Microplastics Riding the Waves: More Microplastics Than Expected Found in South Carolina’s Coastal Waters

Recent testing conducted in the coastal waters of Edisto Island, SC, produced significantly more microplastics than expected based on prior research. While previous research indicated that we would find approximately forty-four microplastics in a seven-liter water sample, we found hundreds of microplastics in each of the samples we tested.

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Just how pervasive are marine microplastics? While previous studies have found microplastics in waters around the world, the scope of the global microplastics problem still is not well understood. This lack of understanding has resulted in a lack of action to address what is quite possibly the most significant plastic-related concern—and potentially the most significant environmental concern—of our lifetime.

Recent testing supports this thesis, and further testing will hopefully serve as the foundation for data-based advocacy that ultimately leads to meaningful change.

Following Seas Marine Impact Research, Inc. is a new 501(c)(3) private operating foundation established by research scientist Lacy Fabian, PhD. Our first significant research effort is our Summer 2026 Pilot Study, which is currently under way. To test our equipment and standard operating procedures in preparation for this study, we spent an afternoon in August 2026 collecting test samples on Edisto Island, SC.

Study Overview: Examining Microplastics in Samples from the Coastal Waters of Edisto Island, SC

We collected test samples from two locations on Edisto Island, one of the South Carolina Lowcountry’s barrier islands on the United States’ East Coast approximately thirty miles south of Charleston. We took one test sample on the beach and another sample on a tidal creek fed by the Atlantic Ocean:

• Location 1 – Atlantic Ocean: Eddingsville Beach, SC, shoreline (32.52539428889741, -80.26546062739419)
• Location 2 – Tidal Creek: Private dock on Frampton Inlet, SC (32.52833585389152, -80.27203842122337)

We used the same sample collection method at both locations, as discussed in detail below. At each location, we also collected data including tide, current, wind speed, wind direction, pH, salinity, and water temperature. While we did not use these additional data points for this preliminary test, we will be using these data in our subsequent research, and collecting them is part of our standard operating procedures. If others have interest in this supplemental data, all Following Seas data are freely available to support mission-driven efforts.

Each sample collected consisted of seven liters of water from the top three inches of the water column. Prior studies have shown that a significant portion of the microplastics in marine environments are suspended in this three-inch zone, and one specific prior study concluded that a seven-liter sample taken in our chosen geographic location should contain approximately forty-four microplastics with a confidence level of 99 percent (p = 0.01). We concluded that this should be a sufficient volume to easily identify the microplastics in each of our samples using our stereo and compound microscopes (Cross, et al., 2025).

While we were expecting to find a volume of microplastics generally consistent with prior research, we were not expecting to exceed this volume significantly with each of our samples. We also were not expecting our samples to vary significantly in the concentration of microplastics they contained. But, this is exactly what happened.

Methods: Sample Collection and Processing

We collected and processed our samples using standard operating procedures developed based on a review of existing literature on water sampling for the collection and identification of microplastics. Our standard operating procedures combine best practices from multiple studies, with three key focuses:

• Documenting the water conditions at the source and time of collection;
• Avoiding sample contamination and accounting for contamination as necessary by using a blank sample; and,
• Processing samples to allow for maximum identification of microplastics collected using a 20-micron sieve and various chemical washes.

Here is an overview of the methods we used:

Sample Collection

We used the “bucket sampling” method to collect water samples from the two locations identified above. As discussed in greater detail below, the bucket sampling method involves filtering each sample through a series of sieves with progressively finer stainless steel mesh. All of the equipment we use for collecting and processing our samples is made of either stainless steel or glass to ensure that we do not introduce additional microplastics while conducting our research.

1. Identification of Sampling Locations

We identified two locations with significantly different characteristics that we could test in close temporal proximity to one another. The first location was a beach on the Atlantic Ocean, allowing us to take a sample of ocean water at the shore.

The second location was a tidal creek fed by an inlet from the Atlantic Ocean near our first testing site. We tested at a site approximately two miles up the winding creek, though it was less than one eighth of a mile from our first testing location as the crow flies. The creek is lined with pluff mud banks that are home to oyster beds, Spartina grass, various shore birds, and minks.

We collected this sample directly from the creek using a private dock to which we had authorized access. We were interested to see how much (if at all) the concentration of microplastics at this location would vary from the concentration at the shore, since both locations were fed by the same ocean source.

2. Establishment of “Blank” Sample

The use of a “blank” sample is important in microplastics collection. Our blank is an open jar of ultra-pure filtered water. By placing an open jar of ultra-pure filtered water at each test location, we are able to collect any microplastics from the atmosphere—and then we are able to account for these atmospheric microplastics in each of our test samples. While microplastics in the atmosphere may ultimately end up in the water, this allows us to identify any likely contamination of our test samples and address this in our analysis and reporting.

3. Collection of Seven Liters of Water

For each of our test samples, we collected seven liters of water from the test location. The decision to test seven liters of water was based on a prior study that examined the concentration of marine microplastics in various locations (Cross, et al., 2025). The study’s authors developed a tool to calculate the likely concentration of microplastics in different locations; and, according to this tool, we should have collected approximately forty-four microplastics at each of our chosen test sites. We determined that this was a sufficient volume of microplastics to facilitate identification and analysis purposes of this preliminary test.

We collected seven liters of water at each of our test locations using a glass bottle that was rinsed with ultra-pure filtered water between tests. Each liter of water was poured into a series of sieves on-site until we had collected microplastics samples from a total of seven liters.

4. Use of “Bucket Sampling” Method to Collect Microplastics

We used the “bucket sampling” method to collect microplastics from each of our water samples. This involves running each water sample through a series of six sieves with stainless steel mesh ranging from 1,000 microns to 20 microns. After the water passes through the 20-micron sieve, our collected microplastics remain in the sieve (along with biological and mineral matter), and we then rinse this sample material into a labeled glass jar using ultra-pure filtered water. We did this separately for each of the testing locations. 

5. Storage of Samples for Processing

We kept the collection jars sealed until they were ready for use; and, as soon as we rinsed each sample into a collection jar, we secured the jar’s lid to prevent contamination. Labeling each jar in advance ensured that we would identify each sample correctly. Once we closed each collection jar, we also closed the blank sample jar, which was also labeled in advance. At this stage, our sampling was complete and each collection jar was ready for processing.

Sample Processing

Processing each of the three samples (our ocean sample, our tidal creek sample, and our blank) was a multi-step process. We had previously outlined these steps in our standard operating procedures; and, after this initial test, we made some slight modifications to our standard operating procedures to streamline our sample processing going forward.

The major steps involved in processing our samples included:

1. Removal of Biological Material

The first step was to remove any remaining biological material from each of our samples. This involved separating each sample from the water in its collection jar using a 20-micron sieve and then submerging the sample in a sulfuric acid wash for five minutes (Forgione, Ferry, Neumann, and Good, 2026).

2. Reduction of Mineral Material (Two-Step Process)

After removing the remaining biological material from each sample, we then reduced the amount of remaining mineral material—first by dissolving much of the mineral material in potassium hydroxide and then using a separating funnel to the remaining mineral material from our sample. Each sample remained in the potassium hydroxide for 24 hours, and then each sample was placed into a calcium chloride solution which was then poured into a separating funnel where it remained for 48 hours. These durations were selected based on Forgione, et al., 2025.

While some mineral material remained, the amount was small enough that it did not interfere with counting the microplastics in each of our samples. We revised our standard operating procedures to further limit the amount of remaining mineral material in our samples going forward.

3. Evaporation of Remaining Water

At this stage, what remained for each sample was: (i) the Calcium Chloride processed through the separating funnel; (ii) an insignificant amount of mineral material; and, (iii) the washed microplastics from each sample. For each sample, Calcium Chloride was rinsed away using ultra-pure filtered water over a sieve, and then what remained was rinsed into a Petri dish with up to 100ml of ultra-pure water. Each Petri dish was then placed at an oven at a temperature of 170 degrees Fahrenheit until the water was fully evaporated.

4. Examination Under Stereo Microscope

To examine our samples, we first looked at each Petri dish using an Amscope SM-1TSX-144S-5M3 stereo microscope. We also took numerous photos of each sample using a 3.5x to 4.5x USB 3.0/5mp microscope camera. With the stereo microscope, several types and varieties of microplastics could be clearly seen, including films, multiple colors of fibers, and black pellets.

5. Examination Under Compound Microscope

After looking and documenting each of our samples using a stereo microscope, we then looked at each sample using an Olympus BX51 compound microscope. We took numerous photos using the compound microscope as well. Using our compound microscope to further analyze the samples allowed us to both: (i) identify additional microplastics; and, (ii) distinguish microplastic types.

Findings: Microplastics Concentration Exceeds Expected Value in Both Test Samples

The concentration of microplastics in both of our test samples greatly exceeded the concentration we expected based on prior concentrations found in the Charleston Harbor in 2015. While we were expecting to find approximately forty-four microplastics in both of our test samples, we found approximately 1,900 microplastics in our ocean sample and approximately 1,000 microplastics in our sample from the tidal creek. Based on Cross’ tool and prior research in Charleston, SC, we should have needed to collect more than 100 liters of water from each of our testing locations to collect microplastics in these concentrations. We also collected approximately 300 microplastics in our blank sample at each location.

This has two potentially significant implications that warrant further research:

• The concentration of microplastics in both of our test samples (and our blank) was significantly greater than anticipated based on prior research. This potentially indicates that the concentration of microplastics in our waters has increased significantly since this prior research was conducted.
• The concentration of microplastics in our ocean sample was significantly greater than the concentration in our tidal creek sample. This potentially indicates that more microplastics remain at the surface level of the ocean due to the wave agitation while microplastics either sink into the mud or become stuck to Spartina grass in the calmer waters of the creek.

At present, we hypothesize that the churning of the ocean waves near the shore helps to keep more microplastics floating in the top three inches of the water column. Additional research is needed to confirm whether this is the case—including additional sampling at the surface level of the ocean and further inland, sampling at deeper levels of the water column in both locations, sampling of inland creek bottoms and Spartina grass, and sampling of the top three inches of the water column in offshore waters. This is all research that we intend to conduct in the future, including, in part, during our Summer 2026 Pilot Study.

Key Takeaways: Findings Confirm Significant Presence of Marine Microplastics & Indicate Need for Further Study

This was a preliminary test with samples taken from two locations on a single day. As a result, the impact of our findings is necessarily limited. With that said, we are confident in our testing procedures; and, as a result, we are confident that our findings help to confirm a significant presence of marine microplastics in our test locations (and likely other locations as well) and the need for further study. With this in mind, some of our key takeaways include:

• The concentration of marine microplastics is potentially greater than previously reported. Whether this is method variations in previous studies or an increase in the concentration of marine microplastics is currently unknown. However, in either scenario, the current concentration of marine microplastics is concerning and consistent with prior research on the United States West Coast that found microplastics concentrations may be underestimated due to larger-size sieves being common (Brandon, Freibott, and Sala, 2019) and is consistent with global estimates on plastic production (Geyer, 2017). 
• Since the previously reported concentrations of marine microplastics were concerning, the current concentrations could be even more so. Previous studies have already concluded that marine microplastics pose significant risks to the environment, marine wildlife, and human health. If concentrations of marine microplastics are greater than previously reported, these risks could be greater than previously assessed as well.
• Additional research is warranted to assess the scope of the global marine microplastics problem. As acknowledged above, we conducted test sampling at just two locations in preparation for our Summer 2026 Pilot Study. Additional research is warranted to confirm the reliability of our findings and to assess the concentration of marine microplastics in other locations around the world.

Even at the previously reported levels, marine microplastics pose significant concerns that have largely been underreported. Additionally, while current plastic reduction initiatives such as limiting single-use plastics and recycling are certainly worthwhile, they overlook the risks associated with microplastics—which are generated by non-single-use plastic-based products ranging from clothing to tires as well as all types of recycled plastic materials.

Next Steps: Continuing to Test South Carolina’s Coastal Waters for Microplastics

So, what are our next steps? At Following Seas, our next step is to continue gathering and analyzing samples—expanding our testing footprint while generating reliable data on the scope of the global marine microplastics problem. Our goal is to provide data that other organizations can use to advocate for meaningful change. If you would like to know more, we invite you to get in touch.