Microbial Interactions with Particulate and Floating Pollutants in the Oceans: A Review

The Earth’s oceans are the final resting place of anthropogenic wastes, mainly plastics, metals, rubber, and fabrics, in order of decreasing abundance. On reaching the sea and the benthos, most of these have assumed fragmented or particulate forms. They become colonized by marine microorganisms and later interact with macroorganisms, leading to potential problems with marine life and the ecosystem. Rapid biodegradation of the polluting materials is a possible, and desirable, result if harmful by-products are not produced or toxic constituents are released. Negative effects are the transport of organisms to other ecosystems, with possible disturbance of the natural biological balance, or transfer of pathogenic organisms. A microbial biofilm can mask unattractive anthropogenic materials, increasing ingestion by marine life, with potentially dangerous results. This article seeks to provide a synthesis of the interactions occurring between oceanic anthropogenic polluting matter in solid and particulate form, and the microbiota present in our seas. It discusses the most important solid and particulate pollutants in the oceans, their sources, adverse effects, interactions with living organisms, mainly microorganisms, and future research for their control. Pollutants included are marine litter (macrodebris), microplastics, engineered nanoparticles, metallic particles, and, finally, sinking particles (“marine snow”) as a potential biodegradation “hot spot”.