The oceans have accompanied us throughout our entire evolutionary process: life originated in the oceans, and most organisms retain this heritage, as we are largely composed of water. Remembering our responsibility for their conservation is only the first step toward what we, as humanity, owe them. Beneath the waves lie the true lungs of the Earth and the refuge of thousands of species: seaweed forests, which today are waging a silent battle for their survival.
In the face of current climate challenges, the Global Change Research Institute of the Rey Juan Carlos University (IICG-URJC) conducts diverse studies with the mission of deciphering and alerting the scientific community about present and future environmental impacts. In this effort, the scientific work of several IICG-URJC researchers who study the marine environment stands out: María del Brezo Díaz-Caneja Martínez, Sandra Hernández Arenas, Rosa María Viejo García, and Rosa María Chefaoui Díaz, who have recently led relevant studies published in prestigious journals such as Marine Pollution Bulletin and Journal of Biogeography.
In temperate-cold latitudes, macroalgae play a fundamental role in marine ecosystems, acting as foundation species and true ecosystem engineers. This means they not only function as primary producers, capturing carbon and transforming sunlight into energy—thus forming the base of the food web—but also provide habitat, shelter, and food for many other species that depend on them. In turn, they support artisanal and commercial fisheries and the coastal biodiversity of the oceans.
However, the warming of seas and oceans, combined with human activities, is promoting the spread of invasive exotic macroalgae, posing a direct threat to native species. Studies show that, on a global scale, water temperature is the main factor determining their distribution. Yet, when processes are analyzed at a regional scale, this factor becomes secondary: the human footprint—especially maritime traffic and proximity to commercial ports—becomes the main pathway for the introduction and spread of these invasive species (Hernández et al., 2024). Studies like this, which combine different spatial scales using species distribution models, reveal an interesting paradox: while climate determines where these algae can live globally, it is human activity that, at regional or local scales, facilitates their arrival and establishment. In other words, climate change sets the stage, but it is us, through our activities, who open the door to these invaders.
Furthermore, as Hernández et al. (2024) point out, under the most unfavorable climate scenario projected for the end of the century, three out of four analyzed species could suffer drastic reductions in their distribution, exceeding 97% at the regional scale. In this context, areas such as Galicia could become one of their last and most fragile climate refuges, thanks to the cooling of its waters caused by coastal upwelling.
Unfortunately, global warming does not only affect macroalgae. In tropical latitudes, corals—which play a similar ecological role—are also seriously threatened. In 2019, researchers from Rey Juan Carlos University analyzed the fire hydrocoral Millepora alcicornis in the Atlantic Ocean, a key structural species that provides habitat to hundreds of marine organisms (Rodríguez et al., 2019). This study stood out for incorporating an innovative early-warning approach: a hybrid species distribution model that included experimentally obtained physiological information about the species—something often absent from traditional models. The results were particularly revealing. While many conventional models underestimate the impact of extreme heat, this work more realistically predicts a future marked by strong contrasts: on the one hand, an alarming contraction of habitat in regions such as the Caribbean and the Gulf of Mexico, where coral areas will exceed their thermal limits; and on the other, a possible expansion toward higher latitudes, as already suggested by its recent colonization of the Canary Islands. These findings are essential for anticipating and managing the future of ocean biodiversity.
This hybrid methodology has already been applied in more recent studies on macroalgae conducted by IICG-URJC researchers (Hernández et al., 2026), where the results once again warn of the urgent need to protect the oceans, because by doing so, we are protecting our own future.
Understanding the problem is not enough; decisive action is required to conserve the life that sustains these ecosystems. The creation of Marine Protected Areas is not an option but an essential tool to ensure the survival of key species and maintain the balance of our seas (Hernández et al., in press). Today, more than ever, the ocean needs our commitment: to reduce our footprint, support science, and demand bold conservation policies. Because every action counts, and we are still in time to preserve the richness that sustains life on this planet.
References:
- Hernández, S., Arenas, F., Haberle, I., Rodríguez, L., Carreño, F., & Martínez, B. D.-C. (2026). Hybrid Projections Improve Prediction of Distributional Shifts of Invasive and Native Seaweeds Under Climate Change. Journal of Biogeography, 53(1), e70152. https://doi.org/10.1111/jbi.70152
- Hernández, S., Franco, J. N., Olabarria, C., de Bettignies, T., Des, M., Barrientos, S., Piñeiro-Corbeira, C., García-Tasende, M., Peteiro, C., Babé Gómez, Ó., Lanza-Arroyo, P., Viejo, R. M., & Martínez, B. D.-C. (2026). Distribution modelling to identify threats and conservation needs for kelp forests in a warming region. Under review en Journal of Environmental Management.
- Hernández, S., Martínez, B. D.-C., & Olabarria, C. (2024). Predicting habitat suitability for alien macroalgae in relation to thermal niche occupancy. Marine Pollution Bulletin, 208, 116953. https://doi.org/10.1016/j.marpolbul.2024.116953
- Rodríguez, L., García, J. J., Carreño, F., & Martínez, B. (2019). Integration of physiological knowledge into hybrid species distribution modelling to improve forecast of distributional shifts of tropical corals. Diversity and Distributions, 25(1), 715-728. https://doi.org/10.1111/ddi.12883