Genes Help Some Corals Handle the Heat
A key to saving coral from climate change may be hidden in the DNA of different populations of the same species of coral.
Nature prepared one population for stress more than the other. A Standford University team of biologists analyzed the genes of two populations and identified 60 DNA sequences activated in the hardy variety, but not the other. The biologists found the activated sequences when the corals were stressed under conditions that cause bleaching, the heat-induced epidemic that reduces coral reefs around the world to pale skeletons.
Two groups of the species, Acropora hyacinthus, on Ofu Island, American Samoa lived in different environments. The group that resided in waters that changed dramatically in temperature, pH, and oxygen levels were able to cope with conditions that killed their cousins. These stress-resistant corals were able to withstand temperatures up to 34 degrees Celsius (93 F) and daily fluctuations of 6 degrees C (10.8 F).
The biologists suggested in their paper published in Proceedings of the National Academy of Sciences that surviving such dramatic natural changes on a daily basis may give this group an advantage in dealing with climate change. Understanding what genes allow them to survive could help save other coral.
The 60 genes they identified in the hardy coral related to heat shock proteins, antioxidant enzymes, cell death regulation, tumor suppression, innate immune response, and cell adhesion. Along with hardy genes, the coral were also found to have a more heat tolerant form of the symbiotic algae, Symbiodinium that feed the coral with the products of photosynthesis in trade for inorganic nutrients that the coral provide.
Bleached coral reef in the Alifu Dhaalu Atoll, Maldives (Bruno de Giusti, Wikimedia Commons)