Scientists uncover kelp's carbon storage power in Portugal's marine forests

The Role of Marine Forests in Carbon Capture

Marine forests along the northern coast of Portugal have been identified as significant contributors to carbon capture and storage, according to recent scientific research. This groundbreaking study was conducted by two key institutions: the Interdisciplinary Centre of Marine and Environmental Research (CIIMAR) and the Marine and Environmental Sciences Centre (MARE). For the first time, scientists have quantified the amount of carbon sequestered by seaweed in these underwater ecosystems.

The research highlights the critical importance of kelp forests in supporting marine biodiversity and ecosystem productivity. These habitats are particularly common on the north coast of Portugal, where unique environmental conditions allow for their development. Some species found here represent the southernmost range of their distribution.

Kelp Species and Their Impact

The study, published in the journal Scientific Reports, focused on two dominant kelp species along the northern coastline: Laminaria hyperborea and Saccorhiza polyschides. These species form extensive underwater forests that play a vital role in maintaining marine ecosystems.

This research marked the first comprehensive analysis of carbon reserves in northern Portugal's kelp habitats. It involved field studies measuring distribution, biomass density, growth patterns, and carbon composition. The findings reveal that these ecosystems store approximately 16.48 gigagrams (Gg) of carbon across 5,189 hectares—equivalent to over 5,000 football fields.

Despite their relatively small size on a global scale, these seaweed forests can capture carbon at levels comparable to or even exceeding those of larger ecosystems. The carbon stored in these kelp habitats represents 14% of Portugal's documented blue carbon inventory, which had previously been limited to salt marshes and seagrass meadows.

The Threat of Climate Change

While these kelp forests are essential for capturing and storing carbon, they face growing threats from climate change. The study reveals that these marine forests account for one-third of all carbon sequestered annually by Portugal's marine plant habitats. However, their contribution to climate mitigation has often been overlooked.

According to Francisco Arenas, co-leader of the study, "marine forests are often unknown and undervalued, despite their extremely important ecological and economic value on the north coast of Portugal." The researchers warn that climate change is putting these ecosystems at risk.

A phenomenon known as tropicalisation is already being observed in Portuguese waters. This process involves warming sea temperatures allowing tropical and subtropical species to expand their range polewards. As a result, the associated biodiversity and the ecological services provided by kelp forests, including carbon capture and storage, are under threat.

Policy Recommendations and Future Actions

The study proposes targeted policies for the surveillance, protection, and potential restoration of these zones. It emphasizes the dual importance of kelp forests as both carbon repositories and critical marine habitats. Given the current climate emergency, researchers advocate for incorporating kelp forests into marine protection and blue carbon frameworks as national and international priorities.

With the European Union's Nature Restoration Law in its early stages of implementation, it is urgent to develop and implement effective ecological restoration techniques. This is especially important for habitats that are highly vulnerable but also have high potential for providing ecosystem services, such as marine forests.

Conclusion

The research underscores the need for increased awareness and action to protect and restore these vital marine ecosystems. By recognizing the value of kelp forests in carbon capture and storage, policymakers and environmental organizations can work together to ensure their long-term survival. This not only benefits the marine environment but also contributes significantly to global efforts in mitigating climate change.