In late 2015 the National Oceanic and Atmospheric Administration declared that we are in the third global coral bleaching event. The previous global coral bleaching event occurred in 2010, due to ocean warming triggered by El Niño.

This latest coral bleaching already has been deemed the longest on record, affecting not only reefs in Hawaii but also in the Caribbean, Puerto Rico, Kiribati and potentially the Republic of the Marshall Islands, among other places.

In Australia alone, some scientists estimate that 1,000 kilometers (620 miles) of the Great Barrier Reef face a major bleaching event. Bleaching occurs when stressed corals eject the symbiotic micro-algae they rely on for nutrition. An extended event can kill the coral. If you factor in ocean acidification due to the the increase of atmospheric carbon dioxide, these additional stresses are catastrophic to corals.

Corals on a patch of reef in Kaneohe Bay, during a temperature induced bleaching event in 2014, show the variation in the health of members of the same coral species (Porites compressa) sitting side by side on the reef. One colony is completely bleached white and very unhealthy, the one right to it is dark brown and healthy.

Corals on a patch of reef in Kaneohe Bay, during a temperature-induced bleaching event in 2014, show the variation in the health of members of the same coral species (Porites compressa) growing side by side. One colony is completely bleached white, while the adjacent one is dark brown and healthy.

Raphael Ritson-Williams

One person who recognized and felt compelled to do something about this growing threat: Dr. Ruth Gates, director of the University of Hawaii’s Hawaii Institute of Marine Biology, located on Moku o Lo‘e, also known as Coconut Island, in Kaneohe Bay.

For the last 25 years Gates has been studying coral reefs. In 2013, she and her team from Hawaii, along with Dr. Madeleine van Oppen from the Australian Institute of Marine Science, were awarded $10,000 by the Paul G. Allen Ocean Challenge. They were among a select group of finalists to submit proposals to address the environmental impacts of ocean acidification.

Then, in 2015, Gates and her team were awarded $4 million by the Paul G. Allen Family Foundation to discover ways coral can become more resilient in the rapidly changing coastal environments. Their goal was to build a toolkit of ways corals would have a fighting chance against the warming and acidification of the ocean. 

“Corals are in decline,” said Gates. “And that decline seems to be outpacing the intrinsic capacity for the system to respond and adapt. So what we are doing is accelerating the rate at which corals do things naturally. Based on what we know, we can assist the evolution of coral. This is what we call assisted evolution.”

Closeup view showing the anatomy of a coral (Pocillopora damicornis). The red is the millions of micro algae inside the animal tissues, the blue are batteries of stinging cells called nematocysts and the green is a protein that is found in the coral animal tissue. The living coral is visualized using a scanning laser confocal microscope under UV light.

Closeup view showing the anatomy of a coral (Pocillopora damicornis). The red is the millions of micro algae inside the animal tissues; the blue are batteries of stinging cells called nematocysts;and the green is a protein found in the coral animal tissue. The living coral is visualized using a scanning laser confocal microscope under UV light.

Amy Eggers

Corals are complex organisms. Reef building corals have a symbiotic relationship with photosynthesizing micro-algae that live inside the coral’s tissues. In this relationship, the coral provides a protected environment; and in return, the micro-algae use photosynthesis to provide the coral with food and oxygen.

When corals get stressed, the relationship between the coral and its micro-algal symbiont goes out of equilibrium, causing the the coral to starve and turn that distinctive white color. Global conditions such as climate change and El Niño are causing ocean waters to rise in temperature, throwing the coral’s sensitive equilibrium out of balance.

You can observe that right here in Kaneohe Bay, where the corals have been stressed due to warming temperatures, raw sewage effluent, over fishing and sediment runoff. Despite these effects, you will still find healthy corals right next to ones that are bleached and dead. Gates observed that in many cases, some reefs do better than others. Just within Kaneohe Bay there is an enormous variation in the response within individual species of coral.

With the Paul Allen grant, Gates and her team are taking a bold approach to maximize on the strengths of the corals that exhibit the most resilience to these stresses. Some corals and their micro-algal symbionts are stronger than others. Gates aims to explore three areas:

• Induced acclimatization: This strategy intentionally subjects corals to stress levels to see if they can become more resistance to change. By applying repeated variations in temperature, the corals could build up their stamina and be better equipped to survive warming trends in the wild.

• Selective breeding: In this approach, corals that have survived a bleaching event are bred to perpetuate their  genes, in the hope that these corals’ genetic makeup may enable them to survive warmer temperatures and more acidic waters. These samples are bred to see if the resilient traits are carried forward to the offspring.

• Modification of symbionts: This idea focuses on studying the micro-algal symbionts and to promote the survival of the coral by determining which algae feed their hosts better or which are more temperature tolerant. By combining symbionts with coral hosts, experiments could show whether symbionts with particular traits can help the coral survive more readily.

TheHawaii Institute of Marine Biology, part of the University of Hawaii, is located on Moku o Loʻe, or Coconut Island, in Kaneohe Bay.

The Hawaii Institute of Marine Biology, part of the University of Hawaii, is located on Moku o Loʻe, or Coconut Island, in Kaneohe Bay.

Joshua Levy

The project is relying, in effect, on selective breeding. It has drawn little scientific criticism. Some scientists have said we should leave the corals to cope naturally. But Gates argues that we have already lost 30 percent of the world’s reefs, and that the negative effects of warming and climate change are harming the reefs faster than they can recover on their own.

The goal of the five-year project is to develop a toolkit of what works and what doesn’t work. Gates emphasized that they are in a proof-of-concept phase and aren’t anywhere near implementing any coral restoration.

“We have nothing to lose by doing the proof of concept,” Gates said. “The question of whether we implement restoration projects using these corals is a conversation we need to develop over time. We need to understand how we might implement and design projects in collaboration with a much broader group of people.”

“We are not at the time when we are thinking of how to use them (corals). We are at the time when we are deciding whether we can do it. Even if we are able to mitigate fossil fuel burning and start to protect coral in their place, we need to somehow stop and stabilize the downward trajectory and get the system to naturally reinvigorate.”

“But in lieu of that happening, to do nothing at this point is too risky, and will have adverse effects on the billions of dollars of economic value associated with the reef resources. And honestly, from the point of view of a researcher conducting basic science, if we fail at this experiment that’s okay. At least we tried.”

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