Bringing the Ocean to Society
2 Jul 2020
More than half of sardines and anchovies in the Western Mediterranean have microplastics in their intestines
The details of the finding are collected in a study including EurOcean Members IEO and Ifremer.

Researchers from the Spanish Institute of Oceanography (IEO), the Institute of Marine Sciences (ICM-CSIC) and the Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), have detected that 58% of sardines in the Western Mediterranean has ingested microplastics, while in the case of anchovies this percentage is 60%.

The production and use of microplastics in the world has increased exponentially since the 1950s, reaching more than 300 million tons in 2017. Microplastics are plastic particles and fibers of less than 5mm in size, invisible to the naked eye and that They primarily affect small fish, invertebrate organisms, and other filter feeders that have the potential to enter the food chain.

Among all the species of small pelagic fish, sardines (Sardina pilchardus) and anchovies (Engraulis encrasicolus) are the most commercialized and consumed fish in the northwest of the Mediterranean Sea, representing up to 39% of the total catches in the region in recent years. Furthermore, these species play a key role in marine ecosystems, where they are important prey for many predators such as tunas, cetaceans, and seabirds.

A study recently published in the specialized magazine Marine Pollution Bulletin reveals that 58% of individuals have eaten microplastics in sardines, a percentage that is 60% in anchovies. According to the researchers, among the factors that influence this incidence is the prevalence of parasites such as larvae, trematodes and nematodes in the intestinal tract. That is, individuals with the highest content of microplastics in their digestive system also have more parasites.

In this sense, the results of the work, in which researchers from the Spanish Institute of Oceanography (IEO), the Institut de Ciències del Mar (ICM-CSIC) and the Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) have participated ), show that, in the case of sardines, individuals with a poorer body condition have a higher probability of ingesting microplastics. In the case of anchovy, on the other hand, the probability of incidence increases in individuals with a gonadosomatic index -weight of the gonad as a percentage of the total body weight used to measure the sexual maturity of individuals- higher and of smaller size. In individuals of both species, a worse body condition implies a higher incidence of both parasites and microplastics.

As Maria Grazia Pennino, first author of the article, points out, "this is one of the first studies to find this type of relationship between the incidence of microplastics and parasites."

For her part, Marta Coll, a researcher at the ICM-CSIC, points out that "the results of this study raise new questions to continue the investigation, since, for example, we still do not know the specific mechanism by which small pelagic fish with the highest incidence microplastics also have more intestinal parasites. " Lastly, Coll stresses that "our results demonstrate the importance of continuous monitoring of the marine environment", since only in this way is it possible to assess the health of marine ecosystems and their impact on human beings ".

According to the study, geographical areas with the highest probability of ingestion of microplastics are the Gulf of Alicante for sardines and the Gulf of León - Delta del Ebro for anchovies. In addition, in both species there is a positive relationship between the presence of parasites and the ingestion of microplastics, which shows that both parasitism and ingestion of microplastics can affect both the health of marine populations and that of human consumers.

Reference article: Pennino, MG, Bachiller, E., Lloret Lloret, E., Albo Puigserver, M., Jadaud, A., Bellido, JM, Coll, M., 2020. Ingestion of microplastics and occurrence of parasite association in Mediterranean anchovy and sardine. Marine Pollution Bulletin, 158, https://doi.org/10.1016/j.marpolbul.2020.111399