Transplant wild-grown coral onto artificial substrate
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Overall effectiveness category Awaiting assessment
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Number of studies: 24
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Supporting evidence from individual studies
A study in 1990–1993 at an area of degraded coral reef in Galu Falhu, Maldives (Clark & Edwards 1999) reported that transplanting coral fragments onto flexible concrete mats (Armorflex) did not lead to an increase in coral cover compared to mats naturally colonized by coral recruits, but approximately half the transplanted fragments survived. After 10 months, coral recruits were observed on the edges of the paving slabs anchoring the Armorflex mats and, after 16 months, recruits were observed on the mats both with and without transplants (data not reported). There was no difference in density of coral recruits after 2.5 years with an average of 4/m2 recorded on mats and 18/m2 on the vertical edges of the paving slabs with and without transplants. After 2.5 years, 41–59% of coral transplants were still alive on the mats. In 1990–1991, Armorflex mats, weighted down using paving slabs, were installed on two 10 × 5 m areas of previously mined coral rubble substrate 0.5–1.8 m deep at four sites. Fragments of coral (number and species not reported) were taken from colonies near the study site and attached to one of the Armorflex mats at each site using marine cement; the other mat was left bare. Monitoring took place every 8–12 months for 2.5 years. Armorflex mats with transplants cost £97/m2 and bare Armorflex mats cost £66/m2 (1999 value).
Study and other actions testedA replicated, controlled study in 1997 at three reefs at Curaço, Netherlands Antilles (Nagelkerken et al. 2000) found transplanted fragments of stony coral Madracis mirabilis had a lower growth rate than unfragmented colonies, growth and survival rates of transplants varied between sites and there was no difference in growth or survival for fragments transplanted between or within sites or prepared using different methods. Sixteen weeks after transplanting, average growth of fragments across the four sites ranged from 8–12 mm/year (transplanted) to 16 mm/year (unfragmented). Average growth of fragments from Carmabi Buoy (13 mm/year) and Rif St. Marie (12 mm/year) were lower than unfragmented colonies at the same sites (both 16 mm/year), there was no difference in growth rate of fragments from Janthiel Bay (transplanted: 8 mm/year, unfragmented: 9 mm/year). Overall survival after 16 weeks ranged from 20–49 % (average 38%) and there was no difference for fragments transplanted between or within sites. There was no difference in growth rate or survival between fragments prepared on the surface (growth 13 mm/year, survival 48%) compared to fragments prepared underwater (growth 12 mm/year, survival 34%). In April 1997, colonies of Madracis mirabilis 5–8 m deep were collected and cut into 10 cm fragments. Fragmentation took place either on the surface (in buckets of seawater) or underwater (see paper for full methods). Six PVC grids (1 × 1 m), each supporting 100 fragments, were secured to permanent quadrats 5–6 m deep at three sites (Carmabi Buoy, Rif St. Marie and Janthiel Bay). Approximately 21–30 colonies were left unfragmented at each site. Photographs were used to measure growth and survival of fragments after 2, 4, 8, 12 and 16 weeks.
Study and other actions testedA replicated study (year not given) at a coral reef at Hurghada, Egypt (Ammar et al. 2000) reported that transplanted wild-grown stony coral fragments attached to plastic mesh substrate survived, and some grew, and those fragments attached using epoxy had higher survival than fragments attached without epoxy but mixed results for growth. One year after transplanting, 64% of Favia stelligera and 11% of Stylophora pistillata fragments attached without epoxy survived. Fragments of Acropora humilis and Pocillopora damicornis attached with epoxy had a higher survival rate (A. humilis: 21%; P. damicornis: 11%) than fragments attached without epoxy (A. humilis: 14%; P. damicornis: 8%). Growth after one year was 0.3 cm for Favia stelligera and growth was higher for epoxy-attached Acropora humilis (0.7 cm) than non-epoxy attached (0.3 cm). Stylophora pistillata and Pocillopora damicornis fragments did not grow. Stony coral fragments (78 A. humilis, 93 P. damicornis, 54 S. pistillata, and 11 F. stelligerea) were collected from colonies near the island of El-Fanadir and transported to Hurghada. Artificial substrate (comprising plastic mesh) was secured to the reef, 57 m deep, using nylon thread tied to a rock or fixed iron bar. Fifty-four S. pistillata, 11 F. stelligera, 36 A. humilis and 37 P. damicornis fragments were attached to the mesh by pushing fragments through holes. The remaining 42 A. humilis and 56 P. damicornis fragments were pushed through holes in the mesh then secured to the mesh using epoxy. Survival and growth of fragments were measured after six and 12 months.
Study and other actions testedA replicated study (year not given) at a coral reef at El-Fanadir, Egypt (Ammar et al. 2000) reported that two species of wild-grown stony coral fragments transplanted onto artificial substrate on the sea-facing (windward) side of the reef had higher survival and growth than fragments on the reef-facing (leeward) side, another three species fragments transplanted on the leeward side survived and two of those grew. One year after transplanting, survival was higher for windward fragments (Acropora humilis: 75%; Pocillopora damicornis: 79%) compared to leeward fragments (A. humilis: 69%; P. damicornis: 71%). Growth was higher for windward fragments (A. humilis: 0.6 cm; P. damicornis: 0.7 cm) compared to leeward (A. humilis: 0.5 cm; P. damicornis: 0.4 cm). Data were not statistically tested. Most fragments of the other three stony coral species transplanted on the leeward side survived (Acropora verweyi 66%; Acropora hemprichii 56%; Stylophora pistillata 60%), and two of three species grew (A. verweyi 0.3 cm; S. pistillata 0.5 cm). Stony coral fragments (32 A. humilis, 28 P. damicornis, 15 A. verweyi, 18 A. hemprichii 15 S. pistillata) were collected from wild-growing colonies near the island of El-Fanadir and transported to the study site. Artificial substrate (comprising plastic mesh) was secured to the reef, 4-5 m deep on the leeward side, using nylon thread tied to a rock or fixed iron bar, and fragments were pushed into the plastic mesh. In addition, 42 of the 78 A. humilis and 56 of the 93 P. damicornis fragments were attached to the mesh secured on the windward side of the reef. Survival and growth of fragments were measured after six and 12 months.
Study and other actions testedA replicated study in 1996–1997 at two coral reefs in central Philippines (Raymundo 2001) found that at one of the two sites transplanted fragments of stony coral Porites attenuata placed on artificial substrate next to live colonies of the same species had higher linear and surface area growth but produced fewer branches than fragments next to dead colonies. After 13 months, at Apo linear growth of fragments was significantly higher next to live colonies (78–95 mm) than fragments next to dead colonies (70–77 mm), but there was no difference at Bais (live: 49–50 mm; dead: 58–66 mm). Average weekly surface area growth was also higher at Apo for fragments next to live colonies (2851 mm2) compared to dead (26–32 mm2), but there was no difference at Bais (live 7–9 mm2; dead: 13–15 mm2). Fragments next to live colonies at Apo produced fewer branches (average 5/fragment), compared to those next to dead colonies (average 10–12/fragment), but there was no difference at Bais (average 1–2/fragment). In June 1996, twenty colonies of Porites attenuata were selected at each reef and four unbranched fragments (~4 cm long) were taken from each colony and fixed into 1-inch PVC pipe using marine epoxy. At each reef, eight cement platforms (1 × 0.3 m) were anchored 30 cm above the substrate, 10–11 m deep. Half the fragments at each site were swapped with fragments from the other site and all were fixed (9/platform) alternating with living or dead colonies. Growth was measured weekly for 13 months and the number of branches was counted after 13 months.
Study and other actions testedA replicated study in 1999–2000 at a coral rubble site in Bunaken National Park, North Sulawesi (Fox et al. 2003) found that transplanting stony coral Acropora yongei fragments on a PVC frame elevated above the soft coral canopy led to higher survival than fragments transplanted within the soft coral. Twelve months after transplanting, the survival rate for fragments on the frame was significantly higher (75%) than those within the soft coral (30%). In April 1999, ninety-nine fragments (~10 cm long with 2–4 branches) were collected from a single wild Acropora yongei colony. Forty-nine were attached to a PVC pipe and elevated 5–10 cm above the soft coral canopy. The remaining fragments were attached directly to the coral rubble substrate within the soft coral. Survival was recorded six and twelve months after transplanting.
Study and other actions testedA replicated, controlled study in 1998–1999 at Titia Reef, Tanzania (Lindahl 2003) found transplanted fragments of wild-grown stony corals Acropora muricata and Acropora vaughani on polythene string-grids had a higher survival rate, lower partial mortality, and a greater relative increase in weight of live tissue than unattached fragments, but no difference in total relative weight gain. After one year, 97% of attached fragments survived compared to 87% of unattached fragments. Although most fragments showed some partial mortality (dead tissue), 13% of attached fragments had no tissue loss compared to 7% of unattached fragments. Relative weight gain (weight gained as a proportion of original weight) of living tissue was higher for attached (1.6 × original weight) compared to unattached (1.1 × original weight) fragments. There was no significant difference in total relative weight gain (including live and dead tissue) between attached (1.9 × original weight) and unattached (1.6 × original weight) fragments. In November 1998, branches (average 34 cm long) from seven colonies of Acropora muricata and six of Acropora vaughani were collected within 2 km of the study site. Twenty-eight fragments were taken from each branch and weighed. Twenty fragments were tied to 2 × 1 m lengths of polythene string at 10 cm intervals, eight fragments were left unattached on the substrate (total 260 attached, 104 unattached fragments). Several (number not specified) of the 1 m lengths of string were tied together to form a grid which was placed (unsecured) on the substrate, 3 m deep. Survival and weight were measured after one year.
Study and other actions testedA replicated, controlled, before-and-after study in 1998–1999 at Titia Reef, Tanzania (Lindahl 2003) found transplanting damaged fragments of stony coral Acropora muricata onto a PVC rack did not result in any difference in relative weight of live tissue compared to undamaged fragments. After eight months, there was no difference in relative weight gain (weight gained as a proportion of original weight) of living tissue between damaged (1.5–3.4) and undamaged (1.5–3.7) fragments. In November 1998, eighteen fragments of stony coral Acropora muricata were collected from each of 12 different coral colonies. Nine fragments from each colony were randomly selected and damaged (to simulate handling damage) by scraping a knife along the main branch and trimming all branch tips by 2 cm to remove soft tissue creating a scar 3–5 mm wide and 1 mm deep. Nine fragments were left undamaged. Fragments (108 damaged and 108 intact) were attached vertically to a PVC rack 3 m deep using cable ties. Fragments were weighed immediately before the treatment and again eight months later.
Study and other actions testedA replicated, before-and-after study in 2004–2005 on five coral patch-reefs in Pangasinan, Philippines (Cabaitan et al. 2008) reported that transplanting branching Acropora and Pocillopora stony coral fragments onto concrete blocks led to a >72% survival of transplanted corals and an increase in percentage cover of branching corals (including growth of existing colonies, transplants and wild recruits) but a similar percentage cover of wild non-branching coral (including growth of existing colonies and recruits) in the surrounding plot compared to before transplantation. Statistical results were not reported. In the plots with transplanted branching Acropora and Pocillopora corals, the average percentage cover of branching corals increased from 2% the month before transplantation, to 11% the month after, and 16% one year after, whereas the average cover of non-branching corals in the plots before-and-after was similar (7% before, 6% after one month, 8% after one year). There was >72% survival of transplanted corals each month. In December 2005, fifty wild-grown Acropora and 50 Pocillopora (~15 cm width) fragments were collected from nearby reefs and transplanted in five 5 m2 plots on degraded reefs (>20 m apart). Fragments were cemented individually onto 20 × 20 × 5 cm concrete blocks. Corals were surveyed using digital photographs taken monthly from September 2004–November 2005. Corals that were found dead during surveys were replaced (numbers not given).
Study and other actions testedA replicated study in 2005–2007 at three degraded coral reefs in North Sulawesi, Indonesia (Ferse 2010) found transplanting wild-grown stony coral species onto pre-cast concrete blocks attached to bamboo frames led to up to 81% of fragments surviving but results were species-dependent. Isopora brueggemanni had the highest overall survival (81% after 11 months) followed by Acropora yongei (33% after 20 months) and Acropora muricata (21% after 15 months) fragments. Pocillopora verrucosa had the lowest survival (5–11% after 15–20 months) (results not tested statistically). Between September 2005 and June 2006, a 100 m2 quadrat was set up at each of three sites of predominantly coral rubble. Quadrats were sub-divided into 100 squares (1 m2) each containing a bamboo frame. Coral fragments (5–10 cm), collected from locally abundant colonies near each transplant site, were fixed onto precast concrete bases using epoxy then attached to the bamboo frames (approximately 50 fragments/frame) using cable ties. The following fragments were attached at each site: Gangga: Acropora yongei (1,855) and Pocillopora verrucosa (475), Meras: Acropora muricata (1,677) and Pocillopora verrucosa (378), Benaken: Isopora brueggemanni (1,749). Monitoring began several months after transplanting and was approximately monthly (Gangga: September 2005–May 2007, Meras: March 2006–June 2007, Bunaken: June 2006–May 2007). Survival was recorded for fragments attached to the concrete base with living tissue on at least one branch. Materials cost 4,395,000 IDR (2010 value). The cost included the bamboo frames, cable ties, epoxy glue and concrete bases but did not include work time for setting up the experiment.
Study and other actions testedA study in 2009–2011 on a coral reef in the Red Sea, Egypt (Herler & Dirnwober 2011) found that all wild-grown stony corals Acropora digitifera and Acropora selago transplanted onto an artificial substrate survived for at least nine to 15 months. Nine or 15 months after transplanting, all transplanted Acropora digitifera and Acropora selago colonies survived. Wild colonies of Acropora digitifera and Acropora selago (approximately 25 cm diameter) were cut from their natural 1–2 m depth reef with a saw, through the coral rock close to their base, rather than live tissue. Four colonies of each species were transplanted in October 2009 and 12 of each species in April 2010. Colonies were attached with epoxy resin to 10 cm2 or 12 cm2 PVC plates, each of which was attached to a 28 × 35 × 5 cm concrete block with two 1.5 × 5 × 0.1 cm steel plates fixed with steel screws and plastic dowels, which could be removed to allow the PVC plate and colony to be weighed. Colonies were orientated towards the same cardinal direction as in their original location. Both colonies were surveyed in January 2011.
Study and other actions testedA site comparison study in 2009 on15 artificial reefs and one natural reef in Aceh, Indonesia (Fadli et al. 2012) found that transplanting stony coral Acropora subglabra and Acropora formosa fragments onto artificial reefs led to increased coral coverage two and three years after transplantation compared to one year after transplantation but there was no difference in the number of coral recruits with age of reef. There was no difference in average coral cover on two- (65%) and three-year-old (64%) artificial reefs and a nearby natural reef (50%), but these were all higher than on a one-year-old artificial reef (24%). However, the average number of coral recruits on one- (53 corals/m2), two- (39 corals/m2) and three-year-old (57 corals/m2) artificial reefs was similar, with one-year-old and three-year-old artificial reefs having more coral recruits than the natural reef (31 corals/m2). There were more types of coral on three-year-old (16) than one- (12) and two-year-old (11) artificial reefs (not tested statistically). In June 2006, August 2007 and December 2008–January 2009, artificial reefs consisting of nine 1.25-m2 concrete cylinders enclosed within four concrete oblong blocks were placed on the substrate. These were topped with plastic pipes (one/cylinder and four/block). After 4–6 weeks, 25 cm stony coral fragments were attached to the pipes with cable ties. Fragments were obtained in 2006 from nearby healthy reefs and in 2007 and 2008 from colonies that had established on the artificial reefs. In November 2009, five artificial reefs from each deployment were randomly chosen and surveyed using digital photos and transects. As a comparison, corals were also surveyed on a nearby natural reef which was denuded in 2005.
Study and other actions testedA replicated study in 2008–2009 at a site in Menorca, Spain (Linares et al. 2012) found that transplanting fragments of juvenile temperate soft coral Eunicealla singularis on PVC and rubber plates above patches of nuisance turf algae led to higher survival and growth compared to corals transplanted on plates attached onto the rocky substrate and exposed to turf algae overgrowth. Fifteen months after transplanting, survival rate of fragments not exposed to turf algae growth was 90% compared to 30% for fragments exposed to turf algae. Growth was higher for fragments not exposed (2.8 mm) compared to exposed turf algae (2.1 mm). In April 2008, small end-tips (<5 cm) were collected from 80 individual colonies of Eunicealla singularis. Tips were attached to ten PVC plates overlayed with rubber (eight tips/plate) using holes and slits cut into the rubber. Five plates were raised above the substrate on a frame, so were not exposed to turf algae growth. Five plates were attached directly onto the rocky substrate, so were exposed to turf algae growth. Survival was recorded in-situ after fifteen months. Growth was measured in a laboratory using 20 randomly selected tips (10 each from exposed and non-exposed plates).
Study and other actions testedA study in 2004 and 2010 at a coral reef restoration site on Maiden Island, Antigua (Cummings et al. 2015) found that transplanting stony coral fragments on artificial structures (Reef Balls) led to lower growth rates for staghorn Acropora cervicornis coral but similar growth for elkhorn Acropora palmata and Porites porites compared to naturally-growing corals (data from other studies). Six years after transplanting, average growth of staghorn fragments was lower (4.9 cm/year, range: 1.67–7.93 cm/year) than reference values for naturally-growing colonies (10.8 cm/year, range 2.52–26.4 cm/year). Average growth of Porites porites fragments was similar (0.96 cm/year, range: 0.21–2.21 cm/year) to reference values (1.31 cm/year). The estimated average growth of two elkhorn fragments was similar (9.6 cm/year) to reference values (7.59 cm/year, range: 5.2–10 cm/year). In 2004 loose fragments of stony coral were collected and broken into 1–3 cm nubbins (small fragments). Nubbins were fixed to cement plugs and attached to approximately 3,500 artificial structures (Reef Balls) (data and methods from other studies). In 2010, six years after Reef Balls were installed, growth rate (linear extension) of fragments from three of the transplanted stony coral species (staghorn Acropora cervicornis, elkhorn Acropora palmata, and Porites porites), was measured using scaled photographs and based on an estimated average length of 1.9 cm/fragment at transplant. For comparison, reference data for naturally growing colonies was taken from previously published papers (see original paper for details).
Study and other actions testedA replicated study in 2013 at a coral reef site in Pulau, Indonesia (Gallagher & Doropoulos 2017) found that transplanting juvenile wild-grown stony corals Porites lobata and Pocillopora damicornis into crevices on artificial settlement tiles led to a higher survival rate compared to transplants in partial crevices or fully exposed on the tile surface, but no difference between small or large crevices. Twenty-nine days after settlement tiles were installed, survival rate for Porites lobata was higher in the full crevices (93%) compared to partial crevices (68%) and fully exposed (28%) and higher in partial crevices compared to fully exposed. All juvenile Pocillopora damicornis except one had died by day eight although those in the full crevice survived longer (8 days) than partial crevice or fully exposed (both 6 days). There was no significant difference between survival rates for either species in different size crevices (data not reported). In June 2013, four hundred and eighty micro-nubbins (juveniles) were taken from each of five wild-grown colonies of Porites lobata and Pocillopora damicornis. Crevices (either 1.2 × 1.2 × 1.0 cm or 2.0 × 2.0 × 2.0 cm) were cut into 40 sand and cement settlement tiles (10 × 10 cm) creating a ‘chequerboard’ pattern. Twenty-four juveniles from the same species were glued to each tile in the full crevice (4/tile), partial crevice (open on one side 8/tile), or tile surface (fully exposed 12/tile). Tiles were placed on the sea floor, 7 m deep. Juveniles were monitored nine times during the 29-day experiment.
Study and other actions testedA randomized, before-and-after study in 2015–2016 on a seawall in the Singapore Strait, Singapore (Toh et al. 2017) reported that 58–100% of corals transplanted onto a subtidal seawall survived, depending on the species, that individuals of five of six species grew, and coral species richness and cover increased. After six months, average transplant survival was lower for Pocillopora damicornis (58%) than for all other stony coral species (Echinopora lamellosa: 100%; Hydnophora rigida: 100%; Merulina ampliata: 91%; Platygyra sinensis: 97%; Podabacia crustacea: 92%). All surviving fragments had positive growth rates (Echinopora lamellosa: 11 cm2/month; Hydnophora rigida: 14 cm2/month; Platygyra sinensis: 4 cm2/month; Pocillopora damicornis: 26 cm2/month; Podabacia crustacea: 4 cm2/month) except Merulina ampliata (-1 cm2/month). Coral species richness and cover on the seawall was higher (8 species, 21% cover) than before corals were transplanted (2 species, 3% cover). In August–December 2014, forty-two coral colonies (approximately 60 cm diameter) were collected from natural reefs and fragmented into 7–10 cm diameter colonies. Fragments were cultivated on nursery tables adjacent to a granite boulder seawall, elevated 0.5 m above the seabed 4 m deep for nine months. In April–August 2015, surviving colonies (213) were transplanted and fixed onto the seawall using epoxy putty. Fragments (diameter: 9–16 cm; area: 48–160 cm2) of six stony coral species (36 fragments/species) were randomly arranged in four patches on the seawall at 3 m deep. Corals were counted on a 20 × 3 m section before and six months after transplants were attached. Transplants were monitored from photographs over six months. Costs (US$): Cultivation and transplantation cost $21,634 (2017 value).
Study and other actions testedA replicated, controlled study in 2016 at a coral reef near Wasini Island, Kenya (Knoester et al. 2019) found that transplanting stony coral Acropora verweyi fragments under cages to exclude fishes led to fewer bites by coral-eating fishes, but lower growth and survival, and higher levels of biofouling, than uncaged or partially caged fragments. Bite rates by coral-eating fishes were lower for caged fragments (0 g/min) compared to uncaged (0.32 g/min) and partially-caged (0.09 g/min), but there was no difference between uncaged and partially-caged. Specific growth rate/day (see original paper for equation) of caged fragments was lower (0.0047) than uncaged (0.0078) and partially-caged (0.0099). After 100 days, survival was lower for caged (89%) than uncaged (98%) and partially-caged (99%) fragments. There was no difference in growth or survival between uncaged and partially-caged fragments. Total fouling (including molluscs, algae, and crustose coralline algae) was higher in caged (484 g/m2) compared to uncaged (61 g/m2) and partially-caged (78 g/m2) structures, and there was no difference between uncaged and partially-caged. In April 2016, forty-five frames, comprising four 26 cm PVC pipes forming a cross, were installed 3 m deep at each of 15 locations along a 100 m stretch of reef. Four hundred and fifty naturally broken fragments of stony coral were collected from a reef, cut into 4 cm lengths, and suspended from the frames by fishing line (10 fragments/frame). A wire cage (0.5 × 0.25 × 0.25 m, 1.3 × 1.3 cm mesh size) was attached to 15 frames, a wire cage with two open sides was placed on 15 frames, and the remaining 15 frames were left uncovered. Bite rate (reported as fish-size-related mass in g/min – see original paper), growth, and survival were estimated each month using photographs. The experiment lasted 100 days.
Study and other actions testedA replicated, controlled study in 2017–2019 at two reefs off Belize (Baumann et al. 2021) found that some stony corals Pseudodiploria strigosa and Siderastrea siderea transplanted between offshore and nearshore reefs survived for at least 17 months and in three of four cases corals grew over that period. For transplants from an offshore to nearshore reef, survival after 17 months was 96% for both species. For transplants from a nearshore to offshore reef, survival after 17 months was 92% for Pseudodiploria strigosa and 32% for Siderastrea siderea. Survival of fragments placed back in their native reef was 100% for Pseudodiploria strigosa (offshore and nearshore) and 100% (offshore) or 72% (nearshore) for Siderastrea siderea. All transplanted Pseudodiploria strigosa had gained weight after 17 months (77–146% increase). For Siderastrea siderea, fragments transplanted to the nearshore reef gained weight (79% after 17 months) but those transplanted offshore did not (-3% after 17 months). Results on endosymbiont density, chlorophyll-a concentration and energy reserves were also reported. In 2017, colonies were collected from a nearshore and offshore reef (6 colonies/reef/species) and fragmented. Fragments were super-glued to plastic dishes with pre-drilled holes, attached to mesh nursery tables using cable ties and installed on the sea floor. Six fragments from each colony (12 colonies/species) were transplanted (nearshore to offshore, or offshore to nearshore) and six were placed back in their native reef. A subset of fragments was collected after three (35 fragments), nine (37) or 17 months (46) to assess growth and survival.
Study and other actions testedA replicated study in 2016 at a coral reef site in Hawai’i, USA (Counsell & Donahue 2021) found that transplanting corals Pocillopora meandrina onto artificial substrate, with or without beneficial invertebrates, resulted in growth over a six-month period. During the first eight weeks, coral growth was lower in corals with two beneficial invertebrate species (Trapezia intermedia and Alpheus lottini; 0.12% change/day) than for corals with just T. intermedia or no beneficial invertebrate species (0.15% change/day), and corals with A. lottini had similar growth to all other treatments (0.14% change/day). Over a period of six months, growth rates were similar for corals with or without beneficial invertebrate species (0.05–0.08% change/day). In May 2016, forty coral colonies (all hosting T. intermedia) were collected from a forereef habitat and assigned to one of four treatments (9–11 corals/treatment): transplanting with two beneficial invertebrate species (A. lottini and T. intermedia), with one (A. lottini or T. intermedia) or with none. All corals were attached to PVC plates and secured to cement blocks and randomly situated within an experimental grid (10 rows of four corals). Coral growth was assessed using buoyant weights for the first eight weeks and using aerial photographs for the subsequent six months.
Study and other actions testedA replicated, controlled study in 2020 on a reef off Florida, USA (Rivas et al. 2021) found that after transplanting wild-grown coral Orbicella faveolata, fragments placed adjacent to staghorn coral colonies Acropora cervicornis had lower predation mortality than those placed 25–50 cm away. Fragments placed adjacent to staghorn colonies had lower predation mortality (64% after four weeks) than corals located 25–50 cm away (86–92% after four weeks). Authors reported that corals placed 25–50 cm away had lower mortality than average predation rates in plots without staghorn colonies (100%), although this result was not tested for statistical significance. Predation mortality increased throughout the course of the experiment (1 week: 3–10%, 2 weeks: 27–61%, 4 weeks: 68–90%). Coral fragments were transplanted to three sites (10 m diameter, 36 fragments/plot) with staghorn coral (4 corals/m2). Fragments were implanted in a cement mixture and placed 2–3 cm, 25 cm or 50 cm from the base of a staghorn coral colony. Every coral fragment was surveyed visually one week, two weeks, and four weeks after transplanting. Mortality was also compared to fragments transplanted into additional plots that were >10 m from staghorn colonies.
Study and other actions testedA replicated, controlled study in 2020 on a reef off Florida, USA (Rivas et al. 2021) found that after transplanting wild-grown coral Orbicella faveolata, fragments protected with cages or spikes had lower predation mortality than those with no protection. Fragments protected by full cages had lower predation mortality after four weeks (0%) compared to those protected with open-top cages (75%), spikes (19%) or fragments with no protection (100%). One week after removing cages and spikes, 72–97% of the corals suffered complete mortality, and 96% of additional fragments that were transplanted at that time with no protection also suffered complete mortality. Predation mortality increased throughout the first month (1 week: 0–25%, 2 weeks: 0–87%, 4 weeks: 0–100%). Seventy-two coral fragments (5 cm3) were transplanted to three reef plots (10 m diameter, 24 fragments/plot). At each plot, 12 fragments were protected by full cages and 12 by open-top cages. In addition, 24 cement “pucks” (10 cm diameter) were placed in each plot, 12 of which were fitted with steel spikes. A coral fragment was glued to the centre of each puck. Cages and spikes were removed after 1 month, and nine additional fragments with no protection were also transplanted at this time. Every coral fragment was surveyed visually one week, two weeks, and four weeks after transplant, and corals in the cage and spike treatments were also monitored one week after cage and spike removal.
Study and other actions testedA replicated, controlled study in 2020 on a reef off Florida, USA (Rivas et al. 2021) found that after transplanting wild-grown coral Orbicella faveolata onto artificial substrate, coral fragments transplanted as individuals suffered higher predation mortality than those transplanted in clusters. Individual coral fragments had higher predation mortality after four weeks (100%) compared to clusters of coral fragments (80%). Individual coral fragments also lost more tissue than clusters of coral fragments (data reported as statistical model results). Predation mortality increased throughout the course of the experiment (1 week: 0%, 2 weeks: 15–45%, 4 weeks: 80–100%). Coral fragments were transplanted onto a cement mixture as either an individual fragment (5 cm2) or as a cluster of five fragments (25 cm2). Three plots were established, with 12 individual fragments and five fragment clusters transplanted to each plot. Fragments were placed haphazardly within plots, no closer than 50 cm from each other. Every coral fragment was surveyed visually one week, two weeks, and four weeks after transplant.
Study and other actions testedA replicated study in 2018–2019 at six coral reef sites off Mauritius (Tiddy et al. 2021) found that after Acropora muricata were transplanted onto an artificial substrate next to existing Porites lutea colonies, Porites lutea colonies with adjacent Acropora muricata had similar bite density and surface area damage compared to in-situ colonies with no adjacent Acropora muricata. Data reported as statistical model outputs. In December 2018, at each of three sites, 40 Acropora muricata fragments were transplanted to 10 existing, isolated Porites lutea colonies (four fragments/ colony). Fragments consisted of a forked branch measuring approximately 30–40 cm in length. Transplanted Acropora muricata and existing Porites lutea were fixed together to concrete blocks with cement and string. Transplanted corals were monitored in February–March, April, and June 2019. In-situ Porites lutea (434 colonies) with no adjacent Acropora muricata were monitored across six sites every two months from September 2018 to June 2019.
Study and other actions testedA replicated, before-and-after study in 2013–2017 at a degraded coral reef in Pulau Badi, Indonesia (Williams et al. 2019) reported that transplanting wild-grown stony coral (mainly Acropora spp.) fragments onto artificial structures led to an increase in live coral cover on the structures and surrounding reef and, in one area, an increase in overall coral cover compared to before the structures were installed. After 24.5 years, the average cover of live coral on the structures ranged from 17%89%. Live coral cover on the natural substrate in one area was 7% before the structures were installed, whereas one year after transplanting, overall coral cover in the area was 48% of which 25% was on the structures. At the end of the study, average live coral cover in the oldest section (deployed in March 2013) was 21% on structures and 41% on the natural substrate. Data were not statistically analysed. Between March 2013 and September 2015, approximately 11,000 hexagonal steel-rod ‘spider’ structures (0.337 m2) were placed 28 cm above the substrate across ~7,000 m2 of degraded coral reefs. Eighteen stony coral fragments (~15 cm in length) were evenly spaced around the spider and attached using cable ties. Coral cover on the structures was recorded every four months for three years from 2014. Some spider structures were vandalized in 2014 and a large storm affected one section in 2017. Costs (US$): Total cost of installing 11,000 spiders (including materials, construction labour, transport, coral attachment and installation labour) was US$174,000 (2015 values).
Study and other actions tested
Where has this evidence come from?
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This Action forms part of the Action Synopsis:
Coral ConservationRelated Actions
| Actions | Effectiveness | Studies | Category | |
|---|---|---|---|---|
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Transplant nursery-grown coral onto natural substrate Action Link |
Awaiting assessment | 22 |
Synopsis Link |
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Transplant nursery-grown coral fragments onto artificial substrate Action Link |
Awaiting assessment | 15 |
Synopsis Link |
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Remove problematic species Action Link |
Awaiting assessment | 7 |
Synopsis Link |
Coral Conservation - Published 2024
Coral synopsis
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