UO students Caitlin Plowman and Kirstin Meyer of the Oregon Institute of Marine Biology in Charleston can boast to the world that they have gathered sexual organs of animals living in the deepest of ocean waters.

Plowman, in fact, is freshly back after participating in the first extensive study of the Mariana Trench, the deepest part of the world's oceans located near Guam in the western Pacific Ocean, as part of a team on board the research vessel Falkor. These deep trenches are known as hadal zones.

In a news release issued Dec. 18, the non-profit Schmidt Ocean Institute provided research highlights from the Falkor's latest mission — the Hadal Ecosystem Studies  expedition, HADES — led by co-chief scientists Jeff Drazen and Patty Fryer of the University of Hawaii. The expedition came home with the deepest rock samples ever collected and new species, including the deepest-dwelling fish ever recorded.

Plowman, who recently completed a bachelor's degree in marine biology from the UO and begins graduate work in January, was on board representing the laboratory of Craig Young, director of OIMB. Her mission was to collect gonads, the sexual organs of the undersea creatures.

"My job on this cruise is to collect the gonads from any hadal invertebrates we find," Plowman wrote in a blog entry while at sea on Nov. 22. "So far, that has only been amphipods (shrimp-like crustaceans), lots and lots of amphipods. Most of the amphipods are only a few millimeters in length and are far too small to dissect. Any bigger than a few centimeters, I get to cut open and go gonad hunting! It really is quite fun."

Young's lab at OIMB is working with collaborators Kevin Eckelbarger at the University of Maine and Alan Hodgson at Rhodes University in South Africa to analyze the gonad samples collected by Plowman and by Meyer, a UO doctoral student, earlier this year while exploring the Kermadec Trench north of New Zealand, Young said.

"Kirsten brought back the deepest gonads collected for reproductive studies to that date, and Caitlin brought back even deeper ones," he said. "Our group is studying reproduction in the deep ocean trenches by preparing the gonads of deep-dwelling animals for electron microscopy. The gonad samples taken on these cruises will reveal details about the speed and timing of egg and sperm production at great depths."

In her blog, Plowman wrote that the sexual organs collected from the amphipods in the Mariana Trench "can be compared to those of their shallow water relatives, which could show us what sort of adaptations these deep-dwelling amphipods may have to the different depths, temperatures, pressures and food inputs of the hadal zone."

The Schmidt Ocean Institute's news release, titled "New Species and Surprising Findings in the Mariana Trench," includes links to photos and videos from the expedition.

—By Jim Barlow, Public Affairs Communications