Connecticut scientist leads the way in freezing coral to give it life later

Marine biologist Mary Hagedorn works on cryopreserving coral cells so that they may later be thawed and developed into colonies for use at zoos or to restore reefs.
Marine biologist Mary Hagedorn works on cryopreserving coral cells so that they may later be thawed and developed into colonies for use at zoos or to restore reefs. Jim Daniels/Special to the Day Buy Photo

Washington - Corals have been around for hundreds of millions of years, but threats to their immediate future preoccupy marine biologist Mary Hagedorn, who spent her childhood summers exploring the Old Saybrook shoreline and is now pioneering the science of applying human fertility techniques to coral.

According to Hagedorn, corals could be gone from the world's oceans in 25 years if there is no intervention.

A senior scientist at the Smithsonian Institution, Hagedorn has spent years honing the cryopreserving process - freezing at very low temperatures - for coral sperm, eggs, embryos and now polyps - the tiny beginnings of reefs.

Coral reefs help protect coastlines from storms and erosion, provide food for millions of people, support tourism and offer new cures for diseases, like the AIDS drug AZT, derived from a Caribbean sponge.

Hagedorn's lab in Hawaii is the only one in the world dedicated to coral cryopreservation. With funding from the Smithsonian and the National Oceanic and Atmospheric Administration, Hagedorn is racing to create frozen archives of live tissue before the endangered Elkhorn and Staghorn corals disappear.

She is working in collaboration with the University of Hawaii's Institute of Marine Biology and SECORE (Sexual Coral Reproduction), an international organization of professional aquarists and scientists.

The numbers of the two Caribbean reef-building corals have declined more than 90 percent since the mid-1980s. In 2008, the International Union for Conservation of Nature added them to its red list of endangered species.

"The only hope of maintaining coral is either in live culture or frozen in a repository," Hagedorn said. "A lot of people, even scientists, don't quite understand or believe the threat. But when you're down in the Caribbean and you see these ecosystems collapsing in front of your eyes, it's just so obvious."

To cryopreserve coral, Hagedorn first exposes the tissue to a cryoprotectant, or antifreeze, that pushes water out of the cells by osmosis and prevents formation of damaging ice crystals. She can then safely freeze the cells in liquid nitrogen at minus 198 degrees Celsius. Such cold temperatures suspend all cellular life and enable her to store fragile genetic material indefinitely. Hagedorn later thaws the frozen coral tissue, fertilizes eggs and grows baby coral colonies, which can be shipped to zoos or used to restore reefs in the wild.

"It's an insurance policy for the corals," said Mike Henley, invertebrates keeper at the Smithsonian's National Zoo in Washington. "If the corals all die off in the wild, we have the beginnings of a captive population in zoos and aquarias. If all those die off, Mary's is preserved in perpetuity. It's another backup plan. And at the rate they're dying off, it's not too soon."

Hagedorn attributes her love of the ocean to spending summers on Long Island Sound in Old Saybrook as a child.

"I don't remember not ever loving the ocean," she said.

Every summer her family drove from New Britain to Point Road on Cornfield Point. Hagedorn recalls spending every day in and around the Sound, swimming, playing, collecting crabs and mussel shells.

"That was my inspiration for becoming a marine biologist," she said.

Hagedorn would watch a neighbor, an old Scandinavian fisherman, cross their yard and head to the rocky point to catch stripers and bluefish after work.

"He knew so much about fish and fishing," Hagedorn said.

She would watch him tie flies every night, and remembered once he even caught a shark.

"He was very respectful," she said. "He never caught more than he could eat, and if he did he gave it away."

Today, Hagedorn has a new summer ritual.

Every August, she goes Puerto Rico for the annual Elkhorn coral spawning. Four days past the full moon, at about 9:15 pm, Hagedorn, Henley and a team of international scientists dive into what Hagedorn described as an "underwater blizzard" to collect coral gametes for breeding and freezing.

"I feel very fortunate to have lived next to the ocean most of my life," Hagedorn said. "It's important to give back, and this is how I give back to the ocean."

Hagedorn earned bachelor's and master's degrees in biology from Tufts University. She then attended the Scripps Institution of Oceanography in San Diego and graduated with a doctorate in 1983. She did a postdoctoral fellowship at Cornell University from 1984 to 1986. For the last five years, Hagedorn has been in Hawaii, coming back to the Smithsonian every few months.

Hagedorn started working on coral, she said, "because nobody had done any cryopreservation of coral at all and I saw it as a huge hole in our conservation need."

In 1978, scientists witnessed a mass coral bleaching, in which large portions of reefs turned white and died. Corals bleach when their symbiotic partners, tiny photosynthetic algae called zooxanthellae, die in response to environmental or thermal stress. Bleaching events continue, with the largest recorded in 2005.

Scientists cite many causes for declining coral reefs. Bottom trawling and dynamite fishing physically destroy reefs. Rivers carry pollution and sediment from deforestation, development and erosion to the ocean, choking reefs. And fertilizers in particular promote the growth of green algae that outcompete coral.

Hagedorn, Henley and other SECORE scientists, including Dirk Petersen from the Netherlands' Rotterdam Zoo, say that rising water temperatures and ocean acidification play a major role in reef decline.

The ocean becomes increasingly acidic as it absorbs carbon dioxide from the atmosphere. Calcium carbonate, the main component of coral and shells, dissolves in acidic environments.

"You know how your mother always told you not to drink soda because it ruins your teeth?" Hagedorn said. "It's the carbonic acid in sodas that really does it, and that's what's happening in the oceans."

Hagedorn joins scientists in a worldwide conservation effort to build frozen archives of genetic material to protect endangered species. At the National Zoo, for example, nearly every department freezes something, from milk and sperm to soil and coral.

"Right now my lab is about the only one in the world that's working on the frozen aspect of coral conservation," she said. "So I feel almost desperate because there is so much work to be done. We are working on pennies and nickels and dimes to do this."

She added, "As we go into the future, hopefully this frozen material will never be needed. But if it is, it can stay frozen for hundreds of years."

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