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Coral Reefs

I swim in coral reefs all over the world. Most recently, South Africa. Most often, the Caribbean. Reef-safe sunscreen is the new big thing in helping our planet. But why is it so important and what even is a coral reef?

Well, first, let me start you off with some numbers. Coral reefs only cover 260-600,000 km2 - that’s less than 0.1% of the Earth’s surface! While coral reefs make up less than 0.25% of the ocean, 25% of all known marine species live there! Coral reef fisheries supply more than half of the protein consumed by people in coastal, tropical regions, which is about $6.8 billion a year globally! Coral reefs are also responsible for about 70 million tourist trips annually. For such a small part of the globe, their impact across multiple industries is monumental.

So what is a coral reef? Coral reefs are marine, or saltwater, ecosystems characterized by reef building corals. They first appeared 485 million years ago and are some of the most diverse and productive ecosystems, which, by the way, an ecosystem is a biological community of organisms and their physical environment.

The coral reef structures we see are colonies of individual animals that have their own mouth and can be made of hard corals and/or soft corals. Most corals are found within the tropics. Areas with cold water upwellings or freshwater runoff tend to have a lower abundance of corals, and in the Caribbean there are not very many due to the storms and changing landmasses. The coral reefs in Sodwana Bay, South Africa were relatively deep compared to most tourist destinations, which helps protect the corals from storms and allows them to grow and thrive longer.

Optimal conditions for corals include high light intensity, good water circulation, clear waters with a low nutrient load, 32-42 ppt salinity, and a temperature between 18-29 C or 64-84F. The Coral Triangle is where most of the world’s coral can be found - Indonesia, the Philippines, Papua New Guinea and Northern Australia.

An exponentially large number of threats face coral reefs and the organisms that live within them. Bottom trawling, changes in temperature and rainfall patterns, coral mining, plastics, and nutrient runoff are just a few.

Coral bleaching is a stress response triggered by many of these factors. Not all coral bleaching is fatal and healthy, resilient reefs can resist a stressful event or recover from it but certain species are more susceptible. Of three global coral bleaching events, the most recent, from 2014-2017, was the longest and most widespread.

Coral reefs are incredible for more than just their beauty. Of 33,000 species of known fish, 8,000 are found on coral reefs. They contain environmental niches and provide a wide variety of food sources. Additionally, reef organisms are used in the treatment of diseases, such as leukemia and other cancers, HIV, cardiovascular diseases, and ulcers. Scientists have even synthesized effective anticancer agents against tumors, especially those of ovaries, in a Caribbean species of sea squirts. There is enormous potential for new drug discovery as only a small percentage of reef organisms have been sampled, analyzed, and tested.

If you’d like to learn more about corals, take the online coral course at

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