James Cook University

About: James Cook University is a education organization based out in Townsville, Queensland, Australia. It is known for research contribution in the topics: Population & Coral reef. The organization has 9101 authors who have published 27750 publications receiving 1032608 citations. The organization is also known as: JCU.

Nitrogen and phosphorus constrain the CO2 fertilization of global plant biomass

Abstract: Elevated CO2 (eCO(2)) experiments provide critical information to quantify the effects of rising CO2 on vegetation 1-6 . Many eCO(2) experiments suggest that nutrient limitations modulate the local magnitude of the eCO(2) effect on plant biomass(1,3,5), but the global extent of these limitations has not been empirically quantified, complicating projections of the capacity of plants to take up CO27,9. Here, we present a data-driven global quantification of the eCO(2) effect on biomass based on 138 eCO(2) experiments. The strength of CO2 fertilization is primarily driven by nitrogen (N) in similar to 65% of global vegetation and by phosphorus (P) in similar to 25% of global vegetation, with N- or P-limitation modulated by mycorrhizal association. Our approach suggests that CO2 levels expected by 2100 can potentially enhance plant biomass by 12 +/- 3% above current values, equivalent to 59 +/- 13 PgC. The globalscale response to eCO(2) we derive from experiments is similar to past changes in greenness(9) and bio-mass(10) with rising CO2, suggesting that CO2 will continue to stimulate plant biomass in the future despite the constraining effect of soil nutrients. Our research reconciles conflicting evidence on CO2 fertilization across scales and provides an empirical estimate of the biomass sensitivity to eCO(2) that may help to constrain climate projections.

Circulating Markers of Abdominal Aortic Aneurysm Presence and Progression

Abstract: Over the last decade abdominal aortic aneurysm (AAA) has increasingly been recognised as an important cause of mortality in older persons. In 1999 for example AAA was noted to be the 15th leading cause of mortality in the USA [1]. Exact estimates of AAA-related fatalities are hampered by the low rate of post-mortems when sudden death occurs in elderly subjects, however, recent figures suggest that AAA accounts for approximately 15,000 deaths annually in the USA despite the increasing numbers of elective AAA repairs [2,3]. Approximately 25,000 endovascular and open AAA repairs are performed annually in the USA [3]. Ultrasound screening of men >65 years has been demonstrated to reduce AAA-related mortality and selective screening (of men aged ≥65 who have ever smoked) has been introduced in the USA [4]. Most screen-detected AAAs are of small size (<55mm) and surgery for these AAAs has not been demonstrated to improve outcome [5-7]. In an screening study of 12,203 men ≥65 years performed in Australia for example, 814 (6.7%) had a small AAA measuring 30-54mm but only 61 (0.5%) a large AAA (≥55mm) [8]. The increase in identification of small AAAs resulting from screening programs, in association with an ageing population, will highlight the number of deficiencies in current diagnosis and management of this condition. Firstly, there are no accurate non-imaging methods of diagnosing small AAAs, with clinical examination being inaccurate [9]. Secondly, prognostic determinants for AAA are relatively poorly defined [10]. Approximately 70% of 40-55mm AAAs expand within 10 years to a size requiring treatment [6,7]. There are however large intra and inter-patient variations in rates of expansion of small AAAs during follow-up [10]. To date only initial aortic diameter has been consistently shown to predict subsequent increase in aortic diameter [10-13]. Smoking has been associated with increased, and diabetes with decreased, AAA expansion in some, but not all studies [10-13]. More accurate prognostic predictors would offer the possibility of selecting patients for different management pathways rather than relying on aortic diameter alone [10]. Finally the management of small AAAs remains controversial despite randomised controlled trials indicating that open surgical repair of 40-55mm AAAs does not reduce mortality [6,7]. Many centres manage all AAAs ≤55mms conservatively. Estimates based on the UK small aneurysm trial support repeat imaging for 30-40, 41-45, 46-50 and 51-55mm AAAs at 24, 12, 6 and 3 monthly intervals respectively [10]. The increasingly utilisation of endovascular repair of AAA, with its lower peri-operative mortality, has been suggested as more appropriate management for small AAAs, particularly those in the 50-55mm range [14,15]. At present however no randomised controlled trial has been completed examining the outcome of endovascular repair of small AAAs, although one such study is expected to report soon [16]. The lack of any proven medical therapy for prevention of progression and rupture of AAAs represents an important challenge [17]. Only one randomised trial has examined the value of a medication (propranolol) for small AAAs in a cohort of reasonable size (>500 subjects) [18].

Mixed responses of tropical Pacific fisheries and aquaculture to climate change

Abstract: Pacific Island countries have an extraordinary dependence on fisheries and aquaculture. Maintaining the benefits from the sector is a difficult task, now made more complex by climate change. Here we report how changes to the atmosphere-ocean are likely to affect the food webs, habitats and stocks underpinning fisheries and aquaculture across the region. We found winners and losers-tuna are expected to be more abundant in the east and freshwater aquaculture and fisheries are likely to be more productive. Conversely, coral reef fisheries could decrease by 20% by 2050 and coastal aquaculture may be less efficient. We demonstrate how the economic and social implications can be addressed within the sector-tuna and freshwater aquaculture can help support growing populations as coral reefs, coastal fisheries and mariculture decline.

Ecological memory modifies the cumulative impact of recurrent climate extremes

Abstract: Climate change is radically altering the frequency, intensity and spatial scale of severe weather events, such as heatwaves, droughts, floods and fires1. As the time interval shrinks between recurrent shocks2–5, the responses of ecosystems to each new disturbance are increasingly likely to be contingent on the history of other recent extreme events. Ecological memory—defined as the ability of the past to influence the present trajectory of ecosystems6,7—is also critically important for understanding how species assemblages are responding to rapid changes in disturbance regimes due to anthropogenic climate change2,3,6–8. Here, we show the emergence of ecological memory during unprecedented back-to-back mass bleaching of corals along the 2,300 km length of the Great Barrier Reef in 2016, and again in 2017, whereby the impacts of the second severe heatwave, and its geographic footprint, were contingent on the first. Our results underscore the need to understand the strengthening interactions among sequences of climate-driven events, and highlight the accelerating and cumulative impacts of novel disturbance regimes on vulnerable ecosystems. The increasing frequency of marine heatwaves suggests that the impacts of successive events may be influenced by previous events. The extent of the 2016 and 2017 bleaching events on the Great Barrier Reef shows that ecological memory played a role in the impacts of the second heatwave.