The Mid-Atlantic Ridge

© NOAA

Overview

The depths of the Atlantic Ocean are home to fascinating geological features and unusual life forms. The Mid-Atlantic Ridge (MAR) is a massive underwater mountain range, 1,700 to 4,200 meters (1 to 2.6 miles) below sea level, that runs from the Arctic Ocean to the Southern Ocean. It is a hot spot for hydrothermal vents, which provide habitat for unique species that could provide insight into the origins of life on Earth.

Hydrothermal vents are fueled by underwater volcanic activity or seafloor spreading, and they spew superheated, mineral-laden water from beneath the ocean floor. As the water cools, minerals precipitate out, forming towers containing copper, gold, silver, and zinc. These minerals are used in electronics such as mobile phones and laptop computers and in cars, appliances, and bridges.

Vent ecosystems support unique species, mostly bacteria, that derive their energy from mineral-rich vent waters rather than sunlight. These microbes form thick, nutrient-rich mats along the seafloor that support shrimp, mussels, worms, snails, and fish. The MAR’s vent fields were discovered only in 1985, and scientists expect future expeditions to reveal new vents and species.¹

The International Seabed Authority (ISA), which is responsible for managing deep-sea mining and protecting the marine environment from its impacts, has entered into exploration contracts along the MAR with France, Poland, and Russia. Once mining begins, equipment will remove or degrade habitats and create sediment plumes that could smother nearby life, while noise and light could also negatively affect deep-sea species. Recovery times for vent communities are unknown.²

Most marine scientists agree that effective protection of the MAR will require a precautionary approach to seabed mining that includes excluding large areas of the seafloor from mining and establishing stringent rules governing how it can occur outside those protected areas.

Endnotes

1. “InterRidge Vents Database Ver. 3.4,” accessed Oct. 10, 2017, http://vents-data.interridge.org; Monterey Bay Aquarium Research Institute, “Challenging Prevailing Theory About How Deep-Sea Vents Are Colonized,” ScienceDaily, July 24, 2017, http://www.sciencedaily.com/releases/2017/07/170724133033.htm.
2. Cindy Lee Van Dover, “Impacts of Anthropogenic Disturbances at Deep-Sea Hydrothermal Vent Ecosystems: A Review,” Marine Environmental Research 102 (2014): 59–72, https://doi.org/10.1016/j.marenvres.2014.03.008.
3. Lisa A. Levin et al., “Hydrothermal Vents and Methane Seeps: Rethinking the Sphere of Influence,” Frontiers in Marine Science 3 (2016), http://doi.org/10.3389/fmars.2016.00072.
4. José Angel Alvarez Perez et al., “Patterns of Life on the Southern Mid-Atlantic Ridge: Compiling What Is Known and Addressing Future Research,” Oceanography 25, no. 4 (2012): 16–31, https://tos.org/oceanography/assets/docs/25-4_perez.pdf.
5. Cindy Lee Van Dover et al., ”Environmental Management of Deep-Sea Chemosynthetic Ecosystems: Justification of and Considerations for a Spatially-Based Approach” (Kingston, Jamaica: International Seabed Authority, 2011), https://www.isa.org.jm/sites/default/files/files/documents/tstudy9.pdf.