Field studies confirm that reef organisms are already chronically exposed to plastic in the natural environment. Yeemin et al. (2025) detected microplastics in every sampled colony of the zoanthid Palythoa caesia across multiple reef sites in Thailand. Particles occurred on mucus layers and within tissues, confirming active uptake. Polymer profiles reflected local pollution sources. Complementary work by Sutthacheep et al. (2025) revealed microplastics across corals, seawater, and sediments, with sediments acting as long-term reservoirs and smaller particles preferentially retained in coral tissues, highlighting that reef organisms experience chronic exposure to plastic pollution throughout their lifespans. As thermal stress events become more frequent and recovery periods shorten, coral stress responses increasingly unfold alongside chronic plastic exposure, raising the likelihood of combined effects.Plastic pollution on reefs extends beyond microplastics. Pengsakun et al. (2025) documented widespread abandoned fishing gear on underwater pinnacles in the Gulf of Thailand. Nets and monofilament lines were associated with tissue necrosis, fragmentation, and algal overgrowth, particularly in massive corals. Such injuries reduce colony integrity and increase susceptibility to bleaching, disease, and storm disturbance. In a warming ocean where disturbances intensify, macroplastic damage directly weakens reef structure and adds further physiological stress. Lasdin et al. (2025) demonstrated that even remote reef systems are not insulated from plastic pollution, where evaluation of beach sediment adjacent to coral reefs in French Polynesia, uncovered prevalent plastic particles and sedimentation processes that enable plastics to accumulate alongside biogenic sands. This establishes baseline contamination in regions distant from local sources and underscores the global reach of plastic dispersal. Future climate stress events are therefore unlikely to occur without co-exposure to plastic, making truly pollution-free climate refugia increasingly rare.A central finding emerging from this Research Topic is that microplastics can alter coral physiological responses under projected climate conditions. Sugierski et al. (2025) exposed the endangered Caribbean staghorn coral, Acropora cervicornis, to future ocean warming and acidification, with and without microplastics over 22 days. Predicted future ocean conditions and microplastics alone caused limited negative impacts. In contrast, combined exposure decreased skeletal growth and lowered host protein levels. These findings suggest that microplastics may diminish tolerance levels and hinder recovery during climate-related stress, highlighting concerns about the impact of microplastics on ecosystems. Thermal stress typically induces coral bleaching, prompting corals to expel symbiotic algae in efforts to prevent cellular damage. However, Sugierski et al. (2025) discovered a different response when microplastics are present. Instead of bleaching, corals exhibited increased symbiont densities, but without a corresponding rise in chlorophyll, indicating a disruption in host-symbiont regulation and stress-response mechanisms. Exposure to microplastics may be energetically costly, leading to protein breakdown and elevated nitrogen levels, which inadvertently feed the symbionts. As a result, algae multiply, causing oxidative stress, while the host depletes its own energy reserves. This cycle promotes symbiont growth at the expense of the host, creating a harmful feedback loop that could weaken the long-term coral resilience to climate stress.Plastic pollution extends beyond adult corals, affecting multiple life stages. Wilkins and Richmond (2025) showed that leachates from common plastic polymers alter the survival and settlement of coral planulae in the Hawaiian corals Montipora capitata and Harbor Porites, with responses depending on polymer type and concentration. Notably, leachates from high-density polyethylene induced elevated settlement rates, indicating that plastic-derived chemical cues may mislead larvae toward suboptimal or degraded substrates. By disrupting settlement behavior and early survival, plastic-associated chemicals introduce a hidden barrier to reef regeneration at the most vulnerable stage from a demographic perspective. Even when adult corals survive thermal stress, compromised recruitment can prevent population replenishment and impair community recovery. This constitutes a previously underestimated mechanism by which plastic pollution can directly affect reef resilience in a warming ocean. Together, these six studies point to a consistent conclusion: Plastic pollution is not a peripheral concern but an emerging component of the stressor landscape shaping coral reef trajectories (Figure 1). Climate change is, without question, the dominant driver of coral reef decline. However, plastic pollution is a pervasive global and local stressor with the potential to affect organismal coral reef responses to climate change. Plastics may amplify climate-driven stress through shared biological pathways. The studies of this Research Topic provide environmental evidence that plastic pollution is omnipresent (Yeemin et al., 2025;Sutthacheep et al., 2025, Lasdin et al., 2025), can cause structural damage (Pengsakun et al. 2025), and impaired recruitment (Wilkins and Richmond, 2025). Chronic exposure to plastic pollution can increase disease susceptibility (Lamb et al., 2018;Mueller and Schupp, 2020), suppress growth rates (Reichert et al., 2019(Reichert et al., , 2024;;Hankins et al., 2021;Rades et al., 2024;Tirpitz et al., 2025), alter photosynthesis (Reichert et al., 2019;Lanctôt et al., 2020), compromise the health of symbionts (Okubo et al., 2018;Xiao et al., 2021), and suppress immune capacity (Tang et al., 2018), mechanisms also common to warming or acidification (Hoegh-Guldberg et al., 2017;Krämer et al., 2022). When these stressors co-occur, corals may face increased energetic demands, which reduce their physiological buffering capacity, effectively lowering tolerance thresholds and narrowing recovery windows (Sugierski et al., 2025). In this context, plastic pollution may act as a modifier of coral resilience, affecting bleaching susceptibility, slowing post-disturbance recovery, and contributing to shifts in reef trajectories. Recognizing these synergistic interactions is essential for assessing the cumulative impacts of in situ stressor complexity on the resilience of coral reefs in a changing ocean.Efforts to reduce plastic pollution must not compete with climate action but complement it by reducing physiological and ecological stress on reef organisms, which are often already at tolerance limits under current conditions. Unlike climate change, plastic pollution can be locally tractable. Waste management, fisheries regulation, and material innovation offer direct opportunities for mitigation. Integrating these measures into reef resilience strategies is both necessary and actionable for protecting coral reefs.
Reichert et al. (Tue,) studied this question.