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  • Writer's pictureEmily Higgins

What Causes Reef Degradation?

Updated: Aug 23, 2021



Long story short: coral reefs are dying around the world. But what are the causes behind it and what does it mean for the ocean as a whole? Like in any natural system, there are interdependent environmental factors, and when one thing goes wrong, the whole ocean can experience a domino effect.


The corals that make up the beautiful reef systems that we know and love work together with tiny algae called zooxanthellae. Zooxanthellae help feed corals through photosynthesis and it’s actually these tiny partners-in-crime living inside coral tissue that give corals their vibrant colors!


While the coral and algae historically worked together to build a reef system, they live in a delicate balance that is sensitive to environmental fluctuations. Slight changes in water temperature, water salinity, and pollution levels can stress corals, forcing them to evict their algal partners from their tissues, leaving behind the white “bleached” appearance of an unhealthy coral.





But a newly bleached coral isn’t dead right away. In fact, if the disturbance is short-term, the coral can reconnect with their algal friends and continue to grow and contribute to a healthy ecosystem. The main problem is, as corals remain without their algal partners-in-crime for longer periods of time, they become more vulnerable to outside environmental stressors such as storms or disease.


When corals remain in an unhealthy bleached state for too long, they are at greater risk to permanent damage from environmental disturbances. These stressors can cause a greater decrease in coral health, leading to coral death and an ecosystem-wide loss of coral cover over time. Should these impacts disrupt a large area, they can severely impact overall reef stability.




While coral reefs account for only 1% of the worlds’ marine habitat, they support people and the environment at a global scale. When reefs are healthy and thriving, they help protect coastlines from flooding and storms, while economically supporting local communities. Economists value coral reefs at over $375 billion dollars for the 500 million people that directly rely on them. Everything from local tourism operations to global fishing industries rely on stable reef environments.


Interested in how coral health affects you? Visit our website to explore the wonderful world of coral and how we’re working to revitalize, restore, and protect our global reefs!


Photo credits:

1. The Ocean Agency / XL Catlin Seaview Survey

2. The Ocean Agency / XL Catlin Seaview Survey

3. Jayne Jenkins / Coral Reef Image Bank


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