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ShaunW 02-01-2006 07:38 PM

Scientific Paper Archives for Marine Aquariums.
This thread is a storage device for scientific papers revelant to marine aquariums. Please don't clutter this thread unnessesarily. THANKS! :grouphug:

ShaunW 02-01-2006 07:47 PM

Biosynthesis of ‘essential ’ amino acids by scleractinian corals

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.

ShaunW 02-01-2006 07:52 PM

1 Attachment(s)
Low temperature X-ray microanalysis of calcium in a scleractinian coral: evidence of active transport mechanisms
Peta L. Clode and Alan T. Marshall*

ShaunW 02-01-2006 07:58 PM

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.

ShaunW 02-01-2006 08:05 PM

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


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.

ShaunW 02-01-2006 08:08 PM

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.

ShaunW 02-01-2006 08:11 PM

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


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.

spykes 02-01-2006 08:16 PM

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.


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.

ShaunW 02-01-2006 08:22 PM

Thanks Dave for helping out! :D 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.

spykes 02-01-2006 08:48 PM

i'll try to find the paper, i only aquired the abstract.
here's another interesting one

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