Sunscreen active ingredients as emerging threats to reef-corals: an integrative review of physiological responses and microbiome alterations

The increasing release of sunscreen active ingredients into coastal environments has been recognized as a contributing factor to coral reef degradation and toxicity. Thus, this work synthesizes current evidence on the effects of these compounds on coral physiology and associated microbial communities. An integrative literature review was conducted following PRISMA guidelines, covering peer-reviewed studies published between 2016 and 2026 and focusing on reef-building corals exposed to organic and inorganic UV filters. Data on toxicological, physiological, and microbiological endpoints were analyzed, including bleaching, oxidative stress, photosynthetic impairment, developmental toxicity, and shifts in the coral microbiome. The reviewed studies indicate that compounds such as oxybenzone, octinoxate, octocrylene, zinc oxide, and titanium dioxide can induce oxidative stress, disrupt symbiotic dinoflagellate performance, reduce calcification, and promote bleaching, even at environmentally relevant concentrations. In contrast, evidence regarding impacts on coral-associated microbiota remains limited and fragmented. Overall, sunscreen active ingredients emerge as contaminants of growing ecological concern for reef ecosystems, highlighting the need for an integrated holobiont-based perspective to support environmental risk assessment, regulatory policies, and the development of genuinely reef-safe photoprotective formulations.