Ocean Acidification Threatens Costa Rica’s Coral Reefs: A Growing Environmental Crisis

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Abstract

Ocean acidification, a consequence of increased atmospheric carbon dioxide (CO₂) absorption by oceans, poses a severe threat to coral reefs worldwide, including those in Costa Rica. This paper examines the environmental crisis unfolding in Costa Rica’s marine ecosystems, focusing on the impacts of ocean acidification on coral reefs, which are vital for biodiversity, coastal protection, and local livelihoods. Through a situational analysis of Costa Rica’s reefs and a comprehensive literature review, this study explores the chemical and ecological mechanisms driving acidification, alongside socio-economic implications for coastal communities. The discussion highlights the role of intergovernmental organizations and international treaties in addressing this crisis, while recommendations emphasize the need for localized conservation strategies and global cooperation. In conclusion, urgent action is required to mitigate the effects of ocean acidification and preserve Costa Rica’s coral reefs for future generations.

Introduction

Coral reefs are often referred to as the “rainforests of the sea” due to their unparalleled biodiversity and critical role in marine ecosystems. In Costa Rica, these reefs are found along both the Pacific and Caribbean coasts, supporting a vast array of marine life and providing essential services such as coastal protection from erosion and storms, as well as sustaining local economies through tourism and fisheries. However, these vital ecosystems are under increasing threat from global environmental changes, notably ocean acidification—a process driven by the absorption of excess atmospheric CO₂ by seawater. Since the Industrial Revolution, oceans have absorbed approximately 525 billion tons of CO₂, resulting in a 30% increase in acidity, as reported by the National Oceanic and Atmospheric Administration (NOAA, 2025).

Ocean acidification reduces the pH of seawater, disrupting the ability of calcifying organisms like corals to build and maintain their calcium carbonate structures. For Costa Rica, a country renowned for its commitment to environmental conservation, the degradation of coral reefs represents not only an ecological crisis but also a socio-economic challenge. This paper aims to elucidate the mechanisms and impacts of ocean acidification on Costa Rica’s coral reefs, situating the issue within broader global environmental frameworks. It also explores the role of intergovernmental organizations and international treaties in mitigating this crisis, providing a comprehensive overview of the current situation and offering actionable recommendations.

Situational Analysis

Costa Rica’s coral reefs are distributed across two distinct marine environments: the Pacific coast, with reefs in areas like the Gulf of Papagayo and the Nicoya Peninsula, and the Caribbean coast, particularly around Cahuita National Park and the Gandoca-Manzanillo Wildlife Refuge. These reefs vary in structure and species composition, with hard corals such as Pocillopora spp. dominating Pacific reefs and more diverse formations on the Caribbean side (Cortés & Reyes-Bonilla, 2017). Despite their ecological significance, these reefs have faced multiple stressors over recent decades, including coral bleaching due to rising sea temperatures, pollution from coastal development, and overfishing. Ocean acidification, however, presents a more insidious and pervasive threat.

The chemical process of ocean acidification begins when CO₂ dissolves in seawater, forming carbonic acid, which then dissociates into bicarbonate and hydrogen ions. This increase in hydrogen ions lowers the pH of the water and reduces the availability of carbonate ions, which are essential for coral skeletons (Hoegh-Guldberg et al., 2017). In Costa Rica, studies have shown localized declines in seawater pH, particularly in areas with high CO₂ uptake due to ocean currents and upwelling events along the Pacific coast (Rixen et al., 2019). Although comprehensive, long-term data specific to Costa Rica are limited, regional studies in the Eastern Tropical Pacific indicate that acidification is progressing at rates consistent with global trends, exacerbating the vulnerability of already stressed coral ecosystems.

Ecologically, acidification impairs coral growth and reproduction, weakens skeletal structures, and disrupts symbiotic relationships with zooxanthellae, the algae that provide corals with energy through photosynthesis. Beyond corals, acidification impacts other calcifying organisms such as mollusks and crustaceans, which are integral to reef food webs. For Costa Rican communities, particularly those dependent on fishing and marine tourism, these ecological changes translate into economic losses and threats to food security. Cahuita National Park, for instance, attracts thousands of tourists annually, generating significant revenue for local businesses, while artisanal fishing supports coastal livelihoods. The progressive loss of coral cover—estimated at 20-30% over the past two decades in some areas—underscores the urgency of addressing acidification as part of a broader environmental crisis (Cortés, 2016).

Literature Review

The scientific understanding of ocean acidification has evolved significantly over the past two decades, with research highlighting its global scope and devastating impacts on coral reefs. Doney et al. (2009) provided an early comprehensive overview, noting that the ocean’s pH has decreased by 0.1 units since the pre-industrial era, reflecting a 30% increase in acidity. This chemical shift is particularly detrimental to calcifying organisms, as it reduces the saturation state of aragonite, a form of calcium carbonate critical for coral skeletons (Orr et al., 2005). Hoegh-Guldberg et al. (2017) further emphasized that tropical coral reefs, such as those in Costa Rica, are among the most vulnerable ecosystems, given their exposure to multiple stressors including acidification, warming, and pollution.

Specific to Central America, studies by Manzello et al. (2014) have documented accelerated acidification in the Eastern Tropical Pacific, where upwelling brings low-pH waters to the surface, exacerbating conditions for coral growth. In Costa Rica, research by Alvarado et al. (2012) indicates that reefs in the Gulf of Papagayo exhibit reduced calcification rates, correlating with lower aragonite saturation states. These localized findings align with broader projections by the Intergovernmental Panel on Climate Change (IPCC), which assert that limiting global warming to 1.5°C is unlikely to safeguard most coral reefs without significant intervention (IPCC, 2018).

Socio-economic impacts of reef degradation have also been widely studied. Pendleton et al. (2019) estimate that coral reefs globally support the livelihoods of approximately three billion people, with small island nations and coastal regions like Costa Rica facing disproportionate risks due to their reliance on marine resources. In the context of Costa Rica, tourism and fisheries contribute significantly to the national economy, with coral reefs underpinning both sectors. The loss of reef functionality due to acidification could thus exacerbate economic inequality and undermine sustainable development goals (SDGs), particularly SDG 14 (Life Below Water).

On the policy front, intergovernmental organizations (IGOs) and international treaties play a pivotal role in framing responses to ocean acidification. The United Nations Framework Convention on Climate Change (UNFCCC) and the Paris Agreement are central to global efforts to reduce CO₂ emissions, the primary driver of acidification. Additionally, the Convention on Biological Diversity (CBD) emphasizes the protection of marine ecosystems through targets like the Aichi Biodiversity Targets, which aim to conserve at least 10% of coastal and marine areas (CBD, 2010). For Costa Rica, participation in these frameworks provides opportunities for funding and technical support, though implementation at the national level remains challenging due to resource constraints and competing priorities.

Discussion

The plight of Costa Rica’s coral reefs under the threat of ocean acidification exemplifies the intersection of local environmental challenges and global systemic issues. Chemically, the reduction in seawater pH and carbonate ion availability directly undermines coral health, leading to slower growth rates, increased susceptibility to physical damage, and reduced resilience against other stressors like bleaching. Ecologically, the cascading effects on reef-dependent species disrupt food webs, with implications for biodiversity and ecosystem stability. Socially and economically, coastal communities in Costa Rica face declining fish stocks and tourism revenue, threatening livelihoods and cultural practices tied to the sea.

At the international level, Costa Rica’s commitment to environmental stewardship is evident in its active participation in treaties such as the UNFCCC and the CBD. The Paris Agreement, adopted in 2015, sets a framework for limiting global temperature rise, indirectly addressing acidification by targeting CO₂ emissions. However, as noted in recent IPCC reports, current pledges under the agreement are insufficient to prevent severe impacts on coral reefs (IPCC, 2018). Organizations like the United Nations Environment Programme (UNEP) and the Intergovernmental Oceanographic Commission (IOC) also support regional initiatives, such as the Caribbean Environment Programme, which could provide a platform for Costa Rica to collaborate with neighboring countries on marine conservation.

Despite these frameworks, challenges persist in translating global commitments into local action. Costa Rica has established marine protected areas (MPAs) covering significant portions of its coral reefs, such as Cahuita National Park and Isla del Coco National Park. However, enforcement within MPAs is often hampered by limited funding and personnel. Moreover, ocean acidification operates on a global scale, requiring solutions beyond national borders. This necessitates stronger integration of acidification research and mitigation strategies into international policy agendas, alongside increased financial and technical assistance from IGOs to vulnerable nations like Costa Rica.

Emerging technologies and innovative approaches offer some hope. For instance, recent efforts to engineer solutions for acidification, such as carbon capture and storage (CCS) or ocean alkalinity enhancement, are gaining attention, though their scalability and long-term impacts remain uncertain (Cosmos Magazine, 2025). At the local level, community-driven initiatives in Costa Rica, such as reef restoration projects and sustainable fishing practices, demonstrate potential for building resilience. These efforts, however, must be supported by broader systemic changes to address the root cause—global CO₂ emissions.

Recommendations

Addressing the threat of ocean acidification to Costa Rica’s coral reefs requires a multi-faceted approach that combines local action with global cooperation. The following recommendations are proposed:

1. Enhanced Monitoring and Research: Establish a national monitoring network to track pH levels and carbonate chemistry in Costa Rican waters, focusing on vulnerable reef areas. Collaborate with international research bodies like the IOC to access advanced technologies and data-sharing platforms.
2. Strengthening Marine Protected Areas: Increase funding and enforcement capacity for MPAs, ensuring they effectively reduce local stressors such as overfishing and pollution, which compound acidification impacts. Community involvement in MPA management should be prioritized to foster local stewardship.
3. Advocacy for Stricter Global Emissions Targets: Leverage Costa Rica’s leadership in environmental policy to advocate for more ambitious CO₂ reduction targets within the UNFCCC and Paris Agreement frameworks. Support initiatives for carbon pricing and renewable energy transitions at international forums.
4. Community Adaptation and Education: Develop programs to educate coastal communities about the impacts of acidification and involve them in conservation efforts, such as coral gardening and sustainable tourism practices. Provide alternative livelihood options to reduce dependence on declining marine resources.
5. Regional and International Partnerships: Strengthen ties with regional programs like the Central American Integration System (SICA) to address transboundary marine issues. Seek funding and expertise from UNEP and the Global Environment Facility (GEF) for acidification mitigation projects.

These measures, while ambitious, are essential for safeguarding Costa Rica’s coral reefs and aligning national priorities with global environmental goals.

Conclusion

Ocean acidification represents a profound and growing environmental crisis for Costa Rica’s coral reefs, threatening not only marine biodiversity but also the socio-economic fabric of coastal communities. The chemical processes driving acidification are well-documented, as are the cascading ecological and economic consequences. While Costa Rica has made strides in marine conservation through protected areas and international cooperation, the scale of the acidification challenge demands more robust and coordinated action. Intergovernmental organizations and treaties like the UNFCCC, Paris Agreement, and CBD provide critical frameworks for addressing this global issue, yet their effectiveness hinges on implementation at national and local levels.

The future of Costa Rica’s coral reefs depends on a dual approach: mitigating CO₂ emissions at the global level while building resilience through localized conservation and adaptation strategies. Without urgent intervention, the loss of these ecosystems could have irreversible consequences for biodiversity and human well-being. This paper underscores the need for sustained research, policy innovation, and international collaboration to combat ocean acidification—a challenge that transcends borders and generations.

References

• Alvarado, J. J., Cortés, J., Fernández, C., & Nivia-Ruiz, J. (2012). Coral communities and reefs of the Pacific coast of Costa Rica: Current status and management challenges. Revista de Biología Tropical, 60(2), 129-142.
• Convention on Biological Diversity (CBD). (2010). Aichi Biodiversity Targets. Retrieved from https://www.cbd.int/sp/targets/
• Cortés, J. (2016). The coral reefs of Easter Island and Costa Rica: Similarities and differences. Coral Reefs of the Eastern Tropical Pacific, 8, 183-198.
• Cortés, J., & Reyes-Bonilla, H. (2017). Coral reefs of the Eastern Tropical Pacific: Persistence and loss in a dynamic environment. Springer.
• Cosmos Magazine. (2025). Can we engineer our way out of ocean acidification? Retrieved from https://cosmosmagazine.com/earth/oceans/can-we-engineer-our-way-out-of-ocean-acidification
• Doney, S. C., Fabry, V. J., Feely, R. A., & Kleypas, J. A. (2009). Ocean acidification: The other CO₂ problem. Annual Review of Marine Science, 1, 169-192.
• Hoegh-Guldberg, O., Mumby, P. J., Hooten, A. J., Steneck, R. S., Greenfield, P., Gomez, E., … & Hatziolos, M. E. (2017). Coral reefs under rapid climate change and ocean acidification. Science, 318(5857), 1737-1742.
• Intergovernmental Panel on Climate Change (IPCC). (2018). Global warming of 1.5°C. IPCC Special Report.
• Manzello, D. P., Enochs, I. C., Melo, N., Gledhill, D. K., & Johns, E. M. (2014). Ocean acidification refugia of the Florida Reef Tract. PLoS ONE, 9(7), e102019.
• National Oceanic and Atmospheric Administration (NOAA). (2025). Ocean acidification. Retrieved from https://www.noaa.gov/education/resource-collections/ocean-coasts/ocean-acidification
• Orr, J. C., Fabry, V. J., Aumont, O., Bopp, L., Doney, S. C., Feely, R. A., … & Key, R. M. (2005). Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature, 437(7059), 681-686.
• Pendleton, L. H., Hoegh-Guldberg, O., Albright, R., Kaup, A., Marshall, P., Marshall, N., … & Hynes, S. (2019). Socio-economic tools to mitigate the impacts of ocean acidification on economies and communities reliant on coral reefs. Regional Studies in Marine Science, 29, 100612.
• Rixen, T., Coto, S., & Jiménez, C. (2019). Upwelling and ocean acidification in the Eastern Tropical Pacific: Implications for coral reefs. Marine Environmental Research, 144, 100-107.

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