Published online October 29, 2024
https://doi.org/10.5141/jee.24.016
Journal of Ecology and Environment (2024) 48:40
Sabah tuz Zohora1 , Shahida Arfine Shimul1
, Saifuddin Rana1
, Antar Sarkar1
, Sui Naing Aye Marma Milky1
, Khing Khing U Marma1
, Kaji Mohammad Sirajum Monir1
, Farhan Azim1
, Tapos Kumar Chakraborty2
and Sk. Ahmad Al Nahid1*
1Department of Fisheries Resource Management, Chattogram Veterinary and Animal Sciences University (CVASU), Chattogram 4225, Bangladesh
2Department of Environmental Science, Jashore University of Science and Technology (JUST), Jashore 7408, Bangladesh
Correspondence to:Sk. Ahmad Al Nahid
E-mail nahid83bau@gmail.com
This article is licensed under a Creative Commons Attribution (CC BY) 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ The publisher of this article is The Ecological Society of Korea in collaboration with The Korean Society of Limnology
Background: Ingestion of microplastics (MPs) by commercially important fish, such as Bombay duck (Harpadon nehereus) can lead to the transport of MPs to humans and negatively impact health and physiology. Thus, assessment of the presence, type, and features of MP in this species is necessary to understand the possible impacts and adopt management measures. The purpose of this study was to determine the presence, occurrence and physicochemical features of MPs in the gastrointestinal tract of Bombay duck (H. nehereus) from the Patenga Sea Beach of the Bay of Bengal, Bangladesh. This area faces high amount of plastic discharge from the Karnaphuli River, industries, tourists, and urban households. Ninety-six fish were collected from the fishing trawlers of the Patenga Sea Beach. Their total length, body weight was measured and gastrointestinal tracts were separated for analysis. The samples underwent digestion, density separation, measurement, microscopic observation, and quantification. The color, type, and size were observed with microscopic image analysis software and polymer composition was determined with Fourier transform infrared spectroscopy method.
Results: The total items of MPs ranged from 25 to 198 per fish with a mean of 98.34 ± 53.11. There was a significant difference in the items of MPs among different sized fish (H = 74.656, p < 0.05). A significant positive correlation (ρ = 0.952, p < 0.05) was found between total length of fish and the number of MPs. Total 05 colors, 04 types and 03 size classes were observed. Filament type, blue color, and 500 μm to < 1 mm sized MPs were dominant. Four (04) types of polymers, polyethylene, polyurethane, polyamide, and polystyrene, were found.
Conclusions: The findings and insights from this study will help to understand the nature and extent of MP pollution in commercially important marine fish and possible impacts on the environment and humans.
Keywords: Bay of Bengal, Bombay duck, fisheries, microplastic, Patenga Sea Beach
Microplastics (MPs) are plastic particles with less than 5 mm in size (Anderson et al. 2016; Avio et al. 2017). They can negatively impact aquatic organisms, environment, and human health and thus MP pollution has become a concerning issue worldwide (Akdogan and Guven 2019). Plastic trash degrades mechanically and thermally into pieces of various sizes and shapes (Andrady 2011; Barnes et al. 2009; Thompson et al. 2009) and takes the form of MPs. The primary drivers of the accumulation of MPs in the oceans include industrial manufacturing, agriculture, and landfilling of solid waste (Driedger et al. 2015; Vandermeersch et al. 2015). Primary and secondary MPs are the two categories of MPs (Karim et al. 2020). Primary MPs are commonly defined as ingredients required to create plastic products and the microbeads found in personal care and health goods (Duis and Coors 2016). The degradation and weathering of plastic objects are typically the source of secondary MPs (Geyer et al. 2017). The common polymers of MPs found in marine environments include polyvinyl chloride, polyethylene (PE), polyethylene terephthalate (PET), and polypropylene (PP) (Avio et al. 2015; EFSA CONTAM Panel 2016; Mercogliano et al. 2020).
MPs have been discovered in a range of habitats, including the oceans, deep-sea, oceanic trenches, rivers, and lakes (Kanhai et al. 2020; Lima et al. 2021; Villegas et al. 2021). Huge amounts of plastic use and irrational dumping of plastic waste is the prime cause of MP pollution. Approximately 275 million tons of plastic garbage are produced annually by coastal nations and 2%–5% of this waste ends up in the oceans (Jambeck et al. 2015). Release from various rivers causes a dumping of between 1.15 and 2.41 million tons of plastics into the oceans each year (Lebreton et al. 2017). Lighter plastics stay suspended in the water column or float on the surface, but denser plastics (> 1.02 g/cm³) settle on the ocean floor (Karim et al. 2020).
Plastic waste is a serious environmental issue due to its difficulties in decomposing (Barnes et al. 2009). MPs are highly persistent and hamper aquatic organisms and ecosystems (Guzzetti et al. 2018). Fish may intentionally consume MPs because MPs resemble small plankton and prey (Ory et al. 2017). Fish can accidentally consume MPs also when their prey adheres to or consumes MP particles (Jovanović 2017). Top consumers at the trophic level, such as marine mammals (Deudero and Alomar 2015) and humans (Crawford and Quinn 2017) may accumulate higher amounts of MPs through the food chain.
MPs are detrimental to organisms because they cause cell toxicity, change feeding and reproductive behavior, clog digestive tract, cause physical injury and inflammation, and lower the progeny survival rate (Cole et al. 2015; Prokić et al. 2019; Savoca et al. 2019; Strungaru et al. 2019). After being consumed by organisms, MPs may retain in their digestive tract or may pass through the stomach and exert negative physiological effects (Browne et al. 2008). MP pollution is an emerging concern for the aquatic environment and organisms of Bangladesh. In several parts of Bangladesh, including the Karnaphuli River estuary (Rakib et al. 2022: Shimul et al. 2023), Kutubdia (Siddique et al. 2023), St. Martin’s Island (Tajwar et al. 2022a) and Cox’s Bazar (Tajwar et al. 2022b), several studies have revealed a notable amount of MP pollution in water, sediment, and fish. There is an estimated health risk of consuming an average of 85,710.08 MP particles per year per capita among the people of Bangladesh (Sultan et al. 2023). Therefore, studies on MP pollution in water, sediment, and aquatic organisms are necessary.
The study area, Patenga Sea Beach, is situated 14 km south of Chattagram City, the port city of Bangladesh and this area is adjacent to the mixing zone of the Karnaphuli River and the Bay of Bengal (Dey et al. 2017). The Patenga region is one of the industrial hotspots of Chattogram for ports, navigation facilities, and fisheries. The area of the Bay of Bengal near the Patenga Sea Beach faces extreme pollution coming from the Karnaphuli River discharge, ship breaking debris, industrial wastage, and the dumping of garbage from Chattogram City (Shill et al. 2021). The area is significant for catching and selling commercially important marine fish. Among these fishes, Bombay duck (
Bombay ducks are consumed in both fresh and dried form. They are typically dried without processing and the gut contents are not removed most of the time (Hossain et al. 2019). Thus, the chances of MP exposure upon dried Bombay duck consumption remain high among its consumers. Bombay ducks swallow planktonic food, tiny fish, and aquatic organisms, and a large volume of water passes through their gills (Ghosh 2014). As a result, MPs retain in their gill rakers and MPs present in their prey or food reach their gastrointestinal (GI) tracts (Daniel et al. 2020; Prusty et al. 2023). Moreover, Bombay ducks serve as prey for larger carnivorous fish in marine environments where transfer and accumulation of MPs take place to higher trophic level organisms. Different studies revealed significant levels of MPs in the GI tracts of Bombay ducks (Hasan et al. 2022, 2023; Hossain et al. 2019; Prusty et al. 2023) but no study was conducted in the Patenga region. Therefore, the present study aimed to observe the occurrence, abundance, and physicochemical characteristics (type, color, shape, size, and polymer composition) of MPs in the GI tract of Bombay duck (
Ninety-six specimens of Bombay duck (
The method described by Avio et al. (2015) was followed with some modifications for this process. The separated GI tracts were taken in 800 mL beakers and 200 mL of 30% hydrogen peroxide (H2O2) was added to the beakers (Li et al. 2015; Su et al. 2016). Then, the beakers were covered with aluminum foil papers and placed in a thermal oscillator at 38°C and 80 rpm (revolution per minute) for 7 days.
The density separation was done to separate the MPs from organic matter and debris. The method described by Coppock et al. (2017) was followed with some modifications in this process. In each beaker, 250 mL of zinc-chloride (ZnCl2) (500 g/L) solution was added and the beakers were kept for 2–3 days or up to 7 days based on the state of organic matter settlement. The layers of MPs floated upwards, whereas undissolved organic residues and inorganic matters subsided at the bottom of the beakers. The supernatant from the density separator was filtered with a vacuum pump filter (Rocker 300; Rocker, New Taipei City, Taiwan) using cellulose nitrate filter paper (pore size: 0.45
The filter papers were examined under a stereo-microscope (B-192; OPTIKA srl, Ponteranica BG, Italy) at 40 × magnification. The presence of MPs was confirmed and the MP particles present on the filter paper were counted under microscope. The lengths of MPs were measured with the method described by Kovač Viršek et al. (2016) with some modifications. Images of the observed MPs were taken with a digital microscope camera (OPTIKA CB3) and the images were observed with “Optika Proview” software for determining types and measuring sizes of MPs. During the observation, MPs were distinguished from any debris following the guidelines by Hidalgo-Ruz et al. (2012). Information on the size, color, type, and shape of MPs was obtained from the microscopic observation.
The polymer composition of the collected MPs was determined with an Fourier transform infrared spectroscopy (FTIR) device (NICOLET IS20, Thermo Fisher Scientific, Waltham, MA, USA) in attenuated total reflection (ATR) mode within a spectral range of 500–4,000 per cm. The parameters in FTIR were fixed according to the manufacturer’s instructions in order to determine the transmittance percentage (%T). The polymer composition of MP was ascertained by carefully examining and analyzing the acquired spectral peaks in the FTIR device.
Fishes were collected, handled, transported, refrigerated, and thawed carefully to prevent any contamination or damage. All equipment, including Petri-dishes, scissors, scalpels, and forceps were rinsed with filtered water. The working place was cleaned and disinfected before and after work. Windows in the laboratory were kept closed during the experiment to prevent air-borne fibers and debris. Presence of airborne particle was observed using a blank filter paper. All the glassware was handled carefully and rinsed with filtered water. Only non-plastic equipment was used to avoid plastic contamination. Gloves and cotton lab coats were used and carefully cleaned after each use.
The collected data on the number of MPs and their physicochemical features were documented and categorized for statistical analysis. Statistical analysis was performed with Microsoft Excel (version 2019; Microsoft, Redmond, WA, USA) and IBM SPSS (version 26; IBM Co., Armonk, NY, USA). Kruskal–Wallis H test was performed to determine possible variations of MPs among the three size classes. Spearman correlation analysis was conducted to assess the relationship between TL (cm) and total item of MPs.
Total items of MPs ranged from 25–198 per fish with a mean of 98.34 ± 53.11 per fish. Highest total items per fish were found in the size class 3 (151.16 ± 33.95), followed by size class 2 (98.43 ± 21.36) and lowest in the size class 1 (45.50 ± 16.74) (Fig. 2). The Kruskal–Wallis H test revealed a statistically significant difference in the total items of MPs among the 03 size classes (H = 74.656,
Five (05) colors of MPs, black, blue, red, white and green, were observed. Among them, blue (36.95%) and black (31.71%) MPs were most dominant followed by white (15.66%) and red (8.28%), and green (7.41%) MPs were observed in lowest proportion (Fig. 4A).
Total 04 types of MPs were observed which were filament, fragment, granule and flakes (Fig. 5). Among these, filaments were mostly found (32.57%), followed by fragments (28.57%), granules (19.88%) and flakes were found in least proportion (18.98%) (Fig. 4B).
Three size classes of MPs, ‘500
Four different types of MP polymers, PE (37.8%), polyurethane (PU) (26.8%), polyamide (PA) (18.6%) and polystyrene (PS) (16.8%), were found in ATR-FTIR analysis. PE (37.8%) was the most abundant and PS (16.8%) was the least abundant type of polymer (Fig. 4D).
The present study observed the occurrence and physicochemical characteristics (type, color, shape, size, and polymer composition) of MPs in a commercially important marine fish, Bombay duck (
Various factors affect how easily fish can absorb MPs. Filter feeding fish are more likely to ingest MPs because they eat less selectively (Lusher et al. 2020; Wesch et al. 2016). Bombay duck swallow planktonic food, tiny fish, and aquatic organisms and large volumes of water pass through their gills (Ghosh 2014). As a result, gill rakers trap MP from water, and MPs already present in their prey are transported to their GI tracts (Daniel et al. 2020; Prusty et al. 2023).
Presence of MPs can vary with different size of fish. For example, the presence of MPs significantly varied (
Fish ingest more MPs as their size increases (Pegado et al. 2018). Presence of plastics in their surrounding environment can also play role in determining the ingestion of MPs (Carbery et al. 2018). Area-specific extent of plastic pollution can influence the occurrence and abundance of MPs in fish (Jabeen et al. 2017). Therefore, understanding which factors most influence MP ingestion in fish is crucial. Larger fish may move through various environments with higher plastic pollution levels than smaller fish. Their larger size means they filter more water through their gills while swimming and feeding, increasing their intake of MPs. Additionally, larger fish often consume more food and a wider variety of prey, which may have already ingested MPs, leading to secondary ingestion. These could be the reasons for the presence of higher number of MPs with increasing size of Bombay duck in this study.
Variation of the presence of MPs in fish can be interspecies and intraspecies. In case of interspecies comparison, MP contamination can vary with size, trophic level, different feeding habits, and digestive physiology (De Frond et al. 2021; Li et al. 2015). In case of interspecies comparison, the variation could come from different ages of specimens and different geographical locations (Bom and Sa 2021; Daniel et al. 2020).
In case of color of MPs, Prusty et al. (2023) reported similar dominant colors (black and blue) in
MPs come in a variety of types which affect their availability and occurrence in the aquatic ecosystem (Mithun et al. 2023). Among the four types of MPs found in this study, dominance of the filament type was compatible to the findings of Prusty et al. (2023) who reported thread or filament as the dominant type in
Different sources, polymer types, and degrees of weathering and breakdown processes produce various sizes of MPs in aquatic environments. In marine settings, larger MPs gradually break down into smaller particles through mechanical action, photo-oxidation, and biodegradation (Arhant et al. 2019; Tosin et al. 2012), resulting in a high abundance of smaller MPs. Recent studies, including Newell et al. (1995), Li et al. (2015), and Kumar et al. (2018), have reported the presence of MPs of various sizes in fish guts. Hossain et al. (2019) found that most MPs (35%–41%) in
The source of MPs can be predicted using the chemical composition (Abayomi et al. 2017). The polymer composition from ATR-FTIR analysis found in this study was compatible to the findings be Hasan et al. (2022) who found three different types of polymers - PE (35%–45%), PS (20%–30%), and PA (30%–45%) in the dried samples of
Upon the consumption of MPs, fish may suffer negative effects since the particles stay in their digestive systems for a long time and even cause death (Ory et al. 2017). In aquatic species, MPs can cause neurotoxicity and genotoxicity as well as interfere with immunological response, energy systems, and neurotransmission (Avio et al. 2015; Barboza et al. 2018). Moreover, exposure to MP may change the expression of important genes involved in several regulatory processes (Rochman et al. 2014). MPs can be transported along the food chain (van Raamsdonk et al. 2020). Drinking water and seafood are two major ways MPs can enter the human food chain (Bergmann et al. 2015; Gray et al. 2018). The potential risks of transfer of MPs to edible portions of fish and subsequent toxicity effects are highly problematic for humans because fish comprise a large portion of human diet (Neves et al. 2015). MPs can carry hazardous pollutants, such as heavy metals and toxic compounds (plasticizers, polychlorinated biphenyls, and polybrominated diphenyl ether) (Jaafar et al. 2021).
The study revealed the presence, feature, and extent of MPs in the Bombay duck (
This study found a significant level of MPs of different types, shapes, colors, sizes, and contents in the digestive tract of Bombay ducks (
Supplementary information accompanies this paper at https://doi.org/10.5141/jee.24.016.
Table S1. Total length and body weight data of
The authors acknowledge the laboratory officers and supporting staffs of the “Aquatic Ecology Laboratory” of Chattogram Veterinary and Animal Sciences University for their supports throughout this research. The authors are thankful to the Jashore University of Science and Technology (JUST) Bangladesh for the laboratory support for polymer composition analysis.
MPs: Microplastics
PE: Polyethylene
PET: Polyethylene terephthalate
PP: Polypropylene
TW: Total body weight
TL: Total length
GI: Gastrointestinal
FTIR: Fourier transform infrared spectroscopy
ATR: Attenuated total reflection
PU: Polyurethane
PA: Polyamide
PS: Polystyrene
EVA: Ethylene-vinyl acetate
STZ conceptualized the study and did research design sampling, laboratory analysis, data collection, and curation. SNAMM, KKUM, KMSM, and FA assisted in sample collection, laboratory analysis, and data collection. TKC helped in polymer composition analysis. SAS and AS wrote the original manuscript and edited and reviewed it. SR did the data analysis, visualization, editing, and reviewing. SAAN supervised the sample collection, laboratory analysis, project administration, resource procurement, supervision, reviewing, and editing. All authors read and approved the final manuscript.
The research was supported by the Chattogram Veterinary and Animal Sciences University (CVASU).
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
Not applicable.
Not applicable.
The authors declare that they have no competing interests.
![]() |
![]() |
![]() |
![]() |
![]() |
![]() |