Deep sea reefs are magnificent and barely explored – they must be preserved.
Sunlit coral reefs are probably the most famous marine habitat and many people have snorkeled or dived on them at some point. Home to a quarter of all known marine life, these “rainforests of the ocean” have been at the forefront of marine research for decades and have been featured in documentaries such as Blue Planet and animations such as Finding Nemo.
However, reefs and corals don’t stop where sunlight fades. Largely hidden from the public are large stretches of deep rock, which collectively have a larger geographic footprint than their lesser counterparts.
Sandwiched between shallow reefs and the deep sea, reefs between 30 and 300 meters have received relatively little scientific attention to date, too deep for shallow-water reef biologists and too little for deep-sea researchers. . Combined with the expense and challenging logistics of studying them, and the widespread perception that they face few threats simply because they are deep, deep reefs are notably underexplored, despite evidence to the contrary. are
Fortunately, recent advances have allowed us to learn more about these unique ecosystems. Specialized scuba equipment, called technical diving, can take you down to 150 meters, and remotely operated or autonomous vehicles, or even small manned submarines, can go even deeper.
As we go deeper and less light penetrates the water, hard corals and other light-dependent organisms that dominate the shallows become less abundant. They are replaced by other photosynthetic groups such as fleshy algae, even sponges, soft corals and sea fans.
I’ve had the privilege of being inside a submarine a dozen times so far, with the acrylic hull giving you a nearly 360-degree view of underwater life. The feeling is unique when you visit the depths of our ocean and observe its creatures – things you usually only see in documentaries. Massive sea fans are a particularly striking sight, often exceeding 2 meters:
I’ve had many encounters with reef sharks, floating tube-like pyrosomes and bioluminescent comb jellies, but the interactions I enjoy the most are always with the curious potato groups that hang around the submarine and Also poses for pictures:
Fish are more mobile than corals or sponges, and therefore fish species are still mostly known in the uppermost deep reefs. However as you go deeper the fish become progressively more unique and adapted to the low light, low food conditions of the deep reefs.
Remarkably, it has only been a few years since scientists first defined and classified a new reef zone—the rariphotic or rare-light zone between about 150 meters and 300 meters deep. A unique collection of seafloor organisms and fish helped define this depth range as an entirely new reef ecosystem. Since we are only beginning to scratch the surface of the deeper rocks, there will be many more exciting discoveries in the coming years.
Deep reefs require target protection.
Deep reefs provide many essential services for people and the planet. They help protect beaches from waves and storms, they provide breeding grounds and protection for fish, and shelters for some organisms that live in high-risk shallow reefs. Natural medicinal products have also been discovered in the deep rocks, including anti-tumor and antifungal compounds found in sponges collected at a depth of 125 meters on the Pacific island of Malik Palau.
The logistical and financial challenges of studying deep reefs mean that fewer data are available than shallow reefs, and deep reefs are rarely used to inform management and conservation activities. Although their unique biological communities warrant conservation efforts, most deep and offshore reef habitats are still unprotected. The few that are preserved are often included incidentally due to geopolitical boundaries and rarely clearly included in management plans and mandate goals.
How can we save deep reefs?
I am part of a team of 18 scientists from various organizations around the world who recently developed a framework for deep reef conservation in the Western Indian Ocean, home to some of the world’s least known deep reefs. Our framework includes practical recommendations, which we hope will enhance deep reef stewardship across the region and eventually be adopted globally.
Below are our top five recommendations:
Security: Highly protect 30% of ecosystems by 2030 (“30 by 30”), and include deep reefs in this target.
save it: Protect deep reef ecosystems and their resources, particularly by including fisheries regulations, marine protected areas and marine spatial planning.
Organize: Expand existing management efforts on shallow reefs to include deep reefs because these ecosystems are often interconnected.
investment: Invest in basic, fundamental and applied research on deep reef biodiversity, ecosystem functioning and services provided.
Collaboration: Promote national and international cooperation in the survey and protection of deep reefs in national and international (high seas) waters.