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. 2023 May 17:1–12. Online ahead of print. doi: 10.1007/s13762-023-04982-x

Microplastics in Perna viridis and Venerupis species: assessment and impacts of plastic pollution

A J G Yu 1,✉, L G Yap-Dejeto 1, R B Parilla 1, N B Elizaga 1
PMCID: PMC10191096  PMID: 37360557

Abstract

This study is divided into two parts. The first part aims to verify the presence of microplastics in bivalves, namely Perna viridis and Venerupis spp. using microscopy and Fourier transform infrared spectroscopy. The second part explores the knowledge, attitude and perception (KAP) of bivalve gleaners on microplastics and plastics. Results of the study confirmed the presence of microplastics in both bivalves, with polyamide fibers being the most common polymer found in the bivalves. The mean size of microplastics found in Perna viridis and Venerupis spp. was 0.25 ± 0.05 mm and 0.33 ± 0.03 mm, respectively. Varying colors and shapes were also observed in both bivalves. Further, results of the KAP showed the lack of knowledge of the gleaners in terms of the basic information about microplastics. Nevertheless, they showed a positive attitude in terms of reducing plastic pollution and perceived coastal waters as important to them. The data on the two parts were used to compute for the estimate of the amount of microplastics that can be transferred to humans through consumption of bivalves, which was found to be 0.003 mg/day.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13762-023-04982-x.

Keywords: Perna viridis, Venerupis species, Knowledge, Attitude, Perception, Polyamide fiber

Introduction

Poorly managed plastic ends up in water ways clogging drainages and polluting water bodies as marine debris. Marine debris include materials that are discarded, disposed, and abandoned in the marine and coastal environment (NOAA 2020). Plastic is known to be the most common form of all these marine litter. This material is never fully biodegraded when in contact with the water (NOAA 2020). Instead, most of these plastics are fragmented into particles smaller than 5.0 mm in size known as microplastics (MP) (NOAA 2015; Naik et al. 2019).

Microplastics (MP) have been observed in the marine ecosystem that includes a wide range of organisms across different habitat and trophic levels (Koelmans et al. 2019). Bivalves have higher microplastic ingestion rate since they are consumed whole (Lusher et al. 2017). They are also considered as bioindicators of marine pollutants (Li et al. 2019) and the most commonly used organisms in microplastic exposure research in the global context (Lusher et al. 2017).

Marine litter must result from human decisions and behavior (Hartley et al. 2018; Koelmans et al. 2019). That is why communities have an important role to play in addressing environmental pollution through their lifestyle choices and waste management practices, among others (Hartley et al. 2018). Hence, their understanding, attitude, and perception toward environmental problems such as plastic pollution are crucial factors that may influence conservation and rehabilitation of resources (Gifford 2014). Brown (2015) emphasized that studies within environmental risk perception are important to determine a person’s likeliness to take concern on a particular issue. A study by Deng et al. (2020) on public attitude on microplastics among the residents in China revealed that knowledge is a key factor to strengthen the willingness of people to reduce microplastic pollution. This was supported by a study of Shaira et al. (2020) which deals with KAP on single-use plastics (SUP) of a rural community in India. The study showed that there was inadequate knowledge on SUP but most of the residents are willing to replace them with better alternatives.

Philippines is highly dependent on marine ecosystem as a source of food and livelihood to the people; hence, protecting and conserving it is important to sustain the ecosystem services it provides. Yet, the country continues to be one of the world’s worst ocean polluters (Onda et al. 2020) which may result to ingestion of microplastics of a wide range of organisms (Koelmans et al. 2019; Lusher et al. 2017).

In the Philippines, though several published papers have studied microplastics on marine waters, rivers, surface sands and sediments and fishes (Cabansag et al. 2021; Avila et al. 2021; Bucol et al. 2020; Esquinas et al. 2020; Limbago et al. 2020; Tanchuling & Osorio 2020; Kalnasa et al. 2019; Paler et al. 2019), only a few have dealt with bivalves (Espiritu et al. 2019; Argamino & Janairo 2016). Bivalves, which are considered as the likely largest source of microplastics from seafood to humans as they are consumed whole (Lusher et al. 2017), are just one of the provisioning services that Cancabato bay provides to the fisherfolk communities (Aguirre et al. 2020). Moreover, human actions and behavior are determined to be the source of plastic pollution. Since humans are the cause of the problem, then they can be the solutions to these problems.

Located in Tacloban City, Cancabato bay with a geographical location of 11°00′ N and 11°20′ N; 124°00′ E and 125°14′E (Aguirre et al. 2020) is a 562.26 hectares bay. It is classified as a class SC waterbody with an intended beneficial use in fishery, recreation and wildlife sanctuary. The bay is a habitat to water birds and a place for gleaning, aquaculture and traditional fishing. Seagrass and mangrove ecosystems are also present in the said bay.

Materials and methods

Study site for bivalves’ sampling

The sampling was conducted on July 24, 2021 in two sites in Cancabato bay, with geographical coordinates of N 11°13′50″, E 125°0′18″ and N 11°13′38″, E 125°0′18″ for Venerupis spp. and Perna viridis, respectively. Fifty (50) samples per species were collected in the said sites. The bivalve samples were wrapped in aluminum foil before they were placed in ziplock bag. Then the samples were placed in the styrofoam box and brought at once in the laboratory for further analysis (Fig. 1).

Fig. 1.

Fig. 1

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Study site for sampling of bivalves

Physicochemical analysis

Around 300 mL of water samples from each site with three (3) replicates each was measured with pH using Orion pH meter, dissolved oxygen (DO) using Orion Star A113 DO meter and salinity and conductivity using Orion versastar multi-parameter, all of which were calibrated before use. The temperature was measured on-site using a bipocket metal thermometer.

Pre-cleaning

Upon arrival in the laboratory, the samples were washed with running water to remove remaining barnacles and other materials that attached in the shell's surface. The samples were shucked using spoon and flat end spatula. The length was measured using a ruler while the net weight was measured by weighing the tissue container (using either beaker of Erlenmeyer flask), taring the Kern Analytical balance and recording the net weight.

Microplastic identification

Digestion of samples

The digestant used in the study was 1 M NaOH. The positive control used was a dental floss, with polyester as one of the wax materials, while the negative control was a reagent blank which contained the digestant only. These controls went through all the processes. A room and balance control were also set up to see any contamination that might be present in the room or in the balance where measurements were conducted. The samples were added with three (3) times the tissue weight of 1 M NaOH, covered with aluminum foil and incubated for 24 ± 5 h at 60.0 °C.

Filtration of samples

After 24 ± 5 h, the samples were filtered in a vacuum filtering manifold system using pre-weighed Whatman filters with a pore size of 10 micrometers (µm). The filter papers were placed in glass petri dish for the visual identification.

Visual identification

The samples were visually identified using 4X magnification of an Olympus CX23 compound microscope. The amount, type, color and shape of microplastics seen were recorded. Photographs were also taken using a 48 MP rear camera of an Android phone. The size of microplastics was identified using ImageJ software, based on the method of Cabansag et al. (2021).

Fourier transform infrared spectroscopy

Filter papers digested with Perna viridis and Venerupis spp., filters papers used for the reagent blank and room control and some suspected microplastics which can be isolated were sent to Department of Pure and Applied Chemistry (DOPAC), VSU, Baybay City, Leyte, for the Fourier Transform Infrared Spectroscopic (FTIR) analysis.

Survey interview

Content validation

The content of the survey questions was validated using a validation form based on the method of Andrade et al. (2020). This was sent through a Google form link to the e-mail addresses of an external body of panel of experts. The panel of experts was identified by the guidance and suggestions of the thesis adviser. Co-authors of various journal publications on public perception studies and professors in the Master’s program were also chosen as panel of experts.

The validation form consists of the survey questions with either Satisfactory if the survey question is appropriate or Other with the reason why the survey question is not appropriate. The results of the validation were collated in Microsoft excel and served as basis on the final survey questions to be employed in the pre- and actual survey.

Pre-survey

The pre-survey was conducted in Fishermen Village, Barangay 88, San Jose, Tacloban City, in July 31, 2021. Ten (10) respondents filled up the Waray translation of the survey form. Comments were recorded in order to improve the survey questionnaire. Reliability test was assessed using Cronbach’s alpha in Stata application.

Actual survey

A total of forty (40) names of respondents, which served as the population size were recorded from coastal barangays 31, 51, 52, 54, 56A, 83A, 85 and 86 within Cancabato bay. The list of respondents were the only ones who are willing to be interviewed during the sampling period, which was done from August to October 2021. A total of 37 respondents were randomly selected through lottery. This number was computed based on the sampling size formula with a 95% confidence interval provided by Israel (2003):

n=N1+Ne2

where n is the sample size, N—population size, and e—level of precision

Data analysis

Statistical analyses were performed in the gathered data. Shapiro–Wilk test was used to compute for normality of data among the variables weight, length, weight/length, size, amount of MP/sample, and amount of MP/gram of bivalves. Wilcoxon rank-sum test was used to determine significant difference between characteristics of microplastics in Perna viridis and Venerupis spp. Spearman rho correlation was used to determine the variables in knowledge, attitude and perception with significance, along with the correlation coefficient.

Results and discussion

Physicochemical analysis

Results of the physicochemical analyses have showed that DO level in Site 1 was beyond the standard level, in accordance to DAO 2016–08. Slightly low DO concentration in this site may be attributed to the wastewater discharges from household areas and industrial sites near the said sampling site, as supported by the study of Espiritu et al. (2019). Site 1 was observed to have brownish water with a sandy substrate, while Site 2 was observed to have dark green water with a muddy substrate.

Microplastic identification

Amount of microplastics

The quantity of recovered microplastics from the soft tissues of Perna viridis and Venerupis spp. was 52 ± 0.20 MP particles and 195 ± 0.17 MP particles, respectively. These values showed a significant difference (p = 0.000) using the Wilcoxon rank-sum test.

In a study by Tenore et al. (1973), it was shown that clams are more efficient in utilizing filtered food and thus have a higher net production as compared to mussels. The rate of pseudofeces production, which is the material cleared from suspension but rejected before ingestion, can be related to the ingestion rate. Gosling (2015) found out that mussels such as Mytilus edulis increase their pseudofecal production to control ingestion rate, while clams such as Venerupis pullastra produce less pseudofeces to maintain consistent ingestion rate.

In one study by Covernton et al. (2019), he showed that clams have significantly higher MP concentration than oysters by tissue weight. This may be explained by the ctenidium or gill structure of bivalves, which in turn may have affected their suspension feeding process. Mussels have simple filibranch gills where contiguous filaments are attached to each other through specialized ciliary junctions (Jones et al. 2020). On the other hand, clams have eu-lamellibranch that have transformed to a more complex gill structure where the contiguous filaments are attached through connective tissue, which may indicate that selection function is lowered (Jones et al. 2020; Covernton et al. 2019). This means that particle selection is species-specific according to the bivalves’ gill structure (Ward et al. 2019; Sendra et al. 2021). Clams can select particles on gills and labial palps, while mussels only select on labial palps.

Another reason that may explain the variation in MP is the attachment mechanism of the bivalves. Mussels are examples of sessile epifaunal bivalves which attached themselves to hard surfaces through their byssal threads, while clams are infaunal burrowers which bury themselves in the sediment on the seafloor or riverbeds (Gosling 2015). Mussels were collected in attached decaying plastic container and rubbers, while the clams were harvested through gleaning. This may have also contributed to a higher MP in concentration in Venerupis spp. compared to Perna viridis (Fig. 2).

Fig. 2.

Fig. 2

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Total number of microplastics in Perna viridis and Venerupis spp. (Relative abundance)

In a particle per weight basis, the quantity of recovered microplastics from the soft tissues of Perna viridis and Venerupis spp. was 0.28 ± 0.07 MP/g particles and 1.53 ± 0.17 MP/g particles, respectively. Based on Wilcoxon rank-sum test, there was a significant difference (p = 0.000) in the number of microplastics.

Characteristics of microplastics

Type

Three types of MP, namely fiber, fragment and film, were observed in Venerupis spp. and Perna viridis. 52% of MP found in Venerupis spp. were fragment, 43% were fiber and 5% were film. Perna viridis consists of 50% fiber, 29% fragment and 21% film.

Fibers may have originated from clothing residues from washing machines, hygiene product and fishnets. Fragments may have come from the breakdown of plastic packaging, bags and containers, household and fishing materials. Films may have been derived from the breakdown of plastic labo bags and single-use supermarket carrier bags (Kalogerakis et al. 2017) since they appear as transparent-like when observed in microscope.

In the study of Tanchuling & Osorio (2020), fragments comprised the highest type distribution in surface water and sediments in almost all sampling sites in rivers and creeks that drain to Manila Bay. The result of the study was also consistent with the result of Webb et al. (2019) who found out that fragments, followed by fiber were the most common morphotype of MP in green-lipped mussel (Perna canaliculus). Fragments were also the dominant type of MP in other studies (Cho et al. 2021).

On the other hand, fibers dominated in the study of Cabansag et al. (2021) who studied fish samples in Cancabato bay. Fibers were more likely to be vertically transported due to their small size and have been found out to be ingested more than the other types of MP. He also noted that fibers, which may appear as clumps, as has been found in some fibers in this study, may have prevented them from being egested. This was also supported by a study of Reguera et al. (2019). Films were found the least abundant which has the same findings in other studies (Tanchuling & Osorio 2020; Cho et al. 2021) (Fig. 3).

Fig. 3.

Fig. 3

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Type of microplastics in Perna viridis (outer) and Venerupis spp. (inner)

FTIR analysis

The Fourier transform infrared spectra of the suspected microplastics along with the negative and positive control are given in Fig. 4. Identified polymer types included high-density polyethylene (HDPE), fiber polyvinylidene fluoride (PVDF) and aromatic polyamides. The spectrum matches were between 60 and 96% which was processed using the open-source spectral classification software, Open Specy (Cowger et al. 2020). As bivalves are filter feeders, microplastics present in the water column can be easily taken up. Sources of which may include fish nets, ropes, fibers from clothing and fragments from plastic bags (Espiritu et al. 2019; Kalogerakis et al. 2017). Negative control matched with a methyl cellulose which is an active component of the filter paper used, while the positive control used was a dental floss with polyester as the active ingredient. Difference between the actual and reference spectra was observed. According to Parlak & Ramasami (2020), the polarity of the solvent used can have an influence in the IR spectra due to the interaction of the solvent and the sample. There is a solvent sensitivity noticed in many infrared absorption bands due to the frequency difference between the hydrogen bond formed by the solvent, O–H and the bonded counterpart, sample-solvent, in the same environment (Allerhand & Schleyer 1963). Kalogerakis et al. (2017) also reported that plastics that undergo under ultraviolet irradiation were modified chemically until fragmentation occurred.

Fig. 4.

Fig. 4

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(Left to right) Photos of samples, FTIR spectra and reference spectra of the following: a HDPE, b Aromatic polyamide, c Fiber polyvinylidene fluoride, d methyl cellulose or the negative control, e Polyester or the positive control. Reference spectra sources: Charles and Ramkumar (2009), Kaspar et al. (2020), Hsiao (2002), Nadour et al. (2016) & Kupstov and Zhizhin (1998, p.155)

On the other hand, the fiber-like microplastics observed in the microscope was difficult to separate because it was embedded in the filter paper; thus, it was not chemically identified. The same challenge was encountered by Espiritu et al. (2019) due to the small sizes of microplastics which did not allow for the FTIR analysis.

Size

The average sizes of microplastics ingested by Perna viridis and Venerupis spp. were 0.25 ± 0.05 mm and 0.33 ± 0.03 mm, respectively. There was a significant difference between the sizes of microplastics (α = 0.05, p = 0.0002). The capture efficiency of particles that are ingested by bivalves can be related to the particle’s size. The mussel Perna perna and Geukensia demissa have shown high retention efficiency for particles that are as small as bacteria. This may be due to narrow space between the latero-frontal cilia of the mussel structure (Gosling 2015) which may have caused smaller MP size to be ingested as compared to clams. This was also supported by Zhang et al. (2019) who found out that the gut retention time of MP in bivalves and their potential to accumulate in tissue increase as MP size decreases (Fig. 5).

Fig. 5.

Fig. 5

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Mean size of microplastics in Perna viridis and Venerupis spp.

Shape

Thin, elongated MP was the most common shape of MP observed. The said shape is associated with the shape of the fibers found. Rebelein et al. (2021) also noted that due to their elongated shape, fiber may have the potential to entangle bivalves’ body parts. Other shapes found are irregular which are common shapes of fragments and film. These MP types do not have definite shapes which may be caused by the fragmentation process they underwent.

Color

Various colors of MP were observed in both Venerupis spp. and Perna viridis. Most of these colors were associated with the fibers found. This may support the notion of fibers from washed clothing as possible source of MP found in the said bivalves. In the study of Reguera et al. (2019), white, gray and blue were the most common colors in MP found in Mytilus spp. Other colors observed in the same study were white, red, green, transparent, cyan and black. Various colors such as colorless, black, blue and white were also found in oysters (Carosstrea gigas), mussel (Mytilus edilus) and Manila clams (Ruditapes philippinarum) (Fig. 6).

Fig. 6.

Fig. 6

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Color of microplastics in Perna viridis (outer) and Venerupis spp. (inner)

Reliability test in pre-survey

The Cronbach’s alpha test for reliability showed that the value of alpha is 0.8799. Based on the study of Taber (2018), an alpha value of 0.8 and above indicated a reliable, reasonable, fairly high, adequate, acceptable, satisfactory and sufficient data, though he also emphasized that there is no apparent consensus on the most applicable labels to describe the alpha values.

Actual survey

Sociodemographics

The sociodemographic profile of the respondents is shown in Table 1. 78% of the respondents were male and in the middle age. All of them have not completed their education. 32% have gleaning as only source of income, while 68% of the respondents have other jobs aside from gleaning, such as fishing, carpentry, construction workers and vendors. A total of 57% of the respondents have children while 43% have not.

Table 1.

Sociodemographic profile of respondents

Variable Response No Percentage (%)
Gender Male 29 78
Female 8 22
Age 20 and below 8 22
21–60 27 73
61 above 2 5
Highest educational attainment Elementary 10 27
High school level 22 59
High school grad 5 14
Place of residence Brgy. 31 2 5
Brgy. 52 3 8
Brgy. 54 2 5
Brgy. 56A 6 16
Brgy. 75 1 3
Brgy. 83A 21 57
Brgy. 85 1 3
Brgy. 86 1 3
Occupation Gleaning only 12 32
Gleaning, fishing and/or other available work 25 68
No. of children 0 16 43
1–2 8 22
3–4 6 16
More than 4 7 19
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Knowledge

Eight (8) questions were designed to determine the respondents’ knowledge of microplastics, which include its definition, classification, effects, sources and approved and proposed policies in the use of plastics. 43% of the respondents have given correct response in terms of the general definition of a microplastic. 65% also classified plastic items that break down to smaller pieces as primary microplastics. Though 54% believed that microplastics are eaten by aquatic organisms, only 22% agreed that they are present in bivalves. Most of them believed that microplastics mostly come from land-based sources. 68% believed that fish nets are one of the sources of microplastics. A higher percentage knew that there exists national law and a passed city ordinance which mandates recycling and single-use plastic ban, respectively.

Results of the study showed that their knowledge on microplastics may have come from their life experiences and so some of the technical information on microplastics are unfamiliar to them. This was also noted in the study of Deng et al. (2020) in which public’s existing knowledge on plastics may be heavily derived from common sense and experience and they may not know the physicochemical properties of plastics. They are aware of the existing and proposed policies on plastics but lack the knowledge on basic information about microplastics.

Attitude

Questions on attitude focus with the respondents’ willingness to do something about plastics. A higher percentage of the respondents see plastic pollution as an important problem and see themselves responsible for mitigating plastic pollution. Interestingly, more than 90% of the respondents are willing to support activities that will reduce plastic pollution. About 86% of them use plastics because they are cheap and 63% said that they recycle plastics that are recyclable. In the contrary, 70% of the respondents answered that they will be encouraged to reduce plastic use and litter if they are given incentives. Otherwise, they will not. The fourth principle of economics which states that “People respond to incentives” (Mankiw 2018, p.7) holds true to the response of a higher percentage of the respondents to this particular question.

According to Pickens (2005), attitude is a tendency to act in a specific way due to a person’s experience or personality. Attitude and the environment of a person work in both ways: Attitude is influenced by the social world as the social world is influenced by a person’s attitude. As the respondents depend on the marine resources provided by Cancabato bay, there is a positive attitude in most questions toward reduction in plastic pollution. The respondents have considered their environment, the Cancabato bay as a source or one of the sources of their livelihood which has a direct effect in their attitude in terms of reducing plastic pollution.

Perception

Questions on perception deal with the intention to do something, perceived importance of a resource, causes of plastic pollution and perceived responsibility. A total of more than 80% of the respondents perceive marine resources as important to their lives. They see coastal waters as important in biodiversity, legacy, scenery and source of food and livelihood. They also perceive that avoiding single-use plastic will help in reducing plastic pollution. In terms of the cause of plastic pollution, a total of 70% and 73% perceived that plastic pollution is the result of the poor implementation of Ecological Solid Waste Management and lack of waste collection system, respectively. A total of 77% believed that it is the government’s responsibility to address solutions to plastic pollution. In terms of the current pandemic, a total of 62% believed that COVID-19 pandemic contributed more plastic wastes.

Perception is the process in which a person interprets an emotion or feeling to produce a meaningful experience (Pickens 2005). Awareness and acceptance of a situation help in the perception process (Pickens 2005). This explains why a higher percentage of respondents perceived coastal waters as important. The gleaners are generally aware that they have to avoid using single-use plastic so that coastal waters will be able to provide livelihood and food to the former. On the other hand, most of the respondents perceive that there is poor implementation in the existing law that mandates proper segregation and recycling of plastics, among others. Most of them also believed that the government is responsible for reducing plastic pollution. This may be because the government has the power to make, legislate, implement and fund these policies (da Costa et al. 2020). According to Buenson et al. (2021), more plastics have been generated and utilized during the COVID-19 pandemic. Perception can be selective and this happens due to the selective interpretation of the respondent which in turn is based on his beliefs, experience and attitudes (Pickens 2005).

Spearman rho correlation coefficients among knowledge, attitude and perception

A rho correlation coefficient of at least 0.05 implies a moderate relationship between two compared variables (Jeremias & Fellizar 2019). There was a moderate positive relationship between the knowledge on the definition and type of microplastics. Moderate positive relationships were also observed between avoiding single-use plastics and importance of coastal waters in supporting biodiversity. Further, strong positive relationships were found between willingness to give up something and support coastal clean ups to reduce plastic pollution and preserve marine life, respectively. This may imply the willingness of the respondents to conserve the coastal waters through simple actions they can do at their level.

On the other hand, there is a moderate positive relationship between avoiding single-use plastics and perception in the poor implementation of Ecological Solid Waste management and lack of collection waste system. This may indicate that amidst lack of trust toward policy implementation of the government, the respondents still know that they have to avoid single-use plastics to reduce plastic pollution. Moreover, there was a strong negative relationship between the importance of coastal waters as a source of food and employment and the perception that the government has the responsibility to reduce plastic pollution. This may indicate that as consideration of coastal waters increases, the perception that the government is responsible for reduction of plastics decreases. Thus, the respondents may still perceive themselves as part of the solution in reducing plastic wastes.

Estimate of human exposure assessment

Using the data in the analysis of bivalves and survey interview, the average amount of MP transferred to humans through consumption of bivalves is 0.003 mg/day. It can be noted that microplastics contribute only a very small amount to the total dietary intake of humans. In a study by Lusher et al. (2017), consumption of 225 g of Chinese bivalves would lead to ingestion of 900 plastic particles or 7 micrograms (µg) plastics per body weight of an average human individual of 70 kg. This study supports the idea of Lusher et al. (2017) that trophic transfer of MP has a negligible effect on the total human dietary intake of these compounds. Covernton et al. (2019) also computed that per capita consumption of Manila clams and Pacific oysters by Canadian citizens resulted to 87 particles per person per year.

Conclusion

Microplastics have been observed in a wide range of marine organisms. Sources of microplastics come mostly in land-based sources. This indicates that human actions and behavior play a role in the generation of microplastics in the marine environment, on the other side, have also a role in reducing them.

As bivalves have higher ingestion rate of microplastics and are considered as bioindicator of pollutanst, the former is used as study organisms . Results of the study showed that microplastics are present in Perna viridis and Venerupis spp. collected in Cancabato bay, with the latter having a higher number of microplastics. The types of microplastics found in the bivalves are fiber, fragment and film. These are confirmed by the FTIR analysis showing polyamide fibers as the most common polymer in the bivalves. Various shapes and colors were also observed in the bivalves.

The social survey of the study showed that the knowledge of respondents about microplastics may come from their life experiences. They showed positive attitude in terms of reduction of plastic pollution. A higher percentage likewise perceived coastal waters as important to them. Spearman rho correlation showed that there is willingness of the respondents to conserve coastal waters amidst lack of trust toward policy implementation. Finally, this study showed that the average amount of microplastics transferred through consumption of bivalves is negligible.

Future studies may consider alternatives with a cost–benefit analysis for single-use plastics that are more sustainable since microplastics have been found in a variety of marine waters and organisms. Social survey may also include households, local government officials and students.

For policy recommendations, to highly encourage the constituents to strictly implement solid waste management programs, incentives may be provided by regulatory authorities to barangays who are showing excellent practices. Information, education and communication campaigns may also be conducted specifically on technical information about microplastics to barangays and local government unit.

Supplementary Information

Below is the link to the electronic supplementary material.

Supplementary file1 (DOCX 56 KB) (56.4KB, docx)

Acknowledgements

The authors are sincerely thankful to the Environmental Management Bureau Regional Office No. VIII, Bureau of Fisheries and Aquatic Resources Regional Office No. VIII and University of the Philippines Tacloban College for allowing the utilization of their laboratory equipment and glassware and identification of bivalve species.

Declarations

Conflict of interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors declare the following financial interests/personal relationships which may be considered as potential competing interest.

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