As the submersible and landers pushed into deeper waters, the variety of species declined, with each depth dominated by a handful of key organisms. At shallow depths in the New Britain Trench, Gallo observed strange rotund but graceful animals called sea cucumbers swimming in the water column. Different species of sea cucumbers were present even in the great depths of the Challenger Deep but appear to have adapted to these depths by decreasing in size, not swimming, and feeding by orienting themselves with the currents. The sea cucumbers seen in the Challenger Deep at approximately 11 kilometers (approximately 36,000 feet) likely represent a new species and are the first recorded abundant population of the animals found in the deepest part of the ocean.
Proximity to land also played a role in the makeup of the deep-sea environment. Deep in the New Britain Trench, located near Papua New Guinea, Gallo identified palm fronds, leaves, sticks, and coconutsterrestrial materials known to influence seafloor ecosystems. The Challenger Deep and Ulithi, both more removed from terrestrial influence, were absent of such evidence. Gallo also spotted a dive weight in the Challenger Deep footage, likely used as ballast on another deep-submergence vehicle.
"These data add valued information to our limited understanding of deep-sea and trench biology," said Gallo. "Only a small fraction of the deep seafloor has been fully explored, so this expedition allows us to better understand these unique deep-sea ecosystems."
Gallo and Ralph Pace, a master's student in the Center for Marine Biodiversity and Conservation at Scripps, are compiling an image reference collection of all organisms identified during these dives to help expand the scientific impact of the expedition.
|Contact: Mario Aguilera or Robert Monroe|
University of California - San Diego