Coral Restoration using Larval Propagation in the Philippines & Australia

Coral growth on a reef in the Philippines after four years of the project. Photo @ Peter Harrison, Southern Cross University

Coral growth on a reef in the Philippines after four years of the project. Photo @ Peter Harrison, Southern Cross University

Listen to a new podcast interview with Dr. Peter Harrison, Director of the Marine Ecology Research Center at Southern Cross University about his mass larval propagation and restoration projects in the Philippines and Australia. We got a chance to sit down with Dr. Harrison during the Great Barrier Reef Restoration Symposium in Cairns, Australia and ask about the methods he’s used for restoration, what has led to success in his projects, and advice for managers and practitioners interested in starting restoration projects.

Listen to the interview

Interview Transcript
Reef Resilience (RR): Hi everyone! Today, Reef Resilience is interviewing Dr. Peter Harrison, Director of the Marine Ecology Research Center at Southern Cross University about his coral restoration efforts in the Indo-Pacific. Peter, can you briefly describe the coral restoration projects that you’ve done to date in the Philippines – for instance the kinds of methods you’ve used and partners that you’ve worked with to do this project?

Peter Harrison (PH): So what we’ve done so far is eight successful coral larval restoration projects, five in the Philippines and three on the Great Barrier Reef. In the Philippines we’ve been working for the last five years, and what we’re doing is capturing coral spawn from healthy corals, rearing it, and so we’re getting high rates of fertilization, lots of larval development, and raising millions of larvae each year. Then we’re putting those larvae directly back on the reef systems. So our work in larval propagation is a bit different to most other research groups around the world we’re focusing on trying to get the maximum success rates directly on the reef. The interesting thing about the Philippines is these are really highly degraded reef systems – they used to have spectacular coral cover – and with blast fishing over many decades, Crown-of-Thorns outbreaks, bleaching, typhoons, everything thrown at it, the the reef is now moribund and there is no natural recruitment happening at a scale that will help that reef recover naturally. So what we’re doing is catching the last remnants of the healthy populations, breeding millions of coral larvae, and putting them back on the reef, and we’re getting some fantastic results.

RR: That’s great. Actually, my question for you is about your results. Do you think these projects have been successful and what do you think has led to their success?

PH: The project outcomes have been fantastic, as good as we would’ve hoped given how bad these reef systems are, so it offers a little bit of hope for what might do in other regions around the world where really highly degraded reef systems have become the norm on what was really spectacular coral reef environments. So what we’ve done so far is we’ve used a range of different coral species, some fast growing Acropora and some slower growing brain corals, and among the fast growing corals we are getting spectacular results. We’re getting growth that’s occurring so quickly that we’re getting breeding initially after 3 years after the larval settled on the reef, so they’ve grown now up to a half meter in diameter – so really, really fast growth. This last year and a couple of years ago, we captured the spawn from the three corals that we’ve settled as larvae and have grown to breeding size and we put those larvae back into other parts of the reef. Surprisingly, we have even faster growth rates in the second generation of corals and we now have the world’s fastest growth to breeding age of any Acropora in the world, so we’ve got a world record. They’ve become breeding age and size at 2 years. So we’ve closed the life cycle directly on the reef for the first time within 2 years, and even highly degraded systems are amenable to this sort of work.

RR: So you have a lot of experience in this area and have done a lot of work, and I was wondering for our managers if you have any advice for new people that are starting in this field – managers or scientists or practitioners?

PH: Yes, there’s great opportunities. Each reef system is a little bit unique, the circumstances are unique, what sort of resources are available, what condition the reef is in, whether or not it’s still got three-dimensional structure that can provide habitats for coral larvae, if it’s been completely wiped out by major typhoons/cyclone impacts and is stripped bare, then you might need to think about some sort of three-dimensional structure coming back in with some fragmentation studies to slow the movement of water down to allow coral larvae in the future to increase in terms of recruitment. I guess the other key message is that we know that probably 95% of the so-called coral restoration projects have relied on fragmentation, and we’ve seen relatively few of those truly successful. The larger scale nursery processes, even though they are more expensive, that are working in the Caribbean with endangered Acropora species are a good example of how large-groups, really well-focused, thinking of this over multi-year programs, can actually come up with a meaningful increase in biomass. But we are still operating at small scale, and one of the advantages of the larval restoration approach is theoretically you can scale this up to much large scales than we are currently doing with asexual fragmentation and coral gardening approaches. We’ve got to two 100 meter square patches of reefs that we’ve been dealing with on the Great Barrier Reef and more recently back in the Philippines. My aim now is to build to a half hectare and then 1 hectare areas with this mass larval restoration process and hopefully in the future we’ll be operating at kilometer scales. When we are operating at kilometer scales, you’re really talking about reef restoration as opposed to smaller scale coral restoration.

RR: Well you’ve given us a lot to think about and provided a lot of great information, so thank you so much for sitting down with us today.

PH: You’re very welcome.

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Learning from Reef Restoration Experiences Around the World Webcast

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July 17, 2018

Broadcast live from the Great Barrier Reef Restoration Symposium in Cairns, Australia, experts from around the globe share lessons learned from years working on coral restoration. From offshore coral nurseries, to restoration mitigation techniques, to climate change adaptation, this presentation session seeks to foster knowledge sharing and exchange between managers and practitioners across the globe.

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The Use of Larvae or Recruits in Coral Restoration Initiatives: Symbiodinium Acquisition Does Not Differ Between Coral Life Stages in the Wild

Abstract: Active restoration initiatives are increasingly considered in natural resource management. Laboratory‐reared coral larvae and recruits have been proposed for stock production but it is unknown if their use impacts subsequent symbiosis once transplanted to the reef. We exposed laboratory and field settled aposymbiotic recruits (recently settled <1 month) to Symbiodinium in the wild, then analyzed the acquired communities using ITS‐2 sequencing. There was no significant difference between treatments based on overall community and diversity metrics, or differential abundance of individual taxa. These results suggest that early acquisition is analogous and thus supports the use of either life‐stage as an option for reef restoration.

Authors: K. M. Quigley, G. Torda, L. K. Bay

Year: 2018

View the article here

Restoration Ecology 26:

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Electrolysis, Halogen Oxidizing Agents and Reef Restoration

Abstract: Applications for electrolysis of seawater include preventing fouling in piping systems, conditioning water for aquaculture and reef restoration. Electrolysis creates a variety of chlorine-produced oxidants that attack essential proteins of living tissues and react with metals, other compounds (e.g., ammonia, nitrites) and organic materials (e.g., amines). The Biorock® process developed by Dr. T.J. Goreau and Dr. W. Hilbertz uses electrolysis for restoring reefs and enhancing growth and survival of corals. It is believed to act by elevating pH and alkalinity at the cathode and/or by reducing enzymatic costs for pumping cations and anions across cell membranes by providing an appropriate electrical gradient (Goreau, 2013). I hypothesize that a third mechanism for enhancing organisms may also be involved: inhibition of microorganisms by significant amounts of chlorine-produced oxidants arising from the anode. Applying Faraday’s laws of electrolysis for a system at 8.0 amperes and 90% efficiency gives an estimated evolution of ~230 grams of chlorine per day (equivalent to ~70 liters of gas at STP). In nature (i.e., an open system), diffuse follow-on reaction products (including hypochlorous acid, hypochlorite, hypobromous acid and hypobromite ion) may benefit macrobiota via inactivation of microbial pathogens and competitors, or by other improvements to water quality, as long as concentrations are too low to harm larger, ecotoxicologically less vulnerable organisms.

Authors: J. Koster
Year: 2018
View the thesis here

ResearchGate (Masters Thesis, UC Santa Cruz) 5:

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Time to Cash in on Positive Interactions for Coral Restoration

Abstract: Coral reefs are among the most biodiverse and productive ecosystems on Earth, and provide critical ecosystem services such as protein provisioning, coastal protection, and tourism revenue. Despite these benefits, coral reefs have been declining precipitously across the globe due to human impacts and climate change. Recent efforts to combat these declines are increasingly turning to restoration to help reseed corals and speed-up recovery processes. Coastal restoration theory and practice has historically favored transplanting designs that reduce potentially harmful negative species interactions, such as competition between transplants. However, recent research in salt marsh ecosystems has shown that shifting this theory to strategically incorporate positive interactions significantly enhances restoration yield with little additional cost or investment. Although some coral restoration efforts plant corals in protected areas in order to benefit from the facilitative effects of herbivores that reduce competitive macroalgae, little systematic effort has been made in coral restoration to identify the entire suite of positive interactions that could promote population enhancement efforts. Here, we highlight key positive species interactions that managers and restoration practitioners should utilize to facilitate the restoration of corals, including (i) trophic facilitation, (ii) mutualisms, (iii) long-distance facilitation, (iv) positive density-dependence, (v) positive legacy effects, and (vi) synergisms between biodiversity and ecosystem function. As live coral cover continues to decline and resources are limited to restore coral populations, innovative solutions that increase efficiency of restoration efforts will be critical to conserving and maintaining healthy coral reef ecosystems and the human communities that rely on them.

Authors: Shaver, E. C., and B. R. Silliman
Year: 2017
View the article here

PeerJ 5:

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Interspecific Hybridization May Provide Novel Opportunities for Coral Reef Restoration

Abstract: Climate change and other anthropogenic disturbances have created an era characterized by the inability of most ecosystems to maintain their original, pristine states, the Anthropocene. Investigating new and innovative strategies that may facilitate ecosystem restoration is thus becoming increasingly important, particularly for coral reefs around the globe which are deteriorating at an alarming rate. The Great Barrier Reef (GBR) lost half its coral cover between 1985 and 2012, and experienced back-to-back heat-induced mass bleaching events and high coral mortality in 2016 and 2017. Here we investigate the efficacy of interspecific hybridization as a tool to develop coral stock with enhanced climate resilience. We crossed two Acropora species pairs from the GBR and examined several phenotypic traits over 28 weeks of exposure to ambient and elevated temperature and pCO2. While elevated temperature and pCO2 conditions negatively affected size and survival of both purebreds and hybrids, higher survival and larger recruit size were observed in some of the hybrid offspring groups under both ambient and elevated conditions. Further, interspecific hybrids had high fertilization rates, normal embryonic development, and similar Symbiodinium uptake and photochemical efficiency as purebred offspring. While the fitness of these hybrids in the field and their reproductive and backcrossing potential remain to be investigated, current findings provide proof-of-concept that interspecific hybridization may produce genotypes with enhanced climate resilience, and has the potential to increase the success of coral reef restoration initiatives.

Authors: Chan, W. Y., L. M. Peplow, P. Menéndez, A. A. Hoffmann, and M. J. H. van Oppen
Year: 2018
View the article here

Frontiers in Marine Science 5:

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Dispersal capacity and genetic relatedness in Acropora cervicornis on the Florida Reef Tract

Abstract: Sexual reproduction in scleractinian corals is a critical component of species recovery, fostering population connectivity and enhancing genetic diveristy. The relative contribution of sexual reproduction to both connectivity and diversity in Acropora cervicornis may be variable due to this species’ capacity to reproduce effectively by fragmentation. Using a biophysical model and genomic data in this threatened species, we construct potential connectivity pathways on the Florida Reef Tract (FRT) and compare them to inferred migration rates derived from next-generation sequencing, using a link and node-based approach. Larval connectivity on the FRT can be divided into two zones: the northern region, where most transport is unidirectional to the north with the Florida Current, and the southern region that is more dynamic and exhibits complex spatial patterns. These bihysical linkages are poorly correlated with genetic connectivity patterns, which resolve many reciprocal connections and suggest a less sparse network. These results are difficult to reconcile with genetic data which indicate that individual reefs are diverse, suggesting important contributions of sexual reproduction and recruitment. Larval connectivity models highlight potential resources for recovery, such as areas with high larval export like the Lower Keys, or areas that are well connected to most other regions on the FRT, such as the Dry Tortugas.

Authors: Drury, C., C. B. Paris, V. H. Kourafalou, and D. Lirman
Year: 2018
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Coral Reefs 37:

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Estimating Nearshore Coral Reef-Associated Fisheries Production from the Main Hawaiian Islands

Abstract: Currently, information on nearshore reef-associated fisheries is frequently disparate or incomplete, creating a challenge for effective management. This study utilized an existing non-commercial fishery dataset from Hawaiʻi, covering the period 2004-13, to estimate a variety of fundamental fishery parameters, including participation, effort, gear use, and catch per unit effort. We then used those data to reconstruct total catches per island. Non-commercial fisheries in this case comprise recreational, subsistence, and cultural harvest, which may be exchanged, but are not sold. By combining those data with reported commercial catch data, we estimated annual catch of nearshore reef-associated fisheries in the main Hawaiian Islands over the study period to be 1,167,758 ± 43,059 kg year-1 (mean ± standard error). Average annual commercial reef fish catch over the same time period – 184,911 kg year-1 – was 16% of the total catch, but that proportion varied greatly among islands, ranging from 23% on Oʻahu to 5% on Molokaʻi. These results emphasize the importance of reef fishing in Hawaiʻi for reasons beyond commerce, such as food security and cultural practice, and highlight the large differences in fishing practices across the Hawaiian Islands

Authors: Mccoy, K. S., I.D. Williams, A.M. Friedlander, H. Ma, L. Teneva, and J.N. Kittinger
Year: 2018
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PLoS ONE 13(4): e0195840.

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Harnessing Ecological Processes to Facilitate Coral Restoration

Abstract: Incorporating ecological processes into restoration planning is increasingly recognized as a fundamental component of successful restoration strategies. We outline a scientific framework to advance the emerging field of coral restoration. We advocate for harnessing ecological processes that drive community dynamics on coral reefs in a way that facilitates the establishment and growth of restored corals. Drawing on decades of coral reef ecology research and lessons learned from the restoration of other ecosystems, we posit that restoration practitioners can control factors such as the density, diversity, and identity of transplanted corals; site selection; and transplant design to restore positive feedback processes – or to disrupt negative feedback processes – in order to improve restoration success. Ultimately, we argue that coral restoration should explicitly incorporate key natural processes to exploit dynamic ecological forces and drive recovery of coral reef ecosystems.

Authors: Ladd, M. C., M.W. Miller, J.H. Hunt, W.C. Sharp, and D.E. Burkepile
Year: 2018
View More and read an interview with the co-authors
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Ecological Society of America 16(4): doi:10.1002/fee.1792

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Corals in Healthy Populations Produce More Larvae Per Unit Cover

Abstract: In coral reef conservation and management, the prevailing metric of reef health is percent coral cover, a measurement commonly used with the assumption that each
unit of live coral tissue has equivalent ecological value. Here we show that the
reproductive output of a coral population is not proportional to the cover of coral present.
Instead, when compared to declining populations nearby, high cover coral populations
produced up to four times more larvae per square centimeter of tissue, resulting in up to
200 times higher larval production per square meter of reef. Importantly, corals that
produced more larvae did not produce smaller larvae, as predicted by resource allocation
theory. Instead, higher fecundity corresponded to higher energetic lipid reserves in higher
cover coral populations. In the wake of unprecedented global coral bleaching, our
findings suggest that the largest reductions in coral reproduction may occur when corals
are lost from previously healthy populations.

Author: Hartmann, A.C., K.L Marhaver, M.J Vermeij
Year: 2017
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Conservation Letters. doi:10.1111/conl.12410

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