Abstract
Ocean acidification, a direct consequence of increasing atmospheric carbon dioxide (CO₂) levels, poses significant challenges to marine ecosystems and human livelihoods worldwide. In São Tomé and Príncipe, a small island developing state in the Gulf of Guinea, the impacts of ocean acidification are particularly pronounced due to the country’s heavy reliance on marine resources for food security, economic stability, and cultural identity. This article explores the effects of ocean acidification on marine biodiversity and coastal communities in São Tomé and Príncipe, focusing on ecological changes, socioeconomic consequences, and potential adaptation strategies. Through a situational analysis and review of global literature, the study highlights the vulnerability of coral reefs, shellfish, and fish stocks critical to local livelihoods. The role of intergovernmental organizations and international treaties, such as the United Nations Framework Convention on Climate Change (UNFCCC) and the Convention on Biological Diversity (CBD), in addressing these challenges is examined. Recommendations are provided for localized monitoring, community-based adaptation, and enhanced international collaboration to mitigate the impacts of ocean acidification in this region. This analysis underscores the urgent need for integrated approaches to safeguard marine ecosystems and support the resilience of coastal communities in small island states like São Tomé and Príncipe.
Introduction
Ocean acidification represents a significant and often under-discussed consequence of anthropogenic climate change, resulting from the oceanic uptake of excess atmospheric CO₂. As CO₂ dissolves into seawater, it triggers chemical reactions that reduce pH levels, decrease carbonate ion availability, and alter the acid-base balance of marine environments. This phenomenon, often referred to as “climate change’s equally evil twin,” has profound implications for marine biodiversity and human communities dependent on ocean resources. Globally, the ocean has absorbed approximately 525 billion tons of CO₂ since the industrial era, with current absorption rates at around 22 million tons per day (Smithsonian Ocean, 2018). While this process mitigates atmospheric warming, it comes at the cost of transforming marine ecosystems, threatening species survival, and disrupting ecosystem services.
São Tomé and Príncipe, an archipelagic nation off the west coast of Central Africa, is particularly vulnerable to ocean acidification due to its geographical, ecological, and socioeconomic characteristics. With a population of approximately 220,000 and an economy heavily reliant on fisheries and tourism, the country faces unique challenges as ocean chemistry changes. Marine ecosystems, including coral reefs, mangroves, and pelagic fish stocks, form the backbone of local food security, employment, and cultural practices. However, limited resources, inadequate infrastructure, and minimal representation in global climate negotiations exacerbate the challenges of addressing ocean acidification in this region. This article seeks to elucidate the specific impacts of ocean acidification on São Tomé and Príncipe, focusing on marine biodiversity and coastal communities, while exploring the role of international frameworks and intergovernmental organizations in mitigating these effects.
Situational Analysis
São Tomé and Príncipe comprises two main islands, São Tomé and Príncipe, along with several smaller islets, situated in the equatorial Atlantic Ocean. The country’s marine environment is characterized by rich biodiversity, including coral reefs, seagrass beds, and diverse fish populations, which are integral to the livelihoods of coastal communities. Fisheries contribute significantly to the national economy, accounting for a substantial portion of protein intake and employment opportunities. Additionally, the tourism sector, often centered on marine attractions such as diving and beach activities, is a growing source of revenue. However, these resources are increasingly threatened by environmental stressors, including ocean acidification, rising sea temperatures, and overfishing.
Ocean acidification in the region is driven by global CO₂ emissions, with local marine environments absorbing increasing amounts of carbon, leading to a decline in pH levels. Although specific data on ocean acidification in São Tomé and Príncipe are scarce due to limited monitoring infrastructure, regional studies in the Gulf of Guinea suggest that acidification trends mirror global patterns. Coral reefs, which provide critical habitats for fish and act as natural barriers against coastal erosion, are particularly vulnerable. The reduced availability of carbonate ions impairs coral growth and weakens existing structures, increasing susceptibility to bleaching and physical damage. Similarly, shellfish and other calcifying organisms face challenges in shell formation, impacting their survival and the food web dynamics that support larger predatory fish species.
Coastal communities in São Tomé and Príncipe are directly affected by these ecological changes. Approximately 60% of the population lives in coastal areas, relying on marine resources for subsistence and income. Declines in fish stocks and shellfish availability threaten food security, while the loss of coral reefs reduces natural coastal protection, exacerbating the impacts of sea-level rise and storm surges. Moreover, the potential decline in tourism due to degraded marine attractions could further strain the economy. The lack of local research capacity and funding for environmental monitoring compounds these vulnerabilities, limiting the ability to develop informed adaptation strategies. Given these challenges, understanding the broader context of ocean acidification and leveraging international support mechanisms are crucial for building resilience in São Tomé and Príncipe.
Literature Review
Extensive research over the past two decades has documented the chemical and biological impacts of ocean acidification on marine ecosystems. When CO₂ dissolves in seawater, it forms carbonic acid, which rapidly dissociates, releasing hydrogen ions and reducing pH. This process also decreases the saturation state of calcite and aragonite, crucial minerals for calcifying organisms such as corals, mollusks, and certain plankton species (NOAA Fisheries, 2021). Laboratory and field studies have demonstrated that acidification can impair the growth, reproduction, and survival of these organisms, leading to cascading effects on food webs and ecosystem services (Doney et al., 2020).
For small island developing states (SIDS) like São Tomé and Príncipe, the socioeconomic implications of ocean acidification are profound. Coastal communities in SIDS often rely on fisheries for up to 90% of their animal protein intake, making declines in fish populations due to habitat degradation particularly devastating (IAEA, 2016). Coral reefs, which support biodiversity and act as natural breakwaters, are also critical for tourism and coastal protection. Studies indicate that under continued acidification, coral reefs could experience net dissolution by the end of the century, fundamentally altering marine ecosystems and the services they provide (US EPA, 2025).
Globally, ocean acidification has been linked to broader climate change impacts, prompting action through intergovernmental organizations and international treaties. The United Nations Framework Convention on Climate Change (UNFCCC) recognizes ocean acidification as a critical issue under its broader climate mitigation and adaptation mandates. The Paris Agreement, adopted in 2015 under the UNFCCC, indirectly addresses ocean acidification by promoting reductions in greenhouse gas emissions, which are the primary driver of acidification. Similarly, the Convention on Biological Diversity (CBD) emphasizes the need to protect marine biodiversity from stressors like acidification through its Aichi Biodiversity Targets and subsequent frameworks (Secretariat of the CBD, 2020). Additionally, the International Atomic Energy Agency (IAEA) has supported research on acidification’s impact on coastal societies, particularly in vulnerable regions, through capacity-building and technical assistance programs (IAEA, 2016).
Despite these international efforts, the specific challenges faced by SIDS often receive insufficient attention. Limited financial and technical resources hinder the implementation of monitoring programs and adaptation measures in countries like São Tomé and Príncipe. Moreover, while global studies provide valuable insights, the localized impacts of acidification can vary widely due to differences in oceanographic conditions, species composition, and human dependence on marine resources. This gap in localized data underscores the need for targeted research and policy interventions tailored to the unique context of São Tomé and Príncipe and other SIDS (Harrould-Kolieb & Herr, 2019).
Discussion
The impacts of ocean acidification on São Tomé and Príncipe are multifaceted, affecting both ecological systems and human well-being. Marine biodiversity in the region is at significant risk, particularly coral reefs and shellfish populations. The degradation of coral reefs not only diminishes habitat availability for fish but also reduces coastal protection, increasing vulnerability to erosion and flooding. Fish stocks, a primary protein source for the population, are indirectly affected through disruptions in prey availability and habitat loss. These ecological changes have direct socioeconomic consequences, including reduced fish catches, loss of income for fishers, and threats to food security. For a country where alternative protein sources are limited and import costs are high, such impacts are particularly acute.
The cultural dimension of these changes should not be overlooked. Fishing is not merely an economic activity in São Tomé and Príncipe but also a cornerstone of community identity and tradition. The loss of marine resources due to acidification and other stressors could erode cultural practices tied to the sea, further compounding the social impacts. Additionally, the tourism sector, which markets the pristine marine environment as a key attraction, faces potential decline as reefs degrade and biodiversity diminishes. This economic diversification challenge is critical for a nation seeking to balance development with environmental sustainability.
International frameworks and intergovernmental organizations play a vital role in addressing these challenges, though their impact in São Tomé and Príncipe remains limited by implementation gaps. The UNFCCC and the Paris Agreement provide overarching structures for reducing CO₂ emissions, the root cause of acidification. However, as a small emitter, São Tomé and Príncipe’s mitigation efforts have minimal global impact, emphasizing the need for adaptation support and climate finance from larger economies. The CBD offers guidance on biodiversity conservation, yet actionable programs tailored to acidification in SIDS are often underfunded. Initiatives by the IAEA, such as supporting research on coastal impacts, are promising but require scaling up to ensure broader geographical coverage and long-term impact.
One of the primary barriers to effective response in São Tomé and Príncipe is the lack of localized data on ocean acidification trends and impacts. Without baseline measurements of pH, carbonate levels, and species responses, developing evidence-based policies is challenging. Furthermore, national capacity for environmental monitoring is constrained by limited funding, expertise, and equipment. Community awareness of ocean acidification is also low, reducing the potential for grassroots adaptation initiatives. These systemic issues highlight the need for international collaboration to bridge capacity gaps and prioritize vulnerable regions in global climate agendas.
Recommendations
Addressing the impacts of ocean acidification in São Tomé and Príncipe requires a multi-pronged approach that combines local action with international support. The following recommendations aim to enhance resilience in coastal communities and protect marine biodiversity:
- Establish Local Monitoring Programs: Develop a national ocean acidification monitoring network to collect data on pH levels, carbonate chemistry, and biological responses in key marine ecosystems. This can be supported through partnerships with intergovernmental organizations like the IAEA and regional bodies such as the Economic Community of Central African States (ECCAS).
- Strengthen Community-Based Adaptation: Implement education and capacity-building programs to raise awareness of ocean acidification among coastal communities. Promote sustainable fishing practices and alternative livelihoods to reduce dependence on vulnerable marine resources, with funding support from international climate finance mechanisms under the UNFCCC.
- Enhance Marine Protected Areas (MPAs): Expand and effectively manage MPAs around São Tomé and Príncipe to safeguard critical habitats such as coral reefs and mangroves. Align these efforts with CBD targets and secure technical assistance from global conservation networks.
- Advocate for Increased International Support: Leverage platforms like the UNFCCC Conference of the Parties (COP) to advocate for dedicated funding and technical support for SIDS facing ocean acidification. Collaborate with other SIDS through alliances such as the Alliance of Small Island States (AOSIS) to amplify their collective voice.
- Integrate Acidification into National Policies: Incorporate ocean acidification into national climate adaptation and biodiversity strategies, ensuring alignment with international commitments under the Paris Agreement and CBD. Develop contingency plans to address food security and economic losses stemming from marine resource decline.
- Foster Research Partnerships: Partner with academic institutions and international research bodies to conduct studies on the localized impacts of acidification. Focus on species of economic and ecological importance to São Tomé and Príncipe, ensuring that findings inform policy and adaptation measures.
These recommendations emphasize the importance of integrating local needs with global frameworks. By combining grassroots initiatives with international cooperation, São Tomé and Príncipe can build resilience against the mounting threat of ocean acidification.
Conclusion
Ocean acidification presents a formidable challenge to São Tomé and Príncipe, threatening the marine biodiversity that underpins coastal livelihoods and national development. The degradation of coral reefs, shellfish, and fish stocks due to changing ocean chemistry has far-reaching ecological and socioeconomic consequences, exacerbating vulnerabilities in a country already grappling with the impacts of climate change. While the global nature of CO₂ emissions necessitates international action, the localized impacts in São Tomé and Príncipe highlight the urgent need for tailored adaptation strategies supported by robust data and community engagement.
Intergovernmental organizations and treaties such as the UNFCCC, Paris Agreement, and CBD provide critical frameworks for addressing ocean acidification, yet their effectiveness in SIDS depends on increased funding, capacity building, and prioritization of vulnerable regions. By fostering partnerships with these entities and regional alliances, São Tomé and Príncipe can access the resources and expertise needed to mitigate impacts and build resilience. The recommendations outlined in this article—ranging from monitoring and community adaptation to policy integration and advocacy—offer a roadmap for navigating the challenges of ocean acidification. Ultimately, a collaborative, multi-scalar approach is essential to safeguard the marine ecosystems and coastal communities of São Tomé and Príncipe for future generations.
References
- Doney, S. C., Busch, D. S., Cooley, S. R., & Kroeker, K. J. (2020). The Impacts of Ocean Acidification on Marine Ecosystems and Reliant Human Communities. Annual Review of Environment and Resources, 45, 83-112. doi:10.1146/annurev-environ-012320-083019
- Harrould-Kolieb, E. R., & Herr, D. (2019). A governing framework for international ocean acidification policy. Marine Policy, 109, 103669. doi:10.1016/j.marpol.2019.103669
- International Atomic Energy Agency (IAEA). (2016). IAEA-Supported Research Examines Impact of Ocean Acidification on Coastal Societies. Retrieved from https://www.iaea.org/newscenter/news
- NOAA Fisheries. (2021). Understanding Ocean Acidification. Retrieved from https://www.fisheries.noaa.gov/insight
- Secretariat of the Convention on Biological Diversity. (2020). An Updated Synthesis of the Impacts of Ocean Acidification on Marine Biodiversity. Retrieved from https://www.researchgate.net/publication
- Smithsonian Ocean. (2018). Ocean Acidification. Retrieved from https://ocean.si.edu/ocean-life
- US Environmental Protection Agency (EPA). (2025). Effects of Ocean and Coastal Acidification on Ecosystems. Retrieved from https://www.epa.gov/ocean-acidification
