34 research outputs found

    Jurnal Optimasi Sistem Industri - Vol 9, No 1 (2010)

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    Coral community response to bleaching on a highly disturbed reef

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    While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on: a) overall bleaching severity during and after the event, b) differences in bleaching susceptibility among taxa during the event, and c) changes in coral community structure one year before and after bleaching. Approximately two thirds of colonies bleached, however, post-bleaching recovery was quite rapid and, importantly, coral taxa that are usually highly susceptible were relatively unaffected. Although total coral cover declined, there was no significant change in coral taxonomic community structure before and after bleaching. Several factors may have contributed to the overall high resistance of corals at this site including Symbiodinium affiliation, turbidity and heterotrophy. Our results suggest that, despite experiencing chronic anthropogenic disturbances, turbid shallow reef communities may be remarkably resilient to acute thermal stress

    Sensitivity of Calcification to Thermal Stress Varies among Genera of Massive Reef-Building Corals

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    Reductions in calcification in reef-building corals occur when thermal conditions are suboptimal, but it is unclear how they vary between genera in response to the same thermal stress event. Using densitometry techniques, we investigate reductions in the calcification rate of massive Porites spp. from the Great Barrier Reef (GBR), and P. astreoides, Montastraea faveolata, and M. franksi from the Mesoamerican Barrier Reef (MBR), and correlate them to thermal stress associated with ocean warming. Results show that Porites spp. are more sensitive to increasing temperature than Montastraea, with calcification rates decreasing by 0.40 g cm−2 year−1 in Porites spp. and 0.12 g cm−2 year−1 in Montastraea spp. for each 1°C increase. Under similar warming trends, the predicted calcification rates at 2100 are close to zero in Porites spp. and reduced by 40% in Montastraea spp. However, these predictions do not account for ocean acidification. Although yearly mean aragonite saturation (Ωar) at MBR sites has recently decreased, only P. astreoides at Chinchorro showed a reduction in calcification. In corals at the other sites calcification did not change, indicating there was no widespread effect of Ωar changes on coral calcification rate in the MBR. Even in the absence of ocean acidification, differential reductions in calcification between Porites spp. and Montastraea spp. associated with warming might be expected to have significant ecological repercussions. For instance, Porites spp. invest increased calcification in extension, and under warming scenarios it may reduce their ability to compete for space. As a consequence, shifts in taxonomic composition would be expected in Indo-Pacific reefs with uncertain repercussions for biodiversity. By contrast, Montastraea spp. use their increased calcification resources to construct denser skeletons. Reductions in calcification would therefore make them more susceptible to both physical and biological breakdown, seriously affecting ecosystem function in Atlantic reefs

    The tobacco industry’s challenges to standardised packaging : A comparative analysis of issue framing in public relations campaigns in four countries

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    Tobacco industry public relations campaigns have played a key role in challenges to standardised cigarette packaging. This paper presents a comparative analysis of industry campaigns in Australia and the United Kingdom, which have implemented standardised packaging legislation; Canada, where policy has been adopted but not yet implemented; and the Netherlands, which has considered, but not enacted regulation. Campaigns were identified via Google searches, tobacco industry websites, media coverage, government submissions and previous research; analysis focused on issue framing and supporting evidence. Public relations campaigns in all case study countries drew on similar frames - the illicit trade in tobacco products, the encroaching 'nanny state', lack of evidence for the effectiveness of standardised packaging, a slippery slope of regulation, and inherent threats to intellectual property rights. These claims were supported by industry research, front groups and commissioned reports by accountancy firms, but were not with verifiable research. Independent evidence that contradicted industry positions was overlooked. Similarities in structure and content of public relations campaigns in countries that have enacted or considered regulation points to a strategic co-ordinated approach by cigarette manufacturers. Countries considering standardised packaging policy can expect powerful opposition from the tobacco industry. Tobacco control communities and policy makers can learn from previous experience, and share best practise in countering industry arguments

    Skeletal growth rates in porites lutea corals from pulau tinggi, Malaysia

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    10.3390/w14010038Water (Switzerland)14138-3

    Multi-colony calibration of barium isotopes between shallow-water coral skeletons and in-situ seawater: Implications for paleo proxies

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    Barium incorporated in coral skeletons has been widely used as paleo proxies to study terrestrial inputs, upwelling and anthropogenic activities in marine environments. However, these applications often face the challenges of poor replication in the coral skeletal Ba/Ca records from multiple coral colonies and complex Ba sources in coastal environments. Recent studies of Ba isotopes in seawater and deep-sea corals have demonstrated the potential to trace Ba sources and water mixing in the ocean, but there is still a lack of calibrations for Ba isotopes in shallow-water corals. In this study, we present the first multi-colony Ba isotope calibration from three shallow-water Porites lutea corals with the contemporaneous in-situ seawater data from the Singapore Strait. We also report the Ba isotope data in the regional water masses around the study area (e.g. South China Sea, Malacca Strait and Johor River estuary). Singapore water Ba concentrations and isotope compositions show a strong influence of terrestrial inputs, following seasonal salinity and monsoon-driven water-mass mixing between the Malacca Strait and the South China Sea. The coral skeletal δ138/134Ba results are generally consistent between the three coral colonies and time-series data closely follow the seasonal δ138/134Ba variations in seawater. Despite the partition coefficient of Ba having a large uncertainty (DBa = 0.91 ± 0.29), the Ba isotope fractionation between the coral skeletons and seawater is relatively constant (Δ138/134Bacoral-sw = -0.28 ± 0.06 ‰) and shows no significant difference between these corals. The mechanism controlling Ba incorporation and isotope fractionation in coral skeletons remains unclear, but the evidence clearly indicates that the coral skeletal Ba is originated from dissolved Ba in seawater. The constant offset of Ba isotopes between coral skeletons and seawater allows for reliable records of seawater δ138/134Ba values. Ba isotopes in coral skeletons could be used to reconstruct surface water salinity variability in the Singapore Strait, reflecting monsoon driven changes in regional water mass mixing.Royal Society Commonwealth Science Conference Fellow-on Grant (CSC\R1\170048) and the National Research Foundation Singapore (Marine Science Research and Development Programme project P03

    Sub-annual fluorescence measurements of coral skeleton: relationship between skeletal luminescence and terrestrial humic-like substances

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    10.1007/s00338-020-01959-xCoral Reef
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