. Scientific Frontline: Identifying Better Ways to Save the World’s Reefs

Wednesday, October 13, 2021

Identifying Better Ways to Save the World’s Reefs

Scientists work to restore damaged coral reefs by
growing health fragments to transplant.
Photo: University of Konstanz/Anna Rolk.
In the race to save the world’s fragile corals from climate change and disease, USF Department of Integrative Biology Assistant Professor John Parkinson is among an international group of scientists looking for better ways to restore damaged reefs. In new research published Tuesday in the journal Nature Reviews Earth & Environment, the team makes its case for nature-based approaches that give coral colonies a boost in their fight to survive warming seas.

Led by the University of Konstanz in Germany, the team calls for the use of new technologies to identify, propagate, and even strengthen naturally resilient coral colonies, which can then be transplanted to threatened reefs. The systematic review evaluates several emerging methods that have been used to improve coral heat tolerance, scoring them in terms of risk, cost, and scalability. The objective of the project is to provide guidance on which interventions might most effectively extend the natural adaptive capacity of corals, the researchers said.

The race to save the world’s coral reefs is a high priority for conservationists: 30 percent of all marine biodiversity depends on reef ecosystems and more than one billion people rely on the reefs for sustaining fishing stocks, tourism, and a healthy marine environment. Even a small rise in ocean temperatures can cause coral “bleaching” – when corals expel the algae living in their tissues causing the coral to turn completely white – leaving the organisms more susceptible to disease and death.

Conservationists have attempted to restore damaged reefs by planting fragments of nursery-grown corals, but the technique has only been marginally successful because those fragments often come from stock that is already near its thermal limit, the researchers said.

“For coral populations to survive, they can’t just keep doing what they’ve done in the past—they need to evolve,” said Parkinson, whose lab focuses on genomic techniques to examine the ecology and evolution of coral-algal symbioses. “Fortunately, we now have methods at our disposal that can help corals help themselves by speeding up adaptive processes.”

For example, conservationists might prioritize transplanting fragments from select coral colonies which have remained resistant in the face of climate change. In a separate work, members of the team developed a rapid thermal stress test (CBASS: Coral Bleaching Automated Stress System) to compare the heat resistance of coral colonies in the field. An initial trial in the Red Sea identified a large natural variation of very resistant and very susceptible colonies even within the same reef, allowing for targeted selection of desirable corals for nursery stock.

Additionally, the algal species that associate with corals also have different levels of stress tolerance. Conservationists might increase reef health by seeding coral larvae with the most resilient algal species. It’s the algae which provide much of the energy corals use for daily functions and growth, and without them reefs cannot grow to be productive or vibrant habitats for other marine organisms.

The team also identified environmental conditioning as a useful method for “priming” coral resilience. After introducing coral larvae and juveniles to low-level stressors in the lab, they grow to be better equipped at dealing with changing environments later in life.

The microbiome is yet another target for boosting coral survival. Just as scientists have discovered in humans, transferring beneficial bacteria from a resilient coral to a susceptible one can help improve the recipient’s health. A similar effect can be accomplished by administering a probiotic cocktail derived from a mix of cultured, beneficial bacteria extracted from particularly resistant colonies, the team said.

The researchers added that these techniques are better approaches than genetic modification of corals, which is expensive, slow, and may carry unknown long-term risks to the larger ecosystem.

The review also emphasizes the need for scientists worldwide to standardize coral conservation procedures. A global database of standardized experiments and results is already being developed, and will be analyzed through artificial intelligence and data science to pinpoint the most effective interventions.

“Unfortunately, it is too late for nature to heal itself,” said lead author Professor Christian Voolstra from the Department of Biology at the University of Konstanz. “Our objective is to make sure enough coral survive to assist in the long-term recovery of reef ecosystems, after climate neutrality is reached. It is up to our generation to identify the arsenal of nature-based adaptive approaches available and intervene accordingly where indicated.”

The research team included scientists from Australia, Saudi Arabia, England and Virginia, as well as Florida scientists from the University of Miami and Mote Marine Laboratory.

Source/Credit: University of South Florida


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