from the coast, the microplastic pollution is equally distributed in the region. Polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), poly(methyl methacrylate) (PMMA), Rayon, and Nylon particles were detected, with a predominance of PE (45.5 %). No significant differences in microplastic concentration were detected among the various species and locations studied. Our research presents findings that demonstrate the extensive occurrence of microplastic contamination in coral colonies located on remote islands.

Contamination of microplastics in tropical coral reef ecosystems of Sri Lanka

Microplastics (MPs) in different marine compartments are a global concern. This study investigated the abundance, distribution, and characteristics of microplastics from ten coral reef ecosystems in Sri Lanka, a non-quantified threat for some context. Microplastics were isolated and quantified in terms of abundance, shape, size, color, and polymer type with average abundances 546.7 ± 170.3 items kg-1, 9.8 ± 7.6 items m-3, and 46.3 ± 29.7 items kg-1 in corals, water, and sediments respectively. The most dominant microplastic type was blue, LDPE fibres. Acropora exhibited the highest amount. The significant differences in average microplastic abundances among corals suggest that they are capable of enriching microplastics depending on species-specific characteristics. Similar microplastic characteristics in corals and reef environment indicate that corals may have enriched microplastics from surface water and surface sediments. Microplastics being ubiquitous in selected reefs highlights the importance of coral reefs as a long-term microplastic sink in the ocean, contributing to the missing plastic phenomena.

Microplastic as an invisible threat to the coral reefs: Sources, toxicity mechanisms, policy intervention, and the way forward

Microplastic (MP) pollution waste is a global macro problem, and research on MP contamination has been done in marine, freshwater, and terrestrial ecosystems. Preventing MP pollution from hurting them is essential to maintaining coral reefs' ecological and economic benefits. However, the public and scientific communities must pay more attention to MP research on the coral reef regions' distribution, effects, mechanisms, and policy evaluations. Therefore, this review summarizes the global MP distribution and source within the coral reefs. Current knowledge extends the impacts of MP on coral reefs, existing policy, and further recommendations to mitigate MPs contamination on corals are critically analyzed. Furthermore, mechanisms of MP on coral and human health are also highlighted to pinpoint research gaps and potential future studies. Given the escalating plastic usage and the prevalence of coral bleaching globally, there is a pressing need to prioritize research efforts on marine MPs that concentrate on critical coral reef areas. Such investigations should encompass an extensive and crucial understanding of the distribution, destiny, and effects of the MPs on human and coral health and the potential hazards of those MPs from an ecological viewpoint.

Distribution and risk assessment of microplastics in typical ecosystems in the South China Sea

Microplastic pollution in the marine environment has attracted worldwide attention. The South China Sea is considered a hotspot for microplastic pollution due to the developed industries and high population density around the South China Sea. The accumulation of microplastics in ecosystems can adversely affect the health of the environment and organisms. This paper reviews the recent microplastic studies conducted in the South China Sea, which novelty summarizes the abundance, types, and potential hazards of microplastics in coral reef ecosystems, mangrove ecosystems, seagrass bed ecosystems, and macroalgal ecosystems. A summary of the microplastic pollution status of four ecosystems and a risk assessment provides a more comprehensive understanding of the impact of microplastic pollution on marine ecosystems in the South China Sea. Microplastic abundances of up to 45,200 items/m³ were reported in coral reef surface waters, 5738.3 items/kg in mangrove sediments, and 927.3 items/kg in seagrass bed sediments. There are few studies of microplastics in the South China Sea macroalgae ecosystems. However, studies from other areas indicate that macroalgae can accumulate microplastics and are more likely to enter the food chain or be consumed by humans. Finally, this paper compared the current risk levels of microplastics in the coral reef, mangrove, and seagrass bed ecosystems based on available studies. Pollution load index (PLI) ranges from 3 to 31 in mangrove ecosystems, 5.7 to 11.9 in seagrass bed ecosystems, and 6.1 to 10.2 in coral reef ecosystems, respectively. The PLI index varies considerably between mangroves depending on the intensity of anthropogenic activity around the mangrove. Further studies on seagrass beds and macroalgal ecosystems are required to extend our understanding of microplastic pollution in marine environments. Recent microplastic detection in fish muscle tissue in mangroves requires more research to further the biological impact of microplastic ingestion and the potential food safety risks.

High Heterotrophic Plasticity of Massive Coral Porites pukoensis Contributes to Its Tolerance to Bioaccumulated Microplastics

Scleractinian corals have been observed to be capable of accumulating microplastics from reef environments; however, the tolerant mechanism is poorly known. Here, we examined the response of Porites pukoensis to microplastic pollution by analyzing algal symbiont density, energetic metabolism, and caspase3 activities (representing the apoptosis level) in the coral-Symbiodiniaceae association. The environments of three fringing reef regions along the south coast of Sanya City, Hainan Province of China, were polluted by microplastics (for example, microplastic concentrations in the seawater ranged from 3.3 to 46.6 particles L^-1), resulting in microplastic accumulation in P. pukoensis (0.4-2.4 particles cm^-2). The accumulation of microplastics was negatively correlated to algal symbiont density in the corals but not to caspase3 activities in the two symbiotic partners, demonstrating that P. pukoensis could tolerate accumulated microplastics despite the decrease of algal symbiont density. Furthermore, results from the carbon stable isotope and cellular energy allocation assay indicated that P. pukoensis obtained energy availability (mainly as lipid reserves) using the switch between heterotrophy and autotrophy to maintain energy balance and cope with accumulated microplastics. Collectively, P. pukoensis achieved tolerance to microplastic pollution by maintaining energy availability, which was largely attributed to its high heterotrophic plasticity.

Ecological disturbances and abundance of anthropogenic pollutants in the aquatic ecosystem: Critical review of impact assessment on the aquatic animals

Anthropogenic toxins are discharged into the environment and distributed through a variety of environmental matrices. Trace contaminant detection and analysis has advanced dramatically in recent decades, necessitating further specialized technique development. These pollutants can be mobile and persistent in small amounts in the environment, and ecological receptors will interact with it. Despite the fact that few researches have been undertaken on invertebrate exposure, accumulation, and biological implications, it is apparent that a wide range of pollutants can accumulate in the tissues of aquatic insects, earthworms, amphipod crustaceans, and mollusks. Due to long-term stability during long-distance transit, a number of chemical and microbiological agents that were not previously deemed pollutants have been found in various environmental compartments. The uptake of such pollutants by the aquatic organism is done through the process of bioaccumulation when dangerous compounds accumulate in living beings while biomagnification is the process of a pollutant becoming more hazardous as it moves up the trophic chain. Organic and metal pollution harms animals of every species studied so far, from bacteria to phyla in between. The environmental protection agency says these poisons harm humans as well as a variety of aquatic organisms when the water quality is sacrificed in typical wastewater treatment systems. Contrary to popular belief, treated effluents discharged into aquatic bodies contain considerable levels of Anthropogenic contaminants. This evolution necessitates a more robust and recent advancement in the field of remediation and their techniques to completely discharge the various organic and inorganic contaminants.

Hidden problems in geological heritage sites: The microplastic issue on Saint Mary's Island, India, Southeast Arabian Sea

Microplastics (MPs) have become a dominant constituent of several oceanic islands. This study focuses on the occurrence and distribution of MPs present in the beach sediments of Saint Mary's Island (SMI), a geological heritage site located in the south-eastern part of the Arabian Sea. The average (standard deviation) abundance of MPs on this island was 97.18 (80.49) particles/kg. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy revealed that MPs are composed of high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyamide (PA). Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) highlighted the presence of Cr, As, Pb, and Cd (harmful pollutants) on MP surfaces. The MPs in the SMI are largely contributed by the nearby fishing harbour, touristic beaches and estuaries. The results of this study, act as a starting point for continuous environmental monitoring in this unique region of the world.

Occurrence status of microplastics in main agricultural areas of Xinjiang Uygur Autonomous Region, China

A large number of plastic products are used in the process of agricultural production, and the recycling efficiency is low, which leads to the production of a large number of microplastics. Therefore, the microplastic contamination in agricultural areas requires being investigated urgently. In addition, the occurrence characteristics of microplastics are also different in agricultural areas with various land use modes. In this study, the main agricultural areas in Xinjiang are taken as the research object. The abundance of microplastics in the main agricultural areas in Xinjiang ranges from 288 to 1452 items/kg. The shape of microplastics is mainly bulks, and white microplastics account for the highest proportion, and the majority of their sizes are less than 0.5 mm. The risk assessment results show that the contamination risk index of microplastics in this area is 108.92 and the risk level is grade III. The research shows that there is little difference in the abundance of microplastics between paddy field and garden land, which may be because there are few sources of microplastics in the land of these two utilization modes, and the potential pollution sources are similar, such as the atmospheric deposition of microplastics, the falling of fibers on people's clothes during farming, and the agricultural use of sludge. This study can provide a reference for further study on the existing circumstances of microplastics in agricultural areas.