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JCU

James Cook University
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27 Projects, page 1 of 6
  • Funder: Swiss National Science Foundation Project Code: 161693
    Funder Contribution: 102,750
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  • Funder: UK Research and Innovation Project Code: NE/J005398/2
    Funder Contribution: 48,230 GBP

    Cyclones and hurricanes exert a major influence on the structure and ecology of shallow water coral reefs. This occurs through the physical destruction of corals (especially branching coral species), with the resultant rubble being a major source of detrital reef framework carbonate. Ecologically, these high magnitude physical disturbance events also exert a profound influence on benthic habitat composition and diversity, and drive the remobilisation and distribution of reef-derived sediments - transporting such materials either shorewards into lagoons or onto beaches, or flushing sediment offshore into deeper water. Many future climate models predict an increasing frequency and intensity of such tropical storms, and thus data on the physical and ecological resilience of shallow water coral reefs is of significant scientific and management interest. Various studies have examined the impact of such physical disturbance events on coral reefs, in many cases basing their findings only on post-impact assessments. In only a few cases have high quality pre- and post-impact data been available, and in most cases this has only been sufficient to consider the (albeit critically important) ecological transitions. It is extremely rare to have the opportunity to undertake multi-proxy assessments of physical disturbance events that can draw on pre-impact data covering not only the reef ecology, but also geomorphology (structure, elevation), contemporary sedimentology, and the late Holocene history of reef development (as preserved in core records). To be able to do this at a range of sites both immediately proximal to a cyclone track and at more distal sites, represents an unprecedented opportunity, especially where data is available from a range of nearshore to offshore depositional settings. Here we have such an opportunity, and one that will allow us to undertake multi-proxy assessments (geomorphical, ecological and sedimentological) of the changes induced by an especially high magnitude recent cyclone. The event in question, Severe Tropical Cyclone Yasi, was a Category 5 cyclone (the highest category on a scale of 1-5) that made landfall on the Queensland coast of Australia, in the vicinity of Mission Beach and Tully, on 3rd Feb 2011. The eye of the storm was ~35 km wide, with a front stretching across ~650 km. Evidence from instrumentation that survived the event shows a central pressure of around 929hPa, with winds gusting up to 285 km/h, and with storm surge heights reaching at least 5 m. Yasi was thus one of the most powerful cyclones to have affected Queensland since records commenced. Previous cyclones of a comparable measured intensity include Cyclone Mahina (1899) in Princess Charlotte Bay ~350 km to the north, and the 1918 cyclones at Mackay and Innisfail. Specifically, we are in a position, having undertaken detailed studies of the structure and ecology of a wide range of reefs in the immediate vicinity of the storm track and its landfall point, to be able to undertake a rapid post-impact assessment, and to compare this data with that collected (between 2006-2009) at the same sites. We are submitting this as an Urgency application because of the need to undertake such post-impact studies as soon as logistically possible. This is of critical importance in marine environments to ensure that as much of the evidence (both ecological and geomorphological) of the event is preserved. We are planning to undertake this study in August 2011, giving a 6 month lead in from this application (this is probably as soon as logistically possible given the need for the review process and subsequent travel planning). The timing will be such, so as to coincide with one of the winter low spring tide periods when site access is far easier. Based on existing post-storm recovery trajectories in other tropical regions we would anticipate such evidence being well preserved within the 6 month lead in time we are working to.

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  • Funder: UK Research and Innovation Project Code: NE/E018807/1
    Funder Contribution: 196,708 GBP

    Many researchers in archaeology and the geosciences obtain timescales for their projects by radiocarbon dating plant or animal remains from the preserved deposits with which they work. Radiocarbon dates are not the same as calendar dates, however, and have to be corrected for variations in the radiocarbon content of the atmosphere at the time that the plant or animal lived. This conversion of radiocarbon dates to calendar ages, known as calibration, is not a straightforward correction. Calibration of radiocarbon dates can only be done by comparison to a suitable calibration curve. Such curves are based on measurements of radiocarbon in samples of known calendar age such as tree-rings, or in a less strict sense, on other types of samples where an independent method of dating can be used. For samples which grew in the ocean, such as shells and corals, a separate calibration curve is needed to account for changes in ocean water circulation which may bring up 'old' water from the ocean depths (the reservoir effect). The calibration curves have been refined periodically to provide better estimates of the calendar ages. In 2004, the IntCal Working Group constructed new calibration curves from radiocarbon dated tree-rings back to 12,400 years before present and from independently dated ocean samples, using an estimated correction for the reservoir effect, back to 26,000 years before present. Rather than simply averaging the data, these curves were constructed with statistical tools (models) that allowed for the uncertainty in the calendar ages of the samples used as well as the radiocarbon dates. At that time data beyond 26,000 years before present did not agree so no curve was provided but an estimate of how far the data sets differed from the underlying true curve was given. In the last few years a lot of research has gone into producing radiocarbon datasets from a variety of records. Many of these datasets are now in fairly good agreement so it should be possible to provide curves for estimating calendar ages back to 55,000 years before present. In addition new tree-ring records are becoming available which will improve the precision of the calibration curve. Statistical methods have also been rapidly advancing and so some of the simplifying assumptions that we made about the models in 2004 will no longer be necessary. Working in collaboration with the IntCal Working Group, this project will develop an easily maintainable database of calibration quality radiocarbon data to be used to produce updates to the calibration curves on a regular basis. Advances in statistics will allow us to improve on the previous models to further refine the calibration curves. Measurements of carefully selected coral will help determine what corrections are needed for ocean samples to be used in calibration curves. By improving radiocarbon calibration this project will improve the understanding of the sequence and timing of events in numerous studies in archaeology and in the reconstruction of past environments.

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  • Funder: UK Research and Innovation Project Code: NE/F01077X/1
    Funder Contribution: 64,128 GBP

    There is a general perception that corals (and coral reefs) are highly susceptible to riverine inputs of terrigenous sediment, and that high rates of such inputs will negatively impact reef health and vitality (usually evidenced by low coral cover and/or high partial mortality rates). In coral reef settings where such inputs have been limited in the past and where corals are not adapted to deal with frequent sediment loading and reduced light penetration, this perception is likely to have considerable validity and may lead, over time, to shifts in coral community structure. However, there is an increasing body of sedimentological, geomorphological and palaeoecological data demonstrating not only long-term (>1,000 year) persistence of coral communities under conditions of high terrigenous sediment input and high turbidity, but also clear evidence of active and rapid reef-accretion. Under these conditions corals seem to be sufficiently adapted to these environmental conditions that coral cover is often high and well-developed reef structures can form. This has been demonstrated at sites in Thailand, Indonesia, Mozambique and at a range of sites along the nearshore (innermost shelf) areas of the Great Barrier Reef (GBR), Australia. An apparent paradox thus exists between the perceived negative effects of high turbidity and terrigenous sediment inputs on coral communities (which are widely referred to in the scientific literature) and the increasing sedimentary and palaeoecological evidence for historical timescale persistence of corals and of reef-building in these settings. This raises an intriguing question about coral carbonate production in these environments and about the nature of skeletal carbonate deposition. Are these coral communities able to produce reef structures, despite high terrigenoclastic sediment input and high turbidity regimes, because of particularly high coral growth and calcification rates? Little data exists from nearshore reefs of this type and there has been no attempt to quantify and compare these processes over temporal and spatial scales. This project thus aims to quantify coral extension (growth) and calcification rates, and to quantify the microskeletal characteristics (i.e., the size and density of key skeletal elements in the coral skeleton) from two of the dominant coral species associated with reef-building within nearshore, turbid-zone settings along the central GBR coastline. The focus for the research will be the two best-studied turbid-zone reefs in the region; Paluma Shoals and Lugger Shoal. Extensive datasets are available on the sedimentary environments, hydrodynamic conditions and contemporary community structures in each locality. In addition, radiocarbon (14C) date-constrained growth models exist for each site that allow data to be placed in a reliable chronological framework. Specifically, we will gather data on a massive coral species (Porites lobata) that makes a major contribution to contemporary reef-flat coral communities in both settings, and a branching coral species (Acropora pulchra) which previous research has demonstrated to have been a major framework contributor throughout the growth history of these reefs. The research will utilise novel Computerised (Axial) Tomography (CT) scanning and established Scanning Electron Microscopy (SEM) approaches to quantify coral growth rates and styles of coral skeletal deposition in these samples. Between-site comparisons will be made against data collected from the same species of Porites and Acropora that were collected from clear water sites at Low Isles during the 1928-1929 Great Barrier Reef Expedition. This extensive and well-catalogued coral repository is stored at the NHM and CT methodologies will allow us to examine the skeletal structures of these corals using non-destructive techniques.

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  • Funder: UK Research and Innovation Project Code: NE/P014992/1
    Funder Contribution: 100,809 GBP

    Climate change creates risks to biodiversity, in particular by changing the climate in which species live, and making it unsuitable for them to continue to live there. In December 2014, under the United Nations Paris Agreement countries agreed to 'pursue efforts to ...limit the temperature increase to 1.5C above pre-industrial levels'. IMPALA seeks to understand these risks to biodiversity arising in a future world in which humans limit climate change to 1.5C warming compared to pre-industrial times, and to compare this with the situation when there is 2C warming (hereafter referred to as 1.5/2C). It seeks understand the relative risks both globally, and at the regional scale. Species also face a challenge in being able to track their preferred climate space across a landscape, both in terms of the speed of movement required and in dealing with natural and/or manmade obstacles to movement. Several previous studies have projected extensive range loss and increased extinction risks across large fractions of species globally or regionally due to climate change e.g. amongst 50,000 species studied, 57+/-5% of plants and 34+/-7% of animals are projected to lose over half their climatic range for a warming of approximately 3.6C above pre-industrial levels. But what difference does 0.5C make? Is there really much difference between 1.5C and 2C of warming when it comes to terrestrial biodiversity? Examination of the large-scale potential changes in climatic ranges of 80,000 species at 2C versus 2.5C suggests that there may be a large difference, at least in some parts of the world. These differences have the potential to put much of the past investment in conservation at risk. This study will look at the areas where it makes the most difference to constrain warming to 1.5 versus 2C, looking specifically at Global Protected Areas, and key conservation regions such as biodiversity hotspots. It will identify which Protected Areas are most, and least, at risk from biodiversity changes at 1.5 vs. 2C, and where corridors between protected areas would do the most good. IMPALA is designed to inform decision makers in the UK government and also within environmental NGOs, in particular World Wildlife Fund-UK. Environmental NGOs are interested in conservation planning, that is deciding which areas of the world need to be brought into the protected area network, or protected by other means such as working with local people to protect habitats for species. Since it is not possible to protect all natural ecosystems, NGOs and Governments need to prioritise, and climate change will affect that prioritisation by changing the places where species can live. IMPALA will inform WWF-UK, other NGOs, and Governments whether the existing protected area system is robust to warming of 1.5/2C, which areas are most at risk, and which areas act as refuges where species can still live after 1.5/2C global warming has occurred. IMPALA considers how species try to move to track climate change, and will also identify places that need to be protected to enable species to move and colonize new areas in response to climate change. Complicating the efforts to allow ecosystems (and biodiversity) to adapt naturally to climate change may be the efforts needed to hold climate change to 1.5C of warming. Many proposals to limit warming to 1.5 and 2C of warming require large areas to be converted to bioenergy crops. There is the risk that it may be necessary to convert large areas of primary/secondary forest and other ecosystems to bioenergy crops, so that agricultural land can continue to grow food. As habitat loss is a major factor in biodiversity loss, then it might potentially be worse for biodiversity at 1.5C warming than 2C warming. This study will look for win-win solutions for biodiversity and mitigation in order to promote Article 2 compliant mitigation - that is, mitigation that hinders neither ecosystems from adapting naturally and the production of food.

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