No one has yet documented the entire vertical sequence of life in the world’s oceans in a single place. In the southern Mariana Trench it will be possible to dive from the trench axis at over 10 km depth and rise up the face of a nearby fault scarp to near-surface – documenting the changes in ecosystems along the way. This could provide the first such complete record of biological diversity from top to bottom in the world’s oceans.
Although the Mariana Trench is the most explored in detail, its unique combination of deep-sea features in a relatively confined area make it a rich scientific target. From blue serpentine mud volcanoes, to 700º hydrothermal vents, to a subduction zone where the Pacific plate is diving under the Philippine plate – the Mariana Trench has a lot to keep researchers busy. [Science note: All deep-sea trenches occur at the boundaries of tectonic plates].
In addition to the sub itself, there will also be a number of autonomous landers that will collect further scientific data and samples as well as capture footage of the submersible as it passes by.
Microbiologist Dr. Doug Bartlett’s (Scripps Institution of Oceanography) and other scientists’ goals will be achieved by use of the landers we will deploy. A series of landers will be utilized that can be armed with bait, motion-activated cameras & lights, as well as sampling equipment to collect water and bottom sediments. The landers will be deployed ahead of the dive and will self-release their ballast – returning to the surface a day after the dive. With sonar locators, the sub should be able to rendezvous with the landers and see what marine life they have attracted.
The water samples they will obtain are not merely a liter or two, but the product of a pump and filter assembly that will circulate 20,000 liters through a filter fine enough to separate microbial and viral particles from the stream. Thus, a far greater amount of material is brought back and sample volumes are large enough to do DNA testing. The Scripps team will study samples brought back from the depths and look for any novel organisms as well as potentially beneficial enzymes or genes.
Well before reaching the bottom, the sub will encounter shooting stars of icy blue light. What marine biologist, Dr. Edith Widder (Ocean Research & Conservation Association), describes as “a silent fireworks display”. Dr. Widder is one of the world’s leading authorities on bioluminescence – light that is generated by living creatures. Beyond recording the hypnotic beauty of this phenomenon, she wants to know who is making all that light and why they spend precious energy doing it. How can bioluminescence be used as a tool to determine the distribution of animals in the ocean? And critically, she believes it can be used to monitor the health of marine ecosystems.
Special thanks to ORCA for allowing us to use these beautiful images!
As this mission stands on the shoulders of the Trieste dive in 1960, one of the interesting goals of the dive will be to try to locate the exact site where the Trieste touched down 50 years ago. The bathyscaphe dropped tons of iron shot ballast in order to rise back to the surface. There most certainly will be a colony of iron-consuming bacteria present. Because of the extremely cold temperature, life moves very slowly at these depths, and the ability to see what has happened after fifty years of exposure will be fascinating. For comparison, the usual experiment exposes mere grams of material for a short time.
Dr. Katrina Edwards (University of Southern California) is also interested in characterizing any microbes that originate beneath the seafloor. She wants to learn more about the microbes that live chemosynthetically, surviving on chemicals found in the earth’s crust – not through photosynthesis or the products of photosynthesis (plant matter and the animals that eat the plants).
Sediment and sea-floor rocks will provide novel samples exposing the entire thickness of the earth’s crust, invaluable to understanding how new continents form. Dr. Patricia Fryer (University of Hawaii), Dr. Sam Hulme (Moss Landing Marine Labs) and Dr. Geoff Wheat (MBARI and University of Alaska) are studying the rocks, mud flows, gases and liquids released during subduction processes near the trenches. They are looking to track fluids and muds as they move through the earth’s mantle and crust. This can help characterize how tectonic plates interact at trenches and give a better understanding of where economically valuable ore deposits might be found.
Some microbes live on hydrogen gas that emanates from near-trench mud volcanoes and springs. This hydrogen is released when mantle rock interacts with deep-derived fluids forming serpentinite. When it is exposed to CO2 in the fluids, methane and other hydrocarbons form naturally. The US Navy has been pursuing this type of reaction (Fischer-Tropsch process) in its laboratories for the development of kerosene-based jet fuel. These enormous serpentinite mud volcanoes are natural laboratories for the study of this process. What part do microbes play in the process? We don’t know…
Studying the area’s mud volcanoes can also help give us insight into the possibility of using a subduction zone for carbon sequestration. In low-temperature environments the serpentinization of mantle rocks could yield as much CO2 uptake as ~ 1 billion tons/km3 of mantle rock per year.
In essence, these dives to the bottom of our world are an unprecedented scientific opportunity—allowing us to better understand everything from how the continents formed to how to protect our home planet and the life forms on it far into the future.
Learn more about the science team.