Pilot testing using the SB Buoy

to filter and analyze microplastics on the coast of Catalonia and Castelló in 2020

We would like to thank L’Ampolla, Calafell, Calella de Mar, Mataró, Sitges and Vinaròs for taking part in this pilot experiment carried out by GPA Seabots



These are the municipalities that have been encouraged to be part of the project.

Thanks to them, we can draw up a map of the current state of microplastic contamination on our coastline.

Thank you very much for their support!


The samples were collected during the summer season 2020 and the analysis of microplastics was carried out between the end of 2020 and the first months of 2021.

The results obtained from more than forty SB BUOYS set in six coastal municipalities are in line with other studies that have taken place on the Western Mediterranean coast, and are a significant example of the increasing ecological footprint that the patterns of human production and consumption are leaving on marine ecosystems.



1. We disassembled the structure of each SB BUOY to remove the nets which had captured the microplastics in 2020.


2. Once the nets had been removed, they were placed in water tanks to scrape the inside and extract all the materials, including the microplastics.


3. After having transferred the filtered plastics into different containers, the microplastics were sorted using two types of filters: one for clothes and a second one for metals. A large part of microplastics remained on the water surface because of density. Anyhow, several of them fell to the bottom of the tank, what made it difficult to identify them


​​4. Once the microplastics were removed, a detailed quantification and analysis of each sample was carried out separately, allowing to obtain the results by municipality and buoy.



The aim of this analysis is to explore the main characteristics of the samples recovered from the buoys installed in the above-mentioned municipalities in the 2020. We do not intend to present a scientific study about microplastic pollution in these coastal towns. However, the results presented may be a good starting point to study this phenomenon on the Mediterranean coast.

MP-1: This typology is formed by some microplastic waste that is characterized by its dark color and a very hard consistency. Its origin is uncertain, although it is likely that it comes from the remains of larger maritime or industrial materials, so these microplastics could be the result of a progressive degradation of them.




MP-2: This category includes transparent or white microplastics. They are thinner and more flexible that the other groups. The most plausible explanation about their origin consists in associating them with the remains of different types of single-use plastics, such as food packaging or commercial and industrial product wrappers. It is one of the most common typologies within the samples obtained.

MP-3: The third type of microplastics consists of pieces of a wide variety of colors —mostly blue, red and yellow—, whose consistency and thickness are higher than in the average of the plastic waste in our sample. This category is one of the most eye-catching ones. Even though their origin is unclear, these microplastics seem to be the result of the degradation of larger plastic structures. This typology is also one of the most common ones in our study


MP-4: This category is formed by white microplastics with a spongy texture. They do not have an easily recognizable appearance as microplastics, because they are probably made of expanded polystyrene (Porexpan). This is the most common typology in the obtained samples, and this is not by chance, since different studies in similar areas on the Western Mediterranean coast confirm that expanded polystyrene is among the most abundant waste in this region

MP-5: Among the samples, a type of debris consisting of small fragments of nylon threads from nets and fishing devices was also found.


MP-6: This category includes microplastics smaller than a millimeter in diameter. They have a great variety of colors and may be traces of paint. The specialized literature points out that most of the paint chips in the sea come from the coatings of the boats. They detach from the boat during construction, maintenance, repair and use, and are mainly composed of polyurethane, epoxy, vinyl and lacquers.