Microplastics in the oceans: the many ways they can harm coral life

Microplastics are one of the main threats to marine ecosystems, but the mechanisms determining their impact on marine life are still largely unknown. We investigated the impact of microplastics on the red coral, an emblematic and threatened species belonging to the Corallium genus, which is distributed at almost all latitudes and depths. We report here that microplastics are ingested and accumulated by corals (primarily polypropylene and polystyrene), either directly (as microplastics are confounded with the coral’s prey, plankton) or through the ingestion of zooplankton containing microplastic particles. Once ingested, microplastics cause multiple biological effects, spanning from feeding impairment and mucus release. Microplastics also cause DNA damage and a shift in the coral microbiome that together with their tissue abrasions, favour the proliferation of opportunistic/pathogenic bacteria. Since microplastic contamination is expected to double in all oceans from 2030-2060, we anticipate that their impact will likely increase in the future, with the potential of causing coral death. The effects reported on the red coral could be similar on many other habitat-forming species (species that transform the environment creating a new habitat) and may act in synergy with other stressors, potentially exacerbating the impacts of heat waves and other climate-driven events.