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  • 1
    Electronic Resource
    Electronic Resource
    Dissolution rates of calcium carbonate in the deep ocean; an in-situ experiment in the North Atlantic Ocean
    Amsterdam : Elsevier
    Earth and Planetary Science Letters 40 (1978), S. 287-300 
    Details
    ISSN: 0012-821X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0012-821X(78)90099-7
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  • 2
    Electronic Resource
    Electronic Resource
    In-situ dissolution experiment of radiolaria in the central North Pacific ocean
    Amsterdam : Elsevier
    Earth and Planetary Science Letters 59 (1982), S. 245-254 
    Details
    ISSN: 0012-821X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0012-821X(82)90129-7
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  • 3
    Electronic Resource
    Electronic Resource
    Phytoplankton nutrient uptake dynamics in earthen marine fishponds under winter and summer conditions
    Amsterdam : Elsevier
    Aquaculture 76 (1989), S. 237-253 
    Details
    ISSN: 0044-8486
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0044-8486(89)90078-1
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  • 4
    Electronic Resource
    Electronic Resource
    Objectivity and subjectivity in thedecision making process (1998)
    Springer
    Annals of operations research 80 (1998), S. 333-345 
    Details
    ISSN: 1572-9338
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract Classical Operations Research assumed objectivity. Operations researchers hardly botheredto ask the decision maker about his or her preferences, assuming that a well-defined singleobjective function was an adequate representation of the decision problem. Many multi-criteriadecision methods began in response to this failure of Operations Research. Othermethods took a totally different and more subjective point of view. In this paper, we discussobjective and subjective descriptions, their interpretation and use in decision making. In thecenter of the ability to distinguish between these objective and subjective components standscientific methods and scientists. We argue that it is possible and necessary to understandwhere and how objective measures should be replaced by subjective measures and judgementin the decision making process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018980318183
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  • 5
    Electronic Resource
    Electronic Resource
    Daily oxygen variations in marine fish ponds, Elat, Israel
    Amsterdam : Elsevier
    Aquaculture 84 (1990), S. 289-305 
    Details
    ISSN: 0044-8486
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0044-8486(90)90094-4
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  • 6
    Electronic Resource
    Electronic Resource
    Competition for inorganic carbon between photosynthesis and calcification in the symbiont-bearing foraminifer Amphistegina lobifera (1989)
    Springer
    Marine biology 103 (1989), S. 253-259 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The processes of photosynthesis and calcification in the symbiont-bearing foraminifer Amphistegina lobifera compete for inorganic carbon (Ci). This conclusion is based on kinetic carbon uptake experiments performed in spring 1987 on specimens from the Gulf of Eilat, Red Sea, that were preincubated in Ci-free seawater in order to empty their internal carbon pools. Photosynthetic rates at 0.8 and 2.2 mM external Ci concentration were initially high and decreased with time while calcification rates started low and increased with time. At Ci=4.2 mM, when inward diffusion of Ci is not rate limiting, both rates were high from the beginning of the experiment. Calcification rates of specimens incubated with 3(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), to inhibit photosynthesis, were high and constant at all Ci levels. Addition of carbonic anhydrase (CA) to the medium, which catalyses the conversion of HCO 3 - to CO2, stimulated photosynthesis but inhibited calcification, probably because it caused the collapse of the internal Ci pool for calcification. Attempts to measure natural CA activity in the foraminifera gave negative results. These observations cannot be explained by models featuring mutual enhancement of photosynthesis and calcification, but instead suggest competition for Ci between these two processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00543355
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  • 7
    Electronic Resource
    Electronic Resource
    Mechanisms for the uptake of inorganic carbon by two species of symbiont-bearing foraminifera (1989)
    Springer
    Marine biology 103 (1989), S. 241-251 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mechanisms for uptake of inorganic carbon (Ci) for photosynthesis and calcification of a perforate foraminifer, Amphistegina lobifera Larsen, and an imperforate species, Amphisorus hemprichii Ehrenberg, from the Gulf of Eilat, Red Sea were studied in 1986–1987 using 14C tracer techniques. Total Ci uptake of A. lobifera and photosynthetic carbon uptake of A. hemprichii fit the Hill-Whittingham equation that describes the overall rate of enzymatic reactions that are provided with their substrate through a diffusion barrier. This suggests that diffusion is the rate limiting step for total Ci uptake in A. lobifera. Photosynthesis by the isolated symbionts and uptake of CO3 2- for calcification obey Michaelis-Menten kinetics indicating that enzymatic reactions determine the rate of the separate processes. Both photosynthesis and calcification can be inhibited without affecting each other. Calcification rates in A. lobifera were optimal at Ca levels around normal seawater concentration and were sensitive to inhibitors of respiratory adenosine triphosphate (ATP) generation and Ca-ATP-ase. This indicates that Ca uptake is also active. Calcification rates of A. hemprichii increased linearly as a function of external Ci concentration over the entire experimental range (0 to 4 mM Ci). In contrast, photosynthetic rates showed Hill-Whittingham type kinetics. The dependence of calcification on the CO3 2- concentration was also linear, suggesting that its diffusion is the rate limiting step for calcification in A. hemprichii. Increasing Ca concentrations yielded higher calcification rates over the entire range measured (0 to 40 mM Ca). Calcification in A. hemprichii was less sensitive to inhibitors of ATP generation than in A. lobifera, suggesting that in A. hemprichii energy supply is less important for this process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00543354
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  • 8
    Electronic Resource
    Electronic Resource
    Stable carbon isotope ratios in Red Sea barnacles (Cirripedia) as an indicator of their food source (1997)
    Springer
    Marine biology 130 (1997), S. 243-247 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The stable isotope ratio 12C/13C was used to investigate the source of carbon in free-living barnacles and in coral-inhabiting barnacles from the Red Sea. The δ13C of most of the barnacles collected on the open shore ranges between −17.5 and −19.7‰, indicating relative enrichment of light carbon originating from the open-sea phytoplankton. Those collected in closed habitats showed heavier isotopic composition. The δ13C of the coral-inhabiting barnacles ranges from −14.1 to −16.7‰, suggesting that the carbon contribution of open-sea plankton to these barnacles is less important than it is to free-living barnacles. We hypothesize that coral organic matter and zooxanthellae expelled by the host coral contribute carbon to the barnacle, and that a mixture of this relatively heavy carbon with carbon from other sources is responsible for the high values of δ13C in coral barnacles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050244
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  • 9
    Electronic Resource
    Electronic Resource
    Skeletal calcification patterns in the sea urchin Tripneustes gratilla elatensis (Echinoidea: Regularia) (1987)
    Springer
    Marine biology 95 (1987), S. 275-287 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A comprehensive study on skeletal calcification in the regular echinoid Tripneustes gratilla elatensis was carried out between 1979 and 1981 in the northern Gulf of Eilat (Red Sea), employing size measurement, allometry and radiotracer techniques. Uptake rates of the isotope 45Ca were used to estimate the calcification rate of whole tests. Calcification rates of the different skeletal parts and the 45Ca uptake along the sutural margins of individual plates were also measured. Whole-test calcification rates for juvenile individuals, 11 to 13 mm in diameter, relative to their skeletal Ca dry weight, calculated using the allometric relationship between skeletal dry weight and diameter, were 1.5 to 1.8% d-1 for 4 to 8 h of incubation, while calcification rates obtained from periodical size measurements and allometrical constants amounted to 2.75% d-1. The apparent discrepancy between these results is explained partly by the short duration of the incubations, during which the internal calcium pools, apparently in the coelom, were not fully saturated with the radioactive tracer. This discrepancy decreased when longer radioactive incubations were used, or when a post-incubational deposition of 45Ca from these pools was allowed. The size of these pools is roughly 10 μmol Ca per 13-mm individual, and it resides probably in the coelom where Ca concentration is ∼ 3 times higher than in seawater. The calcification rates given as percentage of skeleton added per day, both for the radioactive and allometric methods, decreased with the urchins' size. The calcification patterns of various components of the skeleton generally fitted their allometrical trends — a relative decrease in the size of the spines, apical plates and lantern. The teeth calcify rapidly to compensate for the constant erosion of their tips. Calcification per plate decreased exponentially from the apex to the peristome. Plate-edge calcification patterns of both interambulacral and ambulacral plates fitted patterns derived from size increment measurements, using natural growth-lines. Typically, most plates grow more horizontally (latitudinally) than vertically. It is suggested that the vertical vs horizontal calcification ratio (v/h) determines the individual plate growth and affects the whole test morphology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409015
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  • 10
    Electronic Resource
    Electronic Resource
    Skeletal calcification patterns in the sea urchin Tripneustes gratilla elatensis (Echinoidea: Regularia) (1987)
    Springer
    Marine biology 95 (1987), S. 289-297 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Morphometrically determined growth measurements and 45Ca calcification assays were applied to deformed Tripneustes gratilla elatensis collected between 1979 and 1981 from polluted environments in the Gulf of Eilat, Israel, in order to check the effect of various pollutants and treatments on skeletal growth and structure. Deformed sea urchins showed low calcification rates and aberrant plate calcification gradients, as well as irregular sutural calcification patterns, characterized by very high vertical vs horizontal plate-edge growth ratios (v/h). This was consistent with their abnormal skeletal morphology, characterized by high height vs horizontal diameter (H/D) ratio. Similar growth and calcification patterns were shown by hard-substratum sea urchins transferred onto artificial sandy habitats. They became taller (having higher H/Ds), showing irregular sutural calcification patterns and higher v/h ratios. This phenomenon is apparently due to a biomechanical effect related to the weaker adherence of the ambulacral tubefeet suctorial discs. This experiment supports the hypothesis that the pollutants, industrial calcification inhibitors, are causing defomities in T. g. elatensis by affecting their calcification rate as well as their differential growth patterns. These results agree with a recently proposed biomechanical model suggesting that mechanical forces, internal liquid pressure and the activity of various contractile and elastic tissue elements control the growth and calcification of plates along their sutural edges, consequently determining the overall test morphology. It is suggested that the skeletal deformities, observed in earlier studies of this subspecies, resulted from an irreversible abnormal calcification pattern, which is often associated with changes in the proposed stress-balance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409016
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