Published On: Mon, Jun 27th, 2016

In vitro fertilization may save coral reefs

CoralsMarine biologists at the California Academy of Sciences have joined a new international effort to rescue endangered coral reefs from the consequences of widespread human destruction and a warming climate.

Teams of research divers from the academy will set off this summer on expeditions to the Caribbean and Mexico, where they will seed two of the region’s major reefs with millions of coral larvae born from the organisms’ sperm and egg cells.

As colorful as flower bouquets, corals are actually colonies of tiny animals that build their limestone homes from the sea, and derive their colors from the algae that live inside them. Their lives are increasingly threatened by global plagues like expanding human development, ocean pollution, and the twin signals of global climate change: rising temperatures and increasing ocean acidification.
Recent record-shattering El Niños have raised Pacific Ocean temperatures and caused a new worldwide episode of coral bleaching that is turning the organisms dead white. The scourge began in 2014, according to the National Oceanic and Atmospheric Administration, and is already the worst and longest bleaching episode in history.

Bart Shepherd, the director of the academy’s Steinhart Aquarium, and Luiz Rocha, the curator of ichthyology, will lead about 20 divers on a new experiment in coral reproduction.

“If it’s successful,” Shepherd said, “it opens the possibility for widespread application on coral reefs everywhere.”

Shepherd’s group has joined with leaders of an international research and conservation group called Secore International — Sexual Coral Reproduction — whose founder and president, Dirk Petersen, led the original research into a unique method of in vitro fertilization of coral organisms.

Five years ago, Petersen and researchers diving at the Caribbean Marine Biological Institute in Curacao, collected coral sperm and egg cells in the water while the corals were spawning, and reared the coral larvae in the laboratory. When they matured, the researchers transplanted the coral larvae onto small, fist-size tiles that the divers then transplanted to the degraded reef by the thousands.

The experiment was successful and within two years a high proportion of new corals were flourishing and growing, Petersen and his colleagues reported in the journal Global Ecology and Conservation.

“This is now actually a five-year plan, and eventually it could become a global restoration project for corals everywhere,” Petersen said during a recent visit to San Francisco, where he and Shepherd completed working on details of the academy team’s role this summer.

The expedition is scheduled for August because the corals spawn only about once a year, releasing their sex cells into the water by the millions, Shepherd explained. The event, he said, occurs only in August at night and only within a few days after a full moon.

It’s during those fleeting nights of spawning action that Shepherd and his colleagues from the academy will be diving to collect the coral gametes. Then, after they have become larvae in the Caribbean institute’s lab, the divers will return to seed the nearby reef with the fresh infant corals.

The researchers’ first two targets will be on the degraded reef at the institute’s field station in Curacao, and then on the Yucatan Peninsula, where the famed Great Maya Reef stretches more than 620 miles south to the coast of Belize.

The academy’s effort at coral midwifery is part of a $10 million commitment the institution has made specifically to research and restoration efforts on the world’s endangered reefs.

“We’re planning 20 new expeditions over the next five years to regions where coral reefs are threatened,” said Jonathan Foley, the academy’s executive director. “And our people will be putting boots on the ground for a rescue experiment that’s unique — not just for proving out a new technique to restore coral reefs, but for making the technique better.”

By David Perlman


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