ators outfitted with experimental equipment, including respirometers to see how animal metabolisms function at such great depth and niskin water sampling bottles to investigate microbial activity at full-ocean water depths.
The team will use the deep-submergence vehicle, Nereus, which can remain deployed for up to 12 hours, to collect both biological and sediment samples. Nereus will stream imagery from its video camera to the ship via a fiber-optic filament about the width of human hair. This state-of-the-art vehicle, developed by a team of engineers at WHOI, is the result of a combination of some of the greatest advances in technology and science, and has already dove successfully to the deepest part of the ocean—Challenger Deep in the Mariana Trench—on its first mission in May 2009.
This expedition will build on earlier studies of the Kermadec Trench by Alan Jamieson at UA’s Oceanlab and colleagues at NIWA and the University of Tokyo. Using the Hadal-lander, which was developed at Oceanlab, the team has documented new species of animals in the Kermadec and other trenches around the Pacific.
"To date, this method has been successful in observing the deepest fish ever seen alive," Jamieson said. "By combining WHOI's HROV Nereus with Oceanlab's Hadal-Lander technology, the team have the best available technology at their disposal."
Once thought to be devoid of life, trenches may actually be home to many unique species. For one reason, there is growing evidence that food is plentiful there. While it is still unclear why, organic material in the ocean may be transported by currents and deposited into the trenches.
In addition to looking at how food supply varies at different depths, the research team will be investigating the role that energy demand and metabolic rates of trench organisms play in community structure and how these biological systems differ from their shallow water relatives.
Exactly how animals in the trench evolved to withstand the pressures is not completely known, but Shank's objective will be to compare the genomes of trench animals to piece together how they have evolved to live successfully in trenches. "Our challenge is to determine whether life in the trenches holds novel evolutionary pathways that are distinct from others in the ocean," he said.
Hydrostatic pressure, which at depths found in ocean trenches can be up to 1,100 times that at the surface, is known to inhibit the activity of certain proteins. Paul Yancey from Whitman College will be investigating the role that piezolytes—small molecules that protect proteins from pressure—play in the adaptation of trench animals. The use of piezolytes, which was developed and discovered by Yancey and his students, is a novel hypothesis and attempts to explain previous findings that not all deep-sea proteins are able to evolve resistance to pressure within their structures.
"We are trying to discover how life can function under massive pressures in the hadal zones. This is incredibly important because pressure might very well be the primary factor determining what species are able to live in these extreme environments," Yancey said.
In addition to deep-sea life with novel adaptations, there is also evidence to suggest that trenches act as carbon sinks, making the research also relevant to climate change studies. The V-shaped topography along trench axes funnels resources—including surface-derived organic carbon—downwards.
"The bulk of our knowledge of trenches is only from snapshot visits using mostly trawls and camera landers," Shank said. "Only detailed systematic studies will advance our biological understanding and also reveal the role trenches may play as the final location of where most of the carbon and other chemicals get sequestered in our ocean, which ultimately impacts the global carbon budget and climate."
"That's what makes this project so exciting," he added. "This work will provide great insight into our understanding about life on Earth. This type of research simply wouldn't happen without support from the National Science Foundation."
Mo