Climate change is drastically altering the composition and abundance of seaweed-dominated ecosystems throughout our oceans. Ocean warming and associated intensifying marine heatwaves (Wernberg et al., 2016; Bunting et al., Trautmann et al., Gendall et al., Khen et al.), ocean acidification (Koch et al., 2013; Comeau and Cornwall, 2016), and deoxygenation (Altieri et al., 2021) can all impact the physiology of seaweeds and the ecological roles that they play. Ocean warming can cause long-term shifts in the ranges of seaweed species, usually in the form of range retractions at warm edges and expansions at cool edges (Straub et al., 2016). Marine heatwaves can elicit acute heat stress in seaweeds, drive subsequent mortality, and result in phase shifts from one ecosystem type to another (Wernberg et al., 2016, 2024). Ocean acidification causes the slow transformation of ecosystems from those dominated by coralline algal substrate to those characterised by a variety of turfing seaweeds or microalgae (Cornwall et al., 2024). Increasing intensity of ocean deoxygenation and frequency of acute localized events will likely exacerbate the effects of localized threats, but the effects of deoxygenation on seaweed communities remain poorly understood compared to other climate change-linked stressors (Altieri et al., 2021). Additionally, increased sedimentation caused by land use changes and increased storm frequencies brought on by climate change (termed ‘coastal darkening’), is also an important stressor of seaweed communities (Blain et al., 2021). Increased sedimentation can interact with other stressors (e.g., temperature) or act on its own to alter the composition and function of seaweed-dominated ecosystems (Wernberg et al., 2024). To better predict and project how seaweed-dominated ecosystems will fare in the future, we require extensive further evidence regarding how the effects of climate change will manifest on seaweeds of all types across temperate, tropical, and polar regions.
Cornwall C. E., Berbece D. M., Blain C., Johnson M. D. & Starko S., 2025. Impacts of climate change on seaweeds. Frontiers in Marine Science 12: 1702410. doi: 10.3389/fmars.2025.1702410. Article.
