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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Coral reefs 1 (1982), S. 1-1 
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Coral reefs 1 (1982), S. 13-19 
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Accurate determinations have been made of the distribution of uranium in fresh and diagenetically altered coral skeletons occurring both naturally and grown under a variety of experimental conditions. Whereas live coral skeletons are homogeneous in uranium distribution, dead skeletons show heterogeneities relating to lithothamnioid algal encrustations and endolithic sponges. In the analyses of over 100 live coral skeletons, no zonal uranium distributions, described by previous workers, were found. In skeletons, free from organic material, uranium was found to exchange readily with the coral skeleton and/or to be precipitated along trabecular axes and skeletal margins. Bioeroded specimens contained higher uranium concentrations than freshly formed aragonite; they were similar to fossil coral skeletons used by previous researchers for uranium scrics dating.
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  • 3
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Summary Analysis of core from six drill holes and ten vibrocores from One Tree Reef has delineated five major biosedimentological facies: algal pavement, coral head facies, branching coral facies, reef flat rubble facies and sand facies. Holocene growth began around 8,000 years B.P. with a high energy coral head facies on windward margins and a lower energy branching coral facies on patch reefs and on leeward margins. Vertical accumulation rates for these two principal facies are not greatly different; the coral head facies grew at 1.8–7.3 m/1,000 years and the branching coral facies at 0.6–8.3 m/1,000 years. Growth was initially much slower than the rate of sea level rise, a situation which changed only after sea level stabilized around 6,200 years B.P. A facies evolution model with rigidly imposed time constraints divides growth into three phases, i.e. vertical growth to sea level, transitional adjustment of biofacies at sea level, and leeward progradative phases.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Coral reefs 1 (1982), S. 29-34 
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Summary A threshold for atoll formation, herein termed the Darwin Point, exists at the northern end of the Hawaiian Archipelago at 29°N latitude. Hawaiian atolls and coral islands transported northwest by tectonic movement of the Pacific Plate appear to have “drowned” near the Darwin Point during the last 20 million years. Measures of gross carbonate production by corals across the archipelago show that growth rates decrease with increasing latitude. At the Darwin Point, corals may contribute only 20% of the calcium carbonate necessary to keep pace with recent changes in sea level and thus appear to be more important as builders of framework than producers of limestone. Reduction in this function rather than total carbonate production may be the determining factor in the formation of atolls and coral islands. Elsewhere in the world other Darwin Points may exist but probably not at the same latitude due to differences in ecological conditions, coral species composition, island area, rates of erosion and tectonic histories.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Coral reefs 1 (1982), S. 3-11 
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Given the importance attributed to the occupation of space in benthic coral reef communities, this study asks the question: are any particular microhabitat types limiting resources for an assemblage of worm-eating gastropods on Heron reef (Great Barrier Reef). Microhabitat resource use was measured on three occasions, separated by 12 and 20-month periods. The gastropod populations were typical of those of other Indo-Pacific sites with respect to mean shell size and density. Fluctuations in species' size and density are assumed to have not significantly influenced availability of microhabitat resources. Gastropods occurred mainly in the structurally complex “refuge” microhabitats during the day and showed an increased abundance in smooth, exposed, “foraging” microhabitat nocturnally. Nassarius gaudiosus is the most extreme microhabitat specialist diurnally and the most extreme microhabitat generalist nocturnally. A similar, although less pronounced trend was exhibited by other gastropod species. Microhabitat niche overlap was high for Conus coronatus, C. miliaris, C. flavidus, Vasum turbinellus and N. gaudiosus at night and was also high during the day for all these species except N. gaudiosus, which showed little overlap with other gastropod species diurnally. Using gastropod abundance data from all samples, and independently derived microhabitat abundance data, multiple regression analysis demonstrated: 1) A significant relationship between the abundances of N. gaudiosus, C. coronatus, and C. flavidus and the abundance of microhabitat 2 (sand under rocks=“refuge”). 2) No positive association between gastropod abundance and the abundance of microhabitat 7a (thin layer of algal-bound sand on reef limestone). Only N. gaudiosus is abundant in microhabitat 2. Therefore it is concluded that, with some exceptions, microhabitat abundance does not have a significant influence, directly or indirectly, on gastropod abundance. It is possible that density-independent mortality is maintaining gastropod densities below that at which competitive interactions, with respect to microhabitats, have significant effects on the gastropods' use of those resources.
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  • 6
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Summary Changes in the structure of fish communities along a transect from the Australian mainland to the Coral Sea, in the Central region of the Great Barrier Reef, were examined. Visual censuses of fish were made on the outer reef slopes (0 to 13 m deep) of two inshore reefs, approximately 10 km offshore, three reefs on the mid-shelf, 50 km offshore, three reefs on the outer shelf, 100 km offshore, and three reefs in the Coral Sea approximately 200 km offshore. The Pomacentridae, Chaetodontidae, Acanthuridae and Scaridae were examined in detail—the Labridac, Siganidae and the lutjanid genus Caesio in less detail. Major changes in the composition of fish communities occurred along the transect (Fig. 3). There were differences in the composition of assemblages among replicate censuses within individual reefs and also differences between reefs at the same location on the transect but these differences were small compared to those among locations. The nature of the distribution of species across the transect differed between families (Figs. 4–6). Pomacentrid and chaetodontid species were significantly more restricted in distribution than acanthurids, scarids or labrids.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Coral reefs 1 (1982), S. 59-65 
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Summary A microprocessor-based data-acquisition system has been developed to meet the requirements of a range of oceanic sensor inputs. The system described is specially suitable for low-power, long-period underwater applications. Details are given of the hardware and software design, and examples of interface to propeller current sensor and pressure transducer. Preliminary field results in the Northern Great Barrier Reef are described.
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  • 8
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Summary Under standard experimental conditions, sample groups of Acropora acuminata gave calcification results having a coefficient of variation approaching 50%. Because of this, the resolution of radioisotope measurements approaches the magnitude of the effect of light on calcification rate. Differences in calcification rate between samples appear to be caused by short-term variations in calcification rate of samples, rather than size differences between samples. The coefficient of variation associated with results can be decreased by relatively straightforward modifications to the standard technique.
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  • 9
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Summary Scanning electron microscopy and serial petrographic thin sections were used to investigate skeletal elongation and mineralization in the perforate coral, Acropora cervicornis. The axial corallite extends by the formation of randomly oriented fusiform crystals which are deposited on its distal edge. Aragonitic needle-like crystals grow in random directions from the surface of these fusiform crystals. Only those needle-like crystals growing toward the calicoblastic epithelium (i.e. crystals whose growth axis is perpendicular to the plane of the calicoblastic cell membrane) continue to elongate. Groups of these growing crystals join to form well-defined fasciculi which make up the primary skeletal elements comprising the septotheca. The resulting skeleton is highly porous with all surfaces covered by the continuous calicoblastic epithelium. This cell layer is separated by thin mesoglea from the flagellated gastrodermis which lines the highly ramified coelenteron. Porosity and permeability of the skeleton decrease with distance from the tip. Density correspondingly increases due to the addition of aragonite to the fasciculi whose boundaries become less distinct as channels fill with calcium carbonate.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Coral reefs 1 (1982), S. 70-70 
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Type of Medium: Electronic Resource
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