The world’s coral reefs are under threat as never before. Ocean warming, acidification, rising sea levels are all having a profound effect on the viability of our coral reef ecosystems. Just in the last several years we have witnessed Australia’s Great Barrier Reef loosing possibly 50% of its coral and a similar crisis is unfolding for reefs throughout the coral triangle; the Sea of Japan, the South China Sea and the Caribbean.
Can We Reverse the Tide of Coral Reef Decline?
A series of questions were asked in a recent Nexus interview with Diego Lirman, a marine biologist with the University of Miami Rosenstiel School. Here are his answers from Gardening the Sea. to save the World’s Coral. (photo – Rescue-A-Reef, UM Rosenstiel School of Marine and Atmospheric Science)
What is killing coral? –
There are many different factors impacting the health of coral reefs today. “Changes in temperature, more temperature extremes, acidification of the water, changes in storm frequency and sea level rise— all…combine to cause coral mortality.”
Faced with all these threats, can coral reef restoration possibly work?
In the past coral restoration has been done as a response to a singular, destructive event like a ship running aground. The recent Cruise Ship that caused major damage to reefs in Raja Ampat is an example.
“But as global conditions decline for coral reefs, there’s now a need to scale up…we need other tools at larger scales, and that’s where coral reef gardening has come into play…we’re growing and planting these organisms.” (photo – Rescue-A-Reef, UM Rosenstiel School of Marine and Atmospheric Science)
Is there concern that planted coral will dominate the reefs?
“The genus that we’re focusing on, Acropora, is threatened, so these are very important reef-building species…when abundant, they monopolize shallow environments. They form thickets, extensive areas of high-density colonies. That’s the way they used to grow, until about three to four decades ago when they got wiped out by disease and other factors. The branching corals that we’re working with grow between 10 and 15 cm per branch per year, so that’s very fast growth.”
“Mote Marine Lab has developed microfragmentation techniques where they can cut coral colonies very, very small and make them grow very, very fast.”
Consequently, although we “focused on branching corals initially, now most of the programs, especially in Florida, are expanding to other threatened species.” (photo – Rescue-A-Reef, UM Rosenstiel School of Marine and Atmospheric Science)
Are these aquaculture techniques simply buying time?
“You hit the nail on the head. One of the early criticisms of reef restoration was the scale issue and spending a lot of resources working on a very small footprint.” but over the last decade we have expanded to where we are growing and planting thousands and thousands of corals – so the issue of scale is no longer a valid criticism.”
Are you planting corals in the same environments that originally killed them off?
“The other major criticism is that, even though we’re planting a lot of corals, we’re planting them onto environments where the same stressors that caused their initial mortality are in place.” Factors like ocean acidification and increased temperatures, have gotten, progressively worse.
“We’re doing a lot of genomics work to see how corals can increase their resilience. A colleague of mine here at the Rosenstiel School at University of Miami, Andrew Baker, is stress-hardening corals. He works on coral symbiosis, and he found that by applying a little bit of non-lethal stress, he can make corals shuffle their Zooxanthellae” in layman terms it means making the coral more heat tolerant, “you may be able to buy these corals one or two degrees of tolerance, so that they become more resilient to bleaching in future years. That is cutting-edge science.”
“We’re trying to actually find out what makes corals survive, and trying to beef up their defenses and their resilience over time.” That’s made possible because “we have access to all these coral genotypes through the active propagation from coral gardening.” (photo – Rescue-A-Reef, UM Rosenstiel School of Marine and Atmospheric Science)
Combine these efforts with “setting up marine protected areas to protect fish stocks and coral impacts, working to curb land-based sources of pollution, and setting up sedimentation and nutrient controls. And then, on a much larger scale, we’re all trying to curb carbon emissions, trying to limit the greenhouse impacts and acidification impacts. All these tools just help us buy time.”
by Robert Frerck, Blue Ocean Network
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