Scientists Offer A Glimmer of Hope With Strategies For Saving Coral Reefs

Coral reef die-off is expected to continue, and to get worse

Aptly named, black band disease is slowly but steadily killing this brain coral specimen.

Coral researchers expect that coral bleaching and die-off will continue and in fact, will get even worse in coming years due to a variety of reasons including pollution and overfishing, which have been increasing for decades, and stressors such as warming oceans, that are now reaching critical levels. Very few areas in the world have not seen coral death due to the stress of increased ocean temperatures. For example, the northeastern Caribbean, including the US Virgin Islands, was impacted by coral bleaching due to unprecedented heat stress in 2005.  The USVI lost about half of its shallow water coral cover. Events such as this are expected to get worse.

Last fall, the National Academies of Science, Engineering, and Medicine Ocean Studies Board.  (NASEM) appointed members of the scientific community to participate in the study “Interventions to Increase the Resilience of Coral Reefs”. Dr. Tyler Smith, Associate Research Professor of Marine Science at the University of the Virgin Islands (UVI) and a key partner on VI-EPSCoR’s Coral Reef Research team, was one of only twelve scientists invited to provide his expert opinion on the different ways humans can intervene to save coral reefs.

Dr. Tyler Smith, seen above at the Magens Bay Arboretum, is the first faculty from UVI to serve on a NASEM consensus study. His appointment to the committee is a great honor. Photo: Kristin Wilson Grimes.

Smith is the first faculty from UVI to serve on a NASEM consensus study and considers it quite an honor.

“The first major thing that I learned was just how little time we have and how serious climate change is for humanity” said Smith, “Reducing our global carbon emissions now should be the number one priority for humanity, as we only have a few more years before much of the change is irreversible. We also will need to intervene to support coral reefs, even if we can get a handle of greenhouse gas emission, because of committed warming from previous emissions.  Corals are already showing mass global bleaching and we have a lot more warming ahead on top of what has occurred.”

This study was conducted at the request of the National Oceanic and Atmospheric Administration, with support from the Paul G. Allen Family Foundation.

Coral Reef Interventions Can Help…Maybe

The group conceived 23 potential interventions which could be used now or in the future to support coral reefs as global warming continues to increase.  The proposed interventions “affect the genetics, reproduction, physiology, ecology, or local environment of corals or coral populations with the goal of enhancing their persistence and resilience.” (NASEM 2019). Smith was particularly involved in summarizing environmental interventions, such as cloud brightening which can reduce sunlight over coral reefs, reducing water temperatures and decreasing light stress.  

Equally vital was a second report which looked at the risks and benefits of different interventions as compared to no intervention at all. The report also suggested areas of future research, and conducted a case study of interventions in Caribbean coral reefs to tease apart issues in one of the more degraded coral reef regions of the world. Smith was particularly involved in the latter chapter, applying his expertise in Caribbean coral reef ecosystems and coral thermal stress.

These two reports from the NASEM committee lay the foundation for active intervention to support the persistence of coral reefs.   

The funding of the study indicates how seriously the United States is taking the problem of understanding how coral reefs might be saved from ocean warming. Therefore, it is likely that coral reef interventions will soon be available for use in the USVI to support the survival of coral reefs in the face of thermal stress, disease, pollution, and ecological change.  This will boost existing coral restoration strategies to, among other things, provide coral stocks that are more resistant to thermal stress.  

But, Consider the Risks

There are a variety risks, however, that must be assessed before we manipulate natural coral reef ecosystems.  There are risks that might come from moving corals from one region to another, manipulating genetics, favoring certain coral genotypes over others, and so on.  These risks must be evaluated in the local context of the USVI to see if the benefits are greater than the risk.  Also, since coral larvae travel on ocean currents, any intervention must also take into account our neighbors in the highly interconnected Caribbean island chain. 

It is equally critical that interventions be put in place to reduce some of the local stressors that limit coral resistance and slow recovery after a disturbance.  These resilience factors must be in place or any intervention will be doomed to failure.  It is exactly understanding these resilience factors for coral reefs that will be a major focus of the Virgin Islands Established Program to Stimulate Competitive Research next funding request to the National Science Foundation. Thus, the USVI will be at the forefront of protecting coral reefs in a rapidly changing world and will be a leader in establishing the research and management protocols for decades.

Coral Nurseries Can Help
One strategy for supporting coral reefs is to grow fragments in in-water nurseries. The fragments may be out planted at select locations once they have grown to a certain size. Seen here, Allie Durdall, MSc and Master of Marine and Environmental Studies candidate Brad Arrington clean algae off baby corals at the Flat Cay nursery. Photo credit: Marilyn Brandt, Ph.D.

Branching Corals Grow Quickly
Branching corals which play an important role in mitigating storm surge and provide essential habitat for juvenile fish grow quickly in the nursery. Photo credit: Rossie Ennis

Coral Trees
This barracuda cooly swims by a “coral tree” where coral fragments are grown. Maintaining the baby corals is labor intensive. If you are interested in participating in this effort, visit the VI Reef Response page here. Photo credit: Marilyn Brandt, Ph.D.

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Outplanting
Once they have grown to several inches in length, the corals are out planted onto the reef. This is just one of the twenty-three strategies proposed to support the stressed reef ecosystem. Photo credit: Rossie Ennis

About NASEM

An ad hoc study committee will be assembled to review the science and assess potential risks and benefits of ecological and genetic interventions that have potential to enhance the recovery and persistence of coral reefs threatened by rapidly deteriorating environmental conditions that are warmer, less favorable for calcification, have impaired water quality, and pose continuing disease threats. Given these environmental conditions, the committee will consider interventions to address near- future (e.g., 5-20 years) and long-term environmental scenarios as part of an overall risk assessment in an ecosystem context. The coral intervention strategies will be assessed with regard to the goal of increasing the long-term persistence and resilience of tropical coral reefs and their ecological functions. 

About Dr. Smith (from the NASEM website)

Tyler Smith is a research associate professor of marine biology at the Center for Marine and Environmental Studies at the University of the Virgin Islands. His research interests include coral reef refuges and refugia from chronic and acute disturbance, mechanisms of resistance and recovery of coral reef ecosystems to natural and anthropogenic disturbance, coral-algal-herbivore interactions across seascapes, and biophysical processes controlling coral reef ecology. Since 2005, he has been the Coordinator for Research for the U.S. Virgin Islands Coral Reef Monitoring Program. He received his BS in marine biology from Western Washington University and his PhD in coral reef ecology from the University of Miami.