Teacher studies turtles

Teacher travels the ocean to study the mysterious leatherback turtle

Chico Junior High School science teacher Mary Anne Pella-Donnelly shows off a Styrofoam cup that shrank considerably from the pressure it experienced at a depth of 500 feet in the ocean.

Chico Junior High School science teacher Mary Anne Pella-Donnelly shows off a Styrofoam cup that shrank considerably from the pressure it experienced at a depth of 500 feet in the ocean.

Photo By christine g.k. Lapado

Mary Anne Pella-Donnelly held up an empty Styrofoam cup alongside a slightly misshapen, miniature version approximately the size of a shot glass.

The smaller of the two was the end result of a 16-ounce cup being sent down to the depth of 500 meters below the surface of the ocean, Pella-Donnelly explained.

“If it had gone down to a thousand meters,” said the Chico Junior High science teacher, “it would be about the size of a thimble, just because of the pressure at that depth.”

Pella-Donnelly—who spoke recently during the Chico State Museum of Anthropology’s World Explorations Lecture Series—was illustrating one of the many things that she learned first-hand on her two-week trip with National Oceanic and Atmospheric Association (NOAA) scientists on a research boat traveling off the coast of California in September 2008 to learn more about the habits of the endangered leatherback sea turtle.

Pella-Donnelly was chosen by NOAA from candidates across the United States to be part of the organization’s “Teacher at Sea” program.

The shrunken cup that Pella-Donnelly held had taken a ride into the depths of the sea via equipment used to take water samples checking for such information as salinity and water temperature as part of NOAA’s LUTH (The Leatherback Use of Temperate Habitat) Survey.

“I picked up in San Francisco on the second leg of [NOAA’s] month-long trip,” said Pella-Donnelly, who in 2007 had gone on a land-based research expedition to Greenland to study the effects of climate change on a high Arctic seabird called the “little auk.” “We headed out to international waters, out to 200 miles [off the coast], and headed down to San Diego … criss-crossing a warm/cold water front … I had not been on a cruise of any kind before. It was exciting, very different.”

The scientists’ primary objective was to determine why some leatherback turtles, which normally migrate within a few hundred miles of their nesting areas on the Solomon Islands and the island of Palau, are now traveling all the way across the Pacific Ocean to California to “winter”—a journey that Pella-Donnelly said can take a year or more.

“It’s got to be that there’s available food,” she said.

The favorite food of the leatherbacks, explained Pella-Donnelly, is the large (roughly 15 feet long) stinging sea-nettle jellyfish. NOAA scientists had discovered before the trip, using satellite data, that the turtles follow the path of the jellyfish along the California coast. The LUTH Survey trip was conducted to “ground-truth” what the researchers had learned from the satellite data, as Pella-Donnelly put it, using, among other tools, a “brand-new piece of sonar equipment they hadn’t used before.”

One of Pella-Donnelly’s jobs on the research ship, besides keeping a log, was to stay on the top deck of the boat to monitor for marine mammals, such as dolphins and whales. If marine mammals were close by, scientists could not deploy the nets they used to catch the jellyfish they were tracking and studying as part of the survey, according to the guidelines of the Marine Mammal Protection Act.

Pella-Donnelly recalled seeing “common dolphins, Western bottleneck dolphins, Dall’s porpoises, humpback whales, otters and a fin whale—the second largest whale in the world,” as well as Humboldt squids—“voracious” meter-and-a-half-long creatures with parrot-like beaks (Pella-Donnelly pulled a sizable, sharp, curved black beak out of a plastic bag to make her point) that migrated to California “since the last El Niño.

“I would see a dolphin ride the waves next to the boat,” said Pella-Donnelly, “and pretty soon, he would call to his friends, and hundreds of dolphins would come and ride the waves, sometimes for 45 minutes. They were so excited—it was like a playground for them. … I liked it, but it frustrated the scientists who wanted to put in the nets.”

Besides helping protect the leatherback turtle—whose numbers have dropped to about one-fourth of its 1980 population of approximately 115,000—another reason for gathering as much information as possible about its migratory habits is that the leatherback arrives in California at the same time as the commercial swordfish industry is getting under way, said Pella-Donnelly.

Currently, those fishing for swordfish “are shut down 25 miles from the coast and beyond,” said Pella-Donnelly, “because of the migrating leatherbacks. … The commercial swordfish industry is putting pressure on NOAA to narrow down the off-limits area, to become more specific [about the route that the turtles take].”

Pella-Donnelly said that, as a result of her trip, she tells her students that there’s plenty yet to learn about the planet and its creatures.

“I tell them, ‘Don’t just look at The Learning Channel and think that everything’s been discovered.’ There are a lot of opportunities out there for them [when they are older], but they require a lot of chemistry, physics and math.

“A lot of kids don’t realize that jobs in oceanography require those.”

Did she see any turtles?

“Everybody asks me that question,” said Pella-Donnelly. “No, I didn’t. One turtle was tagged in Monterey Bay on the leg before [I joined the boat]. I would have liked to have had a picture of me with the turtles, but it’s a big ocean.

“And seeing the turtle isn’t what’s most important,” she added. “The object of the research isn’t to see the good stuff; it’s to help protect them.”