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New findings suggest that deep reefs out of sight are unique habitats requiring protection. A team of highly qualified scientific divers – led by researchers from the California Academy of Sciences – explored a widely held hypothesis that life stressed by shallow reefs could take refuge at mesophotic depths (100 to 500 feet under the ground). the surface of the ocean). The results are clear: deep, shallow reefs are in fact different systems with their own species, and deep reefs are just as threatened by climate impacts, storms, and pollution as their shallow counterparts. Their work, published today in Science represents a major shift in thinking for scientists, conservation managers and members of the public who hope to give coral reefs a chance.
"We have hope for coral reefs around the world," says Dr. Luiz Rocha, Curator of Ichthyology of the Academy and co-leader of the # Hope for Reefs Initiative . "Rather than taking this hope, these discoveries show us the crucial importance of protecting the reefs of the twilight zone in places we do not normally see. We can not ignore the depths as we throw our collective power behind the protection and restoration of shallow coral reefs Reefs – in the light and in the dark – need our urgent attention. "
Nearly 75% of the world's coral reefs are currently threatened by combined effects of overfishing, habitat destruction, water pollution and climate change Although coral reefs provide human societies with vital goods and services valued at several hundred billions of dollars a year, we know very little about deep shallow reef species – the species they shelter, the threats they face s
Tracing Life in the Depths
Rocha is part of a deep diving research team that explores these mesophotic reefs, the mysterious coral habitats extending over a narrow band of the ocean 100-500. feet under the surface. In these deep reefs, the animals live in partial darkness – beyond the limits of recreational diving, but above the deep trenches patrolled by submarines and ROVs. As part of his initiative Hope for Reefs the Academy team is exploring this unknown frontier with the help of high-tech equipment like closed-circuit recyclers. that allow scientists to extend their research time under water. Many species found in the Twilight Zone are new scientific discoveries – but determining if and how deep and shallow reefs are connected requires further examination of reefs around the world.
"Exploring the Twilight Zone is a scientific adventure that we take very seriously. Says Bart Shepherd, principal director of the Steinhart Aquarium Academy and co-head of Hope for Reefs . "One of the reasons we know so little is that it's difficult to finish the dives safely: from the Philippines to the Bahamas, we've done careful visual surveys of the sea." life we met during these long and incredible dives. to action, deep reefs are not the refuge they thought they were.
The researchers performed visual counts of reef species by arranging transects (an easy path to follow from a 20-meter tape measure) and counting the species appear at different depths . By comparing the field data with the results of the peer-reviewed literature, the team presents evidence contradicting the two main assumptions of the "safe harbor hypothesis": First, there is significant overlap of species in deep and shallow reefs. and two, that deep reefs are protected from local and global threats (they are not).
The Twilight Reefs 'Feel All'
The results published today describe the unique communities – with several endemic species – found in the reefs deep. Species that share shallow and deep coral reefs generally have strong preferences for specific depth zones, meaning that few shallow reef residents move easily between light-filled reefs and shady twilight zones. Even large predators – the major players in the marine ecosystem, such as sharks, groupers and snappers – that move between shallow and deep reefs every day feed largely on light and do not take refuge. not in the depths. The shallow and deep reef populations seem disconnected.
Mesophotic coral reefs are, in fact, equally sensitive to human and natural impacts (such as hurricanes and tropical storms). In 2016, several members of the research team chased the destructive passage of Hurricane Matthew through the Bahamas, capturing a rare glimpse of the impacts of powerful storms at mesophotic depths. The team observed that severe storms can affect even the deepest coral reef ecosystems, stifling living corals and harming marine life with sand, silt and natural debris such as boughs. trees. Waste, including plastic bags, cups, aluminum cans and fishing gear, also seems to reach deep reefs. "Deep reefs smell everything," says Rocha, referring to evidence of mesophotic vulnerability that they have documented across two oceans. . "In addition to the impacts of storms, we have observed familiar signs of intensive fishing, sedimentation, coral bleaching and invasive species in deep reefs." There are true refuges for little reefs deep, we think that they are far from humans. them, but we really see the underwater consequences of the expansion of the human population and the increased demand for food and natural resources.Refine disorders do not stop at 100 feet deep. "
A Light in the Dark
The Academy's commitment to studying and restoring global coral reefs will continue alongside several visionary partners in In the coming years, researchers from the institution will explore the deep reefs of the Pacific in the Marshall Islands
Hope for Reefs The initiative of the Academy that supports expeditions to the world's most remote and unknown reefs and understanding Twilight Zone: Deep Reefs Revealed a unique exhibition that showcases the mysterious undersea kingdom so little frequented by Visitors to the Golden Gate Park Academy of San Francisco.Own visitors can also discover the museum's newest original planetarium show Expedition Reef – Immersive reef visualizations Deep s and shallow reef restoration work with SECORE International – under a world-class planetarium dome. To learn more about unexplored reef habitats, it's important to understand how to protect them, "says Rocha. "Deep reefs are important environments that are rarely included in marine protected areas or sanctuaries, we want to showcase the vast and unexplored wonders of the ocean and inspire a new generation of sustainable development champions.
Learn more:
Deep reefs unlikely to save shallow coral reefs
More information:
L.A. Rocha et al., "Mesophotic coral ecosystems are threatened and ecologically distinct from shallow water reefs", Science (2018). science.sciencemag.org/cgi/doi … 1126 / science.aaq1614
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