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Four-year-old Caribbean Acropora colonies reared from field-collected gametes are sexually mature

BULLETIN OF MARINE SCIENCE. 00(0):000–000. 0000
Bullen of Marine Science
© 2011 Rosensel School of Marine and Atmospheric Science
of the University of Miami
Bulletin of Marine Science
© 2016 Rosenstiel School of Marine & Atmospheric Science of
the University of Miami Portraits of Marine Science
Bull Mar Sci. 92(2):000–000. 2016
Four-year-old Caribbean Acropora colonies reared
from eld-collected gametes are sexually mature
VF Chamberland 1, 3, 4 *, D Petersen 1, 2, KRW Latijnhouwers 4,
S Snowden 1, 5, B Mueller 3, MJA Vermeij 3, 4
1 SECORE Intern ational, c/o Colu mbus Zoo and Aquar ium, 9990 Riversid e Drive, Powell, Ohi o 43065.
2 SECORE International, Arensburgstraße 40, Bremen, Germany.
3 Carmabi Foundation, Piscaderabaai z/n, Willemstad, Curaçao.
4 Aquatic Mi crobiology, Inst itute for Biodive rsity and Ecosyst em Dynamics, U niversity of Amst erdam, Science Par k 700,
1098 XH Amster dam, Netherla nds.
5 Pittsbu rgh Zoo & PPG Aquarium , One Wild Place, Pi ttsburgh, Penn sylvania 15206.
* Corresponding author email: <>.
Rehabilitating populations of Caribbean coral species that have declined in recent
decades has become a management priority throughout the region, stimulating the
development of new methodologies to artificially reseed degraded reefs. Rearing lar-
vae of ecologically important coral species appears a particularly attractive method
to aid the recovery of degraded populations because genetic recombination could
yield new genotypes better capable of coping with the altered conditions on modern
Caribbean reefs. Well-developed elkhorn coral (Acropora palmata Lamarck, 1816)
populations form dense thickets that contribute to the maintenance of healthy and
productive reefs by providing shelter to a variety of other reef organisms (Gladfelter
and Gladfelter 1978). After >95% of A. palmata populations were decimated by a
disease beginning in the mid-1970s, this species was listed as critically endangered
under the Red List of reatened Species (IUCN 2013) and restoration efforts were
initiated throughout the region to assist its recovery (Young et al. 2012). In 2011, we
collected gametes from eight A. palmata colonies in situ off Curaçao, which were
subsequently cross-fertilized to generate larvae. Competent larvae were settled on
clay tiles (Panel A) and reared in a flow-through land-based nursery for one year
(Panels B–C), after which they were outplanted to a breakwater at 2–5 m depth
Fas t Track
BULLETIN OF MARINE SCIENCE. VOL 00, NO 0. 0000106 Bulletin of Marine Science. Vol 92, No 2. 2016
(Panel D) [refer to Chamberland et al. (2015) for details on methodology]. Seven out
of nine outplanted colonies survived and continued to grow in situ (Panels D–E),
reaching a size of 30–40 cm diameter and 20–30 cm height after 4 yrs (Panel F). On
8 and 10 September, 2015, nine and 11 d after the full moon, two colonies were ob-
served releasing gametes between 155 and 175 min after sunset (Panels G–H). is is
the first time that an endangered Caribbean Acropora coral species was raised from
larvae and grown to sexual maturity in the field. Indeed, only one other study has
documented age and colony size at reproductive onset in a broadcast spawning scler-
actinian coral reared from larvae (Baria et al. 2012). e relatively short time until
onset of spawning (≤4 yrs) observed for A. palmata shows that recovery of degraded
coral populations by enhancing natural recruitment rates may be practicable if out-
planted colonies are able to rapidly contribute to the natural pool of larvae.
is research was supported by the European Union Seventh Framework Programme
(FP7/2007-2013) under grant agreement no 244161 (Future of Reefs in a Changing Environ-
ment), the National Oceanic and Atmospheric Administration (NOAA), the Green Founda-
tion, the Walton Family Foundation, TUI Cruises/ Futouris e.V., the Clyde and Connie Wood-
burn Foundation, and the Montei Foundation. We are grateful to the Curaçao Sea Aquarium
staff and all participants from the 2011 and 2012 editions of the SECORE workshop for their
assistance in the field.
L C
Baria MVB, Villanueva RD, Guest JR. 2012. Spawning of three year-old Acropora millepora cor-
als reared from larvae in northwestern Philippines. Bull Mar Sci. 88:61–62. http://dx.doi.
Chamberland VF, Vermeij MJA, Brittsan M, Carl M, Schick M, Snowden S, Schrier A, Petersen
D. 2015. Restoration of critically endangered elkhorn coral (Acropora palmata) popula-
tions using larvae reared from wild-caught gametes. Glob Ecol Cons. 4:526–553. http://
Gladfelter WB, Gladfelter EH. 1978. Fish community structure as a function of habitat struc-
ture on West Indian patch reefs. Rev Biol Trop. 26(1):65–84.
International Union for Conservation of Nature (IUCN). 2013. IUCN Red List of reatened
Species. Version 2013.2. Accessed August 2015. Available from:
Young CN, Schopmeyer SA, Lirman D. 2012. A review of reef restoration and coral propaga-
tion using the threatened genus Acropora in the Caribbean and western Atlantic. Bull Mar
Sci. 88(4):1075–1098.
Date Submitted: 23 October, 2015.
Date Accepted: 4 January, 2016.
Available Online: 28 January, 2016.
... Reproduction in corals consists of a sequence of events which include gametogenesis, spawning (for spawning species), fertilization, embryogenesis, planulation, dispersal, settlement, and recruitment (e.g., Harrison and Wallace, 1990;Baird et al., 2009;Harrison, 2011). These events have been described from different perspectives, including histological (e.g., Duerden, 1902;Fadlallah, 1983;Szmant, 1986;Richmond and Hunter, 1990;Soong, 1991;Steiner, 1998;Morales, 2006;Ritson-Williams et al., 2009;Weil and Vargas, 2010;Harrison, 2011;Soto and Weil, 2016), observational (e.g., Vermeij et al., 2003;Levitan et al., 2004;Van Woesik et al., 2006;Vize, 2006;Bastidas et al., 2012;Chamberland et al., 2016;Keith et al., 2016;Fogarty and Marhaver, 2019), and experimental (e.g., Morse et al., 1988;Webster et al., 2004;Kuffner et al., 2006Kuffner et al., , 2007Nugues and Szmant, 2006;Vermeij et al., 2009;Ritson-Williams et al., 2010;Marhaver et al., 2015;Sharp et al., 2015) studies. ...
... Currently, Coralium lab at the National Autonomous University of Mexico, SECORE International and the Caribbean Research and Management of Biodiversity (CARMABI) are three leading institutions in the Caribbean on this subject. These institutions have played an important role in expanding larval propagation across geographies, improving capacity building, and developing cutting edge technology and protocols applied for coral restoration (e.g., Marhaver et al., 2015;Chamberland et al., 2016Chamberland et al., , 2017Banaszak pers. comm.). ...
... We find these 3 points to be essential to create a robust and scalable program: (1) alliances with private and local stakeholders, (2) financial stability, and (3) adoption of novel technology supported by pertinent training to implement them. In our view, the balance between these components allowed FUNDEMAR to build the laboratory and produce results comparable to others in the Caribbean (Chamberland et al., 2016(Chamberland et al., , 2017. Local engagement and key alliances between different stakeholders and the scientific community has been shown to be a strong pillar that supports conservation actions aimed to preserve coastal marine ecosystems (White and Vogt, 2000;Lundquist and Granek, 2005;Reyes-García et al., 2019). ...
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Coral assisted fertilization, larval rearing and recruit propagation success in significant ecological scales, largely depend on scaling up and replicating these efforts in as many regions as possible. The Dominican Foundation for Marine Studies (FUNDEMAR) has become a pioneer of these efforts in the Dominican Republic, being the first institution to successfully implement coral sexual reproduction techniques in the country and establishing the first mobile larvae culturing facility. Here we share our perspective on three main components behind the success of FUNDEMAR’s program: (1) a self-sustainable program in alliance with local and international organizations, (2) the design and construction of the first Coral Assisted Reproduction Laboratory in the country, and a (3) clearly defined scalable structure for outcome performance. Two years after program implementation, FUNDEMAR has successfully produced an annual regional coral spawning prediction calendar, cultured seven coral species, and seeded over 4,500 substrates with more than 268,200 sexual coral recruits in approximately 1,880 m2 reef areas. Here, we provide a detailed description of a fully functional assisted coral reproduction program, including the lessons learned during its implementation as well as a series of specific solutions. We hope this work will help and inspire other countries and small institutions to replicate FUNDEMAR’s coral assisted reproduction program components and contribute to the expansion of sexual coral restoration efforts in the Caribbean.
... While high survival of sexually propagated A. cervicornis reared on land is a recent development (Henry et al. 2019), coral recruits of varying origin have been used in restoration for over 30 years (Fucik et al. 1984;Richmond and Hunter 1990;Chamberland et al. 2015Chamberland et al. , 2016Doropoulos et al. 2019). Historically, several methodologies have used coral recruits to restore degraded reefs. ...
... These include transplantation of nearly gravid corals to degraded reefs (Fucik et al 1984;Richmond and Hunter 1990) and harvesting wild spawn slicks (Doropoulos et al. 2019;Tabalanza et al. 2020). Furthermore, sexually propagated A. palmata has been used for restoration in the Southern Caribbean (Chamberland et al. 2015(Chamberland et al. , 2016. ...
... Although survival was low for Chamberland et al. (2015), associated cost was greatly reduced by minimizing the land-based period (outplanting two weeks after settlement) and distributing corals on clay tripods affixed using nylon rope and zip-ties. The same group also raised A. palmata on land for one year and had several of these colonies survive and spawn three years after being outplanted (Chamberland et al. 2016). In comparison, we found up to 95% survival 16 months post-outplant in corals reared ex situ for eight months. ...
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Caribbean hard coral cover has decreased by more than 80% in the last 40 years. In response, active coral restoration has grown in popularity as a management tool to sustain degraded reefs. To date, the majority of coral outplanting has employed asexually propagated ramets derived from wild donor colonies. Unfortunately, this strategy is incapable of increasing genetic diversity and limits the adaptive potential of restored coral populations. Methods for sexual propagation in land-based systems offer increasing potential to enhance genetic diversity of target species. However, questions regarding coral performance once placed back into the dynamic marine environment must be considered. Thus, focused experiments to optimize the integration of land reared corals and novel genetic diversity are of immense value. For this reason, we designed a study using two Acropora cervicornis year classes produced in a land-based system and concurrently relocated to an inshore patch reef, a back reef, and placed in an ocean-based nursery (n = 80 sexually propagated colonies per location). A deliberate monitoring strategy measured growth and survival five times over a 480-day period. Major findings were 1) high survival rates (~ 73%) across all 160 outplanted colonies 2) significant differences in survival between outplanting locations and coral recruit year class, and 3) very high survival of sexually propagated corals relocated to the ocean-based nursery (~ 93% overall), with 40-fold greater growth than direct-outplanted colonies. Our study suggests that ex situ sexual coral propagation offers a tractable tool to meet the need for increased A. cervicornis genetic diversity. Lastly, we offer insight and considerations for managing the high input of novel genotypes into restoration systems and suggest further research to maximize the adaptive potential of coral populations.
... However, for most coral species, little is known about corals' early life stages i.e., the period when these organisms have higher mortality rates (Vermeij and Sandin 2008;Doropoulos et al. 2016).This is especially true for the pre-settlement period, when larvae swim in the water column seeking an appropriate substrate to settle, since they can perish due to energy storage depletion (Vermeij 2006). Studying the early life stage ecology of speci c coral species is key for understanding its contribution to the current and future composition of reefs (Chamberland et al. 2016). Therefore, identifying the factors that affect larval recruitment success can inform management decisions aimed at reducing the decline of coral reefs and improve restoration efforts through sexual propagation. ...
... Diploria labyrinthiformis is a common coral species in the Caribbean and, depending on its location, can spawn from April to October before sunset, having a wider and earlier spawning window compared to most broadcast spawning corals in the region (Weil and Vargas 2010;Chamberland et al. 2017). D. labyrinthiformis was selected for this study due to its ability to build 3D structures in reefs, its early and multiple spawning events throughout the year, its high spawning predictability, and the contribution to recent and ongoing research regarding its reproductive potential and early life history stages (Chamberland et al. 2016). FUNDEMAR has been monitoring and documenting spawning events of this species at the Playita reef site since May 2017, producing a spawning prediction calendar for 2020 including this and 7 other coral species (Sellares-Blasco et al. 2021). ...
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Crustose Coralline Algae (CCA) is a well-known settlement inducer for stony corals and, ultimately, recruitment, a vital component for reef growth and resilience. However, potential impacts of diseased CCA on larval settlement are not fully understood, especially on particular coral species. As oceans continue to warm, coral larvae need to be able to respond to settlement cues in elevated temperatures, yet the combined effects of thermal stress and CCA health status on larval behavior is not well known for most coral species. Here we assessed the effect of elevated temperatures and disease on the ability of the CCA Hydrolithon boergesenii to induce settlement of Diploria labyrinthiformis larvae. D. labyrinthiformis planulae were exposed to 4 substrate combinations (healthy CCA, diseased CCA, bare substratum, and bare tissue culture plate) and three temperatures (27.5°C, 29°C, and 31°C). Overall, settlement started earlier and was 1.5-3x higher at 31°C, regardless of CCA health status, but at this temperature, larval mortality increased two-fold in diseased CCA. Settlement differences between healthy and diseased H. boergesenii were only observed at 29°C, with healthy CCA facilitating twice as much settlement and having 3x lower mortality than diseased. Our findings suggest that, even though larvae can settle in both healthy and diseased CCA, temperature plays an important role in whether larvae will settle or perish. This study highlights the importance of healthy CCA to maintain and increase settlement and the ability of larvae to adapt to a warming ocean, contributing to the knowledge of D. labyrinthiformis larval ecology, valuable for larval rearing for restoration purposes.
... Colony age and size determine the sexual maturity in corals (Hall & Hughes 1996). In the present study, most of the remaining A. verweyi coral outplants were reproductively mature at four years post-outplantation, which is within the range of 3 -5 years that is observed in various acroporid species (Iwao et al. 2010;Baria et al. 2012;Chamberland et al. 2016;dela Cruz & Harrison 2017). Interestingly, the smallest size (mean diameter) of sexually mature A. verweyi coral outplants in this study was 11.8 cm. ...
... Several of the larger colonies were likely larger than 11.8 cm diameter at age 3 and thus might have matured the previous year. The results here further support other studies suggesting sexual maturation is achieved upon reaching a specific size, which varies among species (Iwao et al. 2010;Baria et al. 2012;Chamberland et al. 2016;dela Cruz & Harrison 2017). Upon reaching sexual maturity, these coral outplants become valuable sources of gametes, especially with their high fecundity (Harrison 2011). ...
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Most coral reef restoration efforts are carried out over 1–2 years, and few have assessed long term (over 3 years) outcomes. Although, studies of outplantation of sexually propagated corals have reported promising initial results, few studies have followed outplanted corals to maturity. Here, we monitored sexually propagated Acropora verweyi corals for four years post‐outplantation to determine their survival and sexual maturity. These corals were outplanted when four months old in two size classes (small = 0.3–0.5 cm; large = 1.0–1.5 cm) at two sites in the northwestern Philippines. Four years after outplantation, the 240 colonies of A. verweyi exhibited 17.9% survival, with mean diameters ranging from 7.48–26.8 cm. Most of the surviving outplants were gravid (81.4% of the 43 colonies) with mean diameters of at least 11.8 cm. Higher survivorship was detected in the initial large size class outplants than in the small ones at the natal site, but not at the other site. However, four years after outplantation there was no significant difference in terms of geometric mean diameter between the initial size classes or between the sites. Results show that 4‐mo old outplants of sexually propagated corals can survive until sexual maturity and are already capable of contributing gametes for the potential recovery of degraded coral communities at age four years. This article is protected by copyright. All rights reserved.
... Losses of genetic diversity over the course of larval development in ex situ cultures are well illustrated in a lab-bred Acropora palmata cohort on the Caribbean island of Curaçao. This now 10-year-old restored and sexually mature (Chamberland et al. 2015;Chamberland et al. 2016) population of 11 colonies is partially composed of half-siblings and full siblings (Kitchen et al. 2020, Conn et al., unpublished data, Fig. 3.1). That is despite the initial mixing of hundreds of thousands of wild-caught gametes spawned by at least seven colonies on three different nights and on two reefs. ...
As natural coral populations decline, thousands of outplanted corals are poised to dominate reefs in the hardest-hit areas, such as the Florida Keys. Genetic management plans are urgently needed to prevent unintended erosion of genetic diversity in managed populations. Drivers of genetic diversity loss include limited nursery genets available for outplanting or that these genets were reared from crosses among a limited number of parent genets. Existing data indicate that captive rearing of coral larvae can impose substantial genetic bottlenecks that result in closely related cohorts. Thus, questions arise about how to safeguard genetic diversity and optimize the adaptation potential of restored populations. What is the optimal ratio of asexually propagated colonies to sexually produced coral recruits at each site? What breeding scheme should be used if a limited number of donor genets are available? Should breeding be selective to achieve a shift in phenotypes such as thermotolerance at the risk of losing genetic diversity? Population viability analyses (PVA) can answer some of these questions, but current models need to be modified to resolve the most pressing issues. This chapter discusses omics methods to determine genetic diversity of corals and their symbionts and outlines strategies to achieve genetic diversity goals.KeywordsGenetic diversityCoral restorationCoral breedingInbreedingEvolutionary potentialPopulation viability model
... Coral growth rates, however, can vary considerably making it difficult to establish both age and size at sexual maturity in naturally occurring colonies. Only a few studies have sexually propagated corals and reared them until sexual maturity to establish the exact age at onset of maturity, and to date, this has only been done for fast-growing Acropora Baria et al. 2012;Guest et al. 2014;Chamberland et al. 2016;dela Cruz and Harrison 2017;Craggs et al. 2020). Information on colony size and age at first reproduction of most slow-growing massive species as well as fecundity across different size classes are mostly lacking despite their important implications on coral population dynamics and demography. ...
Despite decades of research, many aspects of coral reproductive biology, such as colony size and age at the onset of sexual maturity remain poorly studied. In this study, wild colonies of different size classes and colonies of a known age of the massive scleractinian Favites abdita were examined for the presence or absence of mature oocytes to determine size and age at the onset of maturity. Fecundity for each size class was also determined for wild colonies. Both sexually propagated and wild F. abdita colonies that are 1.8 cm in diameter were found to be sexually mature. Colonies of size class A (0.1–4.0 cm maximum diameter) had lower mean oocyte counts but greater mean oocyte geometric mean diameter per polyp (44 ± 6.08, 340.38 ± 7.68 µm; mean ± SE) compared to colonies of classes B (4.1–8.0 cm) and C (>8.1 cm) (469 ± 62.41, 283.96 ± 6.94 µm; 278 ± 57.15, 317.57 ± 9.18 µm, respectively). Results of this study bring into question the widely applied operational definition of juveniles being colonies ≤4.0 cm diameter and suggest that even quite small colonies can play a role in contributing to the natural larval pool on reefs than previously thought.
... Still, the knowledge about the bacterial population structures during larval development of Acropora humilis in the Southeast Asia has not been deciphered. The cultivation of corals using sexual reproduction technique is relatively new in the past decade with different levels of success depending on sites [33][34][35][36][37] , and we are one of the pioneer groups who have actually been successfully cultivating corals using gametes and have successfully been using our cultured baby corals to restore degraded reefs in Thailand. Here, A. humilis can be a model coral species since this species is a predominant species not only in Thailand but also in the tropical regions, particular in the Southeast Asia. ...
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A symbiosis of bacterial community (sometimes called microbiota) play essential roles in developmental life cycle and health of coral, starting since a larva. For examples, coral bacterial holobionts function nitrogen fixation, carbon supply, sulfur cycling and antibiotic production. Yet, a study of the dynamic of bacteria associated coral larvae development is complicated owning to a vast diversity and culturable difficulty of bacteria; hence this type of study remains unexplored for Acropora humilis larvae in Thai sea. This study represented the first to utilize 16S rRNA gene sequencing to describe the timely bacterial compositions during successfully cultured and reared A. humilis larval transformation in aquaculture (gametes were collected from Sattahip Bay, Chonburi province, Thailand), from gamete spawning (0 h) and fertilization stage (1 h), to embryonic cleavage (8 h), round cell development (28, 39 and 41 h), and planula formation (48 h). The sequencing results as estimated by Good’s coverage at genus level covered 99.65 ± 0.24% of total bacteria. While core phyla of bacteria were observed (Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes), changes in bacterial population structures and differential predominant core bacterial orders were denoted for each larval developmental stage, from fertilization to embryonic cleavage and subsequently from the embryonic cleavage to round cell development ( P = 0.007). For instances, Pseudoalteromonas and Oceanospirillales were found prevalent at 8 h, and Rhizobiales were at 48 h. The bacterial population structures from the round cell stage, particularly at 41 h, showed gradual drift towards those of the planula formation stage, suggesting microbial selection. Overall, this study provides preliminary insights into the dynamics of bacterial community and their potentially functional association (estimated from the bacterial compositions) during the developmental embryonic A. humilis in a cultivation system in Southeast Asia region.
... The modes of sexual reproduction for approximately half of extant species of hermatypic scleractinians have been identified (Baird et al., 2009) and the timing of spawning cataloged for >300 Indo-Pacific coral species (Baird et al., 2021). CLP has been successfully executed in different geographical regions with several species under ex situ and in situ conditions (Omori, 2019;Randall et al., 2020) with sexually propagated colonies that were outplanted to the reef reaching sexual maturity (Nakamura et al., 2011;Baria et al., 2012;Guest et al., 2014;Chamberland et al., 2016). Competent coral larvae have been seeded en masse onto natural substrates to enhance recruitment (dela Cruz and Harrison, 2017;Doropoulos et al., 2019) and substrates have been designed to settle coral larvae for nursery rearing and outplantation improving early survivorship (Guest et al., 2014;Chamberland et al., 2017). ...
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Coral cover on tropical reefs has declined during the last three decades due to the combined effects of climate change, destructive fishing, pollution, and land use change. Drastic reductions in greenhouse gas emissions combined with effective coastal management and conservation strategies are essential to slow this decline. Innovative approaches, such as selective breeding for adaptive traits combined with large-scale sexual propagation, are being developed with the aim of pre-adapting reefs to increased ocean warming. However, there are still major gaps in our understanding of the technical and methodological constraints to producing corals for such restoration interventions. Here we propose a framework for selectively breeding corals and rearing them from eggs to 2.5-year old colonies using the coral Acropora digitifera as a model species. We present methods for choosing colonies for selective crossing, enhancing early survivorship in ex situ and in situ nurseries, and outplanting and monitoring colonies on natal reefs. We used a short-term (7-day) temperature stress assay to select parental colonies based on heat tolerance of excised branches. From six parental colonies, we produced 12 distinct crosses, and compared survivorship and growth of colonies transferred to in situ nurseries or outplanted to the reef at different ages. We demonstrate that selectively breeding and rearing coral colonies is technically feasible at small scales and could be upscaled as part of restorative assisted evolution initiatives. Nonetheless, there are still challenges to overcome before selective breeding can be implemented as a viable conservation tool, especially at the post-settlement and outplanting phases. Although interdisciplinary approaches will be needed to overcome many of the challenges identified in this study, selective breeding has the potential to be a viable tool within a reef managers toolbox to support the persistence of selected reefs in the face of climate change.
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Acropora cervicornis underwent massive mortalities in the Caribbean Sea and its populations have failed to recover after several decades. This study aimed to document the early life history of A. cervicornis from embryogenesis to symbiotic dinoflagellates acquisition. Gametes were collected in Islas del Rosario (Colombia) and a cross-fertilization was performed ex situ. A settlement experiment was performed including two treatments: smooth surfaces and rugose surfaces. Embryogenesis lasted for 63 h and larvae began to settle 8 days after fertilization. There were no significant differences in settlement between rugose (32% ± 16.59) and smooth (21% ± 11.45) surfaces. Survival on rugose surfaces was significantly lower (29% ± 11.71) compared to smooth surfaces (47% ± 35.02), due to the negative effect of sediment accumulation and turf algae. Seventeen days after fertilization 54% ± 4.13 of polyps acquired symbiotic dinoflagellates. This study contributes to the knowledge of early development of A. cervicornis in laboratory conditions, which complements restoration methods based on asexual reproduction.
Land-based coral culture is of increasing interest for conservation and educational display. Shallow water corals generate most of their energy from photosynthesis, and light is a critical abiotic factor in their husbandry. We compared growth, calcification, and photobiology in the coral Acropora cervicornis between natural and artificial (light-emitting diode; LED) light to better understand the impact of light source on coral performance. One tank of a greenhouse recirculating system at The Florida Aquarium's Center for Conservation was used to culture replicate coral colonies. Half of the tank and corals were covered to block sunlight and illuminated with a commercial reef aquarium LED fixture, while the other half was exposed to natural sunlight. Treatments were matched in terms of maximum photosynthetically active radiation and spectral measurements characterized both light regimes. Coral growth and calcification were tracked over a period of 19 weeks by repeated measurements of total linear extension (TLE) and buoyant weight. For the first 5 weeks, photosynthetic yield was measured weekly using a pulse-amplitude-modulated fluorometer. Calcification was significantly higher under LED lighting relative to natural light, but TLE did not differ. Photobiology data suggest that corals in both treatments were acclimated to the same light level, but photosynthetic efficiency was ultimately greater in the natural light treatment. More consistent light delivery and different spectral composition under LED treatment conditions may explain the incongruity between calcification and photosynthetic efficiency. This experiment informs husbandry of shallow-water scleractinian corals maintained in both natural sunlight and enclosed structures.
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Elkhorn coral (Acropora palmata) populations provide important ecological functions on shallow Caribbean reefs, many of which were lost when a disease reduced their abundance by more than 95% beginning in the mid-1970s. Since then, a lack of significant recovery has prompted rehabilitation initiatives throughout the Caribbean. Here, we report the first successful outplanting and long-term survival of A. palmata settlers reared from gametes collected in the field. A. palmata larvae were settled on clay substrates (substrate units) and either outplanted on the reef two weeks after settlement or kept in a land-based nursery. After 2.5 years, the survival rate of A. palmata settlers outplanted two weeks after settlement was 6.8 times higher (3.4%) than that of settlers kept in a land-based nursery (0.5%). Furthermore, 32% of the substrate units on the reef still harbored one or more well-developed recruit compared to 3% for substrate units kept in the nursery. In addition to increasing survival, outplanting A. palmata settlers shortly after settlement reduced the costs to produce at least one 2.5-year-old A. palmata individual from $325 to $13 USD. Thus, this study not only highlights the first successful long-term rearing of this critically endangered coral species, but also shows that early outplanting of sexually reared coral settlers can be more cost-effective than the traditional approach of nursery rearing for restoration efforts aimed at rehabilitating coral populations.
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Coral reef restoration has gained recent popularity in response to the steady decline of corals and the recognition that coral reefs may not be able to recover naturally without human intervention. To synthesize collective knowledge about reef restoration focused particularly on the threatened genus Acropora in the Caribbean and western Atlantic, we conducted a literature review combined with personal communications with restoration practitioners and an online questionnaire to identify the most effective reef restoration methods and the major obstacles hindering restoration success. Most participants (90%) strongly believe that Acropora populations are severely degraded, continue to decline, and may not recover without human intervention. Low-cost methods such as coral gardening and fragment stabilization were ranked as the most effective restoration activities for this genus. High financial costs, the small footprint of restoration activities, and the potential damage to wild populations were identified as major concerns, while increased public awareness and education were ranked as the highest benefits of coral reef restoration. This study highlights the advantages and outlines the concerns associated with coral reef restoration and creates a unique synthesis of coral restoration activities as a complementary management tool to help guide “best-practices” for future restoration efforts throughout the region.
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Polyp age and colony size determine the onset of sexual maturity in scleractinian corals (Hall and Hughes 1996), and this has important ecological and evolutionary implications as it influences rates of adaptation and trade-offs between growth and reproduction. Colony age is normally estimated based on size (e.g., Wallace 1985); however, corals have highly variable growth rates and may undergo fission and fusion, making it difficult to accurately determine age based on size alone (Hughes and Jackson 1985). Here we examined sexual maturity in a single cohort of 3-yr-old colonies of Acropora millepora (Ehrenberg, 1834) that had been reared at Bolinao Marine Laboratory from larvae (A, arrows: newly settled spat reared in 2008) settled to artificial substrates in an outdoor hatchery, and subsequently transferred to an in situ nursery. By 2011, three out of 12 colonies transplanted to natural reef after 6 mo of rearing in the nursery and 17 out of 19 colonies that remained in the nursery (B) were sexually mature (C, arrow: mature pigmented oocytes visible in fractured branches). Gravid colonies had mean diameters ranging from 14.4 to 28.3 cm in the nursery and from 12.3 to 13.7 cm on the reef, whereas colony mean diameters in non-gravid colonies ranged from 11.8 to 13.5 cm in the nursery and 7.8 to 11.0 cm on the reef, indicating that spawning can occur at 3 yrs of age provided colony mean diameter is ≥ 14.4 cm in the nursery and ≥ 12.3 cm on the reef. Four gravid colonies were collected from the nursery and observed to spawn synchronously on the night of the full moon (20 March, 2011) between 20:30 and 21:30 hrs at the land based hatchery (D). This is the first report to confirm Wallace's (1985) estimate of onset of sexual maturity in Acropora at 3 yrs of age, 1 yr sooner than the previous observation for Acropora tenuis (Dana, 1846) colonies reared from gametes (Iwao et al. 2010). Our finding further demonstrates the potential for relatively short generation times in Acropora and highlights the difficulties in estimating age from