Saving Microscopic Threatened Species Through Artificial Insemination

The Smithsonian’s National Zoo recently acquired 12,000 new animals-microscopic Elkhorn coral larvae-as part of an international collaborative program to raise the threatened species. National Zoo scientists hope to one day return the animals to their wild ocean habitat.

In August, National Zoo reproductive scientist Dr. Mary Hagedorn and invertebrates keeper Mike Henley traveled to Puerto Rico with marine scientists involved with Sexual Coral Reproduction (secORE) to collect and artificially inseminate coral. Hagedorn is pioneering the cyropreservation (freezing, storing and thawing) of coral sperm and eggs. Working in collaboration with secORE, she is trying to create a genome resource bank, which will help preserve the genetic diversity of coral.

Hagedorn, Henley and the team captured spawning coral gametes in nets during night dives and transferred them back to their laboratory on the beach for research and artificial insemination.

At the National Zoo’s invertebrates exhibit, Henley has been coaxing the 12,000 coral larvae to settle in to a specially designed tank.

From the original 12,000,158 larvae settled onto specially designed tiles and formed polyps-millimeter-sized corals that could eventually grow to be 10 feet wide.

Coral reefs are dying worldwide, largely due to human influences. In the Caribbean, populations of the massive Elkhorn coral (Acropora palmate), which historically have been the primary and most ecologically important reefbuilding coral, have declined by 90 to 99 percent since the mid 1980s. As a result, it is one of the first corals listed as threatened under the Endangered Species Act.

As many aquarium enthusiasts already know, coral can be easily reared in captivity: New colonies can grow from broken fragments of parent colonies. Those new colonies, however, are clones with the same genetic makeup as the parent coral.

For this reason, the National Zoo’s work with the artificial insemination and captive breeding of coral is essential to fighting its extinction. The more genetically diverse a population, the greater its chance of surviving various environmental stresses.