Test-tube tadpoles at zoo

The Henry Doorly Zoo has scored another leap ahead for conservation and captive breeding with the hatchings of 1,400 dusky gopher frog tadpoles.

Partnering with the Memphis Zoo, the Omaha zoo used in vitro fertilization to produce the tadpoles.

Thirteen hundred were produced by fertilizing the female frogs’ eggs with sperm from male frogs already residing at the Omaha zoo. One hundred more tadpoles were produced by bringing sperm from frogs in Memphis to fertilize the eggs of Omaha female frogs.

It was the first time the transport of amphibian sperm had been attempted.

Only about 100 of the dusky gopher frogs — which used to be plentiful in Mississippi, Louisiana and Alabama — are left in the wild. Most can be found in one pond in Mississippi.

The Detroit Zoo brought the frogs into captivity in 2001. The Memphis Zoo followed in 2003, and the Henry Doorly Zoo in 2004. The successful breeding of the captive frogs was difficult and has occurred only in the past couple of years.

The tadpoles that hatched earlier this month came after scientists from the Memphis Zoo visited Omaha. They trained the Henry Doorly staff on assisted reproductive technologies, including the IVF of some of the Omaha frogs with sperm from the frogs in Memphis.

“This has been a great cooperative project for all parties involved,” said Jessi Krebs, the Henry Doorly Zoo’s curator of amphibians and reptiles. “It was a great experience for the staff here and a great opportunity for them to learn new techniques.”

Fertilizing 100 eggs from a single female frog with sperm from numerous male frogs in a petri dish helps promote genetic diversity of the animals in captivity.

“The number of tadpoles produced this month was amazing in itself,” said Dr. Jen Germano of the Memphis Zoo Conservation and Research Department. “But the fact that we were able to successfully fertilize some of these eggs with sperm collected noninvasively and shipped between zoos was one of the most ground-breaking parts of this trip and is a great sign for future amphibian breeding projects.”

The breakthrough of transporting chilled amphibian sperm from one zoo to another will benefit zoos and aquariums around the world. The technique can be used with other amphibian species without the extra stress of having to move individual animals between facilities.

“Although the transfer of sperm between institutions for artificial insemination is regularly practiced in mammals, the technology has never before been used to reproduce endangered amphibians … and represents a conservation milestone,” said Dr. Andy Kouba, director of Conservation and Research for the Memphis Zoo.

The Nancy and Jim Armitage Herpetological Fund helped provide travel funds for the collaborative project.

The work of the Henry Doorly Amphibian Conservation Area has become increasingly important in the face of the international amphibian extinction crisis. Nearly two-thirds of all known amphibian species — frogs, toads and salamanders — are threatened with extinction and more than 500 species already are extinct in the wild or are critically endangered.

For the time being, dusky gopher frogs are not on display at the Omaha zoo. The entire group is maintained in the Amphibian Conservation Area, Krebs said.

Henry Doorly will keep about 500 of the new frogs, he said, but other zoos are on board with the project and already are indicating they want some of the other frogs. If all goes well, some eventually may be released into restored and protected habitat to help re-establish the wild population.

Contact the writer:

444-1067, carol.bicak@owh.com

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