Microplastic Contamination in Shrimps from the Negombo Lagoon—Sri Lanka

Abstract

Microplastic (MP) pollution is a serious global issue affecting freshwater systems, coastal regions, and oceans. These non-biodegradable materials have a detrimental impact on marine species and ecosystems, disrupting their feeding, breathing, and reproduction. In this study, 120 samples of two species of shrimp, Penaus monodon and Penaus indicus, from ten locations in the Negombo lagoon in Sri Lanka were analyzed. MPs were extracted from gastrointestinal tracts (GI) and gills (GL) by alkali digestion followed by vacuum filtering. Stereomicroscopy coupled with advanced micro-imaging and analysis software was employed for analyzing the isolated MPs. A total of 415 items were identified as MPs with an average of 8.29 ± 4.63 items per gram of GI and GL in Penaus monodon and 5.52 ± 3.78 items per gram of GI and GL in Penaus indicus. The majority of MPs identified were fibers (93%), and the remaining ones were fragments. Most of the MPs were >1000 μm, and the most prevalent color was blue (61%), followed by red (15%), black (9%), and others, comprising polystyrene, polyamide, polyester, polypropylene, and rayon, as revealed by FTIR spectroscopy. This study highlights the prevalence of MPs in shrimps harvested from the Negombo lagoon and displays missing baseline data before the effects of fragmented nurdles from the X-Press Pearl incident.

1. Introduction

Due to its low production cost, durability, and flexibility, demand for plastic has remained high since its original manufacture. In 2022, over four hundred million tons of plastic were produced globally [1], much of which will enter mismanaged waste streams or be littered in the environment [2]. Once in the environment, plastic’s durability is no longer desirable and ensures it persists in the environment indefinitely, negatively impacting ecosystem services [3] and biota [4]. In the environment, litter can fragment into smaller pieces, eventually forming microplastics (MPs) that are below 5 mm in length. They can be divided into main and secondary MPs according to according to their origin. To be more precise, primary MPs are defined as those that have a diameter of less than five mm at the time of production, while secondary MPs are created when bigger plastic components gradually deteriorate due to processes like UV radiation or photo-oxidative degradation [5]. Moreover, MPs come in a variety of sizes, colors, and shapes. Fiber, film, fragment, and granule shapes are among the most commonly observed MP shapes [6]. Due to their small size, MPs are readily ingested by various marine species [7] and can impact development, feeding, breathing, and reproduction [8] and can even be fatal. Concerns regarding MPs, however, expand beyond ingestion since they can act as transport vectors for other contaminants, such as persistent organic compounds, heavy metals [9,10], and pathogens [11]. MPs can also penetrate the food chain through the consumption of contaminated fish and food products, potentially causing harm to human health [12,13]. Moreover, several studies have shown that MPs induce both intracellular and extracellular reactive oxygen species (ROS) in aquatic organisms. ROS can cause lipid peroxidation, protein oxidation, DNA damage, and a compromise in the antioxidant defense system [14,15,16].

Commercial species, such as fish and shellfish, are vulnerable to direct and indirect ingestion of MPs. MPs can be ingested with targeted predation, with evidence of color preferences in some visual predators [17,18], as well as passively through the intake of contaminated water [19]. The digestive tract and gills were often investigated for MPs in the biota as ingestion and respiration are considered the most common routes of exposure [20,21], and gutting the fish will reduce human exposure compared to eating it whole. However, small shrimps and bivalves like clams, mussels, and oysters are exempt from this rule. Crustaceans are particularly susceptible to consuming microplastics due to their varied eating habits, which include scavenger, deposit feeder, suspension feeder, and predator. It is a frequent practice to ingest edible meat combined with a piece of the digestive tract, raising the chance of a health risk. It is known that smaller microplastics are more abundant in the environment [22], with smaller items being more widely bioavailable [23]. Thus, biotas are likely to readily ingest microplastics passively [24] and possibly actively through mistaken identity as prey [17,18,25]. While the effects of MPs on human cells and tissues are still mostly unknown [23,26], some authors have pointed out that MPs can enter the respiratory, digestive, and circulatory systems of humans. They can also function as physical and chemical stressors to these systems, and they have been linked to several diseases, including diabetes, obesity, endocrine disruption, cancer, cardiovascular disease, problems with reproduction, and developmental issues. Consequently, the collective well-being of individuals is undeniably threatened by the onset of these disorders, emphasizing the urgent need for a comprehensive understanding of the implications of microplastic exposure on human health [27,28,29,30].

The sea has traditionally been essential to the economic and nutritional security of the people of Sri Lanka. The fact that Sri Lanka is an island nation in the Indian Ocean gives it a distinct advantage when it comes to being a destination for procuring seafood. About half of all export revenue from Sri Lankan fisheries comes from the export of farmed shrimp. Over 90% of the cultivated shrimp that are collected are exported, with the majority heading to Japan, the US, and EU nations [31]. The Negombo lagoon is a coastal lagoon located in the south-west of Sri Lanka, which has a diverse ecosystem, including mangroves and seagrass beds. The lagoon is also an important breeding ground for shrimp, which is a valuable fishery resource for the local community. However, the Negombo lagoon is also subject to anthropogenic pressures, such as untreated sewage discharge and solid waste dumping [32], which can contribute to the presence of microplastics in the lagoon ecosystem. Additionally, a fire aboard the cargo ship MV X-Press Pearl, which was anchored in May 2021 with a nitric acid leak, nine nautical miles northwest of Colombo in the Sri Lankan Sea, released 1680 tons of nurdles [33]. This is the worst chemical and plastic-based marine disaster from a single vessel in Sri Lanka’s maritime history. The main environmental concerns this event has raised are a massive distant black smoke plume emanating from the fire and a potential release into the ocean of 15 dangerous goods from the ship, including 25 metric tons of nitric acid. Large amounts of plastic pellets, cargo, and other debris from the ship have been washing ashore along Sri Lanka’s west coast, most notably in Negombo [34]. While the X-Press Pearl disaster took place in May 2021, there are limited reports of microplastic abundance and ingestion since, with no baseline data before the spill. Shrimps in the area are likely only to ingest the smallest microplastic particles, with Penaeus species ingesting prey items below 1 mm [34]. While plastics fragment in the environment, this is typically a slow process and it will take several years for the spilled nurdles to fragment to a bioavailable size for many organisms [35]. Thus, the data collected in the present study can be considered baseline data for microplastic ingestion prior to the X-Press Pearl disaster.

The X-Press Pearl environmental emergency highlighted the lack of baseline data for microplastics in Sri Lanka. Immediate effects from the high dose released in the spill are obvious, with turtles and cetaceans stranded on Sri Lanka’s coastline with stomachs containing nurdles [36]. Due to their size, however, nurdles cannot be ingested by a large fraction of marine biota. Nevertheless, these pellets pose a severe health risk as they will fragment over time. It is vital to collect the missing baseline data before the effects of fragmented nurdles are felt. To date, no studies have investigated the presence of microplastics in shrimps harvested from the Negombo lagoon. As shrimps are an important aquatic organism consumed by humans in the region, it is essential to understand the extent of microplastic contamination in this organism to assess the potential risks to human health. Furthermore, baseline data can go on to inform future research directions and monitoring programs. Without these data, it is impossible to determine the long-term repercussions of the spill, and this makes measuring the effectiveness of future policy interventions or mitigation practices difficult.

2. Materials and Methods

2.1. Sample Collection and Processing

Fresh samples of two species of shrimps, Penaeus monodon (n = 25) and Penaeus indicus (n = 95) were collected from ten locations (12 samples from each site) in the Negombo lagoon, western province of Sri Lanka on 12th September 2022. The collected samples were placed in an icebox and transferred to the Laboratory of Environmental Studies division of the National Aquatic Resources Research and Development Agency (NARA) and preserved at −20 °C until further processing and analysis. The specimens of preserved shrimp were defrosted in a metal tray and rinsed with Milli-Q water (Merck, Millipore, Burlington, MA, USA). Body measurements were recorded, including total body weight (wet weight), total length, ocular length, and carapace length. Shrimps were deshelled and dissected with a metal scalpel and forceps; then, the gastrointestinal tract (GI) and gills (GL) were isolated and weighed. (According to previous studies, it has been proven that MPs in most marine animals including shrimps are concentrated in the aforementioned tissues [37,38,39,40]).

2.2. Tissue Digestion and Filtration

Separated tissues were carefully transferred into separate glass bottles, and 20 mL of 10% (w/v) KOH (Sigma-Aldrich, Saint Louis, MO, USA) was added to each of the glass bottles and stoppered, after which the bottles were kept in an oven (GALLENKAMP, Loughborough, UK) at 60 °C for 24 h. Then, the bottles were kept in an orbital shaker (Scilogex SK-0330-Pro, Rocky Hill, CT, USA) at 150 rpm for 24 h. at room temperature. After this, they were allowed to cool to room temperature. Digested samples were vacuum filtered using nitrocellulose membrane filters with 0.45 μm pore size and 47 mm diameter. Filter papers, while still in the filtration system, were covered with a small volume (0.5–1 mL) of 0.01 mg mL⁻¹ Nile red dye (Sigma-Aldrich, Saint Louis, MO, USA) prepared in reagent grade ethanol (Sigma-Aldrich, Saint Louis, MO, USA) and left to stand for 5 min. Then, Milli-Q water (Merck, Millipore) was passed to eliminate the unbound dye [41,42], and filters were allowed to dry out. Each filter paper was stored after filtration in separate, clean Petri dishes with lids for subsequent microscopic analysis.

2.3. Identification and Characterization of Microplastics

Sample identification was performed using a stereomicroscope (Euromex StereoBlue SB.1902-P, Euromex Microscopen bv, Arnhem, The Netherlands) with the lowest detection limit of 10 μm. Herein, the samples extracted on filter papers were placed on the stage plate of the stereomicroscope equipped with a fixed microscope adapter (DC 1355 F050) and observed under blue light (470 nm) with an orange filter to identify the possible microplastics. Microplastics were identified using ImageFocus Plus version 2.2.0 (Euromex Microscopen bv, Arnhem, The Netherlands) software, and photographs were taken according to their physical characteristics. MPs were identified and categorized based on their size, color, type, and composition. In order to measure the size of MPs, for fibers, length was considered, whereas, for the fragments, average height and width were considered. Microplastics were visually identified with a binocular microscope (Leica MZ10 F microscope with a GXCAM-U3PRO-20 camera adapter, Leica Microsystems, Wetzlar, Germany) with a subset selected for polymer identification with FTIR. Suspect polymers were transferred to a Whatman anodisc (VWR, Leicestershire, UK) with a 25 mm diameter and 0.2 m porosity for FTIR examination. The anodics were dried in a drying cabinet (100 L S/S, LTE, Manchester, UK) at 40 °C for at least 24 h. A Lumos II FTIR (Bruker, Billerica, MA, USA) was used to identify polymers. A subset of particles was chosen and analyzed with ATR-FTIR and a liquid nitrogen-cooled MCT detector. In reflectance mode, 32 scans were acquired with a resolution of 4 cm⁻¹ in the range of 4000–500 cm⁻¹ [43]. The polymer composition of the MP fragments with a size >1 mm was identified using ATR-FTIR (ALPHA Bruker, Billerica, MA, USA) in the range 500–4000 cm⁻¹ with 32 scans and resolutions of 4 cm⁻¹. The percentage of the matching score against polymer databases was used to confirm polymer identification (ATR-FTIR-library complete, vol. 1–4; Bruker Optics ATR-Polymer Library; IR-Spectra of Polymers, Diamond-ATR, Geranium-AT and IR-Spectra of additives, Diamond-ATR). Only matches greater than 60% probability were chosen for positive microplastic confirmation and polymer identification.

2.4. Quality Control

The samples were collected, prepared, and observed using glass and metallic materials. Prior to use, all the materials were rinsed with Milli-Q water, and then dried in an oven at 70 °C. Throughout all processes, cotton lab coats and apparel were worn, and 70% ethanol (Sigma-Aldrich, Saint Louis, MO, USA) was utilized to clean the workspaces. To account for potential contamination during the entire procedure, procedural blank samples (n = 4 for each batch) free of tissues were created for each batch of samples. To check for potential contamination, atmospheric blanks (two nitrocellulose membrane filters in clean Petri dishes) were also utilized at each stage of the procedure separately for all sampling sites (a total of 20 blank experiments). The average contamination recorded in the atmospheric blanks was removed from each sample prior to statistical analysis.

2.5. Data Analysis

Visual counts of microplastics were used to calculate the number and mean number of MPs per individual and per gram (of the tissue and the whole organism). Additionally, MPs were described by shape, color, polymer, and size. The percentage abundance of each is reported. Since the data from this study were not normally distributed, a Kruskal–Wallis test was used to evaluate differences in MP distribution between sampling sites. Spearman correlation was performed to know the associations between MP abundance and GL + GI/body weight. The association between the size of MPs and shrimp species was studied using the Chi-square test. All statistical tests and chart designs were conducted using SPSS-Version 28.0 (IBM Corporation, New York, NY, USA). Map diagrams were created using ArcGIS (Esri, Redlands, New York, CA, USA) (Figure 1).

3. Results and Discussion

3.1. Abundance of Microplastics

From the total of 120 samples, 415 MPs were detected in this study (Figure 2). Further, there was no MP identified in atmospheric blanks. The average number of MPs per individual for P. monodon was 4.72 ± 2.72, and that for P. indicus was 3.13 ± 2.04. Furthermore, the average number of MPs per gram of GL and GI weight for P. monodon was 8.29 ± 4.63 items per gram, and that for P. indicus was 5.52 ± 3.78 items per gram (

Table 1. MP abundance in separate sampling sites and morphological characteristics of shrimps.

Sampling Site	Sample Count		MPs per Gram of GL and GI Weight—(g)−1	Identified MPs Count	Body Weight—(g)	GL + GI Weight— (g)	Total/Extended Length—(mm)
	P. monodon	P. indicus
L1	2	10	9.54 ± 4.61	61	4.99 ± 0.86	0.53 ± 0.02	78.83 ± 4.70
L2	2	10	10.42 ± 3.93	69	5.35 ± 2.98	0.55 ± 0.03	84.25 ± 11.25
L3	3	9	5.71 ± 3.45	38	5.57 ± 1.04	0.54 ± 0.03	89.5 ± 6.02
L4	1	11	3.94 ± 2.88	26	5.42 ± 0.89	0.54 ± 0.02	93.75 ± 13.28
L5	0	12	4.17 ± 1.80	28	5.51 ± 0.55	0.55 ± 0.04	89.25 ± 10.28
L6	4	8	4.34 ± 2.63	29	5.50 ± 0.44	0.55 ± 0.01	97.33 ± 7.90
L7	2	10	5.12 ± 1.44	34	5.92 ± 0.67	0.55 ± 0.01	94.25 ± 13.90
L8	4	8	5.09 ± 2.95	34	5.32 ± 0.69	0.55 ± 0.02	87.66 ± 12.98
L9	4	8	5.90 ± 3.93	40	5.62 ± 0.69	0.55 ± 0.03	83.58 ± 9.60
L10	3	9	8.12 ± 5.32	56	5.80 ± 0.57	0.57 ± 0.57	83.83 ± 10.53

). Major morphometric parameters, which are total body weight and total/extended length for P. monodon, were 5.80 ± 2.82 g (mean ± SD) and 85 ± 19 mm, respectively; those for the P. indicus were 4.91 ± 2.31 g and 81 ± 23 mm.

The results revealed that the highest MP abundance was examined at the sampling site L2, whereas the lowest abundance was noticed at site L4. Asymptotic significance (df = 9; p < 0.001; test statistic = 32.779) is displayed in the hypothesis testing of the independent samples Kruskal–Wallis test, indicating at least two groups/sites are significantly different in terms of MP abundance. Box and whisker plots generated using significance test results indicate that groups 5, 7, 9, and 10 have potential outliers that could cause significant differences between the groups (Figure 3). In order to check the significance of outliers, Tukey’s outlier test (α = 0.05) was performed for each sample site. Out of five outliers, only one sample from L10 was identified as a significant outlier, which may have remarkably affected the shift of the mean MP content to a higher value. Furthermore, a pairwise comparison of sample sites performed under the Kruskal–Wallis test (significance values have been adjusted by the Bonferroni correction for multiple tests) revealed that there is a significant difference in MP abundance between sites L4 and L1 (p = 0.04), L4 and L2 (p = 0.004), L5 and L2 (p = 0.009), and L6 and L2 (p = 0.019). However, it is interesting to note that sampling sites L1, L2, and L10, which show the highest levels of MP contamination, are located closer to the heart of Negombo city, which contributes the greatest anthropogenic influence on the lagoon.

Since the weight of GL + GI weight and body weights were similar between both two species (according to the t-test performed (α = 0.05), for body weights; p = 0.09, for GI + GL weight; p = 0.08), it was possible to carry out a correlation analysis. According to the Spearman correlations, there was a positive correlation observed between the GL + GI weight and MP content (r_s (118) = 0.249, p < 0.01), but there was no significant positive/negative correlation observed between body weight and MP content. (r_s (118) = −0.048, p < 0.01) A heavier gut suggests more food has been consumed. It therefore makes sense that more feeding leads to more exposure to MPs. A lack of correlation with body weight might suggest body condition is not affected by MP ingestion—or that MPs are not retained long enough to cause an impact.

3.2. Sizes of Microplastics

In this study, identified MPs were categorized into five groups, 10–100 μm, 100–250 μm, 250–500 μm, 500–1000 μm, and >1000 μm (Figure 4). Out of the five groups, the size of most of the MPs identified from both shrimp species was under the category of >1000 μm. The sizes recorded in the present study are in line with those of previous observations. In the Bay of Bengal, Bangladesh, P. monodon was found to have mostly ingested MPs between 1 mm and 5 mm [15]. In the present study, P. monodon contained 78 (66%) MPs larger than 1000 μm, with 27 (23%) between 500 and 1000 µm, 9 (8%) between 250 and 500 µm, and 4 (4%) MPs in the size range of 100–250 µm. In contrast, P. indicus shrimp had 172 (58%), 91 (31%), 26 (9%), and 8 (3%) MPs under the size categories of >1000 μm, 500–1000 μm, 250–500 μm, and 100–250 μm, respectively. It is important to note that no MPs were identified with a size between 10 μm and 100 μm. This may be caused by the rapid elimination of those very minute MPs from the gills and guts with the flow of water and ingested foods, respectively. Some long fibers were observed in entangled form, suggesting that those fibers remained for a significant time inside the guts or gills of the animal, mainly due to their longer size. According to a previous study, the average level of microplastics in Negombo lagoon’s surface waters varied from 0.86 to 4.29 items m⁻³, with a mean level of 2.46 ± 1.13 items m⁻³. In surface waters, fragments (40.0%), and 2500–1000 μm (41.0%) were the most observed MP types and sizes [5]. Similar observations were reported based on a study in Victoria Australia (Table 2). Accordingly, the mean diameter of MPs in water was found to be in the range of 0.036 to 4668 μm (mean = 942 ± 835 μm), and that in shrimp was 190 to 4214 μm (mean = 764 ± 575 μm) [22]. Further, according to, the Chi-square test performed in this study, the MP size proportion distribution was not significantly affected by the species investigated (χ2 = 2.997; df = 3; p = 0.392).

3.3. Color of Microplastics

In this investigation, MPs under six color categories were observed, the most prevalent of which was blue (61%), followed by red (15%), black (9%), white/transparent (5%), yellow (4%), green (3%) brown (2%) and orange (1%) (Figure 5). Substantial variations could be seen in the distribution of colors of observed MPs in examined sampling locations. Similar variation is reflected in surface water samples analysis by a previous work, where 32.0% were blue. However, for sediment samples, the majority of identified particles were transparent (44.0%) [44].

Blue was the most common color of MP found at all sites, with over 75% of recovered MPs at sites 3, 4, and 7 being blue. Due to their morphological resemblance to natural food products, MP particles may be consumed directly or indirectly through the adherence of MPs to the food particles. Because plastic particles visually resemble their native food or prey, they have an impact on their bioavailability [17].

3.4. Types and Shapes of MPs

In this study, two main types of MPs were identified, fibers and fragments, but no MPs with the shape of films or spheres were identified. The predominant form of MPs was fiber (93.0%), followed by fragments (6.99%) (Figure 6). No nurdle particles were able to be identified during the study. The shrimps’ high fiber content suggests that the MP contamination of the shrimps was not greatly impacted by the nurdle discharge.

Up to 91% of the microplastics found in aquatic samples worldwide were made up of fibers [45,46], which shows great bioavailability and abundance. The relative abundance of fibers compared to other types of microplastics may be of special concern for the aquatic ecosystems’ pollution. A substantial percentage of microplastics in shrimp species were found to be made of fiber, according to earlier studies [37,38,39].

Table 2. Comparative study on the presence of MPs in shrimp species from different regions. WB—whole body; GI—gastrointestinal tract.

Species	Study Area	Abundance (Items/g)	Tissue Examined	Type of Dominant MPs	Reference
Paratya australiensis	Victoria, Australia	24 ± 31	WB	Fibers	(Nun et al., 2020) [39]
Litopenaeus vannamei	Shrimp farm, Guangdong Province, China	14.1 ± 5.7	GI	Fibers	(Curren et al., 2020) [37]
Metapenaeus monoceros	Northern Bay of Bengal, Bangladesh	3.87 ± 1.05	GI	Fibers	(Hossain et al., 2020) [38]
Penaeus monodon	Northern Bay of Bengal, Bangladesh	3.40 ± 1.23	GI	Fibers	(Hossain et al., 2020) [38]
Parapenaeopsis stylifera	Northeastern Arabian Sea	64.8 ± 24.6	GI	Fibers	(Gurjar et al., 2021) [47]
Metapenaeus monoceros	Northeastern Arabian Sea	78.5 ± 48.4	GI	Fibers	(Gurjar et al., 2021) [47]
Penaeus indicus	Northeastern Arabian Sea	47.5 ± 38.0	GI	Fibers	(Gurjar et al., 2021) [47]
Parapenaeopsis hardwickii	Xiangshan Bay, China	0.25 ± 0.08	GI	Fibers	(Wu et al., 2020) [40]

Table 2. Comparative study on the presence of MPs in shrimp species from different regions. WB—whole body; GI—gastrointestinal tract.

Species	Study Area	Abundance (Items/g)	Tissue Examined	Type of Dominant MPs	Reference
Paratya australiensis	Victoria, Australia	24 ± 31	WB	Fibers	(Nun et al., 2020) [39]
Litopenaeus vannamei	Shrimp farm, Guangdong Province, China	14.1 ± 5.7	GI	Fibers	(Curren et al., 2020) [37]
Metapenaeus monoceros	Northern Bay of Bengal, Bangladesh	3.87 ± 1.05	GI	Fibers	(Hossain et al., 2020) [38]
Penaeus monodon	Northern Bay of Bengal, Bangladesh	3.40 ± 1.23	GI	Fibers	(Hossain et al., 2020) [38]
Parapenaeopsis stylifera	Northeastern Arabian Sea	64.8 ± 24.6	GI	Fibers	(Gurjar et al., 2021) [47]
Metapenaeus monoceros	Northeastern Arabian Sea	78.5 ± 48.4	GI	Fibers	(Gurjar et al., 2021) [47]
Penaeus indicus	Northeastern Arabian Sea	47.5 ± 38.0	GI	Fibers	(Gurjar et al., 2021) [47]
Parapenaeopsis hardwickii	Xiangshan Bay, China	0.25 ± 0.08	GI	Fibers	(Wu et al., 2020) [40]

3.5. Polymer Characterization

In the present study, the chemical composition of a set of samples that were randomly selected (n = 26) was determined, and the MPs composed of polystyrene, polyamide, polyester, polypropylene, and rayons were identified. Figure 7 shows some of the FTIR spectra obtained for MP fibers. The results suggested that the common raw materials for ropes, fishing nets, floats, fish baskets, and coatings used in the fishing activities in Negombo lagoon and nearby ocean may be the main origin of the identified MPs in shrimps. According to a previous study, HDPE accounted for 25%, polypropylene for 33%, styrene-ethylene for 17%, styrene-butadiene copolymer (SB) for 8%, LDPE for 8%, and polypropylene copolymer for 8% of principal polymers found in surface water from the Negombo lagoon [44]. Most MP fibers were identified as rayon, which is a type of semi-synthetic fiber that is also found in the deep sea [48]. A similar study conducted on 11 sites of the Greater Melbourne Area (GMA) and the Goulburn River catchment in northern central Victoria on Paratya australiensis indicated that rayon was found in shrimps the most regularly (22.6%) and was found at all 10 locations. At nine sites, polyester was the second-most prevalent material (7.5%) [39]. In another study, the most representative polymer found in the tissues of commercial semi-intensive shrimps from the Gulf of California ecoregion was polyethylene (about 50%), followed by polyamide (about 20%) [49].

4. Conclusions

This study goes some way to plug the gap in knowledge about microplastic abundance in Sri Lanka. In light of the environmental disaster following the nurdle and chemical spill in Negombo in 2021, it is necessary to collect baseline data to inform risk assessments, emergency responses, monitoring programs, and mitigation measures in the country. In this study, researchers collected fresh shrimp samples from ten locations in Sri Lanka’s Negombo lagoon and identified and characterized 415 microplastics in the samples, showing an average of 8.29 ± 4.63 items per gram (GI and GL) in P. monodon and 5.52 ± 3.78 items per gram (GI and GL) in P. indicus. The most prevalent color was blue (61%), and the predominant form of MPs was fiber (93.0%). The chemical composition of most of the MPs identified in the study included polystyrene, polyamide, polyester, polypropylene, and rayons. From this, we deduce that the discovered MPs in shrimps may have originated from fishing equipment used in the Negombo lagoon and the neighboring ocean. It can be suggested that, by eliminating the intestine and gills before readying shrimp for consumption, MP contamination in the edible part of shrimp could be reduced. As a result, the health risks connected with microplastic-contaminated shrimps can be mitigated to some degree. The authors recommend that communities be educated on the risks of microplastic ingestion and how to remove the contaminated organs before ingestion. Additionally, future research should address a temporal assessment of microplastics in shrimp in Negombo to observe whether fragments from nurdles become more abundant in the system. It is hoped that the baseline data collected in the present study can inform best practices in seafood consumption and support future risk assessments for microplastics and emergency spill events.