Abyssal Zone

What are ocean scientists doing to learn more about the abyss?

At the moment, there are a limited number of vehicles capable of descending to the abyssal seafloor. Some are autonomous underwater vehicles (AUVs). These are robotic, pre-programmed submersibles equipped with sensors, probes, and imaging systems that allow researchers to map and collect data in extreme underwater terrain, including trenches and volcano calderas.

Remote-operated vehicles (ROVs) are also used to explore parts of the abyss. They are typically tethered to and piloted from a ship via a fiber-optic cable which allows commands from the ship to reach the ROV and relays data and imagery to the pilots. These allow for real-time video and imagery, so pilots can see where the ROV is at any moment, which also allows them to direct the ROV to collect samples while at depth.

Human-occupied vehicles (HOVs) allow two or three people to descend in the submersible. HOVs can collect mid-column seawater samples, rest on the seafloor, or travel through rough geological features, making maps and collecting samples with its robotic arms along the way. WHOI’s HOV, Alvin, is currently undergoing upgrades that will allow it to descend to 6,500 meters. This will provide access to the abyssal seafloor and will allow Alvin to spend more time exploring once there. This is an essential upgrade that will facilitate new areas of research into the geology, chemistry, and biology of the abyssal zone.

Researchers are currently interested in a wide variety of aspects of the abyss. Although trenches, ridges, and other geologic features have been studied, there is still much to learn about them. Even less is known about the abyssal plains and the organisms found there. Some of the metallic nodules found on plains are home to creatures that live nowhere else. Understanding the needs of these organisms is essential if people are to begin mining the nodules from the seafloor. Evidence to date shows that some of these communities do not recover from disturbance, even decades later, and more information is needed to ensure that future mining efforts do as little damage to deep sea life as possible.

The role of microbes in deep-ocean systems is also under investigation. Microbes, including bacteria and Archaea, are capable of surviving at extreme pressures, temperatures, and in chemical environments that would be hostile to many organisms. Their ability to metabolize chemicals seeping from Earth’s interior is poorly understood but could lead to innovations on land. These microbes likely provide important ecosystem services to the deep ocean, and researchers are working to understand that role. This is essential information, since deep-sea mining would impact microbes as well as larger organisms, and harm to these microscopic communities could reverberate throughout our ocean systems.