Scientists unveil the presence of microplastics in large pelagic fish in the Mediterranean Sea

• Details are documented in a study co-led by the Institute of Marine Sciences (ICM-CSIC) and the Institute of Research on Biodiversity-University of Barcelona (UB), recently published in the journal Marine Pollution Bulletin. 

• The study's findings underscore the urgent need to reduce plastic pollution in the oceans to protect the health of marine ecosystems and, consequently, human health through the food chain. 

Barcelona, September 12, 2024

A recent investigation co-led by the Institute of Marine Sciences (ICM-CSIC) and the University of Barcelona (UB) together with the Spanish Institute of Oceanography (IEO-CSIC), has revealed the "worrisome presence" of microplastics in the stomachs of swordfish (Xiphias gladius) in the western Mediterranean, confirming widespread contamination among pelagic species. The study, recently published in the Marine Pollution Bulletin, highlights the urgent need to reduce plastic pollution in the oceans to protect the health of marine ecosystems and, by extension, human health through the food chain.

Marine pollution, particularly plastic pollution, emerges as a major concern for the health of global marine ecosystems. Recent data indicates that global plastic production has reached unprecedented levels due to its widespread use, low cost, and durability, reaching 6.3 billion tons in recent years. In the marine environment, these plastics degrade into smaller particles known as microplastics, which can act as vectors for chemical contaminants and pathogens.

For the study published now, the scientific team analysed the stomach contents of swordfish caught in the western Mediterranean during two different periods (2011-2012 and 2017-2019). The results reveal the presence of microplastics in 80% of the stomachs, with polyethylene terephthalate, used in the production of bags, films, bottles, among others, being the most detected polymer.

"This study establishes a baseline for monitoring the ingestion of microplastics by swordfish in the western Mediterranean, a species that has recently shown changes in its diet, which could translate into future changes in microplastic ingestion," explain researchers Joan Navarro (ICM-CSIC) and Joan Giménez (IEO-CSIC).

Meanwhile, the UB researcher Odei Garcia-Garin, from the Faculty of Biology and the Biodiversity Research Institute (IRBIO) of the University of Barcelona, asserts that "the results of the work are crucial for the development of actions aimed at the management and conservation of swordfish in the Mediterranean, and establish a baseline for monitoring the ingestion of microplastics by swordfish in the western Mediterranean."

Until now, it was known that microplastics were present in many marine ecosystems and could be ingested by various marine species. However, there was very little information on the presence of microplastics in large pelagic predators such as swordfish in the western Mediterranean. Given their generalist and opportunistic feeding behaviour, these fish are considered good indicators of changes in the ecosystem of the western Mediterranean, and although the Mediterranean population represents less than 10% of the global population, capture levels here are relatively high and comparable to those in larger areas like the North Atlantic.

Looking ahead to future research, the team will focus on evaluating the physiological and toxicological effects of microplastics on swordfish and other species. Additionally, researchers aim to deepen understanding of the transfer of microplastics through the food web and the development of mitigation strategies to reduce plastic pollution, assessing their long-term effectiveness.

Reference article

Torresi, M., Giménez, J., Navarro, J., Coll, M., García-Barcelona, S., Macías, D., Borrell, A., & Garcia-Garin, O. (2024). Microplastic characterization in the stomachs of swordfish (Xiphias gladius) from the western Mediterranean Sea. Marine Pollution Bulletin, 206, 116767.

Researchers contact

Odei García-Garin | odei.garcia@ub.edu

Joan Navarro | joan@icm.csic.es

Joan Giménez Verdugo | joan.gimenez@csic.es

Source: 

Elena Martínez | elenamb@icm.csic.es 

Communication and dissemination office ICM-CSIC