Report on the Blue Carbon Potential of Southern European Kelp Forests and Alignment with Sustainable Development Goals

1.0 Introduction: The Role of Marine Ecosystems in the Sustainable Development Agenda

In the context of the United Nations Sustainable Development Goals (SDGs), particularly SDG 13 (Climate Action) and SDG 14 (Life Below Water), the quantification of carbon sequestered by natural ecosystems is paramount. “Blue Carbon” refers to the organic carbon captured and stored by marine and coastal ecosystems. While traditionally focused on mangroves, saltmarshes, and seagrass meadows, recent evidence highlights the significant, yet often overlooked, contribution of seaweed forests. These ecosystems are critical for climate change mitigation and the preservation of marine biodiversity. However, a lack of standardized monitoring protocols and persistent data gaps have hindered their inclusion in formal carbon-offset frameworks. This report details a study that addresses this knowledge gap by quantifying the Blue Carbon potential of subtidal kelp forests in Northern Portugal, providing critical data to support evidence-based policies for marine conservation and climate action.

2.0 Study Objectives and Methodology

The primary objective was to assess the Blue Carbon storage and sequestration potential of kelp forests in Northern Portugal, focusing on the dominant species Laminaria hyperborea and Saccorhiza polyschides. This assessment provides a scientific basis for integrating these habitats into regional and national strategies aimed at achieving SDG 13 and SDG 14.

2.1 Data Collection and Analysis

The methodology involved a comprehensive in-situ assessment along a 90 km stretch of coastline:

1. Habitat Mapping: A total of 496 video camera surveys were conducted to determine the extent of suitable rocky substrate occupied by kelp forests, establishing a total habitat area of 5,189 hectares.
2. Biomass and Carbon Content: Aboveground biomass was determined from 179 collected samples. Carbon content was measured from 36 samples using an Organic Elemental Analyzer.
3. Productivity and Sequestration: Primary productivity was calculated from the growth rates of 119 individual kelp specimens. The carbon sequestration rate was conservatively estimated based on established models of Net Primary Production (NPP) export to deep ocean sinks, excluding continental shelf burial to avoid double-counting with other Blue Carbon ecosystems.

3.0 Results: Quantifying Contributions to Climate and Ocean Health

3.1 Aboveground Carbon Storage

The kelp forests in Northern Portugal represent a significant reservoir of carbon, directly contributing to the objectives of SDG 14 (Life Below Water) by supporting a healthy and productive marine environment.

• The total estimated aboveground carbon stored in the biomass of these kelp forests is 16.48 Gg C.
• This stock is distributed across 5,189 hectares, with a mean biomass of 2.65 Mg C ha^–1.
• The species Saccorhiza polyschides is the largest contributor, accounting for 15.47 Gg C of the total stock.
• When compared to national data for mainland Portugal, this regional kelp forest stock constitutes approximately 14.5% of the total aboveground biomass of all known Blue Carbon habitats (kelp, saltmarshes, and seagrasses).

3.2 Annual Carbon Sequestration Rate

The capacity of these kelp forests to actively remove CO₂ from the atmosphere underscores their importance for SDG 13 (Climate Action).

• The total estimated annual carbon sequestration is 1,903 Mg C year^–1.
• This corresponds to a sequestration rate of 0.60 Mg C ha^–1 year^–1.
• This single regional kelp forest system contributes an estimated 33.9% of the total annual Blue Carbon sequestration in continental Portugal, compared to saltmarshes (52.1%) and seagrasses (14.0%).
• This finding demonstrates that, when normalized by area, kelp forests sequester carbon at rates that equal or exceed those of traditionally recognized Blue Carbon ecosystems, making them highly efficient natural climate solutions.

4.0 Discussion: Integrating Kelp Forests into National Sustainability Strategies

4.1 Advancing Climate Action (SDG 13)

The substantial carbon sequestration capacity of kelp forests positions them as a vital tool for climate change mitigation. The findings indicate that protecting and restoring these habitats can make a measurable contribution to Portugal’s national climate commitments. However, the report acknowledges that estimates are sensitive to export assumptions, highlighting the need for refined models to improve accuracy for carbon accounting frameworks.

4.2 Conserving Life Below Water (SDG 14)

This study reinforces the ecological significance of kelp forests, which are known to be in decline in some regions. The data provides a compelling rationale for prioritizing their conservation and restoration. Protecting these ecosystems not only secures their carbon sequestration function but also preserves biodiversity, supports coastal food webs, and maintains crucial ecosystem services. The lack of detailed data for other parts of the Portuguese coast, as well as for other habitats like coralline algae beds, represents a critical gap in the sustainable management of marine resources.

4.3 Fostering Partnerships for the Goals (SDG 17)

Effective Blue Carbon assessment requires a multi-faceted approach. This study demonstrates the value of combining fine-scale, in-situ data with broader, national-scale modeling. Achieving a comprehensive national inventory necessitates collaboration among research institutions, harmonization of methodologies, and investment in long-term monitoring programs. Such partnerships are essential for creating robust, evidence-based policies that can be integrated into international frameworks like Japan’s J-Blue Credit programme.

5.0 Recommendations and Future Directions

To fully leverage the potential of kelp forests as a nature-based solution and achieve relevant SDG targets, the following actions are recommended:

5.1 Policy and Management Recommendations

1. Inclusion in National Inventories: Officially recognize and integrate seaweed forests into Portugal’s national Blue Carbon inventories and climate mitigation strategies.
2. Prioritize Conservation and Restoration: Develop and implement targeted conservation and restoration projects for kelp forests to protect existing carbon stocks and enhance future sequestration capacity, directly addressing targets under SDG 13 and SDG 14.
3. Develop Carbon-Offset Mechanisms: Explore the creation of voluntary or compliance-based carbon-offset frameworks that include kelp forests, providing financial incentives for their protection.

5.2 Future Research Priorities

• Expand Geographic Scope: Conduct similar in-situ assessments along the entire Portuguese coastline to create a complete and accurate national baseline.
• Refine Carbon Pathway Models: Invest in research to reduce uncertainties regarding carbon export rates, decomposition, and long-term burial in deep-sea sediments.
• Adopt a Holistic Ecosystem Approach: Broaden research to include other significant but understudied components of the marine carbon cycle, such as coralline algae and dissolved organic carbon (DOC) fluxes.

1. Which SDGs are addressed or connected to the issues highlighted in the article?

SDG 13: Climate Action

The article directly addresses SDG 13 by focusing on the role of marine ecosystems in climate change mitigation. It quantifies the “Blue Carbon” sequestered by kelp forests, highlighting their potential to help mitigate CO₂ emissions. The abstract states that the study’s findings are significant for “regional carbon management” and that conservation efforts should be prioritized for their “potential role in climate mitigation.” The introduction further reinforces this by stating, “The escalating impact of climate change requires accurate identification and quantification of BC [Blue Carbon], as it can aid mitigating current emissions.”

SDG 14: Life Below Water

The article is fundamentally centered on SDG 14 as it investigates the health, extent, and ecological function of coastal and marine ecosystems, specifically kelp forests. It calls for the “conservation and restoration efforts… to protect and enhance the Blue Carbon capacity of kelp forests and associated habitats.” The study assesses the biomass, area, and species composition of these ecosystems, noting that they are “in decline.” This aligns with the goal of sustainably managing and protecting marine life and habitats.

SDG 15: Life on Land

While the focus is marine, SDG 15 is relevant through its emphasis on protecting and restoring ecosystems and halting biodiversity loss. Target 15.9, which calls for integrating ecosystem and biodiversity values into national and local planning, is mirrored in the article’s push to integrate Blue Carbon from kelp forests into “national-scale assessment” and “carbon offsetting frameworks.” The article’s comparison of kelp forests with terrestrial forests’ established carbon-offset mechanisms (like REDD) further connects the marine conservation effort to the broader principles of ecosystem management under SDG 15.

2. What specific targets under those SDGs can be identified based on the article’s content?

1. SDG 13: Climate Action

   • Target 13.2: Integrate climate change measures into national policies, strategies and planning. The article explicitly supports this target by aiming to provide a “scientific foundation for evidence-based policies” and advocating for the inclusion of kelp forests in “blue carbon management frameworks” and “carbon-offset frameworks.” It highlights how Japan’s J-Blue Credit programme serves as a model for integrating these ecosystems into carbon markets.

2. SDG 14: Life Below Water

   • Target 14.2: By 2020, sustainably manage and protect marine and coastal ecosystems to avoid significant adverse impacts, including by strengthening their resilience, and take action for their restoration in order to achieve healthy and productive oceans. The article directly addresses this by quantifying the value (carbon storage) of kelp forests, noting they are “in decline,” and concluding that “conservation and restoration of these forests are crucial for maintaining their ecological and economic value.”
   • Target 14.5: By 2020, conserve at least 10 per cent of coastal and marine areas, consistent with national and international law and based on the best available scientific information. The study contributes to this target by providing “fine-scale, in-situ data” and mapping the extent of these ecosystems (“5189 hectares in northern Portugal alone”), which is essential scientific information for identifying and prioritizing areas for conservation.
   • Target 14.a: Increase scientific knowledge, develop research capacity and transfer marine technology… The entire study is an embodiment of this target. It aims to address a “knowledge gap” by quantifying blue carbon in an “unexplored region.” The “Future research directions” section explicitly calls for expanding “in-situ monitoring,” improving models, and refining data on sequestration rates to strengthen the understanding of these ecosystems.

3. SDG 15: Life on Land

   • Target 15.9: By 2020, integrate ecosystem and biodiversity values into national and local planning, development processes, poverty reduction strategies and accounts. The article advocates for this by pushing for the inclusion of kelp forest carbon sequestration values into “national-scale voluntary schemes” and “blue-carbon budgets,” thereby integrating their ecosystem service value into national accounting and policy.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

Yes, the article mentions and uses several quantitative indicators to measure the status and contribution of kelp forests, which can be used to track progress towards the identified targets.

1. For SDG 13 (Climate Action)

   • Carbon Sequestration Rate: The study calculates this as “1903 Mg C year^–1” for the total area and “0.60 ± 0.05 Mg C ha^–1 year^–1” per unit area. This is a direct indicator of the ecosystem’s contribution to climate mitigation (Target 13.2).
   • Total Carbon Stock: The article quantifies the stored carbon in aboveground biomass as “approximately 16.48 Gg of carbon.” This serves as a baseline indicator for the amount of carbon protected through conservation efforts.

2. For SDG 14 (Life Below Water)

   • Ecosystem Extent/Coverage: The study measures the area covered by kelp forests as “5189 hectares.” This is a direct indicator for tracking progress on conservation coverage (Target 14.5) and for managing the ecosystem (Target 14.2).
   • Aboveground Biomass Density: Measured as “2.65 Mg C ha^–1 ± 1.19 Mg C ha^–1,” this indicator reflects the health and productivity of the ecosystem, which is crucial for assessing the effectiveness of management and protection measures (Target 14.2).
   • Kelp Density: The study uses a heatmap to illustrate kelp density (individuals/m²), which is a key metric for assessing population health and the status of the habitat (Target 14.2).
   • Investment in Research: The study itself, funded by “EEA grants” and “Fundação para a Ciência e Tecnologia,” and its detailed methodology (e.g., “496 video camera point surveys,” “179 samples” for biomass) are indicators of increased scientific research capacity (Target 14.a).

3. For SDG 15 (Life on Land)

   • Integration into National Accounting: The article’s comparison of kelp carbon sequestration (1903 Mg C year^–1) with national figures for saltmarshes and seagrasses (3717 Mg C year^–1) is a step towards creating a comprehensive national blue carbon inventory, which is an indicator for integrating ecosystem values into national accounts (Target 15.9).

4. Create a table with three columns titled ‘SDGs, Targets and Indicators” to present the findings from analyzing the article.

Source: nature.com