We're losing the coral reefs. There's no two ways about it — these massive enclaves of marine life are on the decline. But the secret to saving the coral could be less diversity, not more. We generally think of diverse populations as being more flexible and resistant to harm, able to respond in a robust way to many possible environmental dangers. But new research published in the Proceedings of the Royal Society B shows that diversity, a boon to most ecosystems, might not be a boon to coral.
Coral reefs are composed of two parts, a host animal and a symbiotic algae called an endosymbiont. In return for protection, the endosymbionts produce energy for the coral, enabling it to grow. Corals are able to host a number of different algae species, but this may be less beneficial than we would assume.
Researchers have gathered samples from Moorea, French Polynesia, and have used DNA analysis to identify the different types of algae present in the corals — some of which host just one species, and some of which host many. What they found was that those with just one species were far more resistant to environmental changes than those with multiples.
"The corals we sampled spanned a range of environmental sensitivities from resistant to susceptible, and we were able to link, for the first time, patterns in environmental performance of corals to the number and variety of symbionts they host," said lead author Hollie Putnam in a release. "This is exactly the opposite of what we expected...our findings suggest more is not always better."
With rapid climate change causing horrific damage to the reef systems, it may be the more specialized ones that survive, not the more diverse.
Image copyright Hollie Putnam