Scientific Paper Archives for Marine Aquariums.
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Biosynthesis of ?essential ? amino acids by scleractinian corals
Lisa M. FITZGERALD* and Alina M. SZMANT
ABSTRACT:
Animals rely on their diet for amino acids that they are incapable either of synthesizing or of synthesizing in sufficient quantities to meet metabolic needs. These are the so-called `essential amino acids'. This set of amino acids is similar among the vertebrates and many of the invertebrates. Previously, no information was available for amino acid synthesis by the most primitive invertebrates, the Cnidaria. The purpose of this study was to examine amino acid synthesis by representative cnidarians within the
Order Scleractinia. Three species of zooxanthellate reef coral, Montastraea faeolata, Acropora cericornis and Porites diaricata, and two species of non-zooxanthellate coral, Tubastrea coccinea and Astrangia poculata, were incubated with "%C-labelled glucose or with the "%C-labelled amino acids glutamic acid, lysine or valine. Radiolabel tracer was followed into protein amino acids.Atotal of 17 amino acids, including hydroxyproline, were distinguishable by the techniques used. Of these, only threonine was not found radiolabelled in any of the samples. We could not detect tryptophan or cysteine, nor distinguish between the amino acid pairs glutamic acid and glutamine, or aspartic acid and asparagine. Eight amino acids normally considered essential for animals were made by the ?ve corals tested, although some of them were made only in small quantities. These eight amino acids are valine, isoleucine, leucine, tyrosine, phenylalanine histidine, methionine and lysine. The ability of cnidarians to synthesize these amino acids could be yet another indicator of a separate evolutionary history of the cnidarians from the rest of the Metazoa.
http://www.biochemj.org/bj/322/0213/3220213.pdf
Lisa M. FITZGERALD* and Alina M. SZMANT
ABSTRACT:
Animals rely on their diet for amino acids that they are incapable either of synthesizing or of synthesizing in sufficient quantities to meet metabolic needs. These are the so-called `essential amino acids'. This set of amino acids is similar among the vertebrates and many of the invertebrates. Previously, no information was available for amino acid synthesis by the most primitive invertebrates, the Cnidaria. The purpose of this study was to examine amino acid synthesis by representative cnidarians within the
Order Scleractinia. Three species of zooxanthellate reef coral, Montastraea faeolata, Acropora cericornis and Porites diaricata, and two species of non-zooxanthellate coral, Tubastrea coccinea and Astrangia poculata, were incubated with "%C-labelled glucose or with the "%C-labelled amino acids glutamic acid, lysine or valine. Radiolabel tracer was followed into protein amino acids.Atotal of 17 amino acids, including hydroxyproline, were distinguishable by the techniques used. Of these, only threonine was not found radiolabelled in any of the samples. We could not detect tryptophan or cysteine, nor distinguish between the amino acid pairs glutamic acid and glutamine, or aspartic acid and asparagine. Eight amino acids normally considered essential for animals were made by the ?ve corals tested, although some of them were made only in small quantities. These eight amino acids are valine, isoleucine, leucine, tyrosine, phenylalanine histidine, methionine and lysine. The ability of cnidarians to synthesize these amino acids could be yet another indicator of a separate evolutionary history of the cnidarians from the rest of the Metazoa.
http://www.biochemj.org/bj/322/0213/3220213.pdf
Metamorphosis of a Scleractinian Coral in Response to Microbial Biofilms.
Nicole S. Webster, Luke D. Smith, Andrew J. Heyward, Joy E. M. Watts, Richard I. Webb, Linda L. Blackall, and Andrew P. Negri. Applied and Environmental Microbiology, February 2004, p. 1213-1221, Vol. 70, No. 2 .
Microorganisms have been reported to induce settlement and metamorphosis in a wide range of marine invertebrate species. However, the primary cue reported for metamorphosis of coral larvae is calcareous coralline algae (CCA). Herein we report the community structure of developing coral reef biofilms and the potential role they play in triggering the metamorphosis of a scleractinian coral. Two-week-old biofilms induced metamorphosis in less than 10% of larvae, whereas metamorphosis increased significantly on older biofilms, with a maximum of 41% occurring on 8-week-old microbial films. There was a significant influence of depth in 4- and 8-week biofilms, with greater levels of metamorphosis occurring in response to shallow-water communities. Importantly, larvae were found to settle and metamorphose in response to microbial biofilms lacking CCA from both shallow and deep treatments, indicating that microorganisms not associated with CCA may play a significant role in coral metamorphosis. A polyphasic approach consisting of scanning electron microscopy, fluorescence in situ hybridization (FISH), and denaturing gradient gel electrophoresis (DGGE) revealed that coral reef biofilms were comprised of complex bacterial and microalgal communities which were distinct at each depth and time. Principal-component analysis of FISH data showed that the Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Cytophaga-Flavobacterium of Bacteroidetes had the largest influence on overall community composition. A low abundance of Archaea was detected in almost all biofilms, providing the first report of Archaea associated with coral reef biofilms. No differences in the relative densities of each subdivision of Proteobacteria were observed between slides that induced larval metamorphosis and those that did not. Comparative cluster analysis of bacterial DGGE patterns also revealed that there were clear age and depth distinctions in biofilm community structure; however, no difference was detected in banding profiles between biofilms which induced larval metamorphosis and those where no metamorphosis occurred. This investigation demonstrates that complex microbial communities can induce coral metamorphosis in the absence of CCA.
http://aem.asm.org/cgi/content/full/70/2/1213#top
Nicole S. Webster, Luke D. Smith, Andrew J. Heyward, Joy E. M. Watts, Richard I. Webb, Linda L. Blackall, and Andrew P. Negri. Applied and Environmental Microbiology, February 2004, p. 1213-1221, Vol. 70, No. 2 .
Microorganisms have been reported to induce settlement and metamorphosis in a wide range of marine invertebrate species. However, the primary cue reported for metamorphosis of coral larvae is calcareous coralline algae (CCA). Herein we report the community structure of developing coral reef biofilms and the potential role they play in triggering the metamorphosis of a scleractinian coral. Two-week-old biofilms induced metamorphosis in less than 10% of larvae, whereas metamorphosis increased significantly on older biofilms, with a maximum of 41% occurring on 8-week-old microbial films. There was a significant influence of depth in 4- and 8-week biofilms, with greater levels of metamorphosis occurring in response to shallow-water communities. Importantly, larvae were found to settle and metamorphose in response to microbial biofilms lacking CCA from both shallow and deep treatments, indicating that microorganisms not associated with CCA may play a significant role in coral metamorphosis. A polyphasic approach consisting of scanning electron microscopy, fluorescence in situ hybridization (FISH), and denaturing gradient gel electrophoresis (DGGE) revealed that coral reef biofilms were comprised of complex bacterial and microalgal communities which were distinct at each depth and time. Principal-component analysis of FISH data showed that the Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Cytophaga-Flavobacterium of Bacteroidetes had the largest influence on overall community composition. A low abundance of Archaea was detected in almost all biofilms, providing the first report of Archaea associated with coral reef biofilms. No differences in the relative densities of each subdivision of Proteobacteria were observed between slides that induced larval metamorphosis and those that did not. Comparative cluster analysis of bacterial DGGE patterns also revealed that there were clear age and depth distinctions in biofilm community structure; however, no difference was detected in banding profiles between biofilms which induced larval metamorphosis and those where no metamorphosis occurred. This investigation demonstrates that complex microbial communities can induce coral metamorphosis in the absence of CCA.
http://aem.asm.org/cgi/content/full/70/2/1213#top
The Effect of External Nutrient Resources on the Population Dynamics of Zooxanthellae in a Reef Coral.
L. Muscatine, P. G. Falkowski, Z. Dubinsky, P. A. Cook, L. R. McCloskey
Proceedings of the Royal Society of London. Series B, Biological Sciences, Vol. 236, No. 1284 (Apr. 22, 1989) , pp. 311-324
Abstract:
Experiments were done to determine if ammonium, phosphate and feeding on Artemia nauplii affected the population density of symbiotic algae (zooxanthellae) in the Red Sea coral Stylophora pistillata. Corals were incubated for 14 days under natural sunlight at reduced intensity in running seawater aquaria. The seawater was continuously spiked to give final concentrations of either 20 muM ammonium or 2 muM phosphate, or both. A second set of similarly treated corals was also fed Artemia nauplii daily. Population density of zooxanthellae in corals spiked with ammonium, or ammonium plus phosphate, approximately doubled, and the ratio of zooxanthellae carbon-nitrogen decreased. Phosphate supplementation alone had no effect. The increase in zooxanthellae numbers was linearly proportional to the increase in protein in zooxanthellae, suggesting that availability of inorganic nitrogen leads to increased protein synthesis in zooxanthellae. Feeding on Artemia alone or together with phosphate had no effect on the population density of zooxanthellae. Feeding on Artemia and ammonium produced a small increase in population density but it was not statistically significant. The small effect could be due to insufficient influx of ammonium in fed animals, or growth of both animal and algae resulting in little or no net change in the population density of zooxanthellae. The results are consistent with the hypothesis that the growth of zooxanthellae in S pistillata from the Red Sea is nitrogen limited.
http://www.jstor.org/view/00804649/di002028/00p0024c/0#abstract
L. Muscatine, P. G. Falkowski, Z. Dubinsky, P. A. Cook, L. R. McCloskey
Proceedings of the Royal Society of London. Series B, Biological Sciences, Vol. 236, No. 1284 (Apr. 22, 1989) , pp. 311-324
Abstract:
Experiments were done to determine if ammonium, phosphate and feeding on Artemia nauplii affected the population density of symbiotic algae (zooxanthellae) in the Red Sea coral Stylophora pistillata. Corals were incubated for 14 days under natural sunlight at reduced intensity in running seawater aquaria. The seawater was continuously spiked to give final concentrations of either 20 muM ammonium or 2 muM phosphate, or both. A second set of similarly treated corals was also fed Artemia nauplii daily. Population density of zooxanthellae in corals spiked with ammonium, or ammonium plus phosphate, approximately doubled, and the ratio of zooxanthellae carbon-nitrogen decreased. Phosphate supplementation alone had no effect. The increase in zooxanthellae numbers was linearly proportional to the increase in protein in zooxanthellae, suggesting that availability of inorganic nitrogen leads to increased protein synthesis in zooxanthellae. Feeding on Artemia alone or together with phosphate had no effect on the population density of zooxanthellae. Feeding on Artemia and ammonium produced a small increase in population density but it was not statistically significant. The small effect could be due to insufficient influx of ammonium in fed animals, or growth of both animal and algae resulting in little or no net change in the population density of zooxanthellae. The results are consistent with the hypothesis that the growth of zooxanthellae in S pistillata from the Red Sea is nitrogen limited.
http://www.jstor.org/view/00804649/di002028/00p0024c/0#abstract
Ratio of energy and nutrient fluxes regulates symbiosis between zooxanthellae and corals.
Dubinsky, Z; Jokiel, PL
Pacific Science [PAC. SCI.]. Vol. 48, no. 3, pp. 313-324. 1994.
Ambient irradiance levels determine the rate of carbon influx into zooxanthellae at any given time, and thereby the energy available for the whole coral symbiotic association. Long-term photoacclimation of zooxanthellae to the time-averaged light regime at which the host coral grows results in optimization of light harvesting and utilization. Under high irradiance light harvesting is reduced, thereby avoiding photodynamic damage, whereas under low light, photon capture and quantum yield are maximized. Most of the photosynthate produced by the algae is respired. However, the capability of the zooxanthellae and the coral to retain carbon beyond that required to meet their respiratory needs depends on the availability of the commonly limiting nutrients, nitrogen and phosphorus. Therefore, the ratio of the flux of these nutrients into the colony to that of the photosynthetically driven carbon flux will regulate the growth of the zooxanthellae and of the animal. Nutrients acquired by predation of the coral on zooplankton are available first to the animal, whereas those absorbed by the zooxanthellae from seawater as inorganic compounds lead first to growth of the algae.
Dubinsky, Z; Jokiel, PL
Pacific Science [PAC. SCI.]. Vol. 48, no. 3, pp. 313-324. 1994.
Ambient irradiance levels determine the rate of carbon influx into zooxanthellae at any given time, and thereby the energy available for the whole coral symbiotic association. Long-term photoacclimation of zooxanthellae to the time-averaged light regime at which the host coral grows results in optimization of light harvesting and utilization. Under high irradiance light harvesting is reduced, thereby avoiding photodynamic damage, whereas under low light, photon capture and quantum yield are maximized. Most of the photosynthate produced by the algae is respired. However, the capability of the zooxanthellae and the coral to retain carbon beyond that required to meet their respiratory needs depends on the availability of the commonly limiting nutrients, nitrogen and phosphorus. Therefore, the ratio of the flux of these nutrients into the colony to that of the photosynthetically driven carbon flux will regulate the growth of the zooxanthellae and of the animal. Nutrients acquired by predation of the coral on zooplankton are available first to the animal, whereas those absorbed by the zooxanthellae from seawater as inorganic compounds lead first to growth of the algae.
Nitrate increases zooxanthellae population density and reduces skeletogenesis in corals.
F. Marubini and P. S. Davies
Marine Biology;Publisher: Springer-Verlag GmbH; ISSN: 0025-3162 (Paper); 1432-1793 (Online); DOI: 10.1007/BF00942117; Issue: Volume 127, Number 2 ; Date: December 1996
Abstract:
Very little information exists on the effects of nitrate on corals, although this is the major form in which nitrogen is prescrit in tropical eutrophie coastal waters. In this study we incubated nubbins of Porites porites and explants of Montastrea annularis in laboratory photostats illuminated by halide lamps, with concentrations of nitrate of 0, 1, 5 and 20 uM, for 40 and 30 d, respectively, At the end of this period it was found that the population density of the zooxanthellae had increased significantly with increased nitrate concentration, suggesting nitrogen limitation of the growth rate of zooxanthellae in the control group. There were also significant increases in the amount of chlorophyll a and e2 per algal cell, in the volume of the algal cells, and in the protein per cell. Overall, the protein per unit surface increased, but this was attributable solely to increased algal protein: there was no significant change in host protein. Maximum gross photosynthesis normalized to surface area was enhanced by nitrate addition, reflecting the increase in algal population density. There was no change when normalized on a per cell basis. Respiration rate normalized to protein content was decreased by nitrate. The most dramatic change was in the rate of skeletogenesis, which decreased by ~= in both species when exposed to nitrate enrichment. A model is presented which suggests that the diffusion-limited supply of CO2 from surrounding seawater is used preferentially by the enlarged zooxanthellae population for Photosynthesis, thereby reducing the availability of inorganic carbon for calcification. It is concluded that enhanced nitrate levels in tropical coastal waters will have a hitherto unrecognized effect on the growth rate of tropical coral reefs.
F. Marubini and P. S. Davies
Marine Biology;Publisher: Springer-Verlag GmbH; ISSN: 0025-3162 (Paper); 1432-1793 (Online); DOI: 10.1007/BF00942117; Issue: Volume 127, Number 2 ; Date: December 1996
Abstract:
Very little information exists on the effects of nitrate on corals, although this is the major form in which nitrogen is prescrit in tropical eutrophie coastal waters. In this study we incubated nubbins of Porites porites and explants of Montastrea annularis in laboratory photostats illuminated by halide lamps, with concentrations of nitrate of 0, 1, 5 and 20 uM, for 40 and 30 d, respectively, At the end of this period it was found that the population density of the zooxanthellae had increased significantly with increased nitrate concentration, suggesting nitrogen limitation of the growth rate of zooxanthellae in the control group. There were also significant increases in the amount of chlorophyll a and e2 per algal cell, in the volume of the algal cells, and in the protein per cell. Overall, the protein per unit surface increased, but this was attributable solely to increased algal protein: there was no significant change in host protein. Maximum gross photosynthesis normalized to surface area was enhanced by nitrate addition, reflecting the increase in algal population density. There was no change when normalized on a per cell basis. Respiration rate normalized to protein content was decreased by nitrate. The most dramatic change was in the rate of skeletogenesis, which decreased by ~= in both species when exposed to nitrate enrichment. A model is presented which suggests that the diffusion-limited supply of CO2 from surrounding seawater is used preferentially by the enlarged zooxanthellae population for Photosynthesis, thereby reducing the availability of inorganic carbon for calcification. It is concluded that enhanced nitrate levels in tropical coastal waters will have a hitherto unrecognized effect on the growth rate of tropical coral reefs.
Coral calcification: use of radioactive isotopes and metabolic inhibitors to study the interactions with photosynthesis and respiration. Al-Horani, F. A.; Al-Rousan, S. A.; Manasrah, R. S.; Rasheed, M. Y. Marine Science Station, Aqaba, Jordan. Chemistry and Ecology (2005), 21(5), 325-335.
Abstract
In order to characterize the process of calcification in scleractinian corals, a series of lab. expts. were conducted using radioactive isotopes. Labeled calcium, bicarbonate and glucose were used and the fates of the labeled tracers were followed in the skeleton and the tissue fractions of the coral Galaxea fascicularis. In addn., a variety of metabolic inhibitors were used to test the effects of various enzymes and processes on the incorporation rates. The incorporation rate of 45Ca into the coral skeleton decreased to about one-fifth upon inhibition of metabolic respiration by the specific inhibitor NaCN suggesting a major role of metabolic respiration in coral calcification, and decreased to one-half upon inhibition of carbonic anhydrase by the specific inhibitor acetazolamide indicating a role of the enzyme in the process. The results obtained have also shown that corals are able to incorporate carbon from seawater bicarbonate and added glucose in both skeleton and tissue fractions. The process of incorporation was influenced by light conditions, carbonic anhydrase, respiration and photosynthesis. The incorporation rate of 14C-HCO-3 was reduced to about one-tenth in the skeleton, and one-fifth in the tissue, upon inhibition of carbonic anhydrase suggesting a major influence of the enzyme in the incorporation process. The inhibition of photosynthesis had more influence on the tissue incorporation rate of the tracer than the skeleton suggesting that photosynthesis is the main process responsible for tissue use of seawater bicarbonate in the coral. 14C-glucose incorporation into the skeleton was mainly affected by NaCN addn. and to a lesser extent by dichlorophenyldimethylurea (DCMU) addn., while the tissue fraction was mainly affected by NaCN addn. It was concluded that respiration and photosynthesis, in addn.
to the enzyme carbonic anhydrase, are limiting factors for the process of calcification in the coral, and that various forms and sources of carbon can be used in coral calcification and tissue growth.
Abstract
In order to characterize the process of calcification in scleractinian corals, a series of lab. expts. were conducted using radioactive isotopes. Labeled calcium, bicarbonate and glucose were used and the fates of the labeled tracers were followed in the skeleton and the tissue fractions of the coral Galaxea fascicularis. In addn., a variety of metabolic inhibitors were used to test the effects of various enzymes and processes on the incorporation rates. The incorporation rate of 45Ca into the coral skeleton decreased to about one-fifth upon inhibition of metabolic respiration by the specific inhibitor NaCN suggesting a major role of metabolic respiration in coral calcification, and decreased to one-half upon inhibition of carbonic anhydrase by the specific inhibitor acetazolamide indicating a role of the enzyme in the process. The results obtained have also shown that corals are able to incorporate carbon from seawater bicarbonate and added glucose in both skeleton and tissue fractions. The process of incorporation was influenced by light conditions, carbonic anhydrase, respiration and photosynthesis. The incorporation rate of 14C-HCO-3 was reduced to about one-tenth in the skeleton, and one-fifth in the tissue, upon inhibition of carbonic anhydrase suggesting a major influence of the enzyme in the incorporation process. The inhibition of photosynthesis had more influence on the tissue incorporation rate of the tracer than the skeleton suggesting that photosynthesis is the main process responsible for tissue use of seawater bicarbonate in the coral. 14C-glucose incorporation into the skeleton was mainly affected by NaCN addn. and to a lesser extent by dichlorophenyldimethylurea (DCMU) addn., while the tissue fraction was mainly affected by NaCN addn. It was concluded that respiration and photosynthesis, in addn.
to the enzyme carbonic anhydrase, are limiting factors for the process of calcification in the coral, and that various forms and sources of carbon can be used in coral calcification and tissue growth.
If you can, please provide the actual paper link or pdf. Abstracts are OK but are only superficial information, I like to read the whole paper.i'll try to find the paper, i only aquired the abstract.
here's another interesting one
http://www.botany.hawaii.edu/faculty/duffy/arb/220/v220.pdf
here's another interesting one
http://www.botany.hawaii.edu/faculty/duffy/arb/220/v220.pdf
A MOLECULAR PHYLOGENETIC ANALYSIS OF REPRODUCTIVE TRAIT EVOLUTION IN THE SOFT CORAL GENUS ALCYONIUM
Catherine S. McFadden,a, b Rachel Donahue,a Brandon K. Hadland,a and Rebecca Westona
aDepartment of Biology, Harvey Mudd College, Claremont, California 91711
b E-mail: [email protected]
Abstract.—The soft coral genus Alcyonium is among the most reproductively diverse invertebrate taxa known: The genus includes species that vary both in mode of reproduction (including broadcast spawners, internal brooders, and external brooders) and sexual expression (gonochores, hermaphrodites, and a unisexual parthenogen). Such diversity offers a unique opportunity to examine associations between reproductive and morphological traits in a phylogenetic context. We used an approximately 900-bp sequence of the nuclear ribosomal gene complex spanning the internal transcribed spacer (ITS) regions to construct a molecular phylogeny for 14 European and North American species of Alcyonium onto which we mapped the known distribution of reproductive and morphological traits. The phylogeny suggests that hermaphroditism or parthenogenesis has evolved independently at least twice in this genus, and always in internally brooding species. Broadcast spawning and external brooding only occur in species with large colony size, whereas all species with small colony size brood their larvae internally. Internal brooding and small size appear to be ancestral in this genus; if this is the case, an association between broadcast spawning and large colony size has evolved independently in at least two clades. This tendency of small adults to brood their larvae while large adults broadcast spawn them into the plankton has been observed in a variety of solitary invertebrate taxa, but to date has not been documented in any other colonial invertebrates. Moreoever, it has been suggested that organisms with a colonial growth form should not experience the allometric constraints on brood space that have been proposed to explain the association between adult size and mode of reproduction in solitary organisms. Unlike many other colonial groups, however, module (polyp) size is strongly correlated with colony size in Alcyonium, and constraints on brooding may be imposed by module, rather than colony, allometry. The very close genetic relationship (< 1% sequence divergence) and shared polymorphisms among A. digitatum (a large, gonochoric broadcast spawner), A. siderium, and A. sp. A (intermediate-sized and small hermaphroditic, internal brooders) suggest that evolutionary transitions between broadcast spawning and brooding and between gonochorism and hermaphroditism can occur easily and rapidly in this group.
Corresponding Editor: S. Karl
Key words.—Alcyonium, cnidarian, internal transcribed spacer, larval development, life-history evolution, molecular systematics, ribosomal DNA, sexual expression, soft coral.
Sorry, couldn't find the full article.
Catherine S. McFadden,a, b Rachel Donahue,a Brandon K. Hadland,a and Rebecca Westona
aDepartment of Biology, Harvey Mudd College, Claremont, California 91711
b E-mail: [email protected]
Abstract.—The soft coral genus Alcyonium is among the most reproductively diverse invertebrate taxa known: The genus includes species that vary both in mode of reproduction (including broadcast spawners, internal brooders, and external brooders) and sexual expression (gonochores, hermaphrodites, and a unisexual parthenogen). Such diversity offers a unique opportunity to examine associations between reproductive and morphological traits in a phylogenetic context. We used an approximately 900-bp sequence of the nuclear ribosomal gene complex spanning the internal transcribed spacer (ITS) regions to construct a molecular phylogeny for 14 European and North American species of Alcyonium onto which we mapped the known distribution of reproductive and morphological traits. The phylogeny suggests that hermaphroditism or parthenogenesis has evolved independently at least twice in this genus, and always in internally brooding species. Broadcast spawning and external brooding only occur in species with large colony size, whereas all species with small colony size brood their larvae internally. Internal brooding and small size appear to be ancestral in this genus; if this is the case, an association between broadcast spawning and large colony size has evolved independently in at least two clades. This tendency of small adults to brood their larvae while large adults broadcast spawn them into the plankton has been observed in a variety of solitary invertebrate taxa, but to date has not been documented in any other colonial invertebrates. Moreoever, it has been suggested that organisms with a colonial growth form should not experience the allometric constraints on brood space that have been proposed to explain the association between adult size and mode of reproduction in solitary organisms. Unlike many other colonial groups, however, module (polyp) size is strongly correlated with colony size in Alcyonium, and constraints on brooding may be imposed by module, rather than colony, allometry. The very close genetic relationship (< 1% sequence divergence) and shared polymorphisms among A. digitatum (a large, gonochoric broadcast spawner), A. siderium, and A. sp. A (intermediate-sized and small hermaphroditic, internal brooders) suggest that evolutionary transitions between broadcast spawning and brooding and between gonochorism and hermaphroditism can occur easily and rapidly in this group.
Corresponding Editor: S. Karl
Key words.—Alcyonium, cnidarian, internal transcribed spacer, larval development, life-history evolution, molecular systematics, ribosomal DNA, sexual expression, soft coral.
Sorry, couldn't find the full article.
- Location
- Yonkers, NY
"Benefit of pulsation in soft corals"
Maya Kremien, Uri Shavit, Tali Mass, and Amatzia Genin
---------------------------
Abstract
Soft corals of the family Xeniidae exhibit a unique, rhythmic pulsation of their tentacles (Movie S1), first noted by Lamarck nearly 200 y ago. However, the adaptive benefit of this perpetual, energetically costly motion is poorly understood. Using in situ underwater particle image velocimetry, we found that the pulsation motions thrust water upward and enhance mixing across the coral?water boundary layer. The induced upward motion effectively prevents refiltration of water by neighboring polyps, while the intensification of mixing, together with the upward flow, greatly enhances the coral?s photosynthesis. A series of controlled laboratory experiments with the common xeniid coral Heteroxenia fuscescens showed that the net photosynthesis rate during pulsation was up to an order of magnitude higher than during the coral?s resting, nonpulsating state. This enhancement diminished when the concentration of oxygen in the ambient water was artificially raised, indicating that the enhancement of photosynthesis was due to a greater efflux of oxygen from the coral tissues. By lowering the internal oxygen concentration, pulsation alleviates the problem of reduced affinity of ribulose-1,5-bisphosphate carboxylase oxygenase (RuBisCO) to CO2 under conditions of high oxygen concentrations. The photosynthesis?respiration ratio of the pulsating H. fuscescens was markedly higher than the ratios reported for nonpulsating soft and stony corals. Although pulsation is commonly used for locomotion and filtration in marine mobile animals, its occurrence in sessile (bottom-attached) species is limited to members of the ancient phylum Cnidaria, where it is used to accelerate water and enhance physiological processes.
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Source: http://www.pnas.org/content/early/2013/04/17/1301826110
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A description of the paper contents is available here:
http://www.advancedaquarist.com/blog/why-do-soft-corals-like-xenia-pulse
Maya Kremien, Uri Shavit, Tali Mass, and Amatzia Genin
---------------------------
Abstract
Soft corals of the family Xeniidae exhibit a unique, rhythmic pulsation of their tentacles (Movie S1), first noted by Lamarck nearly 200 y ago. However, the adaptive benefit of this perpetual, energetically costly motion is poorly understood. Using in situ underwater particle image velocimetry, we found that the pulsation motions thrust water upward and enhance mixing across the coral?water boundary layer. The induced upward motion effectively prevents refiltration of water by neighboring polyps, while the intensification of mixing, together with the upward flow, greatly enhances the coral?s photosynthesis. A series of controlled laboratory experiments with the common xeniid coral Heteroxenia fuscescens showed that the net photosynthesis rate during pulsation was up to an order of magnitude higher than during the coral?s resting, nonpulsating state. This enhancement diminished when the concentration of oxygen in the ambient water was artificially raised, indicating that the enhancement of photosynthesis was due to a greater efflux of oxygen from the coral tissues. By lowering the internal oxygen concentration, pulsation alleviates the problem of reduced affinity of ribulose-1,5-bisphosphate carboxylase oxygenase (RuBisCO) to CO2 under conditions of high oxygen concentrations. The photosynthesis?respiration ratio of the pulsating H. fuscescens was markedly higher than the ratios reported for nonpulsating soft and stony corals. Although pulsation is commonly used for locomotion and filtration in marine mobile animals, its occurrence in sessile (bottom-attached) species is limited to members of the ancient phylum Cnidaria, where it is used to accelerate water and enhance physiological processes.
------------
Source: http://www.pnas.org/content/early/2013/04/17/1301826110
------------
A description of the paper contents is available here:
http://www.advancedaquarist.com/blog/why-do-soft-corals-like-xenia-pulse
"Overview on the Diversity of Sounds Produced by Clownfishes (Pomacentridae): Importance of Acoustic Signals in Their Peculiar Way of Life "
Orphal Colleye, Eric Parmentier (2012)
---- Abstract ----
Clownfishes (Pomacentridae) are brightly colored coral reef fishes well known for their mutualistic symbiosis with tropical sea anemones. These fishes live in social groups in which there is a size-based dominance hierarchy. In this structure where sex is socially controlled, agonistic interactions are numerous and serve to maintain size differences between individuals adjacent in rank. Clownfishes are also prolific callers whose sounds seem to play an important role in the social hierarchy. Here, we aim to review and to synthesize the diversity of sounds produced by clownfishes in order to emphasize the importance of acoustic signals in their way of life.
Recording the different acoustic behaviors indicated that sounds are divided into two main categories: aggressive sounds produced in conjunction with threat postures (charge and chase), and submissive sounds always emitted when fish exhibited head shaking movements (i.e. a submissive posture). Both types of sounds showed size-related intraspecific variation in dominant frequency and pulse duration: smaller individuals produce higher frequency and shorter duration pulses than larger ones, and inversely. Consequently, these sonic features might be useful cues for individual recognition within the group. This observation is of significant importance due to the size-based hierarchy in clownfish group. On the other hand, no acoustic signal was associated with the different reproductive activities.
Unlike other pomacentrids, sounds are not produced for mate attraction in clownfishes but to reach and to defend the competition for breeding status, which explains why constraints are not important enough for promoting call diversification in this group.
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Source: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0049179
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Side information: Orphan Colleye was mentioning in an interview that due to the different equipments we have in aquariums, clownfish do lose some of their ability to hear in our setups.
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Videos of clownfish "talking":
Aggressive: https://www.youtube.com/watch?v=6f-AJ5MaV0k
Submissive: https://www.youtube.com/watch?v=EVBjzKiLGVw
Orphal Colleye, Eric Parmentier (2012)
---- Abstract ----
Clownfishes (Pomacentridae) are brightly colored coral reef fishes well known for their mutualistic symbiosis with tropical sea anemones. These fishes live in social groups in which there is a size-based dominance hierarchy. In this structure where sex is socially controlled, agonistic interactions are numerous and serve to maintain size differences between individuals adjacent in rank. Clownfishes are also prolific callers whose sounds seem to play an important role in the social hierarchy. Here, we aim to review and to synthesize the diversity of sounds produced by clownfishes in order to emphasize the importance of acoustic signals in their way of life.
Recording the different acoustic behaviors indicated that sounds are divided into two main categories: aggressive sounds produced in conjunction with threat postures (charge and chase), and submissive sounds always emitted when fish exhibited head shaking movements (i.e. a submissive posture). Both types of sounds showed size-related intraspecific variation in dominant frequency and pulse duration: smaller individuals produce higher frequency and shorter duration pulses than larger ones, and inversely. Consequently, these sonic features might be useful cues for individual recognition within the group. This observation is of significant importance due to the size-based hierarchy in clownfish group. On the other hand, no acoustic signal was associated with the different reproductive activities.
Unlike other pomacentrids, sounds are not produced for mate attraction in clownfishes but to reach and to defend the competition for breeding status, which explains why constraints are not important enough for promoting call diversification in this group.
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Source: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0049179
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Side information: Orphan Colleye was mentioning in an interview that due to the different equipments we have in aquariums, clownfish do lose some of their ability to hear in our setups.
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Videos of clownfish "talking":
Aggressive: https://www.youtube.com/watch?v=6f-AJ5MaV0k
Submissive: https://www.youtube.com/watch?v=EVBjzKiLGVw
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