Why Deep-Sea Corals Are Essential to Our Ocean
By Rachel Plunkett
March 2025
Beneath the ocean’s surface, hidden in the darkness of the deep sea, lies a world of extraordinary beauty and significance—deep-sea coral ecosystems. Unlike their shallow-water relatives that thrive in sunlit waters, deep-sea corals flourish in cold, dark depths, sometimes thousands of feet below the surface. They can live for thousands of years and grow very slowly—some just a few millimeters per day—making them especially vulnerable to human impacts. These unique ecosystems play a vital role in maintaining the health of our ocean and supporting marine life. Many of these coral habitats are found within the boundaries of national marine sanctuaries, where they receive critical protections to ensure their survival. Here are five reasons why deep-sea corals are essential to our ocean and the national sanctuaries that help safeguard them.
1. They Provide Habitat for Marine Life
Deep-sea corals form intricate reef structures that serve as essential habitat for a range of marine species. These reefs offer shelter, breeding grounds, and nurseries for fish, crabs, shrimp, and countless other organisms. Many commercially important fish species, such as groupers and snappers, depend on deep-sea coral habitats for survival at different stages of their life cycles, such as for spawning. By providing a stable environment, deep-sea corals help maintain biodiversity and sustain healthy marine populations. Places like Cordell Bank, Flower Garden Banks, and Papahānaumokuākea national marine sanctuaries protect deep-sea coral communities, ensuring that these vital ecosystems remain intact for generations to come.
2. They Support Global Fisheries
The fishing industry relies on deep-sea coral ecosystems more than many people realize. Many species that inhabit these deep reefs are crucial to global seafood markets, supporting coastal economies and providing food security for millions of people. Healthy deep-sea coral habitats contribute to sustainable fisheries by supporting populations of economically valuable fish species. Protecting these fragile ecosystems helps ensure that future generations can continue to benefit from productive and resilient fisheries. In areas such as Monterey Bay and Stellwagen Bank national marine sanctuaries, sanctuary managers work with fishers to ensure that both fisheries and coral habitats thrive.
3. They Hold Clues to Earth’s History
Deep-sea corals act as natural archives of ocean and climate history. Because they grow slowly and can live for hundreds or even thousands of years, their skeletal structures contain valuable records of past ocean conditions. Scientists analyze coral growth rings, much like tree rings, to understand long-term shifts in ocean temperature, circulation patterns, and even historical climate events. This research helps us better predict future changes and their potential impacts on marine ecosystems and human communities. Many national marine sanctuaries serve as living laboratories where researchers study deep-sea corals to uncover vital environmental data that informs resource management strategies.
4. They Contribute to Medical Discoveries
The deep sea remains one of the least explored places on Earth, but it is also a frontier for medical research. Deep-sea corals are natural disease fighters. They produce unique chemical compounds that scientists are studying for potential medical applications, including treatments for cancer, bacterial infections, and neurological diseases. For example, studies on the cold water coral Lophelia pertusa, which can be found at Flower Garden Banks National Marine Sanctuary, identified bioactive compounds from microorganisms associated with this coral species that exhibit cytotoxic properties against pancreatic and breast cancer cells. The natural compounds found in association with corals like this one could lead to the development of new life-saving drugs, demonstrating the immense value of safeguarding deep-sea ecosystems for future scientific discoveries.
Many national marine sanctuaries safeguard deep-sea coral environments, ensuring that these potential medical breakthroughs are not lost to habitat destruction. The medical potential for corals found in the deep sea goes beyond drug discovery and curing diseases, and includes applications such as biomaterials research as well. For example, bamboo corals provide a model for the artificial synthesis of collagen and may be useful in bone grafting.
5. They Support Thriving Ocean Ecosystems
Deep-sea corals play a vital role in maintaining healthy ocean ecosystems. Their intricate structures provide habitat for a wide array of marine life, supporting food webs that extend throughout the ocean. These corals also contribute to natural ocean processes, including nutrient cycling, that help sustain marine species and coastal economies. When deep-sea corals are disturbed, the effects can be felt across entire ecosystems, influencing species populations and industries that rely on a thriving ocean. Many national marine sanctuaries provide opportunities to study and better understand these unique habitats, ensuring they continue to support marine life and coastal communities for generations to come. There are also projects taking place in Flower Garden Banks and Greater Farallones and Monterey Bay national marine sanctuaries to actively restore damaged deep-sea coral habitats.
Supporting Deep-Sea Coral Habitats for the Future
Deep-sea corals are essential to the ocean’s balance, providing habitat for marine life and contributing to thriving ecosystems and strong ocean economies. NOAA’s Office of National Marine Sanctuaries studies and monitors deep-sea coral communities to better understand their role in the marine environment and how to sustain them. Deep areas within America’s underwater parks, such as National Marine Sanctuary of American Samoa and Papahānaumokuākea, Cordell Bank, Greater Farallones, Olympic Coast, and Flower Garden Banks national marine sanctuaries, offer a refuge for these remarkable coral habitats deep beneath the waves.
The next time you think about the deep sea, imagine the hidden forests of coral that flourish in the dark depths, shaping ocean life in ways we are still discovering. Ensuring their continued presence means maintaining the ocean’s natural benefits—supporting marine life, coastal economies, and the industries and communities that rely on a healthy ocean.
Rachel Plunkett is the content manager and senior writer/editor for NOAA’s Office of National Marine Sanctuaries