Discovery of vast coral diversity could change conservation efforts

According to researchers from Boston University, the University of Rhode Island (URI) and the Woods Hole Oceanographic Institute (WHOI), there may be many more species of coral than we think. never imagined, and they could change our approach to coral reef conservation and restoration. efforts around the world.

Sarah W. Davies, assistant professor of biology, along with postdocs Carsten GB Grupstra and Hannah E. Aichelman, James Fifer, and a team of researchers from URI and WHOI say they have found evidence of at least 24 examples in the world where corals with similar appearances live on the same reef, but have different DNA.

What’s important, they say, is that some corals with “cryptic lineages” – structurally similar but genetically distinct – may be able to withstand higher water temperatures and thus have better survival rates in warming waters. This has important implications as scientists work to conserve and restore coral reefs in light of climate change.

“It’s a game changer. It changes the way we think about our systems. It changes the way we think about coral adaptation and conservation,” said Davies, who has studied cryptic corals in the Caribbean and in the waters off Palau, an island. Western Pacific countries. “This puts an end to what we actually know and opens a can of worms.”

The researchers published their findings in Perspective on February 13 in Ecology and evolution of nature entitled “Integrating cryptic diversity into coral evolution, symbiosis and conservation”.

Corals are animals that harbor algae and communities of bacteria living in their cells. Tropical corals depend on photosynthesis carried out by algae for their nutrients. When temperatures get too high, photosynthesis is interrupted. The corals can then expel the algae, or the algae dies, and the corals lose their primary means of obtaining nutrients. This loss of algae and nutrients causes corals to turn white – called bleaching – and the coral may begin to die.

When scientists examine thermal tolerance in response to climate change, they look at corals, algae and bacteria. Often, cryptic lineages have different types of algae and bacteria, and these algae and bacteria may respond differently to warming waters. New DNA sequencing efforts in the lab of Davies and others have uncovered ample evidence of “cryptic lineages” that might otherwise have been overlooked.

“We find this enigmatic coral diversity on reefs around the world, and we find that when we can compare how these corals behave in the face of a climate change stressor, we find that they tend to respond differently ” said Aichelman. “We think this has big implications for how we think about biodiversity on reefs and how different reefs might be as a result of climate change.”

As part of efforts to stem climate change, restoration projects are underway to take corals from one area of ​​the ocean and move them to another. With this new discovery, Davies and his colleagues fear that conservation efforts may mistake different types of corals for the same ones based on their appearance and thus fail to save certain lineages of the species.

“It’s not that people didn’t notice it; they misinterpreted the meaning of this pattern,” Davies said. “There is a lot of genetic variation that we are just beginning to discover. The presence of such diversity is exciting, but at the same time we could lose species that we didn’t even know existed. That’s what makes fear. “

Scientists still don’t understand why these enigmatic lineages exist, or where they came from, but they know they could hold another key to fighting climate change. The next step for researchers is to find tools to better identify cryptic features in the field without DNA sequences, tools that coral reef conservation and restoration workers could use when working in the field .

“We need to do a lot more work on these cryptic corals,” Grupstra said. “By studying corals, we can learn a lot about ourselves, our environment and other animals. They are such fragile organisms, and yet they have been so successful. They create fantastic ecosystems that have survived for so long. “It’s the building block of these little animals. And we cannot ignore diversity.”