The Tara Ocean expeditions on plastic pollution

The Tara Ocean expeditions investigated plastic pollution and its impact on marine ecosystems for over a decade (Tara Mediterranean, Tara Pacific and Tara Microplastics). Conducted on the research schooner Tara, these projects combined advanced genomic, chemical, and ecological approaches to investigate how microplastics influence microbial life and ecosystem health. We highlighted the alarming extent of microplastic pollution in the semi-enclosed Mediterranean basin, one of the world’s most polluted marine regions. We revised downwards the flows of microplastics from rivers to sea, and lifetimes in the Ocean revised upwards. We described microplastics as sponges for surrounding pollutants that are toxic to organisms. The projects revealed also that plastics serve as substrates for microbial colonization, creating novel "plastispheres" that alter microbial community composition and function, with some bacteria identified as human pathogens. Through high-resolution sequencing and metagenomics, Tara scientists identified unique microbial taxa and potential metabolic pathways involved in plastic degradation, as well as interactions that may influence global biogeochemical cycles. These findings underscore the potential for discovering marine genetic resources with applications in biotechnology. The project data provide a vital resource for understanding the ecological impacts of plastic pollution and emphasize the need for innovative approaches to characterize and utilize marine microbial diversity, advancing efforts toward sustainable ocean stewardship and pollution mitigation.