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Corals are known for their vibrant colors, otherworldly beauty, and intricate formations on the ocean floor—but they also provide a unique look into our planet’s history. As some of the Earth’s oldest organisms, coral reefs give us critical insights about climate change, biodiversity, and the interconnectedness of the world’s species.

Today, corals are in danger of extinction. Changes in climate and ocean temperature have given rise to a phenomenon called coral bleaching, and scientists are working diligently to find new ways to intervene to both prevent bleaching and help corals recover. ECS scientists are part of this effort, partnering with the National Oceanic and Atmospheric Administration (NOAA) Fisheries.

Why corals matter

Though corals take up only one percent of the seafloor, they are home to more than 25 percent of all marine life. Often called “the rainforests of the sea,” coral reefs are among the most diverse ecosystems on the planet. A vast array of plants, sea creatures, and other organisms—up to two million different species, according to some scientists— live in and on coral reefs.

This rich biodiversity has an impact on all forms of life—including human beings. An estimated one billion people depend on coral reefs for food and economic activity related to fisheries, tourism, and medicine. While corals provide the ocean’s greatest wealth, they are also the most sensitive to climate change. Without human intervention, coral reefs are at risk of extinction.

The threat of climate change

Corals are diverse in appearance. Some look like craggy rocks, while others resemble brightly colored plants. In actuality, corals are animals: invertebrates (animals lacking a backbone or spine). Corals get their unique coloring from the symbiotic algae that live inside their tissue and nourish them.

Changes in climate and rising temperatures in the ocean are causing mass coral bleaching events, something scientists have only observed in recent decades. Corals rely primarily on their symbiotic algae for nourishment; as a stress response to the heat, the coral expels its algae. Without it, corals lose their color, revealing a white skeleton that looks bleached. A coral can survive for a few days by eating plankton in the water, but rarely for longer than a week. The longer and hotter these warming events are, the more corals die; and these events are predicted to become more frequent.

Coral restoration

Warming ocean waters have caused alarm bells to sound among scientists. The threat of extinction has sparked a new wave of coral research and restoration efforts. ECS scientists are working at the NOAA Fisheries Office of Science and Technology to learn more about how to preserve the earth’s coral populations.

Work is being done on both global and local levels. Conservationists are encouraging the use of renewable energy and the preservation of carbon-absorbing habitats like forests and wetlands. These long-term solutions are critical, but the carbon that is already in the atmosphere will cause the ocean to continue to get warmer for decades to come. The ocean is becoming inhospitable to corals, dramatically affecting this ancient and diverse organism.

As a result, coral biologists are working to repopulate coral reefs with genetically diverse corals and protect their offspring. The goal is to buy time: scientists hope that with aggressive action on climate change, bleaching events will eventually become less frequent. If they work hard to build some resilience into coral reef ecosystems now, they believe that corals can persist, albeit in an altered state, for future generations.

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