Smithsonian National Zoological Park l Friends of the National Zoo



Coral Reef Conservation with Modern Fertility Techniques

Why Coral Reefs?

Our survival depends directly upon the health of our global ecosystems.  Coral covers only about 0.2 percent of the Earth’s surface, yet coral reefs support 25 percent of all marine life with more density of life in reefs than any in other ocean habitat. 

Our life as humans depends on coral reefs. More than a billion people depend directly on reefs for their livelihood. Coral reefs contribute over 30 billion dollars to the world economy each year. New strains of antibiotics are emerging from coral reef studies to help fight diseases. Coral reefs help drive our weather and provide shoreline protection for human homes and cities, buffering areas from potentially damaging storms and ocean swells.

Kaneohe Reef

In Kaneohe Bay, the barrier reef protects Coconut Island, the home of the Hawaii Institute of Marine Biology (where our lab is located) as well as Oahu, the most populated island in the Hawaiian Island chain. Photo by A. Seale.

Coral reefs play a critical role in the carbon cycle of our planet by taking calcium ions and dissolved carbon dioxide from the water and turning it into the calcium carbonate forming their hard skeletons. This allows our oceans to become a sink for the carbon dioxide in the atmosphere.

Coral reefs are in trouble and need our help. Coral reefs face both local and global threats that may lead to their extinction, possibly within our lifetime.

Locally, coral is being threatened in many ways. Construction runoff from development can smother coral reefs. Runoff from agricultural lands that is too rich in nutrients can cause algal blooms which too can smother reefs. Coral reefs are damaged when tourism goes unchecked and snorkelers or divers are not educated about how to treat our reefs. Many of these threats can be prevented through communication and education, but they continue to harm coral reefs worldwide.

Globally coral reefs face more threats, mainly from rising ocean temperatures and ocean acidification. As temperatures rise, corals around the world become stressed. Bleaching, when corals expel the tiny algae that live symbiotically inside of them occurs. Once this happens the corals die quickly.

blenny atop bleached coral

A blenny sits atop a bleached coral head. Photo by A. Seale.

As carbon dioxide levels in our atmosphere continue to rise, more carbon dioxide is pulled down into our oceans. Coral reefs act as a sink for carbon dioxide, but they cannot uptake it all. As carbon dioxide dissolves into the ocean, the ocean becomes more acidic. As this happens, coral reefs are at risk of having their skeletons dissolve. You can imagine how the acid in sodas can clean a penny and harm your teeth. Much the same will happen to the skeletons of corals as the ocean becomes more acidic.

As coral reefs die or dissolve, their structures will be lost forever. Billions of ocean creatures will lose their homes. Shorelines will be left unprotected and the world economy will be affected.

Smithsonian scientists are working towards building both live and frozen banks to guard against this imminent loss of coral reefs.

Using Modern Fertility Treatments to Help

Using procedures similar to those used in human sperm banks, Smithsonian scientists Mary Hagedorn and her team have develop techniques that allow them to freeze and store coral sperm and stem cells, and in the future, possibly even adult coral fragments. Coral genetic material frozen in this way can be viable for hundreds of years. The frozen sperm can be used to generate new corals and to strengthen small populations by adding genetic diversity. Advances in human stem cell biology may one day allow the frozen stem cells to produce new adults.

Working at the Hawaii Institute of Marine Biology for the past nine years, Hagedorn created the first frozen Hawaiian Coral repository with sperm and stem cells from two species of corals from Kaneohe Bay. Techniques developed working on healthy corals in Hawaii have been taken out into the field from Puerto Rico to Singapore and applied to more impacted corals around the world.

Hagedorn and Carter

Mary Hagedorn and Virginia Carter placing samples into Hawaii’s first frozen coral repository. Photo by J. Daniels.

Hagedorn and her team have banked two endangered species in the Caribbean. From 2006 to 2009 the team worked in Puerto Rico to bank sperm and stem cells from Acropora palmata or elkhorn coral. Hagedorn and her group also traveled to Belize in 2011 to bank embryonic stem cells from the endangered species Acropora cervicornis.

Carter and Acker

Virginia Carter and Jason Acker assess fertilization rates of cryopreserved sperm from the endangered species, Acropora palmata or elkhorn coral. Photo by M. Laterveer-Beer

Most recently, Hagedorn has travelled to the Australian Institute of Marine Science for the past several years for the Great Barrier Reef’s annual spawning, helping create a bank for Australia’s corals. She has also been training scientists from the Australian Institute of Marine Science and the Taronga Conservation Society in coral reef cryopreservation techniques so that they can continue to grow their Great Barrier Reef bank. The team’s work in Australia has resulted in the banking of seven important reef building species there. In 2013, coral produced with cryopreserved sperm will be raised to adulthood and corals will be grown from cryopreserved embryonic cells as well.

Back in Hawaii during the winter months, when corals are not spawning, Hagedorn’s team has been developing techniques for freezing whole adult coral polyps. While still in the preliminary stages, someday frozen coral banks may contain whole adult corals with no need for fertilization from gametes or differentiation from stem cells.

Carter and Acker

Adult coral fragments are turned upside-down and immersed in a solution of cryoprotectant to test the toxicity of the solution to the coral. Photo by V. Carter.