Amphibians are undergoing the most severe declines in biodiversity of any vertebrate group as a result of a fungal disease, habitat loss and other factors. Conservationists keep some frog species in zoos to prevent their extinction, but so little is known about caring for wild amphibians that the long term success of captive populations often falls short of conservation goals. Researchers at the Smithsonian in Panama and Tulane University increased reproduction of captive frogs by feeding them fruit flies fed on diets that included spirulina and other supplements containing carotenoid pigments.
Their discovery that carotenoid pigments are important for frog reproduction will also contribute to one of the longest ongoing projects at STRI’s Bocas del Toro Research Station, which is aimed at understanding the evolution of the different, brightly colored strawberry poison dart frog populations inhabiting the islands of the Bocas Archipelago in the Caribbean. This project requires researchers to breed frogs in captivity.
Captive animals often suffer nutritional deficiencies because their diet is so limited. Wild poison dart frogs eat mites and ants, but captive frogs are fed fruit flies, which are easy to culture in the lab, but may be nutritionally deficient compared to the diet of wild frogs.
The team led by Corinne Richards-Zawacki from Tulane University fed poison frogs fruit flies reared on a carotenoid rich diet consisting of red phaffia yeast, powdered marine algae and spirulina, a cyanobacterium and popular human dietary supplement. They discovered that supplementing the diet of the ?ies with these carotenoid-containing ingredients increases the reproduction of captive strawberry poison frogs (Oophaga pumilio). On the high carotenoid diet, more clutches of eggs produced tadpoles and more tadpoles completed metamorphosis, resulting in an overall increase in the number of offspring.
Carotenoid pigments are extremely common in animal eggs (they make egg yolks yellow) and are also used by countless animals in the ornamentation that attracts mates. While the exact function of carotenoids in poison frogs remains unclear, the results of this work add to growing evidence that carotenoids are important in the health and reproduction of animals.
"Healthy captive populations are important not only to conservation efforts but also to asking a myriad of basic questions about an animal’s biology," said Matt Dugas, first author of the research report. We’re glad to be able to contribute to both of these efforts and thankful for all the help the STRI and Bocas del Toro staff provided over the last several years."
Dugas, M.B., Yeager, J. and Richards-Zawacki, Corinne. 2013. Carotenoid Supplementation Enhances Reproductive Success in Captive Strawberry Poison Frogs (Oophaga Pumilio). Zoo Biol. 32:655–658.