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Hannah Perlkin holds a flower of the seagrass Posidonia oceanica after a dive off the coast of Corsica. (Emily Tucker/Contributed)

SANTA CRUZ -- Last fall, while most of their colleagues sat in the classroom, Hannah Perlkin and Emily Tucker swam through meadows of Neptune grass in the Mediterranean Sea.

Participants in UC Santa Cruz's Marine Ecology Field Quarter, the two undergraduates wondered how this fragile seagrass nourishes ocean life around it. Then a surprising discovery took them in a new direction.

Perlkin and Tucker documented a rare flowering event, and their data could help scientists preserve declining seagrass species worldwide. Now with a grant from the National Science Foundation, they're preparing for a second trip to Europe.

The two were among 30 students who joined UCSC professors Peter Raimondi and Giacomo Bernardi for field work on the French island of Corsica. There, like on the California coast, meadows of seagrass support marine ecosystems by converting sunlight to energy, sheltering fish and preventing erosion. But seagrass colonies have been shrinking, Raimondi said, and efforts to transplant new colonies have been unsuccessful.

Perlkin and Tucker donned scuba gear to observe the bright green ribbons of seagrass swaying in silence. "It's very dreamy," said Perlkin. While their professors set up equipment, they practiced taking samples. "We were just bumbling around," Tucker recalled.

Then they noticed something unexpected. Green buds forming at the base of the grass shoots. They couldn't talk underwater, but their gestures said, "Is this what I think it is?"

Neptune grass produces flowers about every 10 years. It usually grows by sending out runners under the seafloor to create clusters of genetically identical plants. But Perlkin and Tucker had caught a rare season of sexual reproduction. "We came up from the dive and it was just explosive," said Perlkin. "We were so excited."

Perlkin and Tucker changed their project to focus on flower abundance. They found that flowers were concentrated in 10-foot clusters, which they thought might be genetically distinct colonies. But without proper funding, a genetic study remained "a pipe dream," Tucker said.

They reached out to scientists across Europe and learned that the flowering event was widespread. If they could find the genes unique to more productive plants across the Mediterranean, they could target them for transplanting.

Raimondi helped his students submit a rush proposal to the National Science Foundation, which offered $85,000 in support.

Perlkin and Tucker are now preparing to spend March and April working alongside European researchers in coastal France, Spain and Croatia.

Raimondi said the same techniques his students are pioneering in Europe could conserve California's eelgrass, which has also been in decline. "Once we get the results, the next thing we're gonna do is go down to Elkhorn Slough," he said.

Perlkin said she is grateful to have been part of the Marine Ecology Field Quarter, a program unique to UCSC. "I think it came at a right time, where we were really prepared to take advantage of it," she said. Both students plan on pursuing marine ecology in graduate school.