Cultivate corals in an ex-situ nursery
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Overall effectiveness category Awaiting assessment
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Number of studies: 36
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Supporting evidence from individual studies
A replicated, randomized study in 1997–1998 at an ex-situ aquarium and natural reef in the Bahamas (Becker & Mueller 2001), found that fragments of staghorn Acropora cervicornis and elkhorn Acropora palmata corals cultivated in seawater tanks had higher basal growth than fragments cultivated on a natural reef but similar or lower vertical and calcium-carbonate growth. After 10 months, basal growth was higher for fragments cultivated in an aquarium tank (staghorn: 56; elkhorn: 84 mm) compared to fragments cultivated on a natural reef (staghorn: 28; elkhorn 45 mm). Vertical growth of elkhorn fragments was lower for tank (17 mm) than natural reef (41 mm) cultivated fragments but there was no significant difference for staghorn fragments (tank: 40; reef: 31 mm). Calcium carbonate growth of elkhorn fragments was lower for tank (65 mg/day) than natural reef (112 mg/day) but no difference for staghorn fragments (tank: 39; reef 24 mg/day). In July 1997, twelve fragments (~7 cm long) were taken from each of two colonies of staghorn and elkhorn corals (48 fragments). Each fragment was attached upright to a PVC plate using epoxy. Fragments were weighed before-and-after attachment. Fragments were randomly chosen to be transplanted into an open water 1-m-deep tank or transplanted onto a steel array 3 m deep at a nearby patch reef site. After 10 months, corals were collected and weighed to determine calcium carbonate growth. Vertical and basal growth were assessed using photographs.
Study and other actions testedA study in 1998–1999 at an aquarium in Munich, Germany (Petersen & Tollrian 2001), reported that some wild-grown stony coral Acropora florida larvae cultivated in an ex-situ nursery settled (vertically and horizontally), and that surviving spat (settled larvae) grew and produced polyps. Two weeks after 400 stony coral larvae were placed in settlement tanks, 99/400 (25%) had settled onto ceramic tiles (46 on vertical surfaces and 53 on horizontal). After seven weeks, overall survival rate of spat was 83% decreasing to 72% after 19 weeks. Survival rate remained at 27% from week 3240. Coral spat settled on vertical surfaces had a higher survival rate (19/46, 41%) after 40 weeks compared to horizontal (8/53, 15%). The average number of polyps increased from one/colony after two weeks to 13/colony after 32 weeks. In June 1998, four hundred larvae from wild-growing stony coral colonies in Okinawa, Japan, were flown to an ex-situ nursery at an aquarium in Munich, Germany. These were placed into tanks filled with artificial seawater and allowed to settle onto conditioned ceramic settlement tiles. After 32 weeks, tiles with juvenile colonies on their surface were transferred to an aquarium and attached to the rocky substrate using a screw. Survival and growth (number of new polyps) of coral spat and juveniles were monitored after 2, 7, 19, 32 and 40 weeks.
Study and other actions testedA study (year not given) at an aquarium in Eilat, Israel (Shafir et al. 2001), found that cultivated stony coral Stylophora pistillata nubbins (small fragments) survived and grew and there was no difference in survival or growth rate for nubbins taken from the donor colony branch tip compared to mid-branch. After 90 days, all 20 nubbins taken from branch tip or mid-branch survived. The average growth rate was 0.42 polyps/nubbin/day and the average number of polyps had increased from 5–44/nubbin (branch-tip) and 5–47/nubbin (mid-branch). There was no significant difference between average polyp numbers on tip or mid-branch nubbins. One S. pistillata colony was collected from 4–6 m deep and taken to an ex-situ aquarium. Twenty nubbins (~five polyps each) were taken from the colony (eight from branch tips; 12 from mid-branch ~3 cm below the tip), super-glued to glass slides, and placed in a 16-L running seawater aquarium. Survival and growth (number of new polyps) were measured weekly for 90 days using a binocular microscope.
Study and other actions testedA replicated study (year not given) at an aquarium in Eilat, Israel (Shafir et al. 2001) found that cultivated stony coral Stylophora pistillata nubbins (small fragments) in an ex-situ nursery under a combination of Floura, Cool-White, and Blue-Blue lighting had a greater increase in new polyp development than nubbins under individual lights. After 107 days the average number of polyps/nubbin was higher for nubbins cultivated under the combination lighting (34 polyps/nubbin; 195% increase) than those under single Floura (31 polyps/nubbin; 160% increase), Cool-White (24 polyps/nubbin; 128% increase), or Blue-Blue (20 polyps/nubbin; 116% increase) lights. Three wild-growing S. pistillata colonies were collected from 4–6 m deep and taken to an ex-situ aquarium where 192 nubbins (64/colony) were collected from branch tips and mid-branch. Nubbins were super-glued to glass slides and distributed evenly between four 16-L aquarium tanks. Each tank was subjected to a different light regime with three fluorescent tubes/aquarium comprising either Blue-Blue, Cool-White, Fluora, or a combination of all three lights. The number of new polyps was counted each week using a binocular microscope.
Study and other actions testedA replicated study (year not given) at an aquarium and natural reef in Eilat, Israel (Shafir et al. 2001) found that stony coral Stylophora pistiallata nubbins (small fragments) had a higher survival rate in an ex-situ nursery than an in-situ nursery, and that ex-situ nubbins grew. After 40 days, 95% of ex-situ cultivated nubbins had survived compared to none of the in-situ cultivated. After 103 days, 60% of the ex-situ nubbins survived. After 40 days, 153/300 (51%) ex-situ nubbins had grown across the substrate and after 103 days, 117/300 (39%) had grown. Three wild-growing S. pistillata colonies were collected from 4-6 m deep and taken to an ex-situ aquarium where 200 nubbins (5-15 polyps/nubbin) were removed from each colony. Nubbins were super-glued onto 10 × 10 cm plastic squares. Three hundred were placed into ex-situ aquaria and 300 were placed 5 m deep, 1 m above the natural reef substrate (method not reported). Survival and growth were measured after seven, 40, and 103 days (method not reported).
Study and other actions testedA replicated, controlled study in 2000 at a laboratory near Sdot-Yam, Israel (Fine et al. 2002) found that stony coral Oculina patagonica fragments exposed to ultraviolet radiation (UVR) did not show signs of bleaching, and levels of the bacteria Vibrio shiloi, known to cause bleaching, were undetectable compared to fragments shielded from UVR. After 25 days, none of the 20 fragments infected with Vibrio shiloi and exposed to direct sunlight with UVR showed any signs of bleaching. All 20 fragments infected and then exposed to direct sunlight but shielded from UVR showed total bleaching (100% loss of pigmentation) after 10 days. After 8 hours the number of V. shiloi detected in infected fragments exposed to UVR decreased by 97% and was no longer detectable after 10 hours. The number of V. shiloi in infected fragments shielded from UVR increased from 42,000 to 25 million/cm2 after six hours and remained constant for seven days. Ten uninfected control fragments did not show any sign of bleaching whether they were exposed to or shielded from UVR. Forty stony coral Oculina patagonica fragments were each infected with the bacteria Vibrio shiloi (42,000/cm2). Twenty fragments were placed in a tank and exposed to direct sunlight, the other 20 were exposed to direct sunlight but were shielded from UVR by a 5 mm Plexiglass cover that blocks 100% UVR but allows 95% visible light through. Ten control fragments not infected with V. shiloi were placed in direct sunlight (five with and five without UVR shielding).
Study and other actions testedA replicated, randomized study in 1996–1998 at a laboratory and reef in Bolinao, Philippines (Yap & Molina 2003) found that ex-situ-cultivated fragments of stony coral Porites cylindrica and Porites rus survived and grew but less so than fragments in an in-situ (reef) nursery. After 19 months, survival rate was lower for laboratory-cultivated (P. cylindrica: 12%; P. rus: 0.5%) than reef-cultivated (P. cylindrica: 44%; P. rus: 42%) fragments. Weight gain was lower for ex-situ fragments of both species than transplanted (P. cylindrica: ex-situ 18 g, transplanted 78 g; P. rus: ex-situ 80 g, transplanted 165 g). In November 1996, sixty fragments each of P. cylindrica and P. rus were collected and transported to a marine laboratory, trimmed, and super-glued to acrylic plates. Thirty fragments from each species were randomly selected and transplanted to a sandy lagoon. Fragments from both species were distributed evenly across six 1-m2 steel grids, 20 cm above the seabed. The remaining 60 fragments were similarly distributed on plastic grids in one of three seawater-filled plastic tanks in the laboratory. Mortality was recorded every two weeks. Growth was measured every two months for 19 months.
Study and other actions testedA replicated, randomized study in 1997–1998 at a laboratory and natural coral reef in central Philippines (Raymundo & Maypa 2004), found that cultivating Pocillopora damicornis larvae in an ex-situ nursery led to a higher settlement rate and survival compared to larvae cultivated in-situ on a natural reef. Average settlement success was higher for ex-situ cultivated larvae (59%) compared to in-situ cultivated (12%). One week after settlement, average survival was higher for ex-situ cultivated larvae (76%) than for in-situ (42%). Ex-situ cultivated juveniles grew an average of 2.3 mm/week over six months (data not reported for in-situ cultivated). On each of nine sampling months from February 1997–August 1998, five wild-growing P. damicornis colonies were collected from a reef and kept in ex-situ aquarium tanks to spawn. Larvae were collected and either placed into tanks with limestone settlement tiles (48 cm2) or taken to the reef and injected into settlement traps (6–12 traps with 4050 larvae/trap) attached to the reef substrate. Tiles with settled larvae (360–1500 larvae) were transferred to cultivation tanks with flowing unfiltered seawater. Settlement traps on the reef were removed after 24 h and settlement success was measured. Survival was measured each day for a week and then weekly for one month. Growth was measured weekly for six months on a randomly selected group of 20 ex-situ cultivated juveniles settled in February 1997.
Study and other actions testedA replicated, randomized study in 1998–1999 at a laboratory in central Philippines (Raymundo & Maypa 2004), found that cultivated stony coral Pocillopora damicornis larvae survived and developed polyps. Coral spat (settled larvae) that naturally joined in pairs or groups had higher survival and developed more polyps than single spat. Average weekly survival over six months was higher for groups (99.9%) and pairs (99.8%) compared to single juveniles (98.2%) and there was no significant? difference in survival rate between groups and pairs. After six months, the average number of polyps was higher in groups (48 polyps/colony) than in pairs (30 polyps/colony) and single (15 polyps/colony), there was no difference between pairs and single colonies. In July 1998, three wild-growing P. damicornis colonies were collected from the reef and kept in ex-situ aquarium tanks to spawn. Larvae were collected and placed into one of three settlement tanks (60 larvae/500 ml water) to settle onto limestone settlement tiles (48 cm2). Settlement and joining were measured after 24 h. Tiles containing settled juveniles were transferred to cultivation tanks with flowing unfiltered seawater. Survival was recorded weekly or every two weeks for six months , and the number of polyps/colony was recorded weekly for six months for all joined colonies and 40 randomly selected single colonies.
Study and other actions testedA replicated study (year not given) at an aquarium in Colombia (Pizarro & Thomason 2006) found that embryos of mountainous star coral Montastraea faveolata cultivated in vials with aerated seawater died within two hours, whereas all embryos in vials without aeration survived. Two hours after the embryos were placed in the vials, all embryos in the aerated water had turned white (indicating they had died). Embryos in the non-aerated water remained orange (indicating they were still alive). Egg-sperm bundles from mountainous star coral were placed into sealed vials with seawater and submerged in a seawater lagoon for 12 h to allow natural fertilization. Once fertilized, 70–100 embryos were transferred to each of 50 vials. Seawater was aerated in 25 of the vials. All vials were placed in aquarium water baths at 28°C.
Study and other actions testedA study in 2006–2007 at an ex-situ nursery in Spain (Orejas et al. 2008) reported that fragments of cold-water coral Lophelia pertusa and Madrepora oculata cultivated in aquaria grew and developed new polyps and growth rate and polyp development were similar, and sometimes higher, than wild-growing coral. Vertical linear extension of ex-situ cultivated Lophelia pertusa was 15–17 mm/year and Madrepora oculata was 3–18 mm/year. Polyps developed on Lophelia pertusa (4/year) and on Madrepora oculata (5/year). Growth rate and polyp development is reported as similar and sometimes higher than in-situ measurement rates (data from other studies). In August 2006, fragments of cold-water coral Lophelia pertusa and Madrepora oculata (number and size not reported) were collected from approximately 200 m deep in the Cap de Creus Canyon, NW Mediterranean. Fragments were maintained in dark aquaria and fed daily with Artemia sp. and Mysidacea. Water temperature was 11.5–12.5°C. Growth rate and number of polyps were measured in December 2006, March, May and November 2007.
Study and other actions testedA study in 2006–2007 at ex-situ aquaria in Puerto Rico and 10 other locations (Petersen et al. 2008) reported that elkhorn coral Acropora palmata larvae reared from field-collected eggs developed into juvenile corals. In August 2006, eggs from the threatened elkhorn coral were collected and fertilized in a laboratory aquarium. Half the 900,000 fertilized eggs were distributed among 10 aquaria located around the world. Approximately 20% of these eggs settled onto ceramic settlement tiles. Eighteen months after settlement, 800 juvenile corals were established in the aquaria, with some colonies 9 cm in diameter. In August 2006, eggs were collected from elkhorn coral at a reef at the Trés Palmas Reserve, Rincon. No other methodological details are reported.
Study and other actions testedA replicated study in 2006–2007 at an ex-situ nursery in Singapore (Lee et al. 2009) found that a cultivated stony coral Pocillopora damicornis larvae settled in higher numbers on tiles made from cement mixed with coral rubble than on any of five other artificial substrate materials. After ten days, the average number of coral spat (settled larvae)/tile was highest on cement tiles mixed with 10% coral rubble (13 spat/tile) than any of the other materials (acrylic plates: one spat; cement tiles: three spat; ceramic tiles: four spat; glass plates: five spat, and PVC plates: seven spat/tile). Significantly more larvae settled on PVC plates than acrylic or cement tiles. Five wild-growing colonies (10–25 cm diameter) of Pocillopora damicornis were collected from reefs at Kusu Island and Raffles Lighthouse and maintained in tanks. From May 2006–March 2007, larvae were collected from the Pocillopora damicornis colonies and maintained for 1–2 days. Fifty larvae were randomly selected and placed into one of 24 two-litre polythene tanks containing one of the settlement materials (200 larvae/material and four tanks/material). Larvae settlement was counted daily for 10 days.
Study and other actions testedA replicated study in 2006–2007 at an ex-situ nursery in Singapore (Lee et al. 2009) found that a higher number of stony coral Pocillopora damicornis spat (settled larvae) on cement tiles mixed with 10% coral rubble than tiles with other cement and rubble mixes. After ten days, the average number of spat was higher on tiles comprising cement with 10% coral rubble (13/tile) than on tiles comprising cement with 0% rubble (6/tile), 1% rubble (7/tile), 5% rubble (6/tile), and 20% rubble (8/tile). Five colonies (1,025 cm diameter) of Pocillopora damicornis were collected from reefs at Kusu Island and Raffles Lighthouse and maintained in tanks. From May 2006–March 2007, larvae were collected from the Pocillopora damicornis colonies and maintained in darkened plastic containers for 12 days. Fifty larvae were randomly selected and placed into a two-litre polythene tank containing one cement tile mixed with 0%, 1%, 5%, 10%, or 20% coral rubble. There were four tanks for each tile type. Larvae settlement was counted daily for 10 days.
Study and other actions testedA replicated, randomized study in 2008 at a laboratory at Carrie Bow Cay, Belize (Ritson-Williams et al. 2010) found that some five- and seven-day old elkhorn coral Acropora palmata and staghorn coral Acropora cervicornis larvae settled in containers, and settlement rates of seven-day old elkhorn coral larvae were higher in containers containing coralline algae Hydrolithon boergesenii than in containers with three other coralline algae species or coral skeletons. Seven-day old elkhorn coral larvae had higher average settlement rates in containers with Hydrolithon boergesenii fragments (81%) than in containers with fragments of Paragoniolithon solubile (46%), Porolithon pachydermum (39%), Titanoderma prototypum (34%) or staghorn coral skeleton (52%). Settlement rates of five-day old elkhorn coral larvae (17–23%) and five-day old staghorn coral larvae (17–21%) did not differ significantly between the five treatments. In August 2008, wild-collected elkhorn and staghorn coral egg/sperm bundles were cross-fertilized in a laboratory. Five and seven-day old elkhorn coral larvae and five-day old staghorn coral larvae were placed in wells in culture plates or petri dishes (10–20 larvae/container) with fragments of one of four coralline algae species or a fragment of elkhorn coral skeleton (15 containers/treatment). Larave settlement was recorded after 24 h.
Study and other actions testedA replicated study (years not given) in a laboratory in Eilat, Israel (Linden & Rinkevich 2011) found that cultivating stony coral Stylophora pistillata larvae in lidded petri dishes containing two paper discs submerged in seawater led to higher settlement rates than cultivating larvae in open petri dishes containing one paper disc placed in a humidity chamber, and mortality rates did not differ between treatments. On average, a greater percentage of larvae settled in lidded petri dishes containing two paper discs submerged in seawater (60ؘ–63%) than in open petri dishes with one paper disc placed in a humidity chamber (45%). Larval mortality rates did not differ significantly between treatments (lidded dishes: 19–23%; open dishes: 27%). Adding silicone plugs to lidded dishes did not have a significant effect on larval settlement or mortality rates (see original paper). Larvae collected from wild-growing colonies of Stylophora pistillata were placed in 24–30 petri dishes (9 ×1.5 cm; 1–69 larvae/dish) for each of three treatments. Treatments consisted of open dishes fitted with one paper disc (in the bottom) placed in a humidity chamber; and lidded dishes, with and without silicone plugs, fitted with two paper discs (in the top and bottom) submerged in a flow-through seawater table. Discs (made from polyester, double-sided matte paper) were submerged in seawater for at least two months prior to the experiments. After each of two 48-h periods, paper discs were removed and spat (settled larvae) counted. Mortality rates were calculated at the end of the experiment.
Study and other actions testedA replicated study in 2006 in a laboratory in Miami, USA (Mason et al. 2011) reported that mustard hill Porites astreoides and elkhorn Acropora palmata coral larvae settled on red and/or orange but not blue, green or white plastic cable ties, and only settled when illuminated. Mustard hill coral larvae settled on red cable ties (total 32 larvae, 6 of 6 dishes), whereas none settled on green or white cable ties. Elkhorn coral larvae settled on red and orange cable ties (both: total 8 larvae, 4 of 5 dishes), whereas none settled on blue cable ties. For both species, no larvae settled on cable ties in dark conditions. In June 2006, mustard hill coral larvae were collected from eight wild-grown colonies maintained in the laboratory. Ten larvae (<24 h old) were placed in each of twelve 100-ml dishes containing seawater and one each of red, green and white cable ties secured around a white fiberglass rod. In August 2006, egg/sperm bundles were collected from wild elkhorn coral colonies and cross-fertilized to generate larvae. Ten larvae (5 days old) were placed in each of ten 100-ml dishes with seawater and one each of red, orange and blue cable ties secured around a white fiberglass rod. Half of the dishes in each experiment were placed in darkness and half under fluorescent lights for 12 h/day. After 48 h, settled larvae were counted using a dissecting microscope.
Study and other actions testedA replicated study in 2009 in a laboratory in Miami, USA (Mason et al. 2011) found that mustard hill coral Porites astreoides larvae settled on nylon buttons, but in greater numbers on red nylon buttons than on buttons of six other colours. Overall, a greater number of larvae settled on red buttons (total 24 of 100 larvae, 6 of 10 dishes) than on pink (0 larvae), orange (3 larvae, 2/10 dishes), green (0 larvae), blue (1 larva, 1/10 dishes), purple (10 larvae, 1/10 dishes) or white buttons (1 larva, 1/10 dishes). In June 2009, mustard hill coral larvae were collected from eight wild-grown colonies maintained in the laboratory. Ten larvae (<24 h old) were placed in each of 10 petri dishes containing seawater and one each of red, pink, orange, green, blue, purple and white nylon buttons (1.6 cm diameter). Dishes were placed under fluorescent lights for 12 h/day. After 48 h, settled larvae were counted using a dissecting microscope.
Study and other actions testedA replicated study in 2009 in a laboratory in Miami, USA (Mason et al. 2011), found that elkhorn coral Acropora palmata larvae settled on tiles, but in greater numbers on red ceramic tiles than on orange, yellow, green or blue ceramic tiles or limestone tiles. Overall, a greater number of larvae settled on red tiles (total 16 of 100 larvae, 4 of10 tiles) than on orange (6 larvae, 3/10 tiles), yellow (6 larvae, 4/10 tiles), green (4 larvae, 3/10 tiles), blue (1 larvae, 1/10 tiles) or limestone tiles (6 larvae, 2/10 tiles). In August 2009, egg/sperm bundles were collected from wild elkhorn coral colonies and cross-fertilized to generate larvae. Thirty larvae were added to each of ten 20-l tanks containing seawater and one each of red, orange, yellow, green and blue acrylic tiles, and one limestone tile. All tiles (5 × 5 cm) had grooves carved into them. Tanks were placed under fluorescent lights for 12 h/day. After one week, settled larvae were counted using a dissecting microscope.
Study and other actions testedA study in 2007–2008 at an ex-situ nursery in Okinawa, Japan (Nakamura et al. 2011) reported that more than half of stony coral Acropora tenuis larvae cultivated in tanks settled on ceramic tiles, and more than half the spat (settled larvae) survived and grew. In total, 111,000 of 205,000 larvae (54%) settled on ceramic tiles within tanks (average 173 larvae/tile). After 10 months, 66,000 of 111,000 spat (59%) survived and grew into juvenile corals. In June 2007, eggs and sperm were collected from eight wild-grown captive Acropora tenuis colonies and cross-fertilized. Five-day-old larvae were placed in four rectangular tanks (1.7 × 0.8 × 0.4 m), each containing seawater and 160 ceramic tiles (each 12 × 12 × 2.5 cm with five rows of 1.5-cm2 holes) arranged in two layers. After 4–5 days, numbers of settled larvae were estimated and tiles transferred to aerated outdoor tanks (5.2 × 0.8 × 0.4 m) with flow-through seawater, snails, and young fish, and covered with shade nets or transparent vinyl tents. Numbers of surviving juvenile corals were estimated in April 2008. Total cultivation cost ¥7,963,000 (2011 value), plus ¥12,600,000 for collection and transport of coral colonies.
Study and other actions testedA replicated, randomized, controlled study in 2006 at a laboratory in Hawaii, USA (Forsman et al. 2012) reported that almost all stony coral Porites compressa and Montipora capitata nubbins (small fragments) cultivated under different levels of shade and water flow rates survived and grew. After 41 days, 478/480 (99.4%) of fragments survived. Under low water flow, growth rate of P. compressa fragments was highest (0.65 mm increase) under direct sunlight (0× shade) and lowest (0.36 mm increase) under the most shade (3×). Conversely, growth rate of M. capitata fragments was lowest in 0× shade (0.03 mm) and highest in 1× and 2× shade (both 0.16 mm) and 3× shade (0.08 mm). Under high water flow, growth rate was slightly lower than for low water flow and varied between different shading although results were not significantly different for either species (Porites compressa: 0.44–0.52 mm; Montipora capitata: 0.02–0.11 mm). In 2006, eighty nubbins (1 cm2) were collected from each of three colonies of P. compressa and M. capitata and placed in alternating rows on 1 cm2 plastic mesh (15 nubbins/species/mesh). Mesh sheets were placed into one of 16 buckets and randomly assigned to one of four shade treatments under either high (~11 cm/s) or low (~4 cm/s) water flow. Shade was provided by using layers of 50% shade cloth (1x, 2x, and 3x, and a 0x control). Buckets were cleaned and all nubbins were photographed weekly. Growth (area) was measured after 19 and 41 days.
Study and other actions testedA replicated, randomized, controlled study in 2006–2007 at a laboratory in Hawaii, USA (Forsman et al. 2012) found that providing additional food to ex-situ cultivated stony coral Montipora capitata and Porites damicornis nubbins (small fragments) led to an increase in weight compared to unfed nubbins but there was no difference for Porites compressa. After three months, average overall weight increase (all species) was significantly higher for nubbins in tanks with unfiltered seawater fed with Reef Chili® (6.5%) and Reef-Roids® (7.5%) compared to unfed nubbins (2.1%). Weight increase for nubbins in tanks fed with Oyster Eggs® (2.7%) and Roti-Feast® (3.1%) were not significantly different from unfed nubbins. Nubbins of M. capitata fed additional food showed the highest increase in weight (fed: 0.06–0.14; unfed: 0.02), and P. damicornis (fed: -0.03–0.04; unfed: -0.02) whereas weight change was similar for fed and unfed P. compressa (fed: 0.02–0.07; unfed: 0.06). Ten tanks were set up, each with 18 nubbins (6 fragments/species) on plastic mesh. Fragments were collected from wild-growing stony coral M. capitata, P. damicornis and P. compressa colonies. Tanks were randomly assigned to one of four feeding treatments (Oyster Eggs®, Roti-Feast®, Reef Chili®, and Reef-Roids®) or the unfed control (two tanks/treatment). Corals were fed four times/week according to manufacturers’ recommendations for 12 weeks. Measurements of wet weight (g) and displacement (ml) for each nubbin were taken at the start of the experiment and again three months later.
Study and other actions testedA replicated, randomized, controlled study in 2006 at a laboratory in Hawaii, USA (Forsman et al. 2012) found that stony coral Porites compressa and Montipora capitata nubbins (small fragments) cultivated in an ex-situ nursery with additional food supplements survived and grew and there was no difference in growth between fed and unfed nubbins, but growth varied with higher doses of supplements. After 45 days, 99% of P. compressa and 51% of M. capitata fragments had survived. Tissue growth had increased by 65% (P. compressa) and 35% (M. capitata). There was no difference in average net growth after 45 days for fragments fed with the recommended dose of supplements (P. compressa: 0.73 cm2; M. capitata: 0.35 cm2) compared to unfed fragments (P. compressa 0.70 cm2; M. capitata: 0.37 cm2) but net growth of M. capitata decreased with higher doses of supplements (3× dose: 0.32 cm2, 10× dose: 0.26 cm2). In October 2006, nubbins from P. compressa and M. capitata colonies (240 nubbins/species) were attached to 6 × 6 inch ceramic tiles (15 nubbins/species/tile) using marine epoxy. Tiles were placed into one of 16 buckets (18 L) and randomly assigned to one of three feeding treatments (1x manufacturers’ recommended dosage, 3 × recommended, 10 × recommended) or the unfed control. Food supplements (comprising MicroVert®, MarineSnow Plankton Diet®, Phytoplan®, and Salifert Coral Food®) were provided with seawater filtered through a 500 µmfilter. Buckets were cleaned and nubbins photographed each week. Coral tissue area was measured using scaled photographs. Area measurements were taken at the start of the experiment and 45 days later.
Study and other actions testedA replicated, randomized, controlled study in 2006 at an ex-situ nursery in Florida, USA (Serafy et al. 2013) found that staghorn coral Acropora cervicornis cultivated on tiles with algae manually removed or grazed by variegated sea urchins Lytechinus variegatus had greater growth than those on undisturbed tiles. Average growth rates were greater for staghorn coral on tiles with algae manually removed (3.1 mm/day) or grazed by sea urchins (1.9 mm/day) than on those left undisturbed (-0.8 mm/day). In April 2006, circular pieces of staghorn coral (10 mm diameter) were attached to ceramic tiles (5 × 5 cm). Three tiles were added to each of nine containers (24 × 24 × 20 cm) within a fiberglass trough. Three containers were randomly assigned to each of three treatments: tile surfaces scraped every seven days using a razor blade; four variegated sea urchins (1-cm diameter) added; or tiles left undisturbed. Containers were replaced every seven days and corals randomly re-assigned to each treatment. Larval fish, shrimp and zooplankton were added to all containers weekly. Corals were measured on nine occasions over 210 days using photographs. Production costs for 100–2,000 × 50-cm2 coral ramets were $9,620 (2013 value) using sea urchins and $6,302–16,790 using manual scraping. All cost estimates included labour and facility rental and operating costs.
Study and other actions testedA replicated, randomized, controlled study in 2011–2013 at an aquarium on Heron Island, Australia (Nitschke et al. 2016) found that cultivating stony coral Acropora millepora, Acropora selago and Isopora palifera spat (settled larvae) in tanks containing sterilized sediment plus an adult coral fragment led to increased uptake of zooxanthellae (beneficial algae), but mixed results for survival. After 9–12 days, 61–73% of spat in the sediment+adult coral tanks had acquired zooxanthellae compared to 20–52% (sediment only); 14–47% (adult coral only); and 15–19% (seawater control). Survival rates for A. selago were highest in the adult-coral-only (55%) than the sediment+adult coral (27%) and sediment-only tanks (20%). There were no significant differences in survival between treatments for A. millepora (57%–78%) or I. palifera (data reported as statistical model results). For three consecutive years, wild-growing colonies of A. millepora (2011), A. selago (2012), and I. palifera (2013) were taken to an aquarium to spawn or release larvae. Egg/sperm bundles and larvae developed and settled onto pre-conditioned terracotta tiles. Tiles with spat were randomly allocated to one of four treatment tanks filled with sterilized seawater (sediment+adult coral; sediment only; adult coral only; seawater only). One tile was suspended 1 cm above the bottom of the tank in each of five tanks/treatment. Adult coral fragments (5 × 1 cm) were taken from the recently spawned colonies. Sediment was collected from the reef flat and sterilized at 134°C for 20 minutes. Zooxanthellae cells were counted periodically for 12 days (A. millepora and A. selago) and eight days (I. palifera) using a microscope.
Study and other actions testedA replicated study (year not provided) at an ex-situ coral nursery in Honolulu, Hawai’i, USA (Dubininkas 2017) found some variation in tissue growth and survival of stony coral Montipora capita and Porites lobata fragments transplanted onto different natural and synthetic substrate tiles. Average live tissue coverage at the start of the experiment was 1.61 cm2. After 78 days, there was no significant difference between percentage increase in tissue growth on fragments on different substrate types (range: 60% amygdaloidal basalt to 33% porcelain tiles). After 184 days, increase in tissue surface area was higher for fragments on rhyolite breccia (99%) and amorphous coral skeletons (94%) compared to black ‘Aʻā lava (53%) but no other significant differences in tissue growth between the other 53 comparisons, or between species (see paper for results). After 365 days, survival was higher for fragments on marble tiles (100%) than on glass tiles (50%). There were no other significant differences in survival between substrate types and no difference between species (see paper for results). Fragments (2–3 cm long) were collected from colonies of Montopora capita and Porites lobata (132 fragments/species). Three fragments from each species were fixed, using marine expoxy, onto a 100–324 cm2 tile. There were four tiles for each of 11 materials (total 264 fragments, 44 tiles). Percentage increase in tissue surface area was measured after 78 and 184 days, survival was measured after 365 days.
Study and other actions testedA study in 2015–2016 at a laboratory in the Dominican Republic (Calle-Triviño et al. 2018) reported that some staghorn coral Acropora cervicornis larvae settled in plastic buckets containing coral rocks or cement substrates, but most cultivated spat (settled larvae) and polyps died within 30 days. In 2015, during 4–9 days after fertilization, 50% of larvae settled on coral rocks and the walls of plastic buckets containing them. In 2016, during 8–30 days after fertilization, 35% of larvae settled in buckets with cement substrates. Most spat and polyps (90%) died within 30 days of settling. In September 2015 and August 2016, egg/sperm bundles were collected from staghorn coral colonies at an in-situ nursery and cross-fertilized. Fertilized eggs were cleaned with filtered seawater and placed in twelve 1.5-L buckets in a laboratory. Once the larval stage was reached, coral rocks (2015) or red and white cement substrates (2016) were added to the buckets. After 20 days, polyps on half of the settlement substrates were moved to a 45-L aquarium with coral fragments and sediment from the in-situ nursery. In 2015 and 2016, numbers of settled larvae were counted daily for 33 days after fertilization. Spat, and the polyps that grew from spat, were monitored for 332 days.
Study and other actions testedA replicated study (year not stated) at an ex-situ coral nursery in New South Wales, Australia (Tagliafico et al. 2018) found that cultivating wild-grown stony coral Hydnophora rigida fragments upside-down rather than the right-way-up led to higher rate of self-attachment, shorter time to self-attachment and greater attachment-surface growth but similar height gain and weight. After 100 days, self-attachment to the glass substrate was greater for upside-down (20 of 23, 87%) than right-way-up fragments (14 of 24, 58%). Average time to self-attachment was shorter for upside-down (71 days) than right-way-up fragments (81 days). Average monthly attachment-surface growth was greater for upside-down (75 mm2) than right-way-up fragments (31 mm2). However, there was no significant difference in average height gain after 100 days (upside-down: 0.6 mm; right-way-up: 0.9 mm) or average weight (upside-down: 400 mg; right-way-up: 400 mg). Forty-seven 3-cm-long fragments were collected from six stony coral Hydnophora rigida colonies at the Great Barrier Reef. Fragments were fixed to individual glass plates using cyanoacrylate glue (superglue), 23 upside-down and 24 the right-way-up. Self-attachment (growth of fragment over the attachment plate) was recorded every 20 days for 100 days. Average monthly attachment surface growth (mm2), height increment (mm) and weight (mg) were calculated from measurements taken after 100 days.
Study and other actions testedA replicated, controlled study (year not stated) at an ex-situ coral nursery in New South Wales, Australia (Tagliafico et al. 2018) found that providing supplementary food (Artemia sp. or lipid-enriched Artemia sp.) to cultivated fragments of wild grown stony coral Hydnophora rigida led to increased attachment growth and height, but not weight, compared to unfed fragments. After 100 days, attachment growth was greater for fragments fed with normal Artemia sp. (68 mm2/month) or enriched Artemia sp. (68 mm2/month) compared to unfed (19 mm2/month); there was no significant difference between normal and enriched Artemia sp. Average height growth was greater for normal (1.0 mm/month) and enriched Artemia sp. (0.8 mm/month) compared to unfed (0.4 mm/month); there was no significant difference between normal and enriched Artemia sp. There was no significant difference in average monthly weight (normal: 500 mg, enriched: 400 mg, unfed: 300 mg).). Forty-seven 3cm-long fragments were collected from six colonies of stony coral Hydnophora rigida at the Great Barrier Reef near Cairns. Fragments were super-glued to individual glass plates. They were fed with normal Artemia sp. (16 fragments) or lipid-enriched Artemia sp. (16), every two days, or were unfed (15). Self-attachment (fragment growth over the attachment plate) was recorded every 20 days for 100 days. Average monthly attachment-surface growth (mm2), height increment (mm) and weight (mg) were calculated from measurements taken after 100 days.
Study and other actions testedA replicated study in 2014 in Fiji (Beatty et al. 2018) found that cultivating corals in an ex-situ setting resulted in higher short-term survival for larvae originating from a protected area compared to those from a fished reef. Over a six-day period, larvae from the protected area had higher survival (94%) than larvae from the fished area (26–66%). This was true for larvae reared in protected area water (protected area larvae: 94%, fished area larvae: 66%) and fished area water (protected area larvae: 94%, fished area larvae: 26%). In addition, no differences were found in the microbiomes of larvae due to their origin (protected or fished reef) or the water they were held in (data reported as graphical analysis). In 2014, fragments of coral colonies were collected from a protected area and adjacent fished reef (12 colonies/area, 100–500 m between protected and fished areas) and held in separate containers. Four colonies from each area released larvae, and 10 larvae/colony were used to assess the microbiome. Additional larvae were gathered, and four treatments were established based on the origin of the larvae (protected or fished reef) and the origin of water (protected or fished reef), with 10 replicates/treatment, each with 10 larvae. Survival of larvae in containers was assessed after six days.
Study and other actions testedA replicated, randomized, controlled study in 2012 at a laboratory in Austin, Texas, USA (Ali et al. 2019) found that cultivating stony coral Pseudodiploria strigosa larvae in tanks containing sediment from their collection site and an adult stony coral Orbicella faveolata led to a higher uptake of zooxanthellae (beneficial algae) than larvae cultivated without sediment or adult fragment or in natural seawater. Fifty-six days after settled larvae were placed into tanks, uptake of zooxanthellae was significantly higher for larvae in the sediment+coral tanks (100%) compared to the sediment only (67%), coral only (11%) and seawater control (0%). There were no other significant differences between treatments. In August 2012, egg/sperm bundles collected from eight wild-growing Pseudodiploria strigosa colonies at Flower Garden Banks reef, Gulf of Mexico, USA, were left in plastic tubs to cross-fertilize before being transferred to a laboratory and to settle onto plastic settlement tiles. In addition, six one-gallon bags of sediment collected from 23 m deep immediately below the coral colonies and a large fragment from an adult Orbicella faveolate, collected at the same time, were also taken to the laboratory. Twelve tanks, filled with artificial seawater, were assigned one of four treatments (3-cm layer of sediment+O. faveolata fragment; sediment only; coral fragment only; or seawater control). Settled larvae were randomly assigned to one of the 12 tanks. Recruits were monitored daily for a week then every three days for a further 55 days. Uptake of zooxanthellae was assessed using a fluorescent stereomicroscope.
Study and other actions testedA replicated, controlled study in 2017–2020 in a laboratory near Puerto Morelos Reef National Park, Mexico (Grosso-Becerra et al. 2021) found that corals Diploria labyrinthiformis could be cultivated in an ex-situ setting and 68–88% survived for at least two weeks, with some variation due to whether previously frozen or fresh sperm was used for fertilization. On average, post-settlement polyp survival varied from 76–88% when fertilized with frozen sperm to 68% when fresh sperm was used. The percentage of eggs that yielded swimming larvae was lower for sperm frozen for 30 minutes or 12–13 months (22–26%) compared to fresh sperm (53%), but similar for sperm frozen for one month (40%). Authors present additional results on sperm motility, fertilization and settlement (see paper for details). In 2017 and 2018, egg/sperm bundles were collected from the reef and transported to the laboratory. Eggs and sperm were separated, and sperm were frozen at -80°C for 30 minutes, one month, 12 months or 13 months before being thawed out. Fresh eggs were fertilized with either sperm that had been frozen, or fresh sperm. Resulting larvae were placed in 2-L containers with a settlement substrate (1:2 mixture of white cement and sea sand). The number of eggs that developed into larvae was monitored. Post-settlement survival was assessed after two weeks.
Study and other actions testedA replicated, randomized, controlled study in 2017 in a laboratory in southern Taiwan (McRae et al. 2021) found that cultivated Pocillopora acuta larvae survived for at least 7–9 weeks at two different temperatures, but growth rate was not affected by temperature. For larvae sourced from adults held at 26°C, survival was similar at both settlement temperatures (49–56% after 7 weeks). For larvae sourced from adults held at 29.5 °C, survival was similar for all temperature treatments in April (33–50% after 9 weeks), but in May, survival was higher when they settled at 26°C (57% after 7 weeks) than when they settled at 29.5 °C (31% after 7 weeks). Larval growth was not affected by settlement temperature, but larvae from adults held at 26°C were larger in six of seven comparisons than those from adults held at 29.5°C. In addition, colonies held at 26°C released more larvae than those held at 29.5°C in March and April (26°C: 571–1,160 larvae; 29.5°C: 516–671 larvae,), but released fewer larvae in May (26°C: 693 larvae; 29.5°C: 908 larvae). In February 2017, twenty-four coral colonies (diameter 14 cm) were collected from a reef and transported to an ex-situ laboratory (flow-through tanks). Colonies were randomly assigned to one of two temperature treatments (26°C, average spring temperature; or 29.5°C, above average spring temperature) with 12 colonies/treatment. In March, April and May 2017, coral larvae released from adult colonies were collected on peak release days and split across 24 containers (12 containers/temperature treatment). Containers were randomly assigned to tanks at 26°C or 29.5°C. Each tank contained a ceramic tile, and settlement onto the tile was recorded daily for a week. Survival and growth were then monitored one, three, seven and nine weeks after settlement.
Study and other actions testedA replicated, controlled study in 2016–2019 in laboratory conditions in Florida and New York, USA (Pelosi et al. 2021) found that coral polyps Antillogorgia bipinnata cultivated at 26°C had higher survival than those cultivated at 30°C. Polyp survival after 52 days was higher at 26°C (48–74%) than at 30°C (15–52%). An average of 40–100% of polyps took up symbionts Breviolum antillogorgium, with statistically similar uptake for different temperatures and symbiont genotypes. The number of symbionts/polyp taken up after 69 days varied with temperature and genotype (see paper for details). In 2018, branches of coral were collected from a reef and brought into the laboratory. Coral larvae were collected and settled in polypropylene containers. Coral symbionts of one of five genotypes were added to containers (see paper for details of schedule), and 9–10 containers/genotype were kept at 26°C and 6–8 containers/genotype were kept at 30°C. Symbiont cells had been collected from a reef two years previously and maintained in the lab for two years at 26°C (three genotypes) or 30°C (two genotypes). Survival was recorded every 3–4 days, and polyps were visually inspected to assess uptake of the symbionts.
Study and other actions testedA replicated, randomized, controlled study in 2017 in a laboratory setting in Queensland, Australia (Sims et al. 2021) reported that 1–30% of coral larvae settled (depending on the number of species mixed together) and 44–92% of settled larvae survived (depending on the number of settlers and source of water). When a single coral larva settled, survival was similar for corals held in water sourced from tanks containing adult corals (68%) compared to tanks with reef water (70%). When 60 larvae settled, survival was lower with water from coral tanks (44%) than with reef water (92%). Settlement was lower when larvae from two or three species were mixed than when just a single species was used (Acropora millepora: 8–10% vs 38%, A. valida: 5–7% vs 30%, Leptoria Phrygia: 1% vs 7%). In 2017, colonies of six coral species (Acropora hyacinthus, A. millepora, A. valida, Astrea curta, L. phrygia and Porites cylindrica) were collected and maintained in flow-through aquaria until spawning. One-litre cylindrical containers with a settlement tile were placed into outdoor raceways and randomly assigned to different water treatments (water from tanks containing adult corals, or reef water), densities of coral larvae (10, 50, 100), or species (six species), with five replicates for each combination. Survival was assessed 14 days after settlement. In addition, seven containers received 50 larvae of two species (25/species), seven received 51 larvae of three species (17/species), and these were compared to five containers with 50 larvae of a single species. Settlement was assessed after six days.
Study and other actions testedA replicated, randomized, controlled study in a laboratory in Australia (Quigley et al. 2021) reported 69–96% survival of cultivated corals Acropora tenuis over 28–72 days, depending on the temperature and type of symbiont added. At 27°C, survival was lower for corals with heat tolerant symbionts (89%) than for those with natural symbionts (95%) after 28 days, but similar after 72 days (heat tolerant: 80%, natural: 87%). At 31°C or 32.5°C, survival was similar for both types of symbiont at 28 days (93–96%) and 72 days (69–82%). For two measures of growth, corals with heat tolerant symbionts had lower growth than those with natural symbionts in five of 10 comparisons across three temperatures. The study also reports results on symbiont density and performance. Symbiont cells were extracted from wild corals and a heat tolerant strain was developed over 21 generations in laboratory conditions. A mixture of natural strains was also obtained. Coral larvae were settled on aragonite plugs (1,628 plugs), and following uptake of symbionts, transferred to tanks (9 with heat tolerant symbionts, 9 with natural symbionts). Tanks were split evenly between three temperature treatments (27, 31, 32.5°C). Survival and growth were assessed after 28 and 72 days.
Study and other actions tested
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This Action forms part of the Action Synopsis:
Coral ConservationRelated Actions
| Actions | Effectiveness | Studies | Category | |
|---|---|---|---|---|
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Cultivate coral larvae in an artificial nursery located in a natural habitat Action Link |
Awaiting assessment | 15 |
Synopsis Link |
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Cultivate corals in an ex-situ nursery Action Link |
Awaiting assessment | 36 |
Synopsis Link |
Coral Conservation - Published 2024
Coral synopsis
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