• Víctor Hugo Hernández-Elizárraga

Sustainability of coral reefs

Víctor Hugo Hernández-Elizárraga, Autonomous University of Queretaro

Learn more about Victor's initiative by clicking the link down below:

Since I was a child, I have been astonished by marine life. I live intrigued by what seas over the world can offer to us.

After six years of studying the impact of climate change on reef-forming organisms, I am convinced that urgent actions are necessary.

Coral reefs are extremely worthy to the planet Earth. Numerous people depend on these ecosystems due to activities such as fishing and tourism. Besides, coral reefs possess spiritual value for many cultures. Additionally, they are significant for education and research.

Reef-building organisms are fascinating creatures. These submarine rainforest natural constructors live in mutualistic symbiosis with photosynthetic algae from the family Symbiodiniaceae, commonly named zooxanthellae [1]. In this symbiotic relationship, algae provide approximately 95% of nutrients or metabolic requirements (by photosynthetically fixed carbon) to their host. Thus, coral reefs can prosper in poor nutrient (oligotrophic) environments. However, coral reefs are extremely vulnerable to the stress related to greenhouse gas emissions. Particularly, environmental stressors, such as ocean acidification, elevated salinity, UV radiation, and high temperature, can lead to the breakdown of the coral-algal symbiosis.

This phenomenon, commonly known as "coral bleaching", results from the loss of photosynthetic symbionts or algae pigments from host cells, which exposes the white exoskeleton composed of calcium carbonate [2]. Thus, coral bleaching causes the corals to turn completely white. When a coral experiences bleaching, it is not dead, but it is going through great danger. Some corals can survive a bleaching event, but they are under acute stress and are subject to high mortality.

It has been well documented that massive coral bleaching events are among the most harmful effects of global warming, putting the survival of coral reefs at serious risk.

In the last 100 years, the average global temperature has increased by about 1 degree Celsius (according to records of the United States National Oceanic and Atmospheric Administration-NOOA). Notably, during warm waves such as the El Niño-Southern Oscillation (ENSO), severe coral bleaching events have occurred due to seawater temperature rise.

Coral bleaching can lead to reefs' death. Once corals die, reefs rarely come back. Furthermore, with few corals surviving, they struggle to reproduce, and entire reef ecosystems deteriorate[3]. Bleaching is not an isolated phenomenon. Up to date, approximately 75% of the world's tropical coral reefs have experienced heat-stress severe enough to trigger bleaching. Near 30% of the world's reefs that suffer heat-stress have died [4].

Undoubtedly, the current deterioration that coral reefs suffered worldwide due to Anthropogenic climate change is evident. Constantly, several factors such as ocean acidification, thermal stress, and pollution threaten coral reef survival. To preserve the biodiversity offered by the coral reef's ecosystem, sustainability-based practices are needed. Besides, it is crucial to ensure that future generations can enjoy the goods and services granted by these critical organisms.

According to the three pillars of sustainability, the preservation of coral reefs, or any species on Earth, depends on economic development, social development, and environmental protection. However, these aspects remain neglected in many countries. Several reef-forming organisms and many marine species lack economic, ecological, and legal protection. These aspects represent opportunity niches to keep moving towards a radical human-style change. The prognosis of many coral species results is discouraging. As per eco-evolutionary model perspectives, the extinction of coral populations under global warming cannot be stopped if these organisms do not adapt to the constant climate change [5].

There are some issues to consider in order to reduce the rapid decline of coral reefs (e.g. improving tourism management or sustainable fishing). Some of the alternatives can be addressed at local, regional, country, and international levels. However, in my opinion, any action or effective solution should be focused on reducing CO2 emissions.

Unquestionably, the rapid deterioration of coral reefs indicates that the food security, well-being, and livelihoods offered to coral-dependent communities are highly vulnerable [6]. For these reasons, coral reefs' governance should be a universal priority.

Some ways to reach coral sustainability (or any other species) include simple actions starting at home. For example, implementing the three R's of sustainability (reduce, reuse, and recycle), apply anti-consumerism, drive less, and more.

Not all is lost. It is time to take action, starting by ourselves, and encouraging others to join this fight.

Let's prevent this

from turning into this


[1] Davy, S. K., Allemand, D., & Weis, V. M. (2012). Cell biology of cnidarian-dinoflagellate symbiosis. Microbiology and Molecular Biology Reviews, 76(2), 229-261.

[2] Olguín‐López, N., Gutiérrez‐Chávez, C., Hérnández‐Elizárraga, V. H., Ibarra‐Alvarado, C., & Rojas‐Molina, A. (2018). Coral Reef Bleaching: An Ecological and Biological Overview. Corals in a Changing World, 75.



[5] Cropp, R., & Norbury, J. (2020). The potential for coral reefs to adapt to a changing climate-an eco-evolutionary modelling perspective. Ecological Modelling, 426, 109038.

[6] Morrison, T. H., Adger, N., Barnett, J., Brown, K., Possingham, H., & Hughes, T. (2020). Advancing coral reef governance into the Anthropocene. One Earth, 2(1), 64-74.


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