Until quite recently, the bottom of the ocean was thought to be barren, devoid of life, and utterly insensitive to human impacts. As land dwellers and air breathers, it is hard for us to imagine what life in the ocean must be like, especially at depths where light no longer penetrates. In 1960, Jacques Piccard and Don Walsh took a submarine to the deepest part of the ocean in the Mariana Trench, and observed an extensive ecosystem teeming with diverse life. The Mariana Trench is in the Mid-Atlantic Ridge, which sits on a plate boundary, so there is a lot of volcanic activity there. (For more information on plate boundaries, see one of my past posts here.)

When volcanic activity happens underwater, it leads to the formation of hydrothermal vents, which were not discovered until 1977. As cold seawater enters cracks in the Earth’s crust, it is heated by magma and mixed with chemicals before being released from the crust as “hydrothermal fluid” to form the vent. Hydrothermal vents are home to species that have adapted to one of the most extreme and volatile environments on the planet. Bacteria in these ecosystems are chemosynthetic, obtaining their energy from hydrogen sulfide produced in the vents, and form the foundation of deep sea food webs. Here is a picture of a hydrothermal vent:


As it turns out, these hydrothermal vents are not only useful for deep sea life; humans have also taken an interest in the potential mining prospects of these environments. When hydrothermal fluid mixes with the cold seawater surrounding the vent, metal sulfides are deposited to form chimneys rich in iron ore, zinc, and other precious metals. Given the shrinking resources of many metals, the discovery of these deep sea resources sounds great to mining companies. Nautilus Minerals Inc. is the first company to commercially explore the seafloor for sulfide deposits for potential mining. On April 25th, 2014, Nautilus Minerals signed an agreement to mine the deep sea for the first time. Although the project is still in the contracting phase and they have not broken ground yet, Nautilus Minerals will target massive seabed deposits off the coast of Papua New Guinea. The plan is to break up the seafloor and then pump the ore up through a tube to a ship stationed on the surface. This image shows the planned operating system for Nautilus Minerals:


The real question is: How will deep sea mining affect the ecosystems centered around the hydrothermal vents? Since deep sea mining has never been done before, we simply don’t know the answer. Theoretically, the hydrothermal vents will grow back, but that may take decades. Meanwhile, the habitat of the fish, crabs, octopus, and millions of other organisms will be dramatically altered. Nautilus claims that there will be a minimal environmental impact, as the area covers only 10 football fields and is apparently likely to recover rapidly. The problem is that we simply don’t know enough about the deep ocean to know for sure how fast the ecosystem will recover. Deep sea mining will destroy some of the oldest known ecosystems on Earth, quite literally sweeping away organisms that we haven’t even discovered yet.


Giant tube worms live near hydrothermal vents

Humans are about to have a completely new impact on the oceans, and now, more than ever, is the time to think very hard about what we want the ocean, and therefore the whole planet, to look like for future generations. Deep sea mining would alleviate some stressors in the market for precious metals, but the potential cost is far too great. Our lives are inextricably reliant on the health of the ocean, and ripping the seafloor to shreds is far from healthy. We are already putting too much pressure on the oceans through overfishing, acidification, eutrophication, and pollution. Mining the habitat of deep sea life could be the final straw.

* Cover image is from http://oceanleadership.org/wp-content/uploads/vamp-squid.jpg