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A blog by DSCC Executive Director, Sian Owen.

The deep sea remains one of the most mysterious and unexplored realms on Earth. Beneath the sweeping expanse of the ocean’s surface lies a world of staggering diversity, complexity, and, often unexpected, beauty. The vast abyssal plains and towering underwater mountains of the deep sea teem with life, from strange and otherworldly jelly-like creatures to delicate coral gardens. 

To help shed light on this unique and poorly understood environment,  a new film series “Blue Horizons” was produced for the Deep Sea Conservation Coalition and partners by BBC StoryWorks Commercial Productions. Check out this wonderful series and dive into the deep

As we explore the wonders of the deep sea in Blue Horizons, and as our understanding of these vital, fragile ecosystems grows, so does the urgency to protect them from the threats posed by destructive human activity. The DSCC stands at the forefront of the battle to safeguard the deep ocean, advocating for policies and practices that protect vulnerable ecosystems from bottom trawling and deep-sea mining, thus ensuring their long-term health and sustainability.

Having just celebrated World Ocean Day on June 8, with the theme “Awaken New Depths” let’s explore why safeguarding the deep sea is paramount, and the role we can all play in its defense.

Hidden Beneath the Waves

A healthy deep sea is critical for all life on Earth. The largest biome on the planet, it makes up 90% of the marine environment and is key to regulating our planetary systems, not least by absorbing and storing vast quantities of carbon dioxide emitted by human activities. Carbon from the atmosphere is stored away in the deep seabed via numerous biological and physical processes known collectively as the ocean carbon pump. 

Despite the low temperatures, extreme ambient pressures, and absence of sunlight, the deep sea supports an abundance of biodiversity, with new species being discovered on nearly every expedition. Scientists believe as many as 10 million species live in the deep sea – a biodiversity as rich as tropical rainforests. Many deep-sea species are long-lived (some deep-sea corals are estimated to be 4,000 years old), slow to reproduce (some deep-sea octopuses nurture their eggs for up to 4 years before they hatch), and late to mature (it takes Greenland sharks over a century to reach sexual maturity!). These characteristics make them less able to cope with even the smallest impacts to their environment, and therefore, highly vulnerable to change.

Beyond climate and biodiversity, the deep sea plays an important role for many cultures around the world. For some, the deep sea is a repository for both tangible and intangible underwater cultural heritage, encompassing creation stories, oral traditions, trade routes and ancient shipwrecks. This heritage is observed and celebrated through generations, the artifacts and narratives telling stories of past civilizations and illuminating elements of cultural identity, traditions and spiritual practices. We have a collective responsibility to preserve this multifaceted heritage and connection to one of the most remote parts of our blue planet.

Exploitation in the Deep

Although the deep sea appears to be “out of sight, out of mind”, numerous actors are involved in its exploitation, with companies increasingly turning their attention to the deep in search of profit.

One of the most pressing threats comes from deep-sea fishing, specifically bottom trawling on seamounts. These are mountains that can rise, majestically, thousands of meters from the seabed – biodiversity hotspots in a vast ocean. Bottom trawling involves dragging heavy, weighted nets along the ocean floor, indiscriminately catching all marine life in their wake and causing irreversible damage to sensitive, ancient habitats. This threatens the delicate balance of deep-sea ecosystems and the many species that rely upon them. Bottom trawling is also a major source of carbon dioxide emissions, releasing carbon stored in the seafloor. Scientists have estimated that 70m tonnes of planet-heating carbon dioxide is released each year from bottom trawling. Despite a global commitment to protect deep-sea biodiversity from destructive fishing, vessels are still trawling on seamounts across the ocean, compromising their role in providing the wider ocean with food, shelter, spawning grounds and much more. By protecting seamounts and other vulnerable marine ecosystems, we protect the whole ocean.  

Furthermore, the ascendance of deep-sea mining poses a new and potentially catastrophic threat to deep ocean – and thus planetary – health. As demand for minerals such as copper and nickel surges, speculators and mining companies are looking to the deep sea as a new frontier for extraction. Yet rapid technological and circular economy advances mean that defossilization of our global economy is possible without opening up a massive new frontier of extraction in one of our planet’s last wildernesses. Moreover, the full extent of the impacts of deep-sea mining is still not fully understood. Scientists warn that this industry would cause irreversible impacts on ecosystems and habitats, the extinction of species, and associated impacts on the wider ocean, including the ocean’s critical climate regulation services. Concerns are growing across society that the risks outweigh the potential benefits for humankind. This is reflected in the building momentum for a moratorium on deep-sea mining and the calls for a pause by 27 governments. All governments must urgently join this call for a moratorium on deep-sea mining to allow for sufficient science and understanding of the deep sea and the impacts of deep-sea mining on the marine environment.

Taking Action to Defend the Deep

In the face of these threats, we must take action to protect the deep sea for future generations. As individuals, there are several ways we can contribute:

The deep sea sustains life on Earth in ways we are only beginning to understand. In the words of marine biologist Dr Sylvia Earle, “No water, no life. No blue, no green.” Let us join forces to defend the deep and ensure that these precious environments remain intact for generations to come.