This descriptive study used qualitative analysis in detecting and estimating the present microplastics in the fish sold at Borongan City with the use of Microscopic Technique. Also, fish samples were identified and classified either as offshore or onshore dwellers.

This study was conducted at the Chemistry Laboratory of the Biology Department of the College of Nursing and Allied Sciences. Fish samples were gathered from identified rural and urban barangays of Borongan City (see Figure 1 below). Two (2) representative barangays were selected for their strategic location and for their capacity to sell fish; they were the barangays of Tabunan and Maypangdan, wherein onshore as well as offshore fish were sampled.

The following step-by-step processes were used in the study to detect the presence of microplastics in the fish samples from Borongan City, Eastern Samar.

Fish samples were gathered from the local wet market of identified barangays. These samples were kept in a sterilized and disinfected hard plastic to minimize contamination. Sample preservation was done to maximize the integrity of the sample using ice and freezers. The samples were labeled and brought into the laboratory for digestion and microscopic analysis. Representative sample from each kind of locally caught fish was done. Picture Fish application, Fish Base website and the Bureau of Fisheries and Aquatic Resources (BFAR) Regional Consolidated Price Monitoring Report were used to deter mine, as accurately as possible, the scientific names of sampled fishes.

Fish samples were taken to the laboratory for dissection and identified sample preparation will follow the procedure by Bahri, et al. with minor modifications. All equipment was sterilized with distilled water. The fish was dissected, and their digestive tract was taken to extract the microplastics. The digestive tract is inserted into the sample bottle and given a 30% NaOH solution mixed with distilled water up to 3 times the volume of the tissue. The sample is left to stand for 14 days or until the digestive tract of the fish has disintegrated. Then the sample is filtered using filter paper with the help of a vacuum pump followed by a 30 micron nylon mesh. The filtrate was collected and observed using a stereo microscope.

Wet Sampling and Microscopy were done on all fish collected and prepared.

Materials:

Stereomicroscope at 40× magnification

Tweezers, forceps and needles

Microplastic identification reference materials

Disposable gloves and lab coat (as required for safety)

Prepare a clean and dedicated workspace in the laboratory or controlled environment to avoid contamination during the analysis. Wear disposable gloves and a lab coat to maintain a sterile working environment and prevent contamination. Dissolved fish samples were filtered using a 30 micron filter mesh. The filter was allowed to stand and placed on a Petri Dish. The Petri dish was then examined under a stereomicroscope at 40× magnification. The dish was scanned from side to side, moving across the sample area to search for particles that matched the characteristics of microplastics, such as shape, color, and texture. Use the microscope’s focus and illumination controls to obtain a clear view of the particles. Take note of any particles that appear consistent with microplastics based on their size, shape (e.g., fragments, fibers), and visual appearance. Optionally, compare the observed particles with microplastic identification reference materials or images to assist with accurate identification. If needed, capture images of potential microplastics using a digital camera or microscope camera attachment for further analysis or documentation.

Repeat the process with multiple other filters and Petri dishes to different representative digested fish samples for thorough examination. Record and document the characteristics and quantities of identified microplastics, including their size, shape, color, and any additional relevant observations. Clean the filter paper for further use using distilled water and properly dispose of any debris left from the previously observed filter mesh with adherence to laboratory’s waste management protocols. Analyze and interpret the collected data to assess the presence, abundance, and characteristics of microplastics in the water sample. This was done under wet analysis for a thorough identification.

Quality control of this study was done following Egessa’s methods, with some modifications as stipulated by Arcadio. During microscopy, all the wet samples analyzed were kept covered in glass Petri dishes. Background contamination from laboratory sources via the air and laboratory tools and equipment were tested using procedure blanks made from glass filters contained in the Petri dishes and distilled water. At each stage of sample collection and analysis, the Petri dishes were left open to the air. The contents of control Petri dishes were processed and screened for microplastic contamination. The procedural blanks contained no microplastic [13] .

The following name list of fish is commonly sold around Brgy. Tabunan and Brgy, Maypangdan.

Of all 31 fishes ( Table 1 ) that were sampled in this study, 9 of those were taken off shore, meaning they are being caught out in the deep waters off Eastern Samar area. The other remaining fish are caught within the barangay areas or near the vicinity of the barangays.

Some of these fish samples are common food commodities by the majority of people such as Thunnus tonggol, Trachurus mediterraneus and Thunnus albacares. But most of the fish samples are commonly used as food by the local people of Brgy. Tabunan and Brgy. Maypangdan.

Microplastics observed and confirmed were identified as primary or secondary microplastics. Only a total of 5 microplastics were observed in the overall

sample of fishes collected from both Maypangdan and Tabunan. Of the 5 microplastics, all of those were classified as secondary microplastics because of their irregular shape and structure. The microplastics observed were very small, just enough for the 30 micron filter mesh to capture the said contaminant. The image below ( Figure 2 ) shows a microplastic trapped in the filter mesh.

Secondary microplastics are particles that result from the breakdown of larger plastic items, such as water bottles. According to the National Geographic, this breakdown is caused by exposure to environmental factors, mainly the sun’s radiation and ocean waves. Secondary microplastics come from larger pieces of plastic, such as beverage bottles, bags, and toys. Sun, heat, wind, and waves can cause these plastics to become brittle and break into smaller and smaller pieces that may never fully go away. Microplastics are also created when pieces of plastic break off during use. For example, particles of synthetic tires can break off during regular use and through wear and tear.

Similarly, clothing, furniture, and fishing nets and lines may produce plastic microfibers, another type of secondary microplastics. These fibers are extremely common on shorelines across the United States, and are made of synthetic materials, such as polyester or nylon. Through general wear or washing and drying, these tiny fibers break off and shed from larger items.

Most of the microplastics observed were micro fragments, but microfibers ( Figure 3 ) were also observed.

One observable feature of microplastics contamination in aquatic biota is that these microplastics tend to be most prominent in smaller fishes. Of the total 5 microplastics observed, 4 of those were coming from onshore fish samples while the other one was found to be present on Katsuwonu Pelamis, locally known as Budlis.

While larger fish contained a higher number of microplastics, smaller fish contained more microplastics per gram of tissue. These results highlight the uniqueness of microplastics as a contaminant, because they are physical particles rather than dissolved organic chemicals; they may behave differently than chemical contaminants [14] .

Three (3) out of five (5) microplastics observed were of other shapes, since they do not conform to common shapes. The other two (2) were found to be filaments, long structures of polymer plastics. One example of a microplastics contaminant can be seen in the picture below ( Figure 4 ).

This result is predictable as observed since microplastics released by the form as fabric woven with filament polyester are six times more likely to be released into the environment than other forms of microplastics.

Based on the results, of the five (5) microplastics, 2 were observed to be red, 2 were transparent/white and 1 was a filamentous blue color. Coloration of microplastics is common since most plastics used in the market are colored ones. Also, according to the Microplastics Sampling and Processing Guidebook of the Mississippi State University Extension Service, microplastics are usually brightly colored, frequently blue or reddish which further supports the results of this study, in terms of microplastic coloration [15] .

A total of 5 microplastics were observed from all the fish samples. Interestingly,

all the five (5) MPs were also observed from 5 different samples, with it, 4 of those were coming from onshore fish samples or those that were caught on the shoreline or within the aquatic areas of Brgy Maypangdan and Brgy. Tabunan. While the other 1 was found to be present on Katsuwonu Pelamis, locally known as Budlis, an offshore species of fish.

Overall, that constitutes around 0.16 MPs/species of fish, a very small number, yet this means there are contaminations of microplastics in Borongan City, more so to its food source.

The table below ( Table 2 ) summarizes the results obtained in this study; it shows the species where the microplastics were observed and its classification, structure as well as color are also reflected.

A total of 5 microplastics which were classified as secondary MPs were observed from 5 different species of fish that are being sold in the markets of Brgy Tabunan and Brgy Maypangdan. Of the 5 MPs found, 4 of those were microfragments, which were observed to be Other Shape in terms of their structure. The colors were red and transparent/white. Generally, that constitutes around 0.16 MPs/species of fish, a very small number, yet this means there are contaminations of microplastics in Borongan City, more so to its food source.

Toxic elements and compounds have been found to be adsorbed on MNPs owing to the unique high functionalized surface area characteristic of the particles [16] . Plastics’ persistence in the environment as a result of insufficient activity of catabolic enzymes continues to imperil aquatic and terrestrial ecosystems [17] [18] .

The increasing presence of microplastics and nanoplastics (MNPs) in aquatic habitats poses a threat to marine life, and it is predicted that nanoplastics will be just as ubiquitous as macro- and micro-plastics, but far more destructive to living organisms due to their ability to infiltrate cells. Recent research has shown that marine and freshwater biota become entangled with plastic litter, which disrupts the ecosystem. Aquatic creatures are known to absorb and deposit these new pollutants in their digestive systems [19] .

In a study conducted on various marine samples, it was observed that fishes have the highest microplastics abundance (75% ± 12.0%), followed by mollusks (90% ± 3.5%) and crustaceans (20% ± 7.0%). Filter feeders like mussels and oysters might possibly ingest microplastics [20] .

Microplastics present a multifaceted challenge when it comes to waste management and remediation. Their diminutive size makes them exceptionally challenging to capture and remove from aquatic environments, rendering mitigation efforts quite demanding. To effectively tackle the microplastics issue, a comprehensive approach is necessary [21] .