Performance and cost‐effectiveness of sexually produced Acropora granulosa juveniles compared with asexually generated coral fragments in restoring degraded reef areas

1. Sexual and asexual modes of coral propagation are used to produce materials to actively restore coral cover on degraded reefs. It is important to evaluate growth, survival and cost‐effectiveness prior to any large‐scale intervention.
2. This study compared the growth, survival and cost of using sexually, compared with asexually, propagated Acropora granulosa at an in situ nursery and, subsequently, on degraded reef patches in the north‐western Philippines.
3. For sexual propagation, gametes spawned from gravid A. granulosa colonies were collected, fertilized and reared at an outdoor hatchery facility until they were 200‐day‐old juveniles. For asexual propagation, coral nubbins (obtained from colonies used in the sexual propagation experiment) were reared in the hatchery for 1 month before being transferred to an in situ nursery.
4. Sexually and asexually derived corals were reared at the in situ nursery and subsequently out‐planted to a degraded reef. Cumulative survival and growth of sexually derived corals were significantly higher than those of the asexually derived ones, both at the in situ nursery (for 200 days) and on coral bommies (for 382 days). At the in situ nursery, mean growth rates were 0.04 and 0.12 cm³ day^?1 for the asexually produced and sexually produced corals, respectively, while those at the bommies were 0.7 and 1.04 cm³ day^?1, respectively.
5. Production cost (including collection, hatchery‐ and in situ nursery‐rearing) is more expensive in the sexual (US$2.79/coral) than in the asexual (US$2.62/coral) mode of propagation. However, after 13 months post‐out‐planting it was clear that, in the long run, the individual cost of sexually derived corals is cheaper than the asexual counterparts, US$20.01 vs. US$88.15, respectively, owing to better survival rates.
6. Hence, sexual propagation using Acropora is a cost‐effective method with relatively high survival and growth that can be used in active restoration.

     

Revealing the coral habitat effect on benthopelagic fauna diversity in the Santa Maria di Leuca cold‐water coral province using different devices and Bayesian hierarchical modelling

1. Data from two experimental longline surveys and two video inspections carried out in Santa Maria di Leuca cold‐water coral province (Mediterranean Sea) during spring–autumn 2010 were used in order to compare the benthopelagic abundance and diversity between coral and non‐coral habitats and between different devices. The sampling was carried out in two types of habitat: a coral habitat with carbonate mounds and a non‐coral habitat characterized by intermound sea floor.
2. A Bayesian hierarchical modelling approach to accommodate factors influencing community assemblages was used considering the number of species, the Shannon–Wiener diversity index and the two most abundant species represented by the European conger (Conger conger) and blackbelly rosefish (Helicolenus dactylopterus).
3. A relevant effect of the habitat factor was observed for both the number of species and the diversity index, showing a higher species number and diversity index in the coral habitat than in the non‐coral habitat. Concerning the relevance of fixed effects from the model on the probability of observing non‐zero (positive) abundances, the devices considered, longline and baited lander, did not show different influence for either C. conger or H. dactylopterus. In the case of positive abundance, a relevant device effect was only observed for H. dactylopterus, showing higher abundances for longline than for baited lander. A habitat effect was detected, with positive abundances for both species in the coral habitat.
4. This study proves that structurally complex habitats generated by cold‐water corals influence the distribution and diversity of the benthopelagic fauna, and that the use of different devices can provide complementary useful results. Increased knowledge about the role of cold‐water corals in the associated benthopelagic fauna could lead to better conservation of one of the most important hot spots of biodiversity in the Mediterranean Sea.

     

Coral community decline at a remote Caribbean island: marine no‐take reserves are not enough

• 1. Coral reefs around the world have been deteriorating over decades owing to anthropogenic pressure. In the Caribbean recent rates of decline are alarming, particularly for coral reefs under high local human impact, many of which are severely degraded, although regions with lower direct anthropogenic influence seem less affected.
• 2. Little Cayman is a relatively undeveloped island, with less than 150 permanent residents. About 20% of its reefs have been protected by no‐take marine reserves since the mid‐1980s. We analysed the dynamics of coral communities around the island from 1999 to 2004 in order to test the hypothesis that a lack of major local anthropogenic disturbances is enough to prevent decline of coral populations.
• 3. Live hard coral coverage, coral diversity, abundance, mortality, size, and prevalence of disease and bleaching were measured using the Atlantic and Gulf Rapid Reef Assessment methodology (line transects) at nine sites. Despite the apparent undisturbed condition of the island, a 40% relative reduction of mean live coral coverage (from 26% to 16%, absolute change was 10%) was recorded in five years. Mean mortality varied from year to year from 23% to 27%. Overall mean diameter and height have decreased between 6% and 15% on average (from 47 to 40 cm for diameter, and from 31 to 29 cm for height).
• 4. The relative abundance of large reef builders of the genus Montastraea decreased, while that of smaller corals of the genera Agaricia and Porites increased. Disease prevalence has increased over time, and at least one relatively large bleaching event (affecting 10% of the corals) took place in 2003.
• 5. Mean live coral cover decline was similar inside (from 29% to 19%) and outside (from 24% to 14%) marine no‐take reserves. No significant difference in disease prevalence or clear pattern in bleaching frequency was observed between protected and non‐protected areas. It is concluded that more comprehensive management strategies are needed in order to effectively protect coral communities from degradation.

Copyright © 2007 John Wiley & Sons, Ltd.     

Artificial reefs as a reef restoration strategy in sediment‐affected environments: Insights from long‐term monitoring

1. Artificial reefs provide substrates that facilitate the rapid recruitment of marine biota such as corals and fish, and are commonly employed as coral restoration tools to assist recovery in degraded areas. While this strategy is successful in the immediate years post‐deployment, its contribution to restoration over longer time scales is less well understood.
2. The biological communities on Reef Enhancement Units (REUs), which had been deployed for more than a decade on Singapore's sediment‐affected coral reefs, were surveyed.
3. The diversity of sessile lifeforms on the REUs was significantly higher in 2014 (H′ = 1.03) than 2004 (H′ = 0.60). Hard corals and coralline algae contributed most to the temporal dissimilarity and turf algae remained the dominant lifeform category in both years.
4. In 2014, hard corals and abiotic components contributed most to the spatial dissimilarity among the six REU plots that were surveyed. Shannon diversity values of these plots ranged from 0.74–1.3. Scleractinian cover ranged from 0.4–31.5% and differed significantly among the plots.
5. The REUs also augmented ecosystem functioning at their respective plots. Colonies from 10 of the 30 scleractinian genera recorded were sexually mature, and a total of 119 sessile and mobile reef taxa utilized the REUs for food and habitat.
6. The results demonstrate that artificial reefs can contribute to the development of biological communities and ecosystem functioning in degraded coral habitats over the long run, and underscore the need for long‐term monitoring to validate the effectiveness of reef restoration efforts.

     

Feeding of scleractinian coral, Galaxea fascicularis, on Artemia salina nauplii in captivity

Satisfying nutrient requirement of corals is still a major constraint for maintaining corals in marine aquariums. Corals are polytrophic in nature. Heterotrophic feeding on zooplankton is one of the corals’ strategies to overcome nutrient deficiency. Artemia salina nauplii are commonly used as biocarriers for many fish larvae in aquaculture and can also serve as a biocarrier for coral in aquariums, provided coral acceptability, optimal feeding rate, and digestibility of the nauplii are well understood. Feeding rate and digestibility of coral fed on A. salina nauplii at 100, 2,000, 4,000, 6,000, and 10,000 ind. l⁻¹ under light and dark conditions was assessed in this study. The maximum feeding rates of Galaxea fascicularis under light and dark conditions was 113.6 ind. polyp⁻¹ h⁻¹ and 76.9 ind. polyp⁻¹ h⁻¹, respectively. The daily feeding rates of G. fascicularis varies and depends on nauplii density. Light plays an important role in coral feeding. Nevertheless, the quantity of A. salina nauplii consumed by the coral under light and dark conditions was not significantly different (P > 0.05). A. salina nauplii are well accepted by G. fascicularis. Complete nauplii digestion was observed after 180 min. Digestibility of A. salina nauplii by G. fascicularis was positively correlated with digestion time.     

Development of ceramic settlement devices for coral reef restoration using <Emphasis Type="Italic">in situ</Emphasis> sexual reproduction of corals

A ceramic coral settlement device (CSD) was developed to raise juvenile corals in situ in preparation for transplantation. The CSD is designed to be deployed in the water before mass spawning of corals, allowing larvae to settle and grow on the CSD before it is fixed to the reef structure. CSDs were aggregated and fixed on 0.2-m² frames (either 648 or 720 CSDs per frame) and deployed in the Sekisei Lagoon around the full moons of April and May in 2002. Seven frames were collected in August 2002 and settled corals were counted in the laboratory. The maximum number of coral colonies settled on CSDs in one frame was 617, with 94% belonging to the genus Acropora. The aggregated CSDs successfully functioned as a coral settlement substratum, with more appropriate arrangement of CSDs on the frame, enabling greater exposure to sunlight and currents, which is expected to increase the amount of settlement.     

Comparison of three types of adhesives in attaching coral transplants to clam shell substrates

• 1. Nubbins from 12 coral species were transplanted onto dead giant clam shells at three sites in a lagoon near Bolinao, north‐western Philippines. Transplants were attached using three types of adhesives: cyanoacrylate glue (SG), epoxy putty (EP) and marine epoxy (ME) and were monitored over five months for detachment, in situ mortality and natural self‐attachment by tissue growth.
• 2. Corals attached with SG showed a significantly higher rate of detachment (logrank test) than those attached with either EP or ME (P<0.001 in each case). Also, those attached with EP showed a higher rate of detachment than corals attached with ME (logrank=6.46, P<0.05).
• 3. ANOVA (P>0.05) and survival analysis (logrank=2.85, P>0.05) showed no among‐adhesives differences in in situ mortality. Among the species used, Porites cylindrica, Pavona frondifera, Heliopora coerulea and Porites rus had the highest survivorship with 82%, 80%, 76% and 73%, respectively, of nubbins alive at the end of the experiment and also displayed the highest cumulative rates of self‐attachment. Species with the lowest survival rates included Acropora muricata and four pocilloporids.
• 4. Although there was no significant difference in the number of self‐attaching transplants among the adhesives, corals transplanted using ME and EP self‐attached earlier than those transplanted using SG (logrank=11.19, P<0.01).
• 5. Results from this study highlight the importance of selecting the appropriate means of attaching corals to substrates and carefully considering species‐specific traits of candidate corals for transplantation.

Copyright © 2008 John Wiley & Sons, Ltd.     

Scleractinian coral communities of the inner Seychelles 10 years after the 1998 mortality event

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Effects of live rock on the reef-building coral Acropora digitifera cultured with high levels of nitrogenous compounds

Reef-building corals are sensitive to excessive nitrogenous (N) compounds. To maintain levels of inorganic nitrogenous compounds low in coral aquaria, various technologies, mechanical, chemical and biological, have been applied. As one of the biological techniques, “live rock,” which can be defined as a dead coral skeleton covered with crustose coralline algae (CCA), has long been applied for coral aquaria. Until recently, however, there has been little evidence for the effectiveness of live rock in removal of N compounds from coral aquaria. Demonstrating comparative experiments with live rocks, here we report that the live rock is capable of removing N compounds and reduces the mortality of reef-building coral. We cultured the reef-building coral Acropora digitifera with the sea cucumber Holothuria atra as a natural nitrogen producer. H. atra increased the concentration of the inorganic N compounds (NH₄⁺, NO₃⁻ and NO₂⁻) that resulted in high coral mortality. The presence of the live rock remarkably reduced the concentrations and sustained a high coral photosynthetic activity. We detected the functional genes amoA and nirS within the live rock, suggesting the occurrence of both nitrifying and denitrifying bacteria. These results support the idea that “live rock” is an effective biofilter that can maintain water quality suitable for reef-building corals.     

Applying forest restoration principles to coral reef rehabilitation

• 1. 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.
• 2. 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).
• 3. The second is the reef rehabilitation step, where maricultured colonies are transplanted into degraded sites.
• 4. 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.
• 5. 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.
• 6. 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 & Sons, Ltd.     

Leiopathes glaberrima millennial forest from SW Sardinia as nursery ground for the small spotted catshark Scyliorhinus canicula

1. Association between habitat structuring organisms and other species has great relevance for ecosystem‐based conservation measures.
2. Those occurring in temperate areas, particularly in the upper portion of the continental margin, are mostly unknown or not properly understood because of the difficulty to discriminate co‐occurrence and real functional linkages among species.
3. Deep water coral assemblages over the Carloforte Shoal (south‐west Sardinia; 180–210 m depth) were investigated using ROV surveys.
4. During the surveys, more than 740 egg‐capsules of the spotted catshark Scyliorhinus canicula, identified after hatching experiments in captivity, were found attached exclusively to colonies of the long‐living black coral Leiopathes glaberrima.
5. Although based on a spot finding, the results show that coral forests are not only hotspots of biodiversity, but can also serve as nursery grounds for S. canicula. The protection of these millennial coral forests is therefore to be considered a priority.

     

Repeated physical disturbances and the stability of sub‐tropical coral communities in Hong Kong,China

• 1. This paper reports on the dynamics of the coral community structure at A Ma Wan (AMW) and A Ye Wan (AYW) in Tung Ping Chau, Hong Kong, focusing on data collected before and after the summer typhoon seasons in 1997 to 1999. This period (1999) experienced the highest frequency of severe tropical cyclones to hit Hong Kong with one cyclone being the strongest to hit in the last 23 years (1984 to 2006).
• 2. This is part of a long‐term monitoring programme of subtropical coral communities that has been set up in AMW since May 1997 and AYW since May 1998 with nine fixed position 40 m long transects and 0.5 m × 0.5 m permanent quadrats laid at 5 m intervals along each transect. A total of 45 scleractinian coral species from 21 genera (12 families) was recorded, with 40 species in AMW and 32 species in AYW recorded at the beginning of the study.
• 3. Multidimensional scaling ordinations showed distinct spatial variations in the coral communities within and between sites. These variations were probably a result of the differential effects of the repeated cyclone impacts on the communities. Cyphastrea serailia, Goniopora lobata, Montipora peltiformis and Pavona decussata were the dominant species most strongly affected by cyclone impacts at AMW, experiencing a 6.2–16.2% loss of mean area cover during the study period. Some dominant species (e.g. P. decussata) in AYW also experienced a 6.5–14.3% loss of mean area cover within the same period.
• 4. Overall, these coral community structures appeared relatively stable and resistant to repeated physical disturbances. However, they may have low resilience towards more severe disturbances in the future. Preserving the resilience of coral communities/species in Tung Ping Chau should be one of the main goals of coral conservation strategies for the island.

Copyright © 2008 John Wiley & Sons, Ltd.     

The extracts of Angelica sinensis restore the digestive and absorptive capacity through improving antioxidant status in digestive organs of fish treated with trichlorfon

Firstly, a linoleic acid emulsion and fish hepatopancreas homogenate were incubated with ethoxyquin and the extracts of Angelica sinensis. The results demonstrated that ethoxyquin showed the strongest protective effects against lipid oxidation of all of the examined compounds (p < 0.05). However, ethyl acetate extract of Angelica sinensis at high concentrations showed a stronger effect on lipid oxidation than that of ethoxyquin (p < 0.05). Next, seven experimental diets that contained 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, and 6.0 g/kg of ethyl acetate extract of Angelica sinensis were fed to seven groups of carp (Cyprinus carpio var. Jian) respectively. After 60 days, carp were exposed to 2.4 mg trichlorfon/L in water for 4 days. The results displayed that trichlorfon exposure increased the contents of malonaldehyde and protein carbonyl in digestive organs and the activities of glutamate‐oxaloacetate and glutamate‐pyruvate transaminase in plasma, and decreased feed intake, the level of reduced glutathione, and the activities of trypsin, chymotrypsin, lipase, alpha‐amylase, Na⁺,K⁺‐ATPase, alkaline phosphatase, antisuperoxide anion, antihydroxyl radical, superoxide dismutase, glutathione reductase, and glutathione S‐transferase in digestive organs of carp (p < 0.05). Moreover, the dietary ethyl acetate extract of Angelica sinensis prevented the decrease in the above parameters in carp treated with trichlorfon (p < 0.05). These results revealed that the dietary ethyl acetate extract of Angelica sinensis could quench the trichlorfon‐induced structural and functional damage by improving the antioxidative capacity of the digestive organs of fish. Therefore, the extract of Angelica sinensis could be used as an inhibitor of trichlorfon stress in fish.     

Impact of polyculture ecosystems of Ctenopharyngodon idellus with Eriocheir sinensis on bacterial communities in the sediments of Dongping Lake in China: Focus on optimization of polyculture modes

This study investigated the influence of polyculture ecosystems of grass carp (Ctenopharyngodon idellus) and Chinese mitten crab (Eriocheir sinensis) on the bacterial community of sediments in the Lake Dongping in China, using the Illumina HiSeq Sequencing approach. The bacterial community diversity was reduced to different extent due to the polyculture of animals. The bacterial community composition changed significantly among the ecosystems of control (without any animals cultured), G1C1 (with the highest animal biomass: C. idellus, 2 ind/m²; E. sinensis, 1 ind/m²) and G2C2 (with the lowest biomass: C. idellus, 1 ind/m²; E. sinensis, 0.5 ind/m²). Relative abundance increase for sulphide‐oxidizing bacteria and decrease for sulphate‐reducing bacteria were detected with more quantities of fish–crab cultured in ecosystems. Variations in the concentration of sediment sulphate mainly accounted for the shifts of both the bacterial diversity and community composition. Lastly, G2C2 was recommended as the optimal polyculture ecosystem that could be used in the Lake. The results suggested negative impacts of polyculture ecosystems of C. idellus with E. sinensis on the bacterial diversity but positive impacts on the community composition and indicated the role of total biomass of animas in shaping the bacterial community in the sediments of lake ecosystems.     

Genetic monitoring of deep‐water exploited banks of the precious Sardinia coral Corallium rubrum (L., 1758): useful data for a sustainable management

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Long‐term survival and colony growth of Acropora palmata fragments transplanted by volunteers for restoration

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Coral communities of Biscayne Bay,Florida and adjacent offshore areas: diversity,abundance, distribution,and environmental correlates

• 1. Hardbottom habitats of Biscayne Bay, a shallow lagoon adjacent to the city of Miami, Florida, USA, contain a limited number of coral species that represent a small subset of the species found at nearby offshore hardbottom and reef habitats of the Florida Reef Tract. Although the physical characteristics of this basin make it a marginal environment for coral growth, the presence of dense populations of Siderastrea radians and Porites furcata indicate that these, as well as other corals that are found at lower densities, are able to tolerate extreme and fluctuating conditions. Three factors, temperature, sedimentation, and salinity, appear to limit coral abundance, diversity, and distribution within Biscayne Bay.
• 2. Temperatures exhibit high frequencies of extreme high and low values known to cause coral stress and mortality elsewhere. Similarly, sedimentation rates are very high and sediment resuspension caused by currents, storms and boating activities commonly bury corals under sediment layers. Sediment burial was shown experimentally to influence growth and mortality of S. radians.
• 3. The salinity of Biscayne Bay is influenced by freshwater inputs from canal, sheetflow and groundwater sources that create a near‐shore environment with low mean salinity and high salinity fluctuation. Coral communities along this western margin have the lowest coral density and species richness. Chronic exposure to low salinity was shown experimentally to cause a decrease in the growth of S. radians.
• 4. The location of Biscayne Bay, downstream of a large restoration effort planned for the Everglades watershed, highlights the need to understand the relationship between the physical environment and the health of benthic communities. The data presented here provide the type of scientific information needed so that management decisions can take into account the potential impacts of human activities on the health of coral populations that are already near their tolerance limits for temperature, salinity, and sedimentation.

Copyright © 2003 John Wiley & Sons, Ltd.     

A basic experiment of coral culture using sexual reproduction in the open sea

Coral larvae, produced from a mass spawning event, were successfully settled on special stone settlement sticks and raised in situ for eventual transport to other reefs. The test area, Sekisei lagoon, Okinawa Prefecture, Japan, is located close to the warm Kuroshio current and is surmised to be the source from which major Japanese corals are derived. A total of 131 settlement sticks, with small holes in their sides to increase protection from grazing (4 mm in diameter and approximately 5 mm deep), were deployed in the lagoon the day before the coral’s mass spawning. After 3 months, 61 sticks were recovered containing 71 corals, mostly in the holes. After 1 year, three corals were confirmed to be growing well and extending outside the holes of the three sticks out of 70 sticks left in the water at the lagoon site. They survived two potentially lethal conditions, that is, high water temperatures with associated extensive coral bleaching and continuous grazing pressure from predators. This procedure is applicable for large-scale coral transplantation, not only in Japan but also in other tropical countries.     

Coral reef organisms as bioregion indicators off Halmahera,Moluccas, Indonesia

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Survival and Growth of Isolated Polyps of Galaxea fascicularis (Linnaeus 1767) on Six Kinds of Culture Substrates: Implications for Mariculture,Aquarium Culture,and Conservation

Coral aquaculture is viewed as a sustainable method of providing colonies for use in the aquarium trade, pharmacological studies, and coral reef rehabilitation. The production of large, healthy specimens depends on providing conditions that mimic or surpass natural reef environments. Materials with a high degree of variability in physical and chemical properties are utilized as substrates in coral aquaculture, but until fragment–substrate interactions are isolated and independently studied, the possible inhibitory and facilitative effects of each material will remain unclear. To understand potential key roles that substrates can play in coral culture, a comparison was made about the role of various materials on fragment survival and growth. The experiment examined the interactions between isolates of a common scleractinian coral, Galaxea fascicularis, and six commonly used substrates (coral rock, terracotta, polyvinyl chloride, steel, rubber tire, and concrete) and how these affected survival and growth. No differences were observed in the survival, colony size, and polyp production of the resulting microcolonies. The results show that, for G. fascicularis, growth is not affected by substrate type. The results demonstrate the use of a wide variety of materials for the successful aquaculture of scleractinian corals.