Competitive strategies of soft corals (Coelenterata: Octocorallia). II. Variable defensive responses and susceptibility to scleractinian corals

Interactions involving competition for space between several species of alcyonacean and scleractinian corals were assessed experimentally on Britomart Reef, central region of the Great Barrier Reef, Australia. Colonies of three soft coral species, Sarcophyton ehrenbergi Marenzeller, Nephthea brassica Kukenthal, and Capnella lacertiliensis Macfayden Forskal (Coelenterata:Alcyonacea) were relocated within stands of two scleractinian corals, Parités andrewsi Vaughan (= P. cylindrica Dana) and Pavona cactus Förskal (Coelenterata:Scleractinia). Undisturbed scleractinian and relocated alcyonacean controls were also monitored.Alcyonacean corals induced necrosis of tissue in scleractinian corals. Necrosis was significantly more pronounced when colonies were in contact but was also observed in the absence of contact, implicating the presence of active allelopathic agents. Scleractinian coral species varied in their susceptibility to the ill effects of alcyonaceans, with Pontes andrewsi being more susceptible than Pavona cactus. Of the soft corals, Nephthea caused the highest degree of mortality in the two scleractinian corals examined and Sarcophyton the least. Some soft corals appear to retain their toxins while others release them, implying a combination of anti-predatory and anti-competitor roles for the secondary metabolites. Scleractinian corals were often overgrown by soft corals.Both species of scleractinian corals were found to cause approximately equal amounts of tissue necrosis in alcyonaceans. These effects were more pronounced when colonies were in direct contact. The necrotic effects among alcyonacean corals were species-specific. Alcyonaceans also overgrew scleractinian corals and secreted a protective polysaccharide layer in areas proximal to scleractinians. Secretion of this layer was stimulated differentially by the two scleractinian species and also varied in frequency of occurrence among the alcyonaceans.High levels of tissue necrosis were observed in both groups of organisms within 3 wk of initiation of the experiment. Necrosis increased with time in the scleractinian corals and decreased in the alcyonaceans. The development of a protective polysaccharide layer in the alcyonaceans increased with time.     

Defensive strategies of soft corals (Coelenterata: Octocorallia) of the Great Barrier Reef

Summary The relationship between ichthyotoxicity and predation-related defensive functional morphology was examined in alcyonacean soft corals of the central and northern regions of the Great Barrier Reef (GBR), Australia. Approximately 170 specimens were assessed encompassing a number of genera within three families: 1) the Alcyoniidae (Lobophytum, Sarcophytum, Sinularia, Cladiella, Parerythropodium, and Alcyonium); 2) Neptheidae (Lemnalia, Paralemnalia, Capnella, Lithophyton, Nephthea, Dendronephthya, Scleronephthya, and Stereonephthya), and 3) Xeniidae (Anthelia, Efflatounaria, Cespitularia, Heteroxenia, and Xenia). Ichthyotoxicity data were derived from earlier studies which used Gambusia affinis Baird and Girard (Vertebrata, Pisces) as a test organism. These data were compared to morphological data collected from specimens in the field and laboratory. Three sets of statistical analyses were performed, each considering a progressively narrower group of taxa. The first included 68 specimens and considered 16 morphological characters in each, falling into the general categories of gross colony form, colony texture, presence of mucus, colony color, polyp retractility, and sclerite morphology and distribution. These were tested for independence against ichthyotoxicity data. The second set of analyses involved a more restricted morphological data set derived from 28 species of Sinularia in combination with 28 species within the Nephtheidae, comparing them to their respective toxicity ranks. The third analysis considered the previous two taxonomic groups separately in relation to their toxicity levels.The attempt to consider many morphological characters in a taxonomically diverse collection did not reveal any general association in the Alcyonacea between defensive morphology and toxicity, and those associations which did emerge were clearly erroneous. The second analysis, considering only Sinularia spp. and nephtheids, demonstrated a negative association between ichthyotoxicity and the morphological characters of a) polypary armament, b) microarmament of the individual polyp, and c) strong mineralization of the coenenchyme. The third analysis revealed that the negative association found between toxicity and the first two characters was derived entirely from the nephtheids while the association detected between toxicity and the third character was restricted to Sinularia. It is concluded that a relationship between toxicity and morphology can be demonstrated, but it is heavily dependent upon which specific morphological characters are being considered and at what level of taxonomic resolution the analysis is being performed. An approach utilizing many characters over many taxa is unlikely to yield significant, reliable, or meaningful results.Australian Institute of Marine Science Contribution Number 383     

Bleaching as a pathogenic response in scleractinian corals, evidenced by high concentrations of apoptotic and necrotic zooxanthellae

The study of symbiont cells lost from bleached scleractinian corals Acropora hyacinthus, Favites complanata, and Porites solida and octocorals Sarcophyton ehrenbergi, Sinularia sp., and Xenia sp. using flow cytometry shows that Symbiodinium die from either apoptosis or necrosis. Despite the majority of lost Symbiodinium cells being viable at 28 °C, the predominance of apoptotic and necrotic symbiont cells at higher temperatures indicates that the proportion of live cells decreases with increasing temperature. This implies that reinfection of corals at high temperatures by Symbiodinium lost from scleractinian corals may be less frequent than previously described, since many of the symbiont cells exhibit nonreversible symptoms of approaching cell death. The fraction of viable Symbiodinium cells lost from S. ehrenbergi, Xenia sp., and Sinularia at 32 °C was greater than that at 28 °C. At 34 °C, the fraction of viable cells lost from S. ehrenbergi and Xenia sp. fell but not from Sinularia sp., which suggests that their symbionts have higher temperature tolerances. Thus, Symbiodinium from octocorals may represent “pools” of genetically resistant symbionts available for reinfection of other reef organisms. This has been proposed previously for Symbiodinium in some scleractinian corals, but this is the first evidence for such, particularly for an octocoral. Many of the viable cells, determined using Trypan blue staining techniques, are in fact actually undergoing apoptosis or necrosis, when examined using Annexin V-fluor and propidium iodide staining profiles. The characterization of more apoptotic and necrotic cells than viable cells is critical, as this indicates that the loss of Symbiodinium cells cannot be beneficial to other bleached corals for symbiotic reassociation.     

A new family of soft corals (Anthozoa,Octocorallia, Alcyonacea) from the aphotic tropical eastern Pacific waters revealed by integrative taxonomy

The new family Aquaumbridae is described based on distinct morphological characters and supported by a molecular phylogenetic analysis. Aquaumbridae is similar to Nidaliidae, Nepththeidae and Alcyoniidae in having arborescent colonies and lacking axis structure or stolons, but differs from them in having very different sclerite composition and having conspicuous transparent jelly-like lobes. Phylogenetic analysis of two mitochondrial genes, ND2 and mtMutS, strongly supports its placement in a separated clade. Herein we describe Aquaumbra klapferi sp. nov., gen. nov. in the new family. The organisms were obtained from the seamounts, ridges and canyons out of the insular shelf of Isla del Coco, Costa Rica, down to 400 m depth. The new species represents the first discovery of a soft coral in an eastern Pacific oceanic island, and provides hints of the biodiversity of the largely unexplored deep waters of the tropical eastern Pacific.     

The effect of heterotrophy on photosynthesis and tissue composition of two scleractinian corals under elevated temperature

Exogenous food can increase protein levels of coral host tissue, zooxanthellae densities, chlorophyll (chl) concentrations and rates of photosynthesis and is thought to play an important role in the resilience of bleached corals. There is however no information about the effect of heterotrophy on the bleaching susceptibility of corals under elevated temperature conditions. This study investigates potential interactions between food availability, basal metabolic functions (photosynthesis and respiration), energy status (lipid concentrations), total protein concentrations and the bleaching susceptibility (loss of chl and/or zooxanthellae) of the scleractinian corals Stylophora pistillata (Esper) and Galaxea fascicularis (Linnaeus) in response to elevated temperature (daily temperature rises of 3-4 °C) over 15 days. Feeding experiments were carried out in which the corals were either fed daily with zooplankton or starved. Compared to fed corals, starvation of both species resulted in a significant decrease in daily photosynthetic oxygen evolution over time. Gross (Pg) and net (Pn) photosynthetic production of starved corals of both species between 10:00-11:00 hrs had declined by ~50% at day 15 while there were no marked changes in Pg and Pn of fed corals. After 15 days, starved S. pistillata contained significantly lower zooxanthellae densities, lipid and protein concentrations than fed corals. Starved G. fascicularis also displayed a decrease in zooxantllae densities which was accompanied by a significant decline in algal chl concentrations. Contrary to S. pistillata, feeding treatment had no effect on the lipid concentrations of G. fascicularis. Total protein concentrations however were significantly lower in straved than in fed G. fascicularis. Furthermore, starvation resulted in a significant decrease in respiration of S. pistillata during the last four days of the experiment while treatment had no effect on the respiration rates of G. fascicularis. Overall the oxygen consumption of S. pistillata of both treatments was about 39-67% higher than the respiration of G. fascicularis indicating that low metabolic rates may have allowed starved G. fascicularis to conserve energy reserves over the course of the experiment. The combined results reveal a strong positive relationship between food availability, sustained photosynthetic activity and reduced loss in pigmentation of both species under elevated temperature conditions.     

Impacts of bleaching on the soft coral Lobophytum compactum. I. Fecundity, fertilization and offspring viability

We document long-term effects of a simulated bleaching event on the reproductive output and offspring viability of the soft coral Lobophytum compactum. Corals were subjected to temperature and solar radiation treatments to produce both moderately (48–60%) and heavily (90–95%) bleached colonies. Although bleached colonies recovered their zooxanthellae within 10 to 18 weeks, impacts on reproductive output were significant for at least two annual spawning seasons. In the first year, both polyp fecundity and mean oocyte diameter were reduced and inversely correlated with the degree of bleaching, with complete failure of fertilization in the group of heavily bleached colonies. For moderately bleached soft corals, survival and growth of sexual offspring did not differ significantly from those of unbleached colonies. Although no further reductions in zooxanthellae densities in experimental soft corals were recorded throughout the subsequent second year, egg size and fecundity of the heavily bleached soft corals were still significantly reduced 20 months later. Severe bleaching clearly has long-term sub-lethal impacts, reducing overall reproductive output for at least two spawning seasons. Accepted: 1 June 2000     

Comparison of stress susceptibility of in hospite and isolated zooxanthellae among five coral species

Coral species in a similar habitat often show different bleaching susceptibilities. It is not understood which partner of coral-zooxanthellae complexes is responsible for differential stress susceptibility. Stress susceptibilities of in hospite and isolated zooxanthellae from five species of corals collected from shallow water in Okinawa were compared. To estimate stress susceptibility, we measured the maximum quantum yields (F_v/F_m) of in hospite and isolated zooxanthellae after 3-h exposure to either 28 or 34 °C at various light intensities and their recovery after 12 h under dim light at 26 °C. Significant reduction in photochemical efficiency (F_v/F_m) of photosystem II (PSII) was observed in in hospite zooxanthellae exposed to high light intensity (1000 μmol quanta m⁻² s⁻¹), while PSII activity of isolated zooxanthellae decreased significantly even at a lower light intensity (70 μmol quanta m⁻² s⁻¹). The recovery of the PSII activity after 12 h was incomplete in both in hospite and isolated zooxanthellae, indicating the presence of chronic photoinhibition. The stress susceptibility of isolated zooxanthellae was more variable among species than in hospite zooxanthellae. The order of stress susceptibility among the five coral species was different between in hospite and isolated zooxanthellae. The present results suggest that the host plays a significant role in determining bleaching susceptibility of corals, though zooxanthellae from different host have different stress susceptibilities.     

Impacts of bleaching on the soft coral Lobophytum compactum. II. Biochemical changes in adults and their eggs

Experimental bleaching reduces the levels of important biochemical parameters in adult tissues and eggs of the soft coral Lobophytum compactum. Protein, lipid, mycosporine-like amino acids (MAAs) and carotenoid concentrations remained lower in bleached adults than in controls for at least 8 months. Reductions in concentrations of all four parameters were greater in eggs than in maternal tissues, potentially jeopardizing egg and larval viability. In particular, reductions in lipids, proteins and carotenoids in tissues of heavily bleached soft corals were amplified approximately twofold in eggs. In comparison, amplification of maternal tissue reductions were not as great for MAAs, suggesting that MAAs are given higher priority in egg provisioning. Our finding that MAA levels are normally three times higher in eggs than in unbleached maternal tissues supports the importance of MAAs for larval survival. Twenty months after experimental bleaching the biochemical composition of both adult tissues and their eggs were indistinguishable from those of control (unbleached) soft corals. Accepted: 1 June 2000     

Patterns of association between Symbiodinium and members of the Montastraea annularis species complex on spatial scales ranging from within colonies to between geographic regions

Patterns of associations between coral colonies and the major clades of zooxanthellae can vary across scales ranging from individual colonies to widely separated geographic regions. This is exemplified in this study of the Montastraea annularis species complex from six sites on the Mesoamerican Reef, Belize and nine sites in the Bocas del Toro archipelago, Panama. Restriction fragment length polymorphism (RFLP) analysis of small subunit ribosomal DNA (SSU rDNA) was used to identify the zooxanthellae. In Belize (M. annularis), Symbiodinium B (79% of the colonies), Symbiodinium A, and Symbiodinium C were observed. In Panama (primarily M. franksi, but also M. annularis and M. faveolata), there was greater diversity and evenness with Symbiodinium A, B, C, C′ (a new symbiont) and D all being common in at least some host/habitat combinations. Non-metric multidimensional scaling ordinations showed that distribution patterns of symbionts across sites are best explained by enclosure (relative influence of open ocean vs. coastal water) and total suspended solids. Because members of clade D are known to be temperature resistant and Symbiodinium C′ was found in environments characterized by high sedimentation, these Panamanian reefs may have importance from a management perspective as reservoirs of corals better able to tolerate human impacts.     

Exaptation in corals to high seawater temperatures: Low concentrations of apoptotic and necrotic cells in host coral tissue under bleaching conditions

Scleractinian corals are known to suffer bleaching or loss of their symbiotic zooxanthellae under conditions of elevated seawater temperatures often associated with climate change (i.e. global warming). This can occur on a massive scale and has caused the decimation of reefs on a global basis. During the bleaching process, the expelled zooxanthellae suffer cell damage from heat stress, characterized by irreversible ultrastructural and physiological changes which are symptomatic of cell degeneration and death (called apoptosis) or necrosis. A question that remains unanswered, however, is whether the coral hosts themselves are sensitive to seawater temperatures, and, if so, to what degree? In a controlled experiment, we exposed corals Acropora hyacinthus (Dana, 1846) and Porites solida (Forskål, 1775) with their symbiotic zooxanthellae (Symbiodinium sp.) to temperatures of 28 °C (control), 30 °C, 32 °C, and 34 °C for 48 h and also to 36 °C for 12 h. We assessed coral and zooxanthellar cells in-situ for symptoms of apoptosis and necrosis using transmission electron microscopy (TEM), fluorescent microscopy (FM), and flow cytometry (FC). We found that the coral host cells in-situ exhibited, for the most part, little or no mortality from increased seawater temperatures. Damage to the coral hosts only occurred under conditions of prolonged exposure (≥ 12 h) at high temperatures (34 °C), or at exceptionally high temperatures (e.g. 36 °C). On the other hand, we found high levels of apoptosis and necrosis in the zooxanthellae in-situ under all treatment conditions of elevated seawater temperatures. We found that during bleaching, the host cells are not experiencing much mortality - but the zooxanthellae, even while still within the host, are. The host corals exhibit exaptation to accommodate temperatures as high as ≥ 34 °C. Temperature stress within these highly specific and coevolved symbiotic systems is derived not from host sensitivity to temperature, but from the symbiont's sensitivity and the loss of the coral's endosymbiotic partners.     

Some toxicological characteristics of three venomous soft corals from the Red Sea

Three common Red Sea soft corals (Cnidaria: Anthozoa), Nephthea sp, Dendronephthya sp and Heteroxenia fuscescens sting humans. Nematocyst venoms of each animal are lethal to mice and hemolytic to human erythrocytes. However, these hemolysins are partially inhibited by known anti-hemolytic agents. Venoms and their gel chromatography-separated fractions have different dermonecrosis and vasopermeability potency in mouse skin. The venom of Heteroxenia fuscescens (Hf) was more lethal (LD50: 0.7 mg/kg), with one prominent 97-kDa protein fraction (LD50: 0.55 mg/kg). Hf venom was more hemolytic, more dermonecrotic, and had more vasopermeable factors than that of the two other species. SDS polyacrylamide gel electrophoresis of soft coral whole venoms and fractions showed different protein molecular masses ranging from 200 to less than 6 kDa. High IgG titers were assayed from venom-sensitized mice blood sera. Enzyme-linked immunosorbent assays (ELISA) marked significant immunological cross-reaction between the studied soft coral venoms and their bioactive fractions.     

Symbiosis between Symbiodinium (Dinophyceae) and various taxa of Nudibranchia (Mollusca: Gastropoda), with analyses of long-term retention

Long-term retention of zooxanthellae in five different species belonging to two different nudibranch groups (Aeolidoidea and Dendronotoidea) was investigated. Specimens belonging to the species Phyllodesmium briareum, Phyllodesmium colemani, Phyllodesmium longicirrum, Pteraeolidia ianthina and Melibe engeli were cultivated for 70–270 days under various feeding conditions, and photosynthetic activity was analysed by taking pulse amplitude modulated (PAM) fluorometer measurements. All five species showed stable symbiosis and long-term retention of zooxanthellae. Interspecific differences are discussed. Morphological adaptations for housing zooxanthellae in the digestive glandular system were investigated and documented by histological means.     

Interactive effects of ocean acidification and temperature on two scleractinian corals from Moorea,French Polynesia

This study tested the hypothesis that the response of corals to temperature and pCO ₂ is consistent between taxa. Juvenile massive Porites spp. and branches of P. rus from the back reef of Moorea were incubated for 1 month under combinations of temperature (29.3 °C and 25.6 °C) and pCO ₂ (41.6 Pa and 81.5 Pa) at an irradiance of 599 μmol quanta m^?2 s^?1. Using microcosms and CO₂ gas mixing technology, treatments were created in a partly nested design (tanks) with two between‐plot factors (temperature and pCO ₂), and one within‐plot factor (taxon); calcification was used as a dependent variable. pCO ₂ and temperature independently affected calcification, but the response differed between taxa. Massive Porites spp. was largely unaffected by the treatments, but P. rus grew 50% faster at 29.3 °C compared with 25.6 °C, and 28% slower at 81.5 Pa vs. 41.6 Pa CO₂. A compilation of studies placed the present results in a broader context and tested the hypothesis that calcification for individual coral genera is independent of pH, [HCO₃ ^?], and [CO₃ ^2?]. Unlike recent reviews, this analysis was restricted to studies reporting calcification in units that could be converted to nmol CaCO₃ cm^?2 h^?1. The compilation revealed a high degree of variation in calcification as a function of pH, [HCO₃ ^?], and [CO₃ ^2?], and supported three conclusions: (1) studies of the effects of ocean acidification on corals need to pay closer attention to reducing variance in experimental outcomes to achieve stronger synthetic capacity, (2) coral genera respond in dissimilar ways to pH, [HCO₃ ^?], and [CO₃ ^2?], and (3) calcification of massive Porites spp. is relatively resistant to short exposures of increased pCO ₂, similar to that expected within 100 y.     

Response of two species of Indo-Pacific corals, Porites cylindrica and Stylophora pistillata, to short-term thermal stress: The host does matter in determining the tolerance of corals to bleaching

The role of both host and dinoflagellate symbionts was investigated in the response of reef-building corals to thermal stress in the light. Replicate coral nubbins of Stylophora pistillata and Porites cylindrica from the GBR were exposed to either 28 °C (control) or 32 °C for 5 days before being returned to an ambient reef temperature (28 °C). S. pistillata was found to contain either Symbiodinium genotype C1 or C8a, while P. cylindrica had type C15 based on ITS genotyping. Analysis of the quantum yield of photosystem (PS) II fluorescence of the symbionts in P. cylindrica showed that light-induced excitation pressure on the C15 Symbiodinium was significantly less, and the steady state quantum yield of PSII fluorescence at noon (ΔF/Fm′) greater, than that measured in C1/C8a Symbiodinium sp. from S. pistillata. Immunoblots of the PS II D1 protein were significantly lower in Symbiodinium from S. pistillata compared to those in P. cylindrica after exposure to thermal stress. The biochemical markers, heat-stress protein (HSP) 70 and superoxide dismutase (SOD), were significantly greater in P. cylindrica before the experiment, and both species of coral increased their biosynthesis of HSP 70 and SOD when exposed to thermal stress. Concentrations of MAAs, glycerol, and lipids were not significantly affected by thermal stress in these experiments, but DNA damage was greater in heat-stressed S. pistillata compared to P. cylindrica. There was minimal coral mucus, which accounts for up to half of the total energy budget of a coral and provides the first layer of defense for invading microbes, produced by S. pistillata after heat stress compared to P. cylindrica. It is concluded that P. cylindrica contains a heat resistant C15 Symbiodinium and critical host proteins are present at higher concentrations than observed for S. pistillata, the combination of which provides greater protection from bleaching conditions of high temperature in the light.     

Characterization of fatty acid composition in healthy and bleached corals from Okinawa, Japan

Under bleaching conditions, corals lose their symbiotic zooxanthellae, and thus, the ability to synthesize fatty acids (FAs) from photosynthetically derived carbon. This study investigated the lipid content and FA composition in healthy and bleached corals from the Odo reef flat in Okinawa, southern Japan, following a bleaching event. It was hypothesized that the FA composition and abundance would change as algae are lost or die, and possibly microbial abundance would increase in corals as a consequence of bleaching. The lipid content and FA composition of three healthy coral species (Pavona frondifera, Acropora pulchra, and Goniastrea aspera) and of partially bleached and completely bleached colonies of P. frondifera were examined. The FA composition did not differ among healthy corals, but differed significantly among healthy, partially bleached, and completely bleached specimens of P. frondifera. Completely bleached corals contained significantly lower lipid and total FA content, as well as lower relative amounts of polyunsaturated FAs and higher relative amounts of saturated FAs, than healthy and partially bleached corals. Furthermore, there was a significantly higher relative concentration of monounsaturated FAs and odd-numbered branched FAs in completely bleached corals, indicating an increase in bacterial colonization in the bleached corals.     

Photobiology of Symbiodinium revisited: bio-physical and bio-optical signatures

Light is often the most abundant resource within the nutrient-poor waters surrounding coral reefs. Consequently, zooxanthellae (Symbiodinium spp.) must continually photoacclimate to optimise productivity and ensure coral success. In situ coral photobiology is becoming dominated by routine assessments using state-of-the-art non-invasive bio-optical or chlorophyll a fluorescence (bio-physical) techniques. Multiple genetic types of Symbiodinium are now known to exist; however, little focus has been given as to how these types differ in terms of characteristics that are observable using these techniques. Therefore, this investigation aimed to revisit and expand upon a pivotal study by Iglesias-Prieto and Trench (1994) by comparing the photoacclimation characteristics of different Symbiodinium types based on their bio-physical (chlorophyll a fluorescence, reaction centre counts) and bio-optical (optical absorption, pigment concentrations) ‘signatures’. Signatures described here are unique to Symbiodinium type and describe phenotypic responses to set conditions, and hence are not suitable to describe taxonomic structure of in hospite Symbiodinium communities. In this study, eight Symbiodinium types from clades and sub-clades (A–B, F) were grown under two PFDs (Photon Flux Density) and examined. The photoacclimation response by Symbiodinium was highly variable between algal types for all bio-physical and for many bio-optical measurements; however, a general preference to modifying reaction centre content over effective antennae-absorption was observed. Certain bio-optically derived patterns, such as light absorption, were independent of algal type and, when considered per photosystem, were matched by reaction centre stoichiometry. Only by better understanding genotypic and phenotypic variability between Symbiodinium types can future studies account for the relative taxonomic and physiological contribution by Symbiodinium to coral acclimation.     

软珊瑚(Sinularia flexibilis)和柳珊瑚(Plexaura homomalla)化学防御物质研究进展

软珊瑚(Sinularia flexibilis)和柳珊瑚(Plexaura homomalla)属于海洋低等无脊椎动物,虽然这些动物自身缺乏有效的物理防御手段,却能在竞争激烈的海洋环境中生存与繁衍,这主要是依靠其次级代谢产物的化学防御作用.这些次级代谢产物聚积在体内或释放到环境中,作用主要体现在抵御捕食者、抗病原微生物、克生与防附着等方面.珊瑚化学防御物质的研究有助于探讨珊瑚与其环境中其它生物的化学生态关系,属于海洋化学生态学研究的重要内容之一,其研究方法和思路对海洋活性天然产物乃至海洋新药先导化合物的发现,具有重要的启迪作用.综述了软珊瑚和柳珊瑚化学防御物质的研究进展,并阐释了软珊瑚和柳珊瑚中具有拒捕食、克生、防生物附着等生物活性的次级代谢产物的结构及其化学防御作用.     

Danian cold‐water corals from the Baunekule facies,Faxe Formation,Denmark: a rare taphonomic window of a coral mound flank habitat

Well‐preserved cold‐water corals are comparatively rare in the fossil record. This is partly due to the very low fossilization potential of the predominantly aragonitic corals but also due to the fact that coral ecosystems of deep water are a geologically young development. A Middle Danian cold‐water coral mound complex is well exposed in Faxe Quarry, Denmark. The coral mounds are intercalated with bryozoan mounds of various sizes and form the Faxe Formation. The coral limestone displays large variations in diagenesis, and this complicates the palaeoecological reconstructions. However, the Baunekule facies from the Faxe Formation contain a well‐preserved originally aragonitic and calcitic fauna. The aragonitic skeletons have been recrystallized to calcite during early diagenesis and the excellent preservation makes taxonomic identifications straightforward. A diverse fauna of ten scleractinian coral species, nine stylasterine coral species and seven octocoral species has been described from the Baunekule facies. The fossil fauna represents an ecological niche between the dead coral framework and coral rubble on a flank of a growing Dendrophyllia coral mound with multiple colonization events. The diversity and relative abundance of the fossil scleractinian corals are comparable to the modern settings in the NE Atlantic and Mediterranean. The distribution and diversity of the octocorals and the stylasterine corals are suggested to represent coral gardens as described from modern setting in the NE Pacific. The presence of a diverse and abundant stylasterine fauna suggests a stable palaeoenvironment, probably in a bathymetric depth range of 200–400 metre.