A study led by researchers from the University of Barcelona and the Marine and Coastal Research Institute (INVEMAR) in Colombia warns of the presence of potentially pathogenic bacteria in microplastics extracted from water, sediments and the digestive tract of fish in the Ciénaga Grande de Santa Marta, the largest and most productive coastal lagoon system in the Colombian Caribbean. Bacteria form biofilms on the surface of microplastics and give rise to what are known as plastispheres, ecosystems associated with plastic waste that are highly resistant to environmental changes. Microplastics have also been found in fish consumed by the local population, posing an even greater risk to the entire natural ecosystem and human health.
These conclusions are now revealed in an article in the Journal of Hazardous Materials, led by researchers Ostin Garcés-Ordóñez and Miquel Canals, from the Marine Geosciences Consolidated Research Group of the UB's Faculty of Earth Sciences.
The study opens a new perspective on the microorganisms that colonize microplastics in coastal lagoons, an area still little explored by the scientific community. The findings also provide unpublished data on the interactions between microplastics and potentially pathogenic bacteria in ecosystems under increasing environmental pressure.
Plastics and bacteria that also threaten the local population
Covering 1,321 km², the Ciénaga Grande de Santa Marta is a shallow (1-1.8m) lake ecosystem that receives freshwater from four rivers and seawater through a channel connecting it to the Caribbean Sea. Flanked by mangroves, it is home to two national parks - recognized as a Ramsar site - and is a strategic lagoon complex for biodiversity conservation. In this ecoregion of rich fauna and flora, fishing is essential for the livelihoods of local communities.
Despite its ecological value, "the Ciénaga Grande de Santa Marta is seriously threatened by high microbiological contamination and microplastics that affect the water, sediments and organisms. These pollutants alter the quality of the habitat and fishery products and, ultimately, the food security of the local population", says researcher Ostin Garcés-Ordóñez, a member of the UB's Consolidated Research Group in Marine Geosciences and INVEMAR's Marine Environmental Quality Research Group.
