Emergency Response to Mass Coral Bleaching

Christmas Island, Kiribati experienced mass coral bleaching in 2015-16 due to extremely hot waters due to a strong El Nino event super-imposed onto increased temperatures due to climate change. This is the first time in recorded history that a coral reef has experienced such hot water for such long a time. My last report in June, found that >99.9% of all branching corals are dead. This level of coral death due to bleaching is perhaps a first globally for an entire coral reef system. Extensive searching of the lagoon and shallow outer reef slope found expanses of dead corals, with only a few partially alive massive corals remaining, most with only patches of live tissue.The inner lagoon was hit particularly hard, with virtually all corals dying, while the best parts of the outer reef slope and outer lagoon had a maximum 20% survival of the massive corals but no branching corals surviving.  Branching corals are the most important for fish habitiat, so the ecosystem has been badly damaged.

In three days of searching with help from the Fisheries department, we eventually did find two branching Acropora corals: one 20cm colony which was a small remnant of a much larger adult colony that had died, and one was a small 5cm juvenile.  Four surviving branching Pocillopora colonies were also located. These corals were trimmed and branches brought into a nursery, designed to protect them from coral-killing snails and COTS.

This report focuses on my second visit, which took place 2-9th November 2016. The corals in the nursery were found to be thriving and growing. Other than cleaning some hydroids from the nursery table, the nursery required no maintenance after four months, due to the high numbers of herbivorous fish in the site. 

Additional searching for corals was done and we were very excited to find numerous juvenile Acropora corals that were too small to notice in June: three near the coral nursery, 47 in an enclosed reef bay, 11 on the reef slope located in 3 M of water at the top of reef spurs, 14 on the reef crest, and one on the reef flat at Crystal Beach.  These 76 juvenile corals represent the beginning of natural recovery and so we are very encouraged. While it is difficult or impossible to assign a species name to the juvenile corals at this stage, many of them are obviously different species, somewhere between 3-7 species. Within a year, the new corals will have grown to the size of grapefruits, and at which point taxonomic identification will be possible, as well as trimming to bring fragments of each into the coral nursey. This is very exciting development, as we should now have more than two genetically unique individuals within many of the branching Acropora species, which is required for successful spawning- to produce coral larvae, which can then settle out to grow into new colonies- in time leading to coral population recovery through natural processes.    

But without any adult corals surviving, where did these juvenile corals come from?  I believe that they must have come in from Fanning Atoll, which is 300km uncurrent. Their 3-5cm size indicates that the corals are about a year to 18 months old, settling out during the mass bleaching, and acquiring their symbiotic algae, and then somehow surviving the hot water. 

The corals are presently too small to move into the nursery, and so unfortunately they are quite vulerable to predators: drupella snails, crown of thorns starfish, and parrotfish, all of which are known to prefer Acropora corals in their diet.  While relocating the corals into the protected nursery is important it was not possible.  In another six months the corals will become large enough for branches to be trimmed for collection- so a return trip is planned for June, if the funds can be raised. We have hopes that these new corals are bleaching resistant "super corals", and a promnent coral scientist is willing to test samples of the corals for us, to see if they are harbor the bleaching resistant algae or not, so we plan to take small samples for testing next year. 

On our next trip, we plan to collect samples of all the new corals, to plant in an expanded coral nursery.  This will serve as a gene bank of all the Acropora species surviving the mass bleaching: a “Noaks ark” of bleaching resistant corals for the restoration of the reefs of Kiritimati. 

Severe bleaching can be expected to return to Christmas Island in the coming years due to rapidly changing climate and global warming. However, the corals that have survived the last hot water bleaching event can be assumed to be bleaching resistant, offering some hope that adaptation is occurring.  We will confirm that, and then replant populations of the bleaching resistant corals, which will then spread into the environment and restore the reefs through natural larval production and recruitment processes.  So the next mass bleaching should leave the reefs in a much less damaged position, and with many more unbleached corals. 

This work offers some hope that we can help coral reefs survive into the future, in spite of the severe challenges of climate change. Restored and bleaching resistant coral reefs will in turn help secure the ecological, food security, and livelihood services that this precious ecosystem provides to the peoples of Kiribati and the world.  

Because this restoration work is so important to the future of the reefs of Kiribati, is very important to set aside the main restoration reefs into a no-fishing marine protected area (MPA), to strictly limit the number of people visiting the sites and placing fishing lines, nets, or stepping on the reefs, as this will break the regenerating corals. We also need a high density of grazing fish to clean the nurseries and the dead corals, so that living corals thrive and so that once coral larvae are generated through spawning of restored coral populations, they can find a clean place to settle out on and grow. With this strategy in mind, the Director of Fisheries took me to meet key people in government: the Ministry of the Line Islands and the local Christmas Island council, both of who were not yet aware that the coral reef had died.  I stressed the importance of actions to protect the coral reefs and the importance of fast tracking the establishment of the marine reserve that had formerly been proposed by Fisheries, and where we have placed the coral nursery and where we plan to establish the initial restoration sites.      

Christmas Island is a very large Atoll, and millions of corals have perished in the recent mass bleaching event, therefore it will be impossible to replant corals everywhere on the island’s damaged coral reefs. This is not our strategy, rather the “Reefs of Hope” strategy is to help facilitate natural coral recovery process. Firstly we will cultivate as much of the genetic diversity as possible within the nurseries, and then we will use trimmed second generation branches to create genetically diverse patches of spawning corals at intervals along the wider reef, to reseed the reefs naturally with larvae.  Certainly more colonies and additional species will be found in time, and pairing those surviving corals with others of the same species will help ensure effective spawning.  Our long-term goal is to have the coral nursery eventually expand to include hundreds of distinct genotypes, of each surviving Acropora and Pocillopora species. 

The work on Christmas Island goes beyond the simple recovery of this remote atoll’s reefs, rather if we can establish the effectiveness of this program on Christmas Island, it would be vastly relevant to all coral reefs of the planet, facing an uncertain future in a rapidly changing world. What better place to start this pioneering climate change adaptation work? 

As the work thus far has been entirely based on volunteerism, what is most important at this time is to identify funding for continuing and expanding this vital and unique program. The work should ideally expand to include more extensive reef surveys on all parts pf the island, to try to identify more of the surviving corals, the monitoring of restoration patches, genetic testing of corals and their symbionts, increased and intensifying nursery work, awareness raising work within the communities, nation, and region, as well as work to secure the no-take status of Cook Islet Conservation Area as a special and sensitive restoration area of critical importance to the larger coral reef system and the nation of Kiribati.  

Funding for travel was provided by donations through Global Giving, while boats, fuel, nursery materials, and staff were provided by the Kiribati Fisheries Department, kindly facilitated by Mr. Taratau Kirata, Chief Fisheries Officer.  Accommodation was kindly provided by Ereti Tekabwaia through the Tekabwaia lodge.

Coral reefs are the most sensitive ecosystem to climate change and are predicted to be the first ecosystem to collapse due to climate change and the associated increasing temperatures and altered water chemistry.  If we can save the coral reefs we can then save the planet, but if the corals go, geological processes and entire economies and societies will also go with them. And then which system will be next? Coral reefs must become the front-line in saving the planet, and where we must now take our stand. Christmas Island in Kiribati has become the leading edge of this battle front.

Thank you so much for yor contined support! 

Austin

I visited Christmas Island, Kiribati from 8- 15 June 2016 at the request of Mr. Taratau Kirata, head of the Government Fisheries Department for the Line Islands, Kiribati. The purpose of the trip was to assess the condition of the reefs after the major warm-water coral bleaching that had hit the reefs in 2015-2016 during the severe El Nino weather event and to investigate the need for restoration of the coral populations.

Christmas Island (spelled Kiritimati and pronounced Ki-ri-si-mas), is the largest of the Line Islands, which is composed of nine islands or Atolls, three of which are US dependencies (Jarvis, Kingman and Palmyra), the rest belong to the island nation of Kiribati (pronounced Ki-ri-bas). The islands run Northwest-Southeast, with Christmas Island being the Southern most of the group.  Christmas Island, with a population of some 7,000 people, has the largest land area of any atoll on the planet (>400km²), about half the total land area for the nation of Kiribati.  The island is out of the cyclone belt, being very close to the equator, but is in a vulnerable area for repeating El Nino events.  Formerly Christmas Island had the highest coral cover and highest coral diversity of the Central Pacific, but the present disaster has severely impacted the island and has changed that status.

Christmas Island was in the center of the 2015-2016 global mass bleaching crisis, impacted by the strongest and most prolonged El Nino weather condition ever recorded. By June 2016 the bleaching had passed, and the bleached corals had mostly died, with very few recovering. An estimated 80-90% of massive and lobate corals have died on outer reefs, an estimated 98% of all corals are dead in the lagoon areas, and virtually all (~99.99%) branching corals are now gone overall.  This loss will undoubtedly have major ecological consequences over time, as the branching Acropora and Pocillopora corals are vital as habitat for small planktonivorous and post-larval reef fish. 

We searched extensively for three days in both inner lagoon and outer lagoon areas, reef front, and passes, over shallow dead former Acropora dominated zones of the shallow fore reef zone and the formerly staghorn coral dominated mid and inner lagoon, and we could find absolutely none of these corals alive. 

The corals of the inner lagoon certainly must have formerly been adapted to very hot water, but this event must have gone way over that threshold. In hindsight, if some of these thermally adapted corals had been moved from the hottest inner lagoon to the cooler outer lagoon, they might have survived this bleaching event unscathed. This is a possible lesson learned for other reefs preparing for unprecedented heat stress levels; to move the thermally adapted corals into less heat stressed waters, so that the bleaching resistant corals have a chance of surviving and passing on their superior qualities to help reefs adapt into the future, rather than allowing them to cook to death within enclosed lagoons, where under normal conditions only the strongest of the strong can survive.  

With the thought that the former populations of thermally tolerant corals of the inner lagoon might have already produced larvae that carried the traits for tolerance, and that these heat tolerant larvae might have settled in areas of less thermal stress, I began searching the cooler shallow reefs between the lagoon and the ocean, in the hope that some progeny of the exceptionally tolerant corals had settled and grown in that area of somewhat less stress and had therefore survived the mass bleaching. With this strategy, we did finally find a few surviving corals near the pass at Cook Islet. 

Pocillopora formerly dominated the outer lagoon reefs, with some colonies as big as a minivan, but we could find none of the species alive in the main outer lagoon area.  We finally found four Pocillopora colonies alive in shallow areas in the South pass; three very healthy colonies, and one half dead and still partially bleached colony, all of these corals were surrounded by dead corals of the same and other species.  This helps verify my hypothesis that the pass area remained cool enough for the few super tolerant corals which carry the resistance of their parents, while the same heat levels killed off all corals that were adapted to the cooler waters normally found there.  

In a 1M deep enclosed lagoon pool adjacent to shore at the Cook Islet Conservation Area, we found two small living branches of Acropora, part of a much larger dead colony.  We also found a 10cm, bright blue, juvenile Acropora coral in the adjacent enclosed bay, again near shore in an area that would be heat stressed during normal years. This coral must have recruited during or right before the mass bleaching.    

We were greatly relieved that the notorious coral-killing crown of thorns starfish were not seen, neither were the coralivorous Drupela snails.  However coral predation is a continuing concern.  After the 2000 mass bleaching in southern Fiji, coral predators succeeded in killing off virtually all of the surviving bleaching resistant corals within months.  The danger is that the major coral predators much prefer the branching Acropora and Pocillopora corals, but they can survive on the less favorable massive coral species when their preferred coral prey species are gone.

We set up a coral nursery in the area of the South pass, in a shallow (2 meters deep) area adjacent Cook Islet and within the no-take conservation zone, near where we had found the few surviving branchingcorals. We trimmed and planted branches from the wild corals and we were also able to pick up the rock that the juvenile Acropora had settled onto and bring that into the nursery.  We established four genotypes of Pocillopora, and one genotype each of two species of Acropora in the nursery.  The coral nursery is in an ideal area for observation and monitoring over time, has good water circulation so that it is ideal for coral growth, is well protected from storm surge, is predator resistant by design, and the area has a large population of grazing fish to keep it cleaned of algae.

Unless more Acropora and Pocillopora individuals can be found, there is very little hope of recovery of the branching corals on Christmas Island, as survivors will be too far from others of their species for successful spawning, and as no coral reefs exist up-current of Christmas Island.  Local extinction of several species of branching corals has most likely already occurred, but much more work is needed before drawing that conclusion.  Certainly if nothing is done to intervene, the possibility of recovery of the branching species appears to be quite bleak, in particular for the Acropora species.  Fanning Atoll is the nearest reef to Kiritimati, and although a few hundred kilometers up-current, is near enough to be considered the same ecoregion for restoration purposes.  No assessment has yet been done for Fanning Atoll.

What is needed now is a systematic project to search more systematically on Kiritimati and Fanning Atolls, with the goal of finding more surviving colonies of branching corals. These colonies should be marked with GPS for monitoring over time, and branches should be trimmed for inclusion in nurseries, which in time would become gene banks for recovery.  The goal would then be to propagate these corals into large “mother” colonies of each of the surviving species, to re-trim these corals twice annually in order to propagate many colonies of each coral genotype of each species and then to replant them back to restoration patches located on the reef.  The challenge would be to find at least two genotypes of each species, so that sexual reproduction, through successful spawning, can eventually be re-established. The end goal of the coral nursery work would be to establish genetically diverse patches of each coral species at key positions on the reef, so that coral larvae are once more produced in large numbers, restoring the natural process by which coral reefs recover.  It is impractical to replant large areas of reef, and really no need, once sexual reproduction is restored.

The proposed coral gardening strategy is a strategy that has potential to bring the branching coral species that have survived back from the brink of local extinction. We should go forward with a sense of urgency, realizing that all corals that have survived are in fact genetic treasures- they are “super corals”, proven by this crisis to be bleaching tolerant in hot water. These corals offer a thin ray of hope in the face of climate change, and they must be nurtured and protected, otherwise the coral reef is unlikely to recover to its pre-bleached condition- ever.  Urgent action is therefore needed for the conservation, propagation, and restoration of the bleaching resistant corals. 

If there is a positive side to this crisis, we now have a heightened level of community awareness that something is very wrong in the environment, especially among commercial and subsistence fishers in Kiribati, with the entire nation experiencing mass die off of corals, and so we have an excellent opportunity to educate communities to the impacts of climate change and sea level rise.

Communities should become involved at this stage, as the best way to urgently find the surviving corals would be to involve the wider community in searching for the branching corals during their fishing activities; to mark them with a small plastic bottle buoy, so that samples can be later taken and incorporated into the coral nursery by trained Fisheries staff. Additional involvement of community volunteers should also take place during the outplanting phase which would begin about two years later.

Funding for a major project is needed, and for at least five years if possible. Reports indicate that the main islands of Kiribati have also been badly affected by severe bleaching and coral death, so the project should become a national level one if at all possible.  Other affected island nations, such as Samoa, the Marianas, FSM, and Palau, where severe bleaching is presently occurring, might also want to be included in a regional project. 

This proposed strategy of bringing branching corals back from the brink of local extinction has already been effectively carried out in Belize, where bleaching and disease wiped out virtually all of the Acropora corals on the southern sector some ten years ago.  We successfully located the few surviving super corals, grew them within nurseries, and replanted them within the national park, restoring many acres, with over 60 thousand second and third generation corals replanted, restoring natural reproduction and recruitment processes in the wider reef system.  I have included a brief description of that work in an appendix at the end of the report.

A short report on our findings on Christmas Island has already been published in MPA News and has also been reported to the NOAA coral bleaching reporting network.

Acknowledgements:

Accommodation was kindly provided by Ereti Tekabwaia through the Tekabwaia lodge. Boat, fuel, nursery materials, and staff were provided by the Kiribati Fisheries Department.

• MPA News report on the Kiribati Project (DOC)