Coral Nurseries Research Articles

Climate Change and Active Reef Restoration—Ways of Constructing the “Reefs of Tomorrow”

The continuous degradation of coral reef ecosystems on a global level, the disheartening expectations of a gloomy future for reefs’ statuses, the failure of traditional conservation acts to revive most of the degrading reefs and the understanding that it is unlikely that future reefs will return to historic conditions, all call for novel management approaches. Among the most effective approaches is the “gardening” concept of active reef restoration, centered, as in silviculture, on a two-step restoration process (nursery and transplantation). In the almost two decades that passed from its first presentation, the “gardening” tenet was tested in a number of coral reefs worldwide, revealing that it may reshape coral reef communities (and associated biota) in such a way that novel reef ecosystems with novel functionalities that did not exist before are developed. Using the “gardening” approach as a climate change mediator, four novel ecosystem engineering management approaches are raised and discussed in this article. These include the take-home lessons approach, which considers the critical evaluation of reef restoration outcomes; the genetics approach; the use of coral nurseries as repositories for coral and reef species; and an approach that uses novel environmental engineering tactics. Two of these approaches (take-home lessons and using coral nurseries as repositories for reef dwelling organisms) already consider the uncertainty and the gaps in our knowledge, and they are further supported by the genetic approach and by the use of novel environmental engineering tactics as augmenting auxiliaries. Employing these approaches (combined with other novel tactics) will enhance the ability of coral reef organisms to adaptably respond to climate change.

The Use of Forest Restoration Techniques in the Restoration of Coral Reefs

Coral gardening is a tool useful in restoring coral reefs and is comparable to silviculture through source material, location, type, choice of species and outcome (Table 1). For both trees and corals, resource requirements are similar and include inorganic substances, light, and space [2]. Key criteria for both forest and coral reef restoration include promotion of asexual and sexual reproduction, allowing restored systems to maintain themselves. Asexual culture of corals has great potential in reef restoration in a similar way to how silviculture in land-based nurseries supports forest reforestation projects [3]. For forests, ramets, seeds, and seedlings are used; for reefs, ramets, nubbins, planulae, larvae, and spat are forms of source material. Locations for forest restoration projects are often located in degraded forest areas or on plantations; for reefs, coral nurseries are constructed on or adjacent to degraded reefs or established in land-based aquaculture facilities for later transplantation. Tree species are collected from mono-culture or mixed species plantations as well as natural forests and coral species are collected from marine culture of local key coral species [1].

Augmenting the post-transplantation growth and survivorship of juvenile scleractinian corals via nutritional enhancement.

Size-dependant mortality influences the recolonization success of juvenile corals transplanted for reef restoration and assisting juvenile corals attain a refuge size would thus improve post-transplantation survivorship. To explore colony size augmentation strategies, recruits of the scleractinian coral Pocillopora damicornis were fed with live Artemia salina nauplii twice a week for 24 weeks in an ex situ coral nursery. Fed recruits grew significantly faster than unfed ones, with corals in the 3600, 1800, 600 and 0 (control) nauplii/L groups exhibiting volumetric growth rates of 10.65±1.46, 4.69±0.9, 3.64±0.55 and 1.18±0.37 mm3/week, respectively. Corals supplied with the highest density of nauplii increased their ecological volume by more than 74 times their initial size, achieving a mean final volume of 248.38±33.44 mm3. The benefits of feeding were apparent even after transplantation to the reef. The corals in the 3600, 1800, 600 and 0 nauplii/L groups grew to final sizes of 4875±260 mm3, 2036±627 mm3, 1066±70 mm3 and 512±116 mm3, respectively. The fed corals had significantly higher survival rates than the unfed ones after transplantation (63%, 59%, 56% and 38% for the 3600, 1800, 600 and 0 nauplii/L treatments respectively). Additionally, cost-effectiveness analysis revealed that the costs per unit volumetric growth were drastically reduced with increasing feed densities. Corals fed with the highest density of nauplii were the most cost-effective (US$0.02/mm3), and were more than 12 times cheaper than the controls. This study demonstrated that nutrition enhancement can augment coral growth and post-transplantation survival, and is a biologically and economically viable option that can be used to supplement existing coral mariculture procedures and enhance reef restoration outcomes.

Rearing juvenile ‘corals of opportunity’ in in situ nurseries – A reef rehabilitation approach for sediment-impacted environments

Scleractinians which have recruited on unstable substrates could function as a source of ‘corals of opportunity’ (COP). This study investigated the rearing of juvenile ‘corals of opportunity’ in an in situ coral nursery to assist in the rehabilitation of reefs in sedimented environments. Juvenile COPs of Pectinia paeonia (n = 71) and Pachyseris speciosa (n = 45) were collected from coral reefs in Singapore, categorized into three size classes (0.1–1.5, 1.6–3.0, 3.1–4.5 cm) and monitored at an in situ coral nursery for five months. Pectinia paeonia juveniles had higher overall survivorship than P. speciosa (93.0 and 69.6%, respectively) and no significant differences in survivorship among the size classes for either species were observed. The mid-sized and large juveniles of both species grew faster than the small ones. Fortnightly sedimentation and growth rates of all size classes of juveniles were weakly correlated (R < 0.22). The study highlighted the feasibility of rearing juvenile COPs in nurseries as material to supplement reef rehabilitation efforts in locations with high sediment load and unconsolidated substrate.

In Situ Coral Nurseries Serve as Genetic Repositories for Coral Reef Restoration after an Extreme Cold‐Water Event

During an unusual cold‐water event in January 2010, reefs along the Florida Reef Tract suffered extensive coral mortality, especially in shallow reef habitats in close proximity to shore and with connections to coastal bays. The threatened staghorn coral, Acropora cervicornis, is the focus of propagation and restoration activities in Florida and one of the species that exhibited high susceptibility to low temperatures. Complete mortality of wild staghorn colonies was documented at 42.9% of donor sites surveyed after the cold event. Remarkably, 72.7% of sites with complete A. cervicornis mortality had fragments surviving within in situ coral nurseries. Thus, coral nurseries served as repositories for genetic material that would have otherwise been completely lost from donor sites. The location of the coral nurseries at deeper habitats and distanced from shallow nearshore habitats that experienced extreme temperature conditions buffered the impacts of the cold‐water event and preserved essential local genotypes for future Acropora restoration activities.

Raiding the Coral Nurseries?

A recent shift in the pattern of commercial harvest in the Keppel Island region of the southern inshore Great Barrier Reef raises concern about the depletion of a number of relatively rare restricted range taxa. The shift appears to be driven by demand from the United States (US) for corals for domestic aquaria. Data from the annual status reports from the Queensland Coral Fishery were compared with export trade data to the US from the Convention on International Trade in Endangered Species (CITES). Evidence was found of recent increases in the harvest of species from the Mussidae family (Acanthastrea spp.) which appears to be largely driven by demand from the US. On present trends, the industry runs the risk of localized depletion of Blastomussa and Scolymia; evidenced by an increase in the harvest of small specimens and the trend of decreasing harvest despite a concurrent increase in demand. Considering their relatively high sediment tolerance compared to other reef-building species, and the current lack of information about their functional role in reef stability, the trend raises concerns about the impact of the harvest on local coral communities. The recent shift in harvest patterns could have impacts on slow-growing species by allowing harvest beyond the rate of population regeneration. In light of these factors, combined with the value of such species to local tourism, a commercial coral fishery based on uncommon but highly sought-after species may not be ecologically sustainable or economically viable in the Keppels.

Creating stocks of young colonies from brooding coral larvae, amenable to active reef restoration

Coral reefs are declining worldwide, even though traditional reef practices continuously underlie reef protection. This calls for exploration and integration of novel restoration techniques and tools, such as the “gardening” concept. The gardening approach, which has been successfully applied in various reef sites worldwide, is based on farming coral stocks in mid-water nurseries. To date, the farming of asexually produced coral material has chiefly been studied. Here, we test the performance of a novel spat-stocking tool for planulae of Stylophora pistillata, a brooding coral species. Two prototypes of a new settlement apparatus and one original apparatus made of Petri dishes lined with preconditioned transparency (Mailer's paper) disks had been stocked with >3730 planulae. After 96h, only 95.3% of >2080 settlers were found on the Mailer paper provided. One-month-old survivors (80.8% of initial settlements) that were kept ex situ in a flow through seawater table were detached from the papers, “transglued” onto plastic pins, and transferred to mid-water coral nursery, where the trays were covered with fitted plastic nets (1cm2 mesh) to prevent predation and detachment. Four months later, more than 89% survivorship was documented, with colonies starting to form 3D structures. We estimate that 676 person-hours would be required to create 10,000 5-month-old genotypes of equal size to small branch fragments. This novel methodology allows farming of large quantities of colonies originating from sexually produced planulae and may enhance local populations' genetic variability within a short period. This method is inexpensive and easy to perform in remote places for incorporation in coral reef management practices.

Poor Performance of Corals Transplanted onto Substrates of Short Durability

Worldwide, coral reefs are degrading due to increasing anthropogenic pressures. Yet, management of reefs still falls short of effectively addressing these threats, and active restoration methods are increasingly being called for. Coral transplantation is frequently advocated as a possible means of coral reef rehabilitation. Fragments produced in coral nurseries or farms have been proposed as a potential source for transplantation, and culture media (inexpensive but non-durable materials such as wood or bamboo) may serve as transplantation substrate if placed directly in the reef. However, the performance of coral transplants attached to such substrates has not been examined yet. Here, the long-term survival of transplants attached to bamboo substrates is reported. A total of 6,164 fragments of 4 coral species (Acroporids and Pocilloporids) were monitored for up to 20 months at three sites in North Sulawesi/Indonesia. Bamboo failed as a suitable inexpensive substrate in at least two of the three sites examined. Mortality of transplants 2 years after transplantation was high in three of the four species (67-95%) and was partially linked to substrate disintegration. The results show that, in places were currents or waves threaten to dislocate transplants, a higher effort needs to be directed at a strong and durable attachment of transplanted corals.

Mid-water rope nursery—Testing design and performance of a novel reef restoration instrument

Fast degradation of coral reefs worldwide has promoted the exploitation of active restoration instruments, one of which is the ‘gardening concept’. This concept comprises two phases: (1) establishing in situ coral nurseries for rearing large numbers of coral fragments; (2) their transplantation onto denuded reefs. This study tested the design and performance of a novel mid-water floating nursery instrument, a ‘rope nursery’. This nursery accommodated small coral fragments attached to a rope, creating an easily constructed nursery bed that is rapid and inexpensive. Two sets of experiments were conducted: the first tested two mid-water rope nursery prototypes in small-scale trials that tested depth, coral genotypes and construction stability, whereas the second set incorporated lessons learned from the first set, and was designed to carry larger numbers of colonies. These highly economical nurseries (US$ 0.11/fragment) revealed high survivorship low detachment and fast growth rates compared to previous coral-nursery types. Moreover, the coiling force of the ropes adequately held fragments without adhesives, and the minimal surface area of rope nursery beds provided not only improved water flux around farmed corals, but also reduced proliferation of fouling organisms. The rope nursery prototypes studied here attest to the diversity of their potential uses under various conditions and demands, making the construction of large scale nurseries a very feasible target. This restoration instrument was proven to be an effective coral reef rehabilitation tool.

Improved sustainable maintenance for mid-water coral nursery by the application of an anti-fouling agent

The ‘gardening concept’ for reef restoration focuses on coral colonies farming in mid-water nurseries before their transplantation onto denuded reef areas. Nurseries situated in a nutrient-enriched environment significantly curtail nursery time, but extend labor, as nursery construction and farmed corals must be frequently cleaned from competing fouling organisms. Mass farming of corals calls, therefore, for efficient and cheap maintenance methodologies, which we here tested by employing Aqua-guard M250, an anti-fouling agent used in the fish farming industry. We found that this anti-fouling paint, while reducing fouling organisms on nursery components during the crucial phase of coral ramets' development from nubbins and small fragments sizes to colony sizes suitable for transplantation, is not toxic to maricultured coral fragments that staged more than 2 cm away from the paint. Applying small quantities of such antifouling paint to coral nurseries, while restricting its use to nursery components that are not in direct contact with farmed coral material, reduces fouling coverage and cleaning procedures by 90%.

Fixed and suspended coral nurseries in the Philippines: Establishing the first step in the “gardening concept” of reef restoration

The worldwide degradation of reef ecosystems has promoted the advocators of restoration acts to the foreground. Here, we describe the results of the first step of large-scale restoration based on the “gardening with corals” concept. During June–September 2005, two coral nurseries were established in Bolinao, the Philippines, in front of Silaqui Island, in a shallow (2 m depth) sandy lagoon. Two types of nurseries were employed: (1) suspended nursery; (2) leg-fixed nursery. The nursery held a total number of 6824 ramets, from seven coral species representing different growth forms (branching, leaf-like and sub-massive forms) and different growth rates (fast and slow growing species). Each species was represented by several genotypes. During one year, we analyzed and compared survivorship, bleaching and growth rates of fragments between the different nurseries, species and genotypes. Survivorship, which was high in both nurseries, > 85%, fluctuated between the different species indicating that different species require different rearing methodologies. Mortality and detachment was subjected to environmental conditions, especially affected by the typhoons prevailing in this part of the world. The one-year nursery phase produced sizeable colonies, especially of branching forms, suitable for transplantation.

A floating mid-water coral nursery as larval dispersion hub: testing an idea

The global decline in reef health has prompted the need for eVective management method- ologies, including the development of active restoration measures. One such approach is the 'gardening concept' that involves use of underwater nurseries where coral fragments are farmed before their transplantation into denuded reefs. Here we document enhanced sexual reproduction in colonies of the coral Stylophora pistil- lata cultured in mid-water Xoating nursery situated in nutrient enriched water, near the Wsh farms in Eilat, Red Sea. We found that after 2 years of nursery, the average number of oocytes per polyp in farmed colo- nies was ca. 35% higher than in corresponding naturally growing colonies. Small branches in the nursery devel- oped gravid colonies that released equal (or more) numbers of planula larvae as compared to similar size, 5-year old naturally growing colonies. These nursery- borne planulae possessed more zooxanthellae and con- tained more chlorophyll per larva. While settled and metamorphosed in equal rates compared to planulae originated from reef-grown colonies, the nursery borne planulae developed faster growing young colonies. We estimate that a coral nursery could generate, during the reproductive season, tens of millions of planula larvae and therefore should be regarded as a 'larval dispersion hub' that can be used as a management tool for natural recruitment enhancement.

Steps in the construction of underwater coral nursery, an essential component in reef restoration acts

Many coral reefs worldwide are rapidly declin- ing, but efficient restoration techniques are not yet available. Here, we evaluate methodologies for reef res- toration based on the ''gardening concept''. A floating mid-water prototype nursery was placed at 6 m depth (14 m above sea-bottom) within the nutrient-enriched environment of a fish farm (Eilat, Red Sea). Ten colonies from five branching coral species provided 6,813 frag- ments (0.5-3 cm height). The fragments, each attached to a plastic pin, were inserted into plastic nets that were tied to a rope-net floating nursery. After 144 nursery days, only 13.1% of the fragments died and 21.2% were de- tached by mechanical forces. Small colonies ready for transplantation developed within 144-200 days. Ramets' ecological volumes increased 13-46 folds and their heights by a factor of 3.5. After 306 days, the ecological volumes of the colonies increased 147-163 fold as com- pared to original volumes (revealing a daily growth rate constant of 1.67% during the first 5-10 months) and height values by a factor of six. Building and maintenance costs of the nursery were low. This nursery prototype demonstrates the feasibility of the coral ''gardening concept'' by fulfilling several important needs, namely, mass production of coral colonies at low costs, high survivorship, fast growth, short nursery phase and im- proved methodologies for handling farmed colonies.

Conservation of Coral Reefs through Active Restoration Measures: Recent Approaches and Last Decade Progress

The scientific discipline of active restoration of denuded coral reef areas has drawn much attention in the past decade as it became evident that this ecosystem does not often recover naturally from anthropogenic stress without manipulation. Essentially, the choices are eitherthe continuous degradation of the reefs or active restoration to encourage reef development. As a result, worldwide restoration operations during the past decade have been recognized as being a major tool for reef rehabilitation. This situation has also stirred discussions and debates on the various restoration measures suggested as management options, supplementary to the traditional conservation acts. The present essay reviews past decade's (1994-2004) approaches and advances in coral reef restoration. While direct coral transplantation is still the primer vehicle of operations used, the concept of in situ and ex situ coral nurseries (the gardening concept), where coral materials (nubbins, branches, spats) are maricultured to a size suitable for transplantation, has been gaining recognition. The use of nubbins (down to the size of a single or few polyps) has been suggested and employed as a unique technique for mass production of coral colonies. Restoration of ship grounding sites and the use of artificial reefs have become common tools for specific restoration needs. Substrate stabilization, 3-D structural consideration of developing colonies, and the use of molecular/biochemical tools are part of novel technology approaches developed in the past decade. Economic considerations for reef restoration have become an important avenue for evaluating success of restoration activities. It has been suggested that landscape restoration and restoration genetics are important issues to be studied. In the future, as coral reef restoration may become the dominant conservation act, there would be the need not only to develop improved protocols but also to define the conceptual bases.

Applying forest restoration principles to coral reef rehabilitation

Abstract Forest restoration through silviculture (gardening) programs revives productivity, biodiversity, and stability. As in silviculture approaches, the coral ‘gardening’ strategy is based on a two‐step protocol. The first step deals with the establishment of in situ and/or ex situ coral nurseries in which corals are farmed (originating from two types of source material: asexual [ramets, nubbins], and sexual [planula larvae, spat] recruits). The second is the reef rehabilitation step, where maricultured colonies are transplanted into degraded sites. We compare here the rationale of forest restoration to coral reef ecosystem restoration by evaluating major key criteria. As in silviculture programs, a sustainable mariculture operation that focuses on the prime structural component of the reef (‘gardening’ with corals) may promote the persistence of threatened coral populations, as well as that of other reef taxa, thus maintaining genetic diversity. In chronically degrading reef sites this may facilitate a halt in biodiversity depletion. Within the current theoretical framework of ecosystem restoration, the recovery of biodiversity indices is considered a core element since a rich species diversity provides higher ecosystem resilience to disturbances. The gardening measure may also be implemented worldwide, eliminating the need to extract existing colonies for transplantation operations. At degraded reef sites, the coral gardening strategy can assist in managing human and non‐human stakeholders' requirements as is done in forest management. Copyright © 2003 John Wiley &amp; Sons, Ltd.

Review: Current trends in coral transplantation – an approach to preserve biodiversity

Ammar MSA,El-Gammal F, Nassar M, Belal A, Farag W, El-Mesiry G, El-Haddad K, Orabi A, Abdelreheem A, Shaaban A. 2013. Review: Current trends in coral transplantation – an approach to preserve biodiversity. Biodiversitas 14: 43-53. The increasing rates of coral mortality associated with the rise in stress factors and the lack of adequate recovery worldwide have urged recent calls for actions by the scientific, conservation, and reef management communities. This work reviews the current trends in coral transplantation. Transplantation of coral colonies or fragments, whether from aqua-, mariculture or harvesting from a healthy colony, has been the most frequently recommended action for increasing coral abundance on damaged or degraded reefs and for conserving listed or “at-risk” species. Phytoplanktons are important for providing transplanted corals with complex organic compounds through photosynthesis. Artificial surfaces like concrete blocks, wrecks or other purpose-designed structures can be introduced for larval settlement. New surfaces can also be created through electrolysis. Molecular biological tools can be used to select sites for rehabilitation by asexual recruits. Surface chemistry and possible inputs of toxic leachate from artificial substrates are considered as important factors affecting natural recruitment. Transplants should be carefully maintained, revisited and reattached at least weekly in the first month and at least fortnightly in the next three months. Studies on survivorship and the reproductive ability of transplanted coral fragments are important for coral reef restoration. A coral nursery may be considered as a pool for local species that supplies reef-managers with unlimited coral colonies for sustainable management. Transplanting corals for making artificial reefs can be useful for increasing biodiversity, providing tourist diving, fishing and surfing; creating new artisanal and commercial fishing opportunities, colonizing structures by fishes and invertebrates, aving large corals during the construction of a Liquified Natural Gas Plant.