Soft Coral Species Research Articles

A new genus with two new capitate species of dimorphic soft corals (Octocorallia : Alcyoniidae) from north-western Australia

Soft coral diversity in tropical northern Australia remains relatively understudied compared with other parts of the world. As a result of ongoing biodiversity surveys, we describe here a new genus of Octocorallia, Anastromvos, gen. nov., and two new species, A. aldersladei, sp. nov. and A. catherinae, sp. nov., collected from waters off the Pilbara, Kimberley and Darwin. To test the validity of the new genus, we used traditional morphological approaches combined with a molecular phylogeny using three mitochondrial genes (COI, mtMutS, ND2) and nuclear 28S. The markers did not amplify for the colony of A. catherinae, sp. nov., which was described on the basis of morphology only. The new genus, belonging to the family Alcyoniidae, is dimorphic, possessing autozooids and siphonozooids, and is characterised by its unique capitate growth form, stone-like colony consistency, heavy autozooid polyp armature and the possession of clubs, tuberculated spindles and/or oval-shaped sclerites and crosses. The molecular phylogeny shows the new genus as the sister group to Sarcophyton+Lobophytum, and forms a unique clade among other alcyoniid clades. The Sarcophyton–Lobophytum group of taxa can be ecologically dominant in shallow-water coral reef communities but there is still much taxonomic refinement needed for these and related genera. http://zoobank.org/urn:lsid:zoobank.org:pub:71E96A7A-A24D-4485-AF3B-834CEF959578

Studies With Soft Corals – Recommendations on Sample Processing and Normalization Metrics

Soft corals (Octocorallia) often constitute the second most abundant macrobenthic group on many tropical and temperate reefs. However, the gelatinous and leather-like nature of their tissue and their variable hydroskeleton entails a number of problems for tissue homogenization and data normalization. An easy and fast protocol for tissue homogenization, as well as a normalization metric that can be used to perform inter-studies or inter-species comparisons, are thus needed. In this study, we tested whether the tissue sample state before processing (frozen vs freeze-dried samples) and the media used for tissue homogenization (0.2 µm filtered seawater; FSW vs milliQ water; DI) affects the quantitative measurements of tissue descriptors (chlorophyll, protein and Symbiodinium concentrations) in the model species Heteroxenia fuscescens. Furthermore, the suitability of dry weight (DW) and ash-free dry weight (AFDW) as size-normalizing metric was investigated across different soft coral species. Our results reveal that freeze-drying the samples and homogenizing them in DI water exhibited several benefits, namely enhancing chlorophyll and protein concentrations up to 50%, saving processing time and providing a more accurate determination of DW and AFDW. Overall, this optimized tissue processing protocol offers a more reliable quantification of tissue descriptors and reduces the chance of underestimating these parameters in soft corals. Finally, since the contribution of sclerites to the total DW of the colony can highly differ between species, we demonstrate that AFDW is a reliable metric for normalizing soft coral data, particularly when inter-species comparisons are made.

Soft corals are significant DMSP producers in tropical and temperate reefs

Corals synthesise large quantities of the sulphur metabolite dimethylsulphoniopropionate (DMSP), which contributes to key roles in coral reef ecology including the capacity of corals to withstand various stressors. While closely related to scleractinian corals and often occupying similar ecological niche space, it is currently poorly defined to what extent soft corals produce DMSP. We, therefore, examined DMSP content within four key species of soft coral in February and July–August of 2017, including two temperate species from Sydney Harbour (Erythropodium hicksoni, Capnella gaboensis) and two tropical species from the Great Barrier Reef (Sinularia sp., Sarcophyton sp.). We compared DMSP content of these soft coral species to that of commonly occurring temperate (Plesiastrea versipora) and tropical (Acropora aspera) scleractinian coral species. DMSP content was normalised to coral protein content, with soft coral DMSP content highly variable across species and locations [56–539 nmol (mg protein)−1], and lower than for the tropical [1242–4710 nmol (mg protein)−1], but not temperate [465–1984 nmol (mg protein)−1] scleractinian species. Further comparison with previously published values demonstrated that soft coral DMSP content falls within the “low–mid range” of scleractinian corals. Notably, DMSP content was also higher in summer samples than winter samples for the scleractinian corals, but did not differ between seasons for soft corals. Such contrasting dynamics of DMSP production by soft corals compared to scleractinian corals indicates that the regulation of DMSP content differs between these two important benthic cnidarian groups, potentially as a consequence of dissimilar ecophysiological roles for this compound.

Quorum Sensing Interference and Structural Variation of Quorum Sensing Mimics in Australian Soft Coral

Bacterial Quorum Sensing (QS), the indirect regulation of gene expression through production and detection of small diffusible molecules, has emerged as a point of interaction between eukaryotic host organisms and their associated microbial communities. The extracellular nature of QS molecules enables interference in QS systems, in many cases via mimicry. This study targeted QS induction and inhibition in soft coral holobionts, as many soft coral species commonly contain compounds with structural similarities to the well-studied bacterial QS molecules acyl homoserine lactones. Screening with two bacterial biosensors, Agrobacterium tumefaciens A136 and Chromobacterium violaceum CV026, demonstrated that QS interference differed between the two biosensor strains and extended across the soft coral families Alcyoniidae, Clavulariidae, Nephtheidae, and Xeniidae. Bioassay-guided fractionation revealed chemical activity patterns, particularly in the induction of QS. Cembranoid diterpenes from active fractions were purified and tested for QS interference activity. Interestingly, the type of QS activity (induction or inhibition) in A. tumefaciens A136 correlated with structural variability of the secondary oxygen ring; cembranoid diterpeneswith a furan ring or five-membered lactone induced QS, while compounds with larger (six or seven membered) lactone rings inhibited QS. Addition of the dominant cembranoid diterpene in the soft coral Lobophytum compactum, isolobophytolide, to bacterial culture media increased the number and morphological diversity of bacteria recovered from the mucosal layer of this soft coral, demonstrating a selective effect on certain members of the soft coral bacterial community. The identity and QS activity of recovered isolates differed between the mucosal layers of L. compactum and Sinularia flexibilis. In conclusion, this study provides information on the complexity of the interaction between soft corals and their associated bacteria, as well as, a structural understanding of how QS mimic compounds are able to interfere with a bacterial communication system.

Revisionary systematics of the endemic soft coral fauna (Octocorallia: Alcyonacea: Alcyoniina) of the Agulhas Bioregion, South Africa.

The Agulhas Bioregion of southern South Africa supports a unique octocoral fauna that is entirely endemic to the region. Recent molecular phylogenetic studies indicate that this endemism extends to deeper taxonomic levels than had previously been recognized, and that most of these endemic species belong to genera and families that are also endemic to South Africa. Here we revise the taxonomy of soft corals (subordinal group Alcyoniina) that were previously assigned to the cosmopolitan families Alcyoniidae, Nephtheidae and Nidaliidae, describing three new families endemic to South Africa, along with four new genera and four new species. We reassign the endemic genera Acrophytum, Pieterfaurea and Lampophyton to Acrophytidae n. fam, and describe a new species of Lampophyton, L. spinatum n. sp. The endemic species Protodendron bruuni is reassigned to a new, monotypic genus, Corymbophyton bruuni n. comb., and family, Corymbophytidae n. fam. The endemic genus Leptophyton is placed in a third new family, Leptophytidae n. fam., along with three new genera that are established for species previously assigned to Alcyonium: Circularius wilsoni n. comb., Porphyrophyton distinctum n. comb., and Tenerodus fallax n. comb. In addition, we describe new species of Leptophyton, L. fustis n. sp.; Tenerodus, T. pollex n. gen. n. sp.; and Alcyonium, A. dolium n. sp.; reassign Protodendron verseveldti to Tenerodus verseveldti n. comb.; and reassign the endemic genus Dimorphophyton to family Paralcyoniidae. Although molecular phylogenetic analyses unite Acrophytidae, Corymbophytidae and Leptophytidae within a well-supported monophyletic group, both morphological and molecular distinctions support maintaining them as three separate families. These revisions increase the number of endemic species of shallow-water soft corals known from the Agulhas Bioregion to 40, and the number of endemic genera to 13.

Đa dạng loài sinh vật biển quần đảo Thổ Châu, tỉnh Kiên Giang

The research results in the field survey from March, 2011 to October, 2015 of Research Institute for Marine Fisheries (RIMF) presented an overall picture of the marine species diversity in coral reef ecosystems and other coastal areas surrounding Tho Chau archipelago, Kien Giang province. A total of 1,101 marine species were identified, including 161 species of phytoplankton; 75 species of zooplankton; 57 species of seaweed; 6 species of seagrass; 11 species of mangrove plant; 147 species of coral (131 species of hard coral, 16 species of soft coral); 261 species of coral reef fish; and 383 species of zoobenthos (223 species of mollusca, 77 species of echinodermata, 59 species of arthropoda, 24 species of annelida). These research results provided an important scientific foundation for management, conservation and development of marine resources in this area.

Bioactive sterols and sesquiterpenes from the Red Sea soft coral Sinularia terspilli

The ethanolic extract of the Red Sea soft coral Sinularia terspilli was subjected to several chromatographic techniques resulting in the isolation of compounds 1–8 including (five sterols 1–5 and three sesquiterpenes 6–8). The isolated compounds have been identified by 1D and 2D NMR spectral analysis and by comparison with literature data. Different biological activities for the isolated compounds and some synthetic derivatives have been carried out. Compounds 4 and 5 exhibited strong cytotoxic activity against human leukemia cell lines HL60 and K562 with IC50 values ranging from 2.0 to 25 nM. This is the first reported isolation of these metabolites from this soft coral species.

New cytotoxic cembranoid from indonesian soft coral Sarcophyton sp.

Context:Sarcophyton is a soft coral species that contains various secondary metabolites with cytotoxic activity. The production of cytotoxic compounds in soft corals is suggested as their allelochemical to win space competition. Therefore, if a particular soft coral species dominates a reef area, it may suggest to contain interesting bioactive compounds.Aims:This research aimed to characterize the cytotoxic compounds in dominant soft coral species (Sarcophyton sp.) on the reef at the Western side of Mahengetang Island, Indonesia.Subjects and Methods:Isolation of cytotoxic compounds through ethanol extracts had been done with preparative high-performance liquid chromatography and bioassay-guided fractionation by MCF-7 (breast) cancer cell lines. The structures of each cytotoxic compounds were elucidated on the basis of mass and nuclear magnetic resonance spectroscopic studies.Results:Elucidation through all compounds found a new cembranoid, namely, 2-hydroxy-crassocolide E (1), alongside with 5 known cembranoids; sarcophytoxide (2), sarcrassin E (3), 3,7,11-cembreriene-2,15-diol (4), 11,12-epoxy-Sarcophytol A (5), and sarcophytol A (6). All of these cembranoids were showed to inhibit the growth of MCF-7 (breast) cancer, with 50% inhibition of tumor cell lines growth lower than 30 mg/L.Conclusions:Results of this study suggest that a soft coral species which dominate a reef area is a potential source for various bioactive compounds.SUMMARYElucidation of cytotoxic compounds from Sarcophyton sp. that dominate the reef at Mahengetang Island Indonesia revealed a new compound (2-hydroxy-crassocolide E) alongside with 5 known cembranoid compounds.Abbreviations Used: SCUBA: Self-contained underwater breathing apparatus; HPLC: High performance liquid chromatography; NMR: Nuclear magnetic resonance; IT-TOF: Ion trap-time of flight; MTT: 3-(4,5-dimethylthiazol-2-yl)-2; 5-diphenyltetrazolinon bromide; DEPT: Distortionless enhancement by polarisation transfer; COSY: Correlation spectroscopy; HMBC: Heteronuclear multiplebond correlation; NOE: Nuclear overhauser effect; IG50: 50% inhibition growth

Hedera caerulescens (Alcyonacea : Alcyoniidae), a new genus and species of soft coral from the temperate North Atlantic: invasive in its known range?

We describe a novel alcyoniid species of stoloniferous octocoral found off the coast of North Carolina, USA. Colonies have an encrusting morphology with pale to bright blue monomorphic polyps connected by spongy, sclerite-dense stolons that often form mats. Sclerites are colourless and sparsely tubercled. Sclerites of the stolons are predominantly spindles and rods with rare irregular fused forms, butterflies, and crosses. Polyps have a crown and points formation that consists of rods and spindles that can be curved or irregularly branched. Tentacles contain short flattened rods and rare crosses. Both the mitochondria-encoded COI-5P and mtMutS were sequenced and BLAST searches revealed no close homology with any previously sequenced species. Phylogenetic analyses of the sequence data suggested a closest relationship with species of Alcyonium Linnaeus, 1758 (Alcyoniidae) and Gersemia Marenzeller, 1877 (Nephtheidae) and supported the recognition of a new genus. This species was not previously reported in the Carolinas region despite extensive historical sampling and a recently published key to octocorals of the South Atlantic Bight. Reports and photographs from local divers suggest that this species may have been introduced in North Carolina waters ~2002–04, where it has been found on both shipwrecks and hard bottom ledges, at 13–34m depth.

Close genetic connectivity of soft coral Sarcophyton trocheliophorum in Indonesia and its implication for marine protected area

The genetic connectivity of soft coral is influenced by current and distance between islands. The complexity of islands and geographical region in Indonesia might influence the distribution of soft corals. The information of genetic connectivity can be used to design marine protected areas and to avoid destruction and possible extinction. The objective of the present study was to analyze genetic connectivity of one species of soft coral, Sarcophyton trocheliophorum, in three populations spanning Java, Nusa Tenggara, and Sulawesi’s waters, and to describe its implication for marine protected area. The mitochondrial protein-coding gene (750 bp of ND2) was used to analyze genetic population structure and genetic connectivity. Genetic connectivity was found in all populations with Fst value of 0.227 to 0.558, indicating populations had the close genetic relationship. The local and Indonesian currents were expected to distribute the larva to islands as a stepping stone, they moved slowly to spread them self far away. Tanakeke island (Sulawesi population) might be a center connectivity of S. trocheliophorum populations. This island connected with islands in west and east Indonesia, therefore that area need to protect

Low symbiont diversity as a potential adaptive strategy in a marginal non-reefal environment: a case study of corals in Hong Kong

Symbiosis with genetically diverse Symbiodinium has been shown to affect host coral physiological responses to environmental stresses. Hong Kong, located in a subtropical region, is a marginal environment for coral growth largely due to its wide annual temperature fluctuation with low mean winter sea water temperature (~16 °C) and variable salinity conditions. The symbiont diversity in Hong Kong corals is therefore worth investigating to enrich our understanding on symbioses in marginal and fluctuating environments. Examination of 56 scleractinian coral species and five soft coral species using denaturing gel gradient electrophoresis of the internal transcribed spacer region 2 found only five distinct subclades of Symbiodinium with C1 the dominant type occurring in all but one scleractinian coral and all soft coral species investigated. C15 and C21 Symbiodinium were found in Porites spp. and Montipora peltiformis, respectively, both of which are vertical transmitters. D8-12 was found in Oulastrea crispata, a stress-tolerant species, and D1 in a single sample of Goniastrea aspera. No spatial differences in Symbiodinium composition were found among different regions of Hong Kong. Seasonal monitoring of tagged Platygyra acuta and Porites spp. colonies also revealed no changes in their symbiont types despite wide ranges of in situ temperature fluctuation. Hong Kong scleractinian corals hosted a remarkably low symbiont diversity compared with corals in the surrounding regions. The predominance of a single subclade, C1 Symbiodinium, suggests that this subclade is best acclimatized to local fluctuating conditions and/or low winter temperature. Forming symbiosis with the best acclimatized symbiont, instead of with a diverse group of symbionts with different physiological performances, either sequentially or simultaneously, may be a strategy used by Hong Kong corals to cope with stressful conditions.

Marine soft corals as source of lead compounds for anti-inflammatories

Marine soft corals are known to produce a wide array of secondary metabolites, particularly diterpenoids and steroids, and often characterized by uncommon structural features and potent bioactivities. The remarkable abundance and diversity of bioactive small molecule which have been isolated from soft corals have made these organisms an important source of new drug candidates for human diseases, particularly for their anti-inflammatory activity. In this paper, the authors reported anti-inflammatory marine natural products isolated from diverse species of soft corals determined in vitro by their inhibition of lipopolysaccharide-induced expression of inducible NO synthase and cyclooxygenase-2 in murine macrophage cells (RAW 264.7).

Changes in soft coral <em>Sarcophyton</em> sp. abundance and cytotoxicity at volcanic CO<sub>2</sub> seeps in Indonesia

This study presents the relationship between benthic cover of Sarcophyton sp. living on coral reefs and their cytotoxicity (an assumption of soft coral allelochemical levels) along acidification gradients caused by shallow water volcanic vent systems. Stations with moderate acidification (pH 7.87 ± 0.04), low acidification (pH 8.01 ± 0.04), and reference conditions (pH 8.2 ± 0.02) were selected near an Indonesian CO 2 seep (Minahasa, Gunung Api Island, and Mahengetang Island). Cover of the dominant soft coral species ( Sarcophyton sp.) was assessed and tissue samples were collected at each site. The cytotoxicity tissue extracts were analyzed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolinon bromide (MTT) method. Levels of cytotoxicity were strongly correlated with Sarcophyton sp. cover ( p 2 = 0.60 at 30 ppm and 0.56 at 100 ppm), being highest at mean pH 8.01 where the soft corals were most abundant. This finding suggests that Sarcophyton sp. can be expected to survive ocean acidification near Indonesia in the coming decades. How the species might be adversely affected by further ocean acidification later in the century unless CO 2 emissions are reduced remains a concern.

New cytotoxic constituents from the Red Sea soft coral Nephthea sp.

Nephthea are soft coral species rich in sesquiterpenoids and steroids. An organic extract of Nephthea sp. resulted in the isolation of a new steroid (1), as well as several previously reported metabolites (2–9). Structures were elucidated by employing NMR and HR-EI-MS analyses. The total extract, fractions and purified compounds exhibited differential cytotoxicity against the breast cancer MCF-7 cell line.

Distribution and spatial modelling of a soft coral habitat in the Port Stephens–Great Lakes Marine Park: implications for management

Habitat mapping is a useful method for understanding the complex spatial relationships that exist in the marine environment, and is used to evaluate the effectiveness of management strategies, particularly in regards to marine protected areas. This study explored the observed and predicted distribution of an uncommon soft coral species, Dendronephthya australis within the Port Stephens–Great Lakes Marine Park. Dendronephthya australis was mapped by video operated by a SCUBA diver towing a time synchronised GPS. A species distribution model was created to explore the possible occurrence of D. australis outside of the mapped area, using four environmental parameters: bathymetry, slope of seabed, velocity of tidal currents, and distance from estuary mouth. Dendronephthya australis colonies occurred along the southern shoreline in the Port Stephens estuary between Fly Point and Corlette Point, but no colonies were found within sanctuary (no-take) zones within the marine park. The model illustrated limited habitat suitability for D. australis within a larger section of the estuary, suggesting this species has specific environmental requirements survival. Owing to its current threats (anchor damage and fishing line entanglement), implications from these findings will assist future management and protection decisions, particularly in regard to its protection within a marine park.

Chemical versus structural defense against fish predation in two dominant soft coral species (Xeniidae) in the Red Sea

Soft corals of the family Xeniidae are particularly abundant in Red Sea coral reefs. Their success may be partly due to a strong defense mechanism against fish predation. To test this, we conducted field and aquarium experiments in which we assessed the antifeeding effect of secondary metabolites of 2 common xeniid species, Ovabunda crenata and Heteroxenia ghardaqensis. In the field experiment, the metabolites of both investigated species reduced feeding on experimental food pellets in the natural population of Red Sea reef fishes by 86 and 92% for O. crenata and H. ghardaqensis, respectively. In the aquarium experiment, natural concentration of crude extract reduced feeding on experimental food pellets in the common reef fish Thalassoma lunare (moon wrasse) by 83 and 85%, respectively. Moon wrasse feeding was even reduced at extract concentrations as low as 12.5% of the natural concentration in living soft coral tissues. To assess the potential of a structural anti-feeding defence, sclerites of O. crenata were extracted and mixed into food pellets at natural, doubled and reduced concentration without and in combination with crude extract at 25% of natural concentration, and tested in an aquarium experiment. The sclerites did not show any effect on the feeding behavior of the moon wrasse indicating that sclerites provide structural support rather than antifeeding defense. H. ghardaqensis lacks sclerites. We conclude that the conspicuous abundance of xeniid soft coral species in the Red Sea is likely a consequence of a strong chemical defence, rather than physical defences, against potential predators.

How can surgeonfish help pediatric surgeons? A pilot study investigating the antinociceptive effect of fish aquariums in adult volunteers.

Multiple distraction strategies have been proposed to reduce the incidence of anxiety and pain in children. Animal-assisted therapy is acknowledged and used in children as an adjunctive treatment with cognitive, physical, psychosocial and spiritual benefits. To determine the effect of fish aquarium animal-assisted therapy (FA-AAT) on pain perception in a cohort of healthy volunteers. Sixty-nine healthy subjects (mean age 27.3 years) were exposed to >20 different species of soft or hard corals and >25 fish in a 1000 L saltwater aquarium. Pain perception was assessed using an electrical stimulation device, the Pain Matcher (Cefar Medical AB, Sweden), after 5 min, 10 min, 20 min and 30 min of continuous aquarium viewing. The measurements were repeated 10 min after stopping aquarium viewing. A statistically significant pain perception threshold augmentation was observed after a 5 min aquarium viewing. This threshold augmentation was also increased after 10 min, 20 min and 30 min of FA-AAT. A remnant effect was noted up to 10 min after exposure. This short post-viewing time period could be useful in clinical practice to perform certain painful procedures in children, such as those involving needles, under improved conditions immediately after aquarium exposure. In the authors' department, FA-AAT is now used as a nonpharmacological antinociceptive technique in association with a protocol of inhalated oxygen⁄nitrous oxide mixtures for needle-related procedures. Children and parents are invited to watch the aquarium during the 10 min to 20 min before venous punctures.

Inhibition of bacterial fouling by soft coral natural products

Six common soft coral species (Sarcophyton sp., Sinularia sp.1 and sp.2, Cladiella sp., Scleronephthya sp. and Dendronephthya sp.) from Bandar Al-Khayran (Sultanate of Oman) had significantly lower bacterial density in comparison with surfaces of empty shells. Methanol: chloroform (1:1) extracts of these species were tested against Gram positive (Micrococcus luteus, Staphlococcus aureus, Bacillus subtilis, Bacillus sp.) and Gram negative (Salmonella enterica, Pseudomonas aeruginosa, Escherichia coli, Cytophaga sp., Pseudomonas sp., Shewanella sp.) marine biofouling and pathogenic bacterial strains. All tested extracts had some activity against human pathogens and the highest antimicrobial activity was observed for extracts of Sinularia sp.1 and Cladiella sp. (inhibited 50% and 60% of the strains, respectively). Only ethyl acetate extracts of Cladiella sp. inhibited growth of biofouling bacteria. The active fraction was purified and identified as a mixture of hexadecyl palmitate and hexadecyl stearate. Pure hexadecyl palmitate inhibited growth (Bacillus sp. and Psychrobacter sp.) and attachment (Bacillus sp., Cytophaga sp., Pseudomonas sp., Psychrobacter sp., Shewanella sp.) of the marine biofouling bacteria. The results of this study suggest that soft corals have developed mechanisms to combat microbial infections and inhibit bacterial fouling.

Use of Dendra2 to monitor degradation of the transcription factor Nrf2 in promyelocytic leukemia‐nuclear bodies in living cells (594.1)

Using a cellular fractionation approach, we have shown that the transcription factor Nrf2 can be degraded in the nucleus [Malloy et al. (2013) J. Biol. Chem. 288, 14569‐14583]. The use of photoconvertible proteins, which undergo irreversible change in color upon photoactivation, is a novel approach to monitor real‐time protein movement at the single cell level. In order to use this approach to assess degradation of Nrf2 within the nuclear compartment, we cloned Nrf2 into a plasmid expressing Dendra2, a photoconvertible protein derived from the soft coral species Dendronephthya. When expressed in cells, Dendra2 is a green‐colored fluorescent protein. Upon exposure to a high intensity laser pulse at 405 or 488 nm, its color changes irreversibly from green to red. Photoconversion of the Nrf2‐Dendra2 fusion protein within a region of interest such as within PML‐NB domains facilitates tracking the fate of the fusion protein via time‐lapse imaging. To locate such domains, we also constructed a plasmid expressing the fusion protein Crimson‐PML‐I to identify co‐localization of PML and Nrf2‐Dendra2 within PML‐NB domains. By measuring fluorescence intensity of Nrf2‐Dendra2 in PML‐NBs, we can determine the involvement of these nuclear bodies in the degradation of Nrf2 in the nucleus.Grant Funding Source: Supported by NIH grants SC1CA143985, T32GM007628‐36 and by CTSA award No. UL1TR000445

Environmental variabilities and the distribution of octocorals and black corals in Hong Kong

A recent comprehensive survey covering 125 sites in Hong Kong waters recorded 29 soft coral species in 14 genera, 38 species of gorgonians in 19 genera and six species of black corals in two genera. Environmental variabilities based on water quality data collected by Hong Kong Environmental Protection Department were analyzed using multivariate statistics to find variables that are significantly correlated with coral distribution patterns. Eleven water quality zones with similar environmental variabilities were recognized, which could further be classified into five groups, namely Inner Bay, Outer Bay, Eastern, Western and Southern waters. LINKTREE analysis provided an overall trend indicating the importance of salinity, sediment and nutrient loadings in affecting octocoral and black coral distribution from west to east of Hong Kong waters, and from inner to outer bays. Furthermore, water turbidity and wave exposure could also affect the coral distribution patterns from north, northeast to southern waters.