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Successful Capture of Ultradeep Sea Animals From the Puerto Rico Trench

By Nichola C. Lacey • Dr. Alan J. Jamieson • Dr. Fredrik Søreide

One of the recovered Scopelocheirus schellenbergi amphipods from more than 8,000 meters in the Puerto Rico Trench. (Photo Credit: Toyonobu Fujii)
On a deployment last year to more than 8,000 meters depth in the Puerto Rico Trench, a prototype robotic vehicle system, the 11k, recovered several samples of deep-sea animals (Sea Technology magazine, December 2012). The 11k, developed by Promare (Chester, Connecticut), also recorded HD video of the seafloor. The most conspicuous aspect of the footage was the swarm of benthic amphipods (crustaceans commonly known as hoppers), which rapidly accumulated at the bait tied to the vehicle. These amphipods, collected by small nets mounted on the 11k, are now being studied to further understand the fauna of deep trenches.

Amphipods are prolific scavengers in the deep sea, dominating the deepest trench communities. While the diversity of amphipods decreases with depth in each trench, their abundance increases exponentially. Therefore, at the deepest points, large swarms of amphipods rapidly consume bait and are comprised almost exclusively of one species.

Exactly what species dominate any given trench appears to be trench-specific. Their survival at extreme depths is thought to be due to a combination of diet plasticity, rapid consumption of relatively large food parcels, incredible pressure tolerance and the ability to survive long periods of starvation, as they are very reliant on infrequent food falls descending from overlying waters.

Amphipod Location
The samples recovered by 11k were Scopelocheirus schellenbergi, a species of lysianassoid amphipod that have so far only been found in ultradeep trenches. They are typically found in the deep subduction trenches of the Pacific Ocean from the Aleutian Trench in the north Pacific and the Kuril-Kamchatka, Japan, New Hebrides and the Tonga-Kermadec trenches, which run down the western Pacific Rim. In these trenches S. schellenbergi has been found between 6,000 and 9,104 meters, the deepest of which came from the Kermadec Trench.

The interesting point concerning the presence of this species in the Puerto Rico Trench is that there is no direct corridor of equivalent depth between the north and western Pacific Trenches and the Puerto Rico Trench. This level of isolation offers a tantalizing question as to how the same species came to be in multiple trenches that are isolated from one another. Furthermore, the closest trench to the Puerto Rico Trench is the Peru-Chile Trench. Although thousands of amphipods were captured from 4,000 to 8,000 meters in 2010 by the Hadal Environmental Science Education Program (HADEEP), not a single S. schellenbergi was found.

Extending the Reach of Amphipod Research
S. schellenbergi was first discovered in the Puerto Rico Trench in 1948 when the Swedish vessel Albatross, under the leadership of Hans Pettersson, successfully bottom trawled between depths of 7,625 and 7,900 meters. Among other benthic fauna, the recovered amphipods were later described as S. schellenbergi by Russian scientists J.A. Birstein and M.E. Vinogradov in 1958. To continue this article please click here.

Nichola Lacey is a Marine Alliance for Science & Technology for Scotland-funded Ph.D. student based at the University of Aberdeen's Oceanlab under the supervision of Dr. Alan Jamieson. Lacey's research is focused on understanding the ecology and physiology of amphipods inhabiting hadal depths at 6 to 11 kilometers deep.

Dr. Alan Jamieson is a lecturer in marine biology at the University of Aberdeen, based at Oceanlab. His research focuses on the development of novel deep-sea technology for biological research at abyssal and particularly hadal depths.

Dr. Fredrik S'reide is the vice president of Promare and is responsible for its new deepwater exploration initiative. He is also a professor of marine engineering at the Norwegian University of Science and Technology. He has been involved in numerous marine scientific and exploration projects around the world.

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