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  • 1
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Ecology, Evolution, and Systematics 29 (1998), S. 405-434 
    ISSN: 0066-4162
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Abstract The coastal zone is where land, ocean, and atmosphere interact. It exhibits a wide diversity of geomorphological types and ecosystems, each one displaying great variability in terms of physical and biogeochemical forcings. Despite its relatively modest surface area, the coastal zone plays a considerable role in the biogeochemical cycles because it receives massive inputs of terrestrial organic matter and nutrients, is among the most geochemically and biologically active areas of the biosphere, and exchanges large amounts of matter and energy with the open ocean. Coastal ecosystems have therefore attracted much attention recently and are the focus of several current national and international research programs (e.g. LOICZ, ELOISE). The primary production, respiration, calcification, carbon burial and exchange with adjacent systems, including the atmosphere, are reviewed for the major coastal ecosystems (estuaries, macrophyte communities, mangroves, coral reefs, and the remaining continental shelf). All ecosystems examined, except estuaries, are net autotrophic. The contribution of the coastal zone to the global carbon cycle both during pristine times and at present is difficult to assess due to the limited metabolic data available as well as because of major uncertainties concerning the magnitude of processes such as respiration, exchanges at the open ocean boundary, and air-sea fluxes of biogases.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Coral reefs 9 (1991), S. 173-182 
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The morphology and skeletal characteristics of colonies of the coral genus Stylophora living on the reef edge at 1 m depth on the Jordanian coast of the Gulf of Aqaba (Red Sea) are those of S. mordax (Dana 1846) which has not been reported previously from that area. These colonies were considered earlier as ecomorphs of S. pistillata (Esper 1797) which lives down to at least 67 m on the reef slopes. Growth, organic content and metabolism were compared in colonies living at different depths (1,5,10 and 30 m). The trends of twelve parameters between 1 and 5 m were different from the variation observed between 5 and 30 m. Colonies living at 1 m have a higher chlorophyll content but a lower metabolic activity and growth rate than colonies living at 5 m. Most of these pecularities cannot be explained by the influence of environmental factors. It is therefore suggested that S. mordax is a valid taxon.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0975
    Keywords: Keywords Coral ; Nitrogen ; Phosphorus ; Eutrophication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract  The effect of prolonged (9 week) nutrient enrichment on the growth and photosynthetic rates of the zooxanthellate coral Stylophora pistillata was investigated. The main questions were: (1) what is the exposure time needed to induce measurable change in growth rate? (2) which are the concentrations of nitrogen and phosphorus required to cause changes in these rates? (3) what is the recovery potential of the corals after the nutrient stress? For this purpose, three tanks (N, P, NP) were enriched with ammonium (N), phosphorus (P) or both nutrients (NP), respectively. A fourth tank (C) served as a control. The growth of 40 nubbins (10 in each tank) was monitored during four periods: period 1 (nutrient-poor conditions), period 2 (10 μm NH4 and/or 2 μm PO4 enrichment), period 3 (20 μm NH4 and/or 2 μm PO4) and period 4 (nutrient-poor conditions). Period 4 was performed to study the recovery potential of corals after a nutrient stress. During period 1, growth rates remained constant in all tanks. In the P tank, growth rates declined during the two enrichment periods, with a total decrease of 60% by the end of period 3. In the N tank, growth rates remained nearly constant during period 2 but decreased in period 3 (60% decrease). In the NP tank, 50% and 25% decreases were observed during periods 2 and 3. At the end of the recovery period, a regain in growth rate was observed in the N and NP tanks (35 and 30% increase, respectively, compared with the rates measured at the end of period 3) and growth rates returned to 60% of the initial rates. By contrast, in the P tank, there was no regain in growth and a further decrease of 5% was observed. Rates of photosynthesis were often higher during the enriched than the nutrient-poor period (up to 150% increase). Corals with the highest percent increases in maximal gross photosynthetic rate (P g max ) had the smallest decreases in growth rate due to nutrient enrichment. In conclusion, high ammonium (20 μm) and relatively low phosphorus concentrations (2 μm) are required to induce a significant decrease in coral growth rate. The largest reduction was observed with both ammonium and phosphorus enrichment. The decrease in growth rate was rapid following nutrient enrichment, since a 10% decrease or more could be observed after the first week of treatment.
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  • 4
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An experimental set-up was designed to investigate photosynthesis, respiration and calcification of zooxanthellate scleractinian corals under submerged and exposed conditions. The results of experiments to determine the effect of exposure to air on the metabolism of Stylophora pistillata (Esper, 1797) revealed that: (1) maximum gross photosynthesis ( p g max) is 3.6 times higher in water than in air; (2) an indicator of photoadaptation (I k ) does not reveal any difference between water and air; (3) the difference between submerged and aerial respiration is not statistically significant; (4) aerial photosynthesis–irradiance (P–I) curves display lower initial slopes (α) than aquatic P–I curves; (5) there is no calcification in air.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A sensitive experimental protocol using cloned corals (hereafter “microcolonies”) of the branching scleractinian coral Stylophora pistillata and 45Ca has been developed to enable reproducible measurements of physiological and biochemical mechanisms involved in calcium transport and compartmentalization during coral calcification. Cloned S. pistillata microcolonies were propagated in the laboratory from small fragments of parent colonies collected in 1990 in the Gulf of Aqaba, Jordan. Cloned microcolonies have several intrinsic properties that help to reduce unwanted biological variability: (1) same genotype; (2) similar sizes and shapes; and (3) absence of macroscopic boring organisms. Errors specifically associated with long-standing problems to do with isotopic exchange were further reduced by producing microcolonies with no skeletal surfaces exposed to the radioisotope-labelled incubation medium. The value of the technique resides principally in its superior ability to elucidate transportation pathways and processes and not in its ability to quantitatively estimate calcium deposition by corals in nature. We describe here a rapidly exchangeable calcium pool in which up to 90% of the radioactive label taken up during incubations is located. This pool (72.9±1.4 nmol Ca mg-1 protein) is presumably located within the coelenteric cavity as suggested by the following: (1) it has 4-min half-time saturation kinetics; (2) the accumulation of calcium is linearly correlated with the calcium concentration of sea-water; and (3) its insensitivity to metabolic and ion transport inhibitors indicate that membranes do not isolate this compartment. Washout of this large extracellular pool greatly improved estimates of calcium deposition as evidenced by 10 to 40% reduction in coefficients of variation when compared with previous 45Ca2+ methods described in the literature. Comparisons of calcification measurements simultaneously carried out using the alkalinity anomaly technique and the 45Ca protocol described here show that the correlation coefficient of both techniques is close to 1. Unlike previous reports, our 45Ca2+-derived measurements are slightly lower than those computed from the alkalinity depletion technique.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Concentrations of phytoplankton (cyanobacteria, autotrophic flagellates, and microphytoplankton) and planktonic microorganisms (bacteria, heterotrophic flagellates, and ciliates) were measured in the water over a fringing coral reef at Miyako Island (Japan). Their in situ growth and production rates, as well as their grazing rates, were estimated using diffusion chambers. Bacteria dominated the heterotrophic biomass (37–73% of total C), whereas nanoflagellates dominated the autotrophic biomass (65–75% of total autotropic C). Growth and production rates showed that these microbial populations over the reef were in a very dynamic state: growth rates ranged between 2 and 4 doublings day−1 for the bacteria, and between 1.5 and 3 doublings day−1 for the auto- and heterotrophic pico- and nanoplankton. This led to high production rates (10–25 μg C liter−1 day−1 for bacteria and flagellates). The microbial biomass was removed rapidly, since 60–70% of the bacterial production and 30–50% of the autotrophic production were grazed by the heterotrophic flagellates and ciliates, which themselves were grazed (50–70% of the production) by the higher trophic levels. These results suggest that dissolved organic matter was continuously channeled through the microbial loop to the higher trophic levels and the microbes had an important trophic role in terms of nutrient for the benthic organisms.
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  • 7
    Publication Date: 1999-11-09
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 8
    Publication Date: 2012-03-30
    Description: The production of transparent exopolymeric particles (TEP) by the coccolithophores, Emiliania huxleyi , Calcidiscus leptoporus and Syracosphaera pulchra was investigated in batch cultures. The abundance, size spectra and carbon content of TEP were examined during the exponential growth phase of both haploid and diploid life stages grown under ambient (400 µatm) and elevated (760 µatm) CO 2 partial pressure (pCO 2 ) conditions. Results showed species- and life stage-specific differences in TEP production rate (day –1 ) derived from abundance and carbon content of TEP. At 400 µatm, TEP production rate was the highest in the diploid stage of S. pulchra and E. huxleyi , while TEP carbon content per cell was the highest in the diploid stage of C. leptoporus . At 760 µatm, TEP production rate increased in almost all species and was closely related to the cell growth rates (except in the diploid stage of C. leptoporus ), while the slope values of the regression lines between TEP size distribution and concentration decreased. This means that the contribution of smaller size TEP was relatively more important than larger TEP in the high pCO 2 treatment. Elevated pCO 2 is potentially able to alter TEP size distribution. TEP-C content cell –1 generally decreased with increasing pCO 2 . TEP-C accounted for 1–24% of the cell particulate organic carbon production and was inversely related to increasing pCO 2 . TEP production by C. leptoporus and S. pulchra has not previously been documented. The amount of organic carbon released as TEP by these coccolithophores is comparable to and may even exceed TEP production by some diatoms.
    Print ISSN: 0142-7873
    Electronic ISSN: 1464-3774
    Topics: Biology
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  • 9
    Publication Date: 2014-03-08
    Description: The widespread distribution of pteropods, their role in ocean food webs and their sensitivity to ocean acidification and warming has renewed scientific interest in this group of zooplankton. Unfortunately, their fragile shell, sensitivity to handling, unknowns surrounding buoyancy regulation and poorly described feeding mechanisms make thecosome pteropods notoriously difficult to maintain in the laboratory. The resultant high mortality rates and unnatural behaviours may confound experimental findings. The high mortality rate also discourages the use of periods of acclimation to experimental conditions and precludes vital long-term studies. Here we summarize the current status of culture methodology to provide a comprehensive basis for future experimental work and culture system development.
    Print ISSN: 0142-7873
    Electronic ISSN: 1464-3774
    Topics: Biology
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  • 10
    Publication Date: 2015-07-29
    Description: The effect of ocean warming and acidification was investigated on a natural plankton assemblage from an oligotrophic area, the bay of Villefranche (NW Mediterranean Sea). The assemblage was sampled in March 2012 and exposed to the following four treatments for 12 days: control (~360 μatm, 14°C), elevated p CO 2 (~610 μatm, 14°C), elevated temperature (~410 μatm, 17°C), and elevated p CO 2 and temperature (~690 μatm, 17°C). Nutrients were already depleted at the beginning of the experiment and the concentrations of chlorophyll a (chl a ), heterotrophic prokaryotes and viruses decreased, under all treatments, throughout the experiment. There were no statistically significant effects of ocean warming and acidification, whether in isolation or combined, on the concentrations of nutrients, particulate organic matter, chl a and most of the photosynthetic pigments. Furthermore, 13 C labelling showed that the carbon transfer rates from 13 C-sodium bicarbonate into particulate organic carbon were not affected by seawater warming nor acidification. Rates of gross primary production followed the general decreasing trend of chl a concentrations and were significantly higher under elevated temperature, an effect exacerbated when combined to elevated p CO 2 level. In contrast to the other algal groups, the picophytoplankton population (cyanobacteria, mostly Synechococcus ) increased throughout the experiment and was more abundant in the warmer treatment though to a lesser extent when combined to high p CO 2 level. These results suggest that under nutrient-depleted conditions in the Mediterranean Sea, ocean acidification has a very limited impact on the plankton community and that small species will benefit from warming with a potential decrease of the export and energy transfer to higher trophic levels.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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