The research provides evidence that corals may have multiple mechanisms that facilitate recovery from bleaching induced by environmental stresses.
Scientists have known that corals can recover from bleaching episodes, but they did not know why.
It has not been clear whether recovery resulted from the few remaining symbiotic algae, or algal symbionts, remaining within the coral tissue since early development, or if coral could acquire entirely new ones from their aquatic environments.
Corals survive and thrive because of the symbiotic relationship they develop with the single-celled algae called zooxanthellae (zo-zan-thel-y), which live inside them and help supply them with food.
But certain environmental stresses, such as high or low light or sea temperatures, can lead to a reduction in algal densities or loss of pigmentation, leaving the coral's white skeleton visible through the clear tissue.
"Our data show that corals have the potential to take up new symbionts, providing a mechanism for resilience in the face of environmental change," said Mary-Alice Coffroth, Ph.D., associate professor of biological sciences in UB's College of Arts and Sciences, and senior author on the paper.
Coffroth and her co-author, Cynthia L. Lewis, who recently received her master's degree in biological sciences from UB, induced bleaching in gorgonian soft corals (a type of sea rod common to Caribbean reefs) by keeping them in darkness in the laboratory.
After 12 weeks of darkness, cell densities of symbionts in the coral had plunged to less than one percent of their population density when the corals were he
Contact: Ellen Goldbaum
University at Buffalo