Abundance, characteristics, and risk assessment of microplastics in indigenous freshwater fishes of India

Driving aspects of microplastic uptake: Influence in the Bentho-Pelagic ecosystem and its associated ecological risks along the coast of Goa, India

Microplastics (MPs) interference in bentho-pelagic system plays a crucial role in understanding its impact on marine health and ensuring seafood safety. This study was an initial attempt to understand the realistic perspective of how habitat and feeding behaviour of marine species can be the driving causes for MPs ingestion. A total of 251 individuals from 9 pelagic and benthic fish and shellfish species were studied in Goa's rich coastal ecosystem. Habitat wise higher MPs contamination was found in benthic realm (55 %) and sediment (2500 particles/kg d.w.) compared to pelagic realm (45 %) and water column (120 MP/L). Particularly, among finfish, Stolephorus indicus (8.8 ± 2.3 MPs/individual, pelagic) and Arius jella (10.1 ± 4.7 MPs/individual, benthic) emerge as prominent accumulators of MPs, while Meretrix meretrix showed the highest MPs concentration (3.3 ± 2.4 MP/g) among shellfish. Scrutinizing MPs in both gastrointestinal tract (GIT) and gills, MPs accumulated most in the GIT, indicating it as the primary ingestion pathway. High abundance of fibrous MPs (20-300 μm), mainly polyamide and polyester, indicated fishing activities and wastewater discharge could be the key pollution sources. In response to the risk assessment of MP's interference, Polymer Hazard Index (PHI >1000) were found considerably higher for certain polymers. Nutritional indices unveiled compromised Condition Index (CI) and Microplastic Index (MPI) in shellfish raising serious concerns due to their reduced nutritional values. Considering all possible factors contributing to MPs bioaccumulation, human consumption through shellfish was estimated to be ∼10,780 particles/person/year. Hence, this study provides insights on MPs contamination in seafood, highlighting its bioaccumulation, trophic transfer, and potential risks to coastal populations.

Microplastic and microfiber contamination in the Tiber River, Italy: Insights into their presence and chemical differentiation

Microplastics (MPs) are an emerging environmental concern, but studies on these contaminants, particularly in river ecosystems, remain scarce. Research has indicated that MPs in the environment are predominantly microfibers (MFs); however, a few studies suggest that the MFs encountered are chiefly of natural origin. In this study, we aimed to improve the understanding of MP/MFs (both plastic and natural), among microparticle (solid particles >10 μm to <5000 μm; mainly of plastic as well as natural origin) loads in the Tiber River, Italy, by analyzing the physicochemical properties of surface water and assessing the abundance and characteristics of MPs-MFs at three sites: Ponte Grillo, Aniene, and Magliana, along a 60 km stretch. MPs-MFs were visually inspected with a stereomicroscope and a fluorescence microscope and chemically characterized by FTIR. Interestingly, MP-MF concentrations were highest upstream at Ponte Grillo and lowest downstream at Magliana, an unconventional pattern likely related to atmospheric deposition and total suspended solids. Across sites, microparticles were mainly MFs, with MP fragments forming a minor fraction; at Ponte Grillo, Aniene, and Magliana, the MF abundances were 375.1, 58.1, and 28.8 items/L, respectively, while fragment abundances were 32.7, 14.4, and 4.8 items/L, respectively. At all sites, natural MFs (cellulose-based) were more prevalent than plastic ones (petroleum-based). The highest proportion of petroleum-based MFs, primarily PET, was observed at Magliana. Our findings indicate that although MPs-MFs in rivers stem from textile wear, laundry effluent, and WWTPs, atmospheric deposition is a dominant pathway, especially in remote, upstream, sparsely populated regions.

Microplastics in the benthic fish from the Canadian St. Lawrence River and Estuary: Occurrence, spatial distribution and ecological risk assessment

Microplastic contamination in the St. Lawrence River and Estuary (SLRE), Canada, poses potential risks to aquatic species. However, limited understanding of microplastic contamination in benthic fish, potentially more vulnerable than pelagic species, impedes effective risk assessment in this crucial ecosystem. This study addressed knowledge gaps by analyzing microplastics in the gastrointestinal tracts (GIT) and gills of Channel Catfish (Ictalurus punctatus) and Atlantic Tomcod (Microgadus tomcod) in the SLRE. Forty-two fish from ten stations were examined using KOH digestion, density separation, wet-peroxidation, and spectroscopy. Results indicated an average abundance of 3.0 ± 0.4 (mean ± SE) microplastic particles per individual fish. Most detected particles were small microplastics (<809 μm) and fibers, with blue and transparent colors. Major polymers identified included polyethylene terephthalate and polyethylene. While catfish showed higher microplastic abundances per individual than tomcod, data based on GIT weight do not support microplastic biomagnification in this predator-prey relationship. Catfish from downstream of Québec City showed elevated levels of microplastics and more variations in their characteristics compared to average abundance found from a site located 50 km upstream. Urban activity may increase microplastic accumulation in downstream benthic fish and others. This highlights the need for further studies on the migratory capacities of fish species. Ecological risk assessment revealed medium to high-risks for the catfish stations close to the Québec City due to the prevalence of smaller microplastics <809 μm and highly toxic polymers (polymethyl methacrylate, polyvinylchloride, polyurethane, acrylonitrile butadiene styrene). This study provides a baseline for monitoring plastic pollution in the SLRE fish and assessing ecological risks.

The role of habitat preference and feeding strategy on exposure to microplastic pollution in freshwater fish species

Microplastic (MP) pollution has been observed in a variety of ecosystems, but there is a limited number of studies on reservoir ecosystems. The aim of this study was to determine the levels of MP contamination in sediment, water and commercially important fish species (Cyprinus carpio, Perca fluviatilis, Atherina boyeri and Sander lucioperca) collected from the Yamula Reservoir in Türkiye. Water samples were collectes at five stations. Four sediment samples were collected from the lake. As sediments from the lake represent a vital element of the lake ecosystem, they function as a historical archive that reflects alterations in land use and the characteristics of the lake over time. The average amounts of MPs observed in sediment and water samples were 0.12 MP/g and 0.58 MP/m3 respectively. The digestive systems of 30 individuals of each fish species were examined. The highest amount of MP was observed for C. carpio (6 ± 5.9 MP/individual), while the lowest amount of MP was observed for A. boyeri (1.8 ± 1.7 MP/individual). MP abundance in S. lucioperca and P. fluviatilis was 2 ± 2.8 and 4.6 ± 6.3 MP per individual. The most commonly observed polymer types were polypropylene (67%), polyvinyl alcohol (13%), polyethylene resin (13%) and high-density polyethylene (7%). The pollution load indexes determined for each fish species from the highest to the lowest were as follows: 1.83 (C. carpio) 1.6 (S. lucioperca) 1.05 (P. fluviatilis) and, 1 (A. boyeri). The findings of the study indicate that all sampling stations, including both sediment and water, are contaminated with MPs. Furthermore, the results demonstrate that all examined fish species ingest MPs. Additionally, the results indicate that fish inhabiting a wide range of habitats and consuming diverse diets are more susceptible to MP contamination.

Temporal variability of microplastics in shrimp (Litopenaeus vannamei), feed, water and sediments of coastal and inland culture ponds

Aquaculture, particularly shrimp farming, is crucial for global food security. However, the increasing presence of microplastics (MPs) in marine environments, shrimp feeds, and atmospheric particles has made MP contamination in shrimp tissues inevitable. This study systematically investigates the abundance, characteristics, and temporal trends (from 15th to the 120th day of culture) of MPs contamination in Litopenaeus vannamei, along with associated feed, water, and sediment across 12 shrimp ponds of two major shrimp-producing regions of India. MPs were detected in 93.7 % of shrimp samples and all environmental matrices, with the highest abundance recorded in coastal culture ponds. The overall average MPs abundance in shrimp was 4.07 items/individual (1.24 MPs items/g). MP sizes ranged from 8 μm to 4.22 mm, with MPs smaller than 100 μm being predominant in shrimp samples, though their prevalence decreased over the culture period. Fragments and fibers were the dominant morphotypes across all matrices, with a shift towards larger MPs and an increased proportion of fibers and films over time. Micro FTIR analyses revealed polyethylene (PE) and polypropylene (PP) were the most common polymers detected, indicating their widespread environmental distribution. Feed was identified as the primary source of MPs contamination in shrimp. The presence of MPs in shrimp raises significant concerns for consumer health, food safety, and trade, as shrimp are among the most widely consumed aquatic food products. This study underscores the dynamics of MP contamination in shrimp aquaculture and highlights the urgent need for targeted strategies to mitigate contamination, ensuring consumer safety and industry sustainability.

Microplastic contamination in the aquaculture icon Oreochromis mossambicus: Prevalence, characteristics, and comprehensive overview

The global production of plastics has surged to 368 million tonnes annually, leading to significant plastic waste accumulation, projected to reach 12,000 Mt by 2050, impacting aquatic ecosystems. Fish, crucial for their protein and nutrients, are particularly vulnerable to microplastic (MP) ingestion. As a major aquaculture producer and fish consumer, India faces rising plastic pollution in freshwater, which disrupts fish health and growth, posing a significant threat to the sustainability and productivity of aquaculture systems and potential health risks. This study focuses on Mozambique tilapia (Oreochromis mossambicus), valued for its widespread aquaculture use, rapid growth, and nutritional benefits. Our research reveals significant MP contamination (69.23 %) in Mozambique tilapia, with over 80 % from the Ulhas River and 60 % from the Bhima River contaminated and females showing higher susceptibility. These findings emphasise the need for further research on MP impacts on human health and the development of mitigation strategies.

Are microplastics a new cardiac threat? A pilot study with wild fish from the North East Atlantic Ocean

Global environmental contamination by microplastics (MPs) is a growing problem with potential One Health impacts. The presence of MPs in vital organs, such as the heart, is of particular concern, but the knowledge is still limited. The goal of the present pilot study was to investigate the potential presence of MPs in the heart of wild specimens of three commercial fish species (Merluccius merluccius, Sardina pilchardus, and Trisopterus luscus) from the North East Atlantic Ocean. Heart samples from 154 fish were analysed for MP content (one heart sample per fish). A total of 44 MPs were recovered from heart samples from the three species. MPs had varied chemical composition (5 polymers), shapes (4) and colours (5). Differences in the profile of the MPs among species was observed (p ≤ 0.05). Thirty fish (19%) had MPs in their hearts, with a total mean (±SD) concentration of 0.286 ± 0.644 MPs/fish. S. pilchardus had the highest heart contamination (p ≤ 0.05). There were no significant (p > 0.05) differences between M. merluccius and T. luscus. These findings in fish with different biological and ecological traits together with literature data suggest that heart contamination likely is a disseminated phenomenon. Therefore, further research on the presence of MPs in the cardiovascular system and its potential health effects is very much needed.

The abundance and localization of environmental microplastics in gastrointestinal tract and muscle of Atlantic killifish (Fundulus heteroclitus): a pilot study

Microplastics (MPs) have been found in a diverse range of organisms across trophic levels. While a majority of the information on organismal exposure to plastics in the environment comes from gastrointestinal (GI) data, the prevalence of MP particles in other tissues is not well understood. Additionally, many studies have not been able to detect the smallest, most prevalent, MPs (1 µm - 5 mm) that are the most likely to distribute to tissues in the body. To address these knowledge gaps, MPs in the GI tract and muscle of Atlantic killifish (Fundulus heteroclitus) collected from two sites (Falmouth and Bourne) on Buzzards Bay, Cape Cod, MA were quantified down to 2 µm in size. Eight fish from Falmouth and 10 fish Bourne site were analyzed. Fourier-transform infrared spectroscopy and Raman spectroscopy were used to identify all particles. The mean concentrations of MPs in the GI tract and muscle from fish collected from Falmouth was 85.5 ± 70.2 and 11 ± 12.5 particles per gram wet weight, respectively. Fish collected from Bourne site had mean particle concentrations of 12.2 ± 18.1 and 1.69 ± 5.36 particles per gram wet weight. Of the 2,008 particles analyzed in various fish tissue samples, only 3.4% (69 particles) were identified as plastic; polymers included nylon, polyethylene, polypropylene, and polyurethane. MPs detected in the GI tract samples also tended to be more diverse in both size and polymer type than those found in the muscle. We found that MPs < 50 µm, which are often not analyzed in the literature, were the most common in both the GI tract and muscle samples. There was not a significant correlation between the MP content in the muscle compared to the GI tract, indicating that GI tract MP abundance cannot be used to predict non-GI tract tissue MP content; however, MP abundance in muscle correlated with fish total length, suggesting potential bioaccumulation of these small MPs.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s43591-024-00101-w.

Microplastics abundance and potential ecological risk assessment in sediment, water and fish of Deepor Beel-a Ramsar Wetland of the Brahmaputra plain, India

Microplastics (MPs) are increasingly recognized as environmental contaminants with complex impacts on fish and other aquatic organisms. This study determined the microplastics abundance and the induced-ecological risks of microplastics in water, sediment, and commonly harvested fishes of a Ramsar site, Deepor Beel of Assam, India. Six samples of water and sediment were collected with nine individuals of two commonly harvested fish species Puntius sophore (Pool Barb) and Gudusia chapra (Indian River Shad). The abundance of microplastics in water and sediments were analyzed through organic matter digestion using hydrogen peroxide (H2O2, 30%) and sodium chloride (NaCl) for density separation. Potassium hydroxide (KOH, 10%) was used for digestion of fish gut. The microplastics were identified visually and chemically characterized through micro-Raman spectroscopy. Total 467 microplastic particles in water and sediment, and 62 particles in fish were identified. An average concentration of 0.55 ± 0.06 particles/L in water, 4.03 ± 0.41 particles/100 g in sediment samples, 3.83 ± 2.26 particles/individual in Puntius sophore, and 6.5 ± 3.40 particles/individual in Gudusia chapra were detected. Fibers accounted to the major shape of microplastic in water (54%) and sediment (50%), whereas fragments (65%) were the major shapes detected in both fishes. The color composition includes blue, black, red, green, brown, yellow, and transparent. Fiber particles size ranged between 150 and 1782 µm, fragments within 85-325 µm, and sphere within 85-220 µm. Chemical characterization of microplastics revealed polymer types including polypropylene (PP = 27%), polyvinyl chloride (PVC = 25%), acrylonitrile-butadiene-styrene (ABS = 18%), polycarbonate (PC = 13%), polyethylene (12%), and polystyrene (PS = 5%). PHI levels were at hazard level III and V for water and sediment samples and at level IV for both fish species. The PLI at hazard level I indicated low pollution levels, whereas the PERI were within danger and extreme danger levels. This study is the first report in abundances of microplastics and the ecological risk assessment of microplastics in surface waters, sediments and fishes of Deepor Beel wetland.

Microplastics in different tissues of historical and live samples of endangered mega-fish (Acipenser sinensis) and their potential relevance to exposure pathways

The Chinese sturgeon (Acipenser sinensis) is an endangered freshwater mega-fish (IUCN-red listed) that survives in the Yangtze River Basin, but the population of which has declined significantly in response to environmental pressures generated by human activities. In order to evaluate the interaction between Chinese sturgeon and microplastics (MPs) for the first time, we examined the gut and gills of historical samples (n = 27), in conjunction with the blood and mucus of live samples (n = 10), to explore the potential pathways involved in MP uptake. We detected MPs in 62.9 % of the field fish, with no significant difference between guts (mean=0.9 items/individual) and gills (mean=0.8 items/individual). The abundance of MPs in fish from 2017 was significantly higher than that from 2015 to 2016 with regards to both gills and gut samples. The size of MPs in gills was significantly smaller than those in guts, yet both contained mostly fibers (90.2 %). No MPs were confirmed in blood, however 62.5 % of mucus samples contained MPs. The MPs in mucus indicated the possibility of MPs entering Chinese sturgeons if their skins were damaged. The body size of Chinese sturgeons affected their MPs uptake by ingestion and inhalation, as less MPs were detected in the gut and gills of smaller individuals. Combining the evidence from historical and live samples, we revealed the presence of MPs in different tissues of Chinese sturgeon and their potential relevance to exposure pathways. Our work expands the understanding of multiple exposure pathways between MPs and long-lived mega-fish, while emphasizing the potential risks of long-term exposure in the field.

Exploring luminescent carbon dots derived from syrup bottle waste and curcumin for potential antimicrobial and bioimaging applications

In this study, we utilized a navel hybrid material, prepared by fusing fluorescent Carbon Dots SyCDs, derived from syrup bottles, with curcumin. This innovative approach not only offers significant advancements in antimicrobial activity and bioimaging but also represents a stride in sustainable and eco-friendly nanotechnology. The core of our study is the development of an efficient, cost-effective, and environmentally conscious method for synthesizing SyCDs. This is achieved by repurposing waste syrup bottles, thus addressing the pressing issue of plastic waste. The incorporation of curcumin, renowned for its biological properties, enhances the luminescent characteristics of SyCDs and augments their functionality. This combination overcomes the inherent limitations of curcumin when used in isolation. The hybrid material exhibits enhanced antimicrobial properties and proves to be a potent alternative to conventional fluorescent dyes for bioimaging, marking a substantial leap in the field of sustainable nanomaterials. Our work not only demonstrates the versatile applications of luminescent SyCDs in health and environmental science but also underscores the potential of sustainable approaches in addressing global environmental challenges. This study, represents a significant contribution to the domain of sustainable nanotechnology, highlighting the transformative power of integrating waste management with advanced material science.

Microplastics Contamination in the Edible Fish Mozambique Tilapia (Oreochromis mossambicus) from the Selvampathy Wetland of Coimbatore, Tamil Nadu, India

The present study investigated the microplastics (MPs) contamination in the gastrointestinal (GI) tract, gills and muscle of the Mozambique tilapia, Oreochromis mossambicus sampled from the Selvampathy Lake of Coimbatore, Tamil Nadu. MPs abundance was found in 10 to 28, 8 to 27, and 4 to 12 particles and their size ranged between 4.4 and 210, 4.6 to 180, and 4.5 to 194 μm in the GI tract, gills and muscle, respectively. MPs were dominantly shaped as fibres (95%) and fragments (5%) with the following colour pattern of blue > black > pink > transparent > and others. Extracted MPs polymer nature were polyethylene (54%), polyamide (38%) and polypropylene (8%). The present study reveals that the edible fish O. mossambicus had MPs that can be transferred to consumers. Moreover, urban discharges, including domestic wastes, agricultural and rainwater runoff, might be possible MPs sources to the studied wetland.

Assessment of microplastic contamination in the gastrointestinal tracts of indigenous fishes from north eastern hill regions of Bhogdoi, a tributary of River Brahmaputra, India

Microplastic (MP) pollution in freshwater environments has drawn considerable attention over the decades due to the risk posed by MPs to the aquatic fauna and human health. In this study, the occurrence of MPs was assessed from the gastrointestinal tracts (GIT) of indigenous fishes from Bhogdoi River, a tributary of River Brahmaputra, northeast hill region, Assam, India. All the fish species (n = 180) analysed showed 100% occurrence of MPs sampled from three stations of River Bhogdoi. A total of 488 microplastic particles were recorded from GIT of fishes collected. The mean abundance of MPs was highest in Station-II (7.64 ± 2.77 numbers individual-1) with lowest in S-I (3.17 ± 0.99 numbers individual-1). The MP size of 100-500 μm, MP shape of fibre (43.33%) and fragments (35.33%), blue colour MPs (26-37%) and polymer type PA (23-30%) were most prevalent in fishes analysed from River Bhogdoi. The mean abundance of MPs was higher in herbivore fishes (8.52 ± 1.22 numbers individual-1) as compared to carnivorous and omnivorous fish species with highest abundance in Labeo rohita (12.11 ± 2.13 numbers individual-1). Fibre and fragments with size range of 100-500 μm were dominant among all the feeding habits. Blue and black colour MPs were abundant among herbivore and carnivore fishes. Fourier transform infrared spectroscopy results confirmed that polyamide and polypropylene were the most abundant MP polymer in the fishes analysed. The present study provides baseline information of MPs in River Bhogdoi, Assam, for its future monitoring and assessment of contaminants.

Characterization of microplastics in digestive tract of commercial fish species from the Oman Sea

Microplastics (MPs) content of the digestive tract of two commercial fish from the northern shores of the Oman Sea were investigated. The MPs were characterized by optical microscopy, fluorescent microscopy, and SEM-EDX for their number, shape, size, and color. Polymer composition was analyzes using micro-Raman spectroscopy (RMS). MPs were recovered in all fish samples (100 %), with an average of 43.16 ± 8.23 items/individual in Otolithes ruber, and 29.9 ± 2.73 items/individual in Acanthopagrus latus. The predominant shape of MPs in both fishes was fiber (46 %) with black, transparent, and white colors. The majority of MPs were <1000 μm (75 %), and half of the MPs were smaller than 300 μm in size. Their synthetic nature was confirmed by Nile Red staining and determination of the elemental composition of selected items. Polypropylene (PP) and polyethylene (PE) were the dominant plastic polymers in the fish digestive tracts. This study reveals abundance distribution of MPs in digestive tract of commercial marine fish. High number of ingested MPs can alarm the accumulation of MPs in the northern of Oman Sea ecosystem with anthropogenic activities and raises issues in public health.

Microplastics in the River Ganga and its fishes: Study of a Himalayan River

The River Ganga has been explored for microplastics (MPs) majorly in the lower or middle course, while the upper course from where the river starts its journey remains untouched. This study investigates the occurrence and distribution of MPs in the river environment (water and sediment) and common fishes inhabiting the upper stretch of River Ganga in the Uttarakhand state of India. A volume-reduce method by using sieve filtration was used to take water and sediment samples from the study area while fish samples were collected using net method. The samples underwent alkali digestion, microscopic examination, and chemical analysis using Fourier Transformed Infrared Spectroscopy (FTIR). An average of 118.5 ± 49.65 particles per 1000 L and 131.5 ± 53.60 particles/kg dry weight were found in water and sediment respectively. While in the fishes, Tor tor, Schizothorax richardsonii, Labeo dero and Gara gotyla gotyla MPs were 53.13 ± 63.77, 36.33 ± 22.34, 15.42 ± 9.33 and 12.63 ± 5.93 particles/individual respectively. A positive correlation was observed between the number of MPs in fish and their body length, weight, and gut weight, while no correlation was found between feeding habit and MP accumulation. The majority of MPs detected were fibers ranging from 100 μm to 1 mm in size. Polymer types varied among water, sediment, and fish samples, with polyethylene (PE) predominant in water, polypropylene (PP) dominant in sediment, and polyethylene terephthalate (PET) and polystyrene (PS) most abundant in fish samples.

Microplastics in lentic environments: implications for Indian ecosystems

The paper focused on occurrence, characterization, and analytical methods of microplastic (MP) pollution in the lentic environment mainly for the Indian scenario. To understand the flow of MP from plastic waste, a material flow diagram was developed using STAN, assigning the transfer coefficients based on existing scientific literature and primary survey from local recycling facilities and industries. The quantity, morphology, and polymers of MP in the water and sediments of the lentic environment were compared for various states from 2011 to 2022. The reasons for the geographical heterogeneity in microplastics may be the migratory routes of MPs in the ecosystems like commercial uses and wastewater characteristics which possibly discharged in lentic system. Factors like particle density, water surface area, water surface depth, wind speed and direction, and water flow size mainly affect MP concentrations in the lentic water body, and mainly PHI and PLI are keys to MP risk analysis. The surface characteristics of MPs reveal that it absorbs many toxic contaminants including heavy metals. The impacts of MP on ecosystem and human health were also discussed. The impacts of socioeconomic conditions on MP concentrations for different states in India were also added. Proposed methods for plastic waste generation control also included which will help for developing policy in future to prevent MP pollution in lentic environments and also motivate future researchers to establish new standardized methods of MP analysis.