Scientists uncover coral adapted to global warming conditions

Transcript

Researchers in New Caledonia have uncovered a new type of coral ecosystem that may already be genetically adapted to global warming conditions. That's sparking fresh hope for the future survival of coral reefs.

Scientists from IRD, the French Institute for Research and Development in Noumea and the University of Technology in Sydney studied a mangrove area on the west coast of New Caledonia and found corals thriving in warm and acidic waters.  Associate Professor, David Sugget, spoke with Bridget Grace about the findings.  

David Sugget: When we've looked at mangrove coral populations in other sites before we find few species persisting.  What we found in New Caledonia totally blew us away, we saw almost 30 percent coral cover within the mangrove system, which is absolutely unprecedented.  In fact some reefs worldwide struggle to maintain 30 percent coral cover as a result of anthropogenic pressures, but within that coral cover there were at least 20 species of coral, and importantly a lot of the coral cover was dominated by branching species, so really architecturally complex.  And these are the species usually considered the most vulnerable to climate change stresses.  

Bridget Grace: Are these species that scientists haven't noticed before or have they recently been adapting to changing conditions?

DS: We think they just haven't been looked at before. I think the important thing to point out is that mangrove waters are pretty nasty, they're considered what we call black water.  So they don't transmit much light so it's really hard to see what's under the surface and mangroves are usually considered to be very muddy and just not hospitable to corals. What we're really surprised by when we look at these findings is that most fringing reefs have some element of mangroves bordering them so we actually think it's an entire ecosystem that corals have been populating worldwide that just simply hasn't been explored yet.  And we may have overlooked a really important source of genetic variance inherent to coral populations and perhaps how they've already adapted to survive extremes.  

BG: So this could mean that there are already coral species adapted to mangroves and can survive in these warm and acidic conditions?

DS: That's the critical part.  We've been frantically running experiments for the last decade on reef corals, subjecting them to pH and temperature stress that we think will be representative of the future and kind of what we've forgotten is that if we look hard enough in nature there are conditions and populations that are already adapted to these conditions.

BG: What are the wider implications of these findings in terms of global warming, is it sort of, that it's not doom for corals anymore?

DS: Well I think we have to be a little bit cautious with that point, and that's the optimistic view for sure, by looking at these populations it might paint the picture that corals aren't in trouble, that's absolutely not the case.  Corals worldwide are threatened by lots and lots of stress, not just climate change.  But what these findings give us is that populations can adapt over relatively rapid time scales, and we have a genetic resource available for considering reef resilience type management strategies.  As I said we've been casually exploring these mangrove systems for the last few years, but we've just never seen a thriving community.  And what was the really exciting part I guess is not only do we have this really broad coral carpet of coral cover and species diversity.  But actually when you get your eye in and look at the broader diversity they were sustaining really rich fish assemblages as well.  It's not just a coral population that we're seeing thriving in these waters but it's extending to the entire ecosystem.  It opens up so many new possibilities in terms of research and what we can do.

Associate Professor David Sugget is a Team Leader of the Coral Physiology Group at the Climate Change Cluster at the University of Technology Sydney.  He is also a ARC Future Fellow, funded by the Australian Research Council.