32 research outputs found

    Decoupled carbonate chemistry controls on the incorporation of boron into Orbulina universa

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    In order to fully constrain paleo-carbonate systems, proxies for two out of seven parameters, plus temperature and salinity, are required. The boron isotopic composition (ÎŽ11B) of planktonic foraminifera shells is a powerful tool for reconstructing changes in past surface ocean pH. As B(OH)4− is substituted into the biogenic calcite lattice in place of CO32−, and both borate and carbonate ions are more abundant at higher pH, it was suggested early on that B ∕ Ca ratios in biogenic calcite may serve as a proxy for [CO32−]. Although several recent studies have shown that a direct connection of B ∕ Ca to carbonate system parameters may be masked by other environmental factors in the field, there is ample evidence for a mechanistic relationship between B ∕ Ca and carbonate system parameters. Here, we focus on investigating the primary relationship to develop a mechanistic understanding of boron uptake. Differentiating between the effects of pH and [CO32−] is problematic, as they co-vary closely in natural systems, so the major control on boron incorporation remains unclear. To deconvolve the effects of pH and [CO32−] and to investigate their impact on the B ∕ Ca ratio and ÎŽ11B, we conducted culture experiments with the planktonic foraminifer Orbulina universa in manipulated culture media: constant pH (8.05), but changing [CO32−] (238, 286 and 534 ”mol kg−1 CO32−) and at constant [CO32−] (276 ± 19.5 ”mol kg−1) and varying pH (7.7, 7.9 and 8.05). Measurements of the isotopic composition of boron and the B ∕ Ca ratio were performed simultaneously using a femtosecond laser ablation system coupled to a MC-ICP-MS (multiple-collector inductively coupled plasma mass spectrometer). Our results show that, as expected, ÎŽ11B is controlled by pH but it is also modulated by [CO32−]. On the other hand, the B ∕ Ca ratio is driven by [HCO3−], independently of pH. This suggests that B ∕ Ca ratios in foraminiferal calcite can possibly be used as a second, independent, proxy for complete paleo-carbonate system reconstructions. This is discussed in light of recent literature demonstrating that the primary relationship between B ∕ Ca and [HCO3−] can be obscured by other environmental parameters

    Assessing the risk of climate change to aquaculture: a national-scale case study for the Sultanate of Oman

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    Aquaculture is expanding globally and is an increasingly important component of world food security. However, climate change can impact aquaculture through a variety of mechanisms varying by location and aquaculture type with implications for future productivity. Understanding the risks that climate change poses on different culture systems in different locations is important to enable the design of targeted adaptation and resilience building actions. Here we present an aquaculture climate risk assessment framework, applied to the aquaculture sector of the Sultanate of Oman, that identifies the sensitivity and exposure of different components of the sector to climate change risk. Oman has aspirations to significantly expand aquaculture over the next decade focussing on coastal shrimp ponds, finfish sea cages, land-based recirculating aquaculture systems, and ponds and raceways. We quantify overall climate risk as the combination of four risks: (1) species’ temperature sensitivity, (2) flooding and storm surge exposure, (3) low-oxygen hazard and (4) disease vulnerability. Shrimp culture is identified as highest risk due to high exposure of shrimp ponds to flooding and storm surges, and high disease vulnerability. Seabream cage farming also faces high risk due to high thermal sensitivity and high potential of low-oxygen levels affecting sea cages. Following the risk assessment a stakeholder workshop was conducted to identify targeted adaptation measures for the different components of the sector. The framework for assessing climate risk to aquaculture demonstrated here is equally applicable at the regional, national or sub-national scale to support design of targeted resilience building actions and enhance food security

    Remote constraint induced therapy of the upper extremity (ReCITE): A feasibility study protocol

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    Background: Difficulty using the upper extremity in everyday activities is common after stroke. Constraint-induced movement therapy (CIMT) has been shown to be effective in both sub-acute and chronic phases of stroke recovery and is recommended in clinical practice guidelines for stroke internationally. Despite reports of equivalence of outcome when stroke rehabilitation interventions are delivered using telehealth, there has been limited evaluation of CIMT when using this mode of delivery. ReCITE will (a) evaluate the feasibility and acceptability of CIMT when delivered via telehealth to stroke survivors (TeleCIMT) and (b) explore therapists' experiences and use of an online support package inclusive of training, mentoring and resources to support TeleCIMT delivery in clinical practice. / Methods: A prospective single-group, single blinded, study design with embedded process evaluation will be conducted. The study will be conducted at three outpatient services in Sydney, Australia. A multi-faceted therapist support package, informed by the Capabilities, Opportunity, Motivation- Behaviour model (COM-B), will be used to support occupational therapists to implement TeleCIMT as part of routine care to stroke survivors. Each service will recruit 10 stroke survivor participants (n = 30) with mild to moderate upper extremity impairment. Upper extremity and quality of life outcomes of stroke survivor participants will be collected at baseline, post-intervention and at a 4 week follow-up appointment. Feasibility of TeleCIMT will be evaluated by assessing the number of stroke participants who complete 80% of intensive arm practice prescribed during their 3 week program (i.e., at least 24 h of intensive arm practice). Acceptability will be investigated through qualitative interviews and surveys with stroke survivors, supporter surveys and therapist focus groups. Qualitative interviews with therapists will provide additional data to explore their experiences and use of the online support package. / Discussion: The COVID-19 pandemic resulted in a rapid transition to delivering telehealth. The proposed study will investigate the feasibility and acceptability of delivering a complex intervention via telehealth to stroke survivors at home, and the support that therapists and patients require for delivery. The findings of the study will be used to inform whether a larger, randomized controlled trial is feasible

    Climate change impacts on the coral reefs of the UK Overseas Territory of the Pitcairn Islands: Resilience and adaptation considerations

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    The coral reefs of the Pitcairn Islands are in one of the most remote areas of the Pacific Ocean, and yet they are exposed to the impacts of anthropogenic climate change. The Pitcairn Islands Marine Protected Area was designated in 2016 and is one of the largest in the world, but the marine environment around these highly isolated islands remains poorly documented. Evidence collated here indicates that while the Pitcairn Islands' reefs have thus far been relatively sheltered from the effect of warming sea temperatures, there is substantial risk of future coral decalcification due to ocean acidification. The projected acceleration in the rate of sea level rise, and the reefs' exposure to risks from distant ocean swells and cold-water intrusions, add further uncertainty as to whether these islands and their reefs will continue to adapt and persist into the future. Coordinated action within the context of the Pitcairn Islands Marine Protected Area can help enhance the resilience of the reefs in the Pitcairn Islands. Options include management of other human pressures, control of invasive species and active reef interventions. More research, however, is needed in order to better assess what are the most appropriate and feasible options to protect these reefs

    Systematic Review and Meta-Analysis Toward Synthesis of Thresholds of Ocean Acidification Impacts on Calcifying Pteropods and Interactions With Warming

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    Interpreting the vulnerability of pelagic calcifiers to ocean acidification (OA) is enhanced by an understanding of their critical thresholds and how these thresholds are modified by other climate change stressors (e.g., warming). To address this need, we undertook a three-part data synthesis for pteropods, one of the calcifying zooplankton group. We conducted the first meta-analysis and threshold analysis of literature characterizing pteropod responses to OA and warming by synthetizing dataset comprising of 2,097 datapoints. Meta-analysis revealed the extent to which responses among studies conducted on differing life stages and disparate geographies could be integrated into a common analysis. The results demonstrated reduced calcification, growth, development, and survival to OA with increased magnitude of sensitivity in the early life stages, under prolonged duration, and with the concurrent exposure of OA and warming, but not species-specific sensitivity. Second, breakpoint analyses identified OA thresholds for several endpoints: dissolution (mild and severe), calcification, egg development, shell growth, and survival. Finally, consensus by a panel of pteropod experts was used to verify thresholds and assign confidence scores for five endpoints with a sufficient signal: noise ratio to develop life-stage specific, duration-dependent thresholds. The range of aragonite saturation state from 1.5–0.9 provides a risk range from early warning to lethal impacts, thus providing a rigorous basis for vulnerability assessments to guide climate change management responses, including an evaluation of the efficacy of local pollution management. In addition, meta-analyses with OA, and warming shows increased vulnerability in two pteropod processes, i.e., shell dissolution and survival, and thus pointing toward increased threshold sensitivity under combined stressor effect

    Shelled pteropods in peril: Assessing vulnerability in a high CO2 ocean

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    The impact of anthropogenic ocean acidification (OA) on marine ecosystems is a vital concern facing marine scientists and managers of ocean resources. Euthecosomatous pteropods (holoplanktonic gastropods) represent an excellent sentinel for indicating exposure to anthropogenic OA because of the sensitivity of their aragonite shells to the OA conditions less favorable for calcification. However, an integration of observations, experiments and modelling efforts is needed to make accurate predictions of how these organisms will respond to future changes to their environment. Our understanding of the underlying organismal biology and life history is far from complete and must be improved if we are to comprehend fully the responses of these organisms to the multitude of stressors in their environment beyond OA. This review considers the present state of research and understanding of euthecosomatous pteropod biology and ecology of these organisms and considers promising new laboratory methods, advances in instrumentation (such as molecular, trace elements, stable isotopes, palaeobiology alongside autonomous sampling platforms, CT scanning and high-quality video recording) and novel field-based approaches (i.e. studies of upwelling and CO2 vent regions) that may allow us to improve our predictive capacity of their vulnerability and/or resilience. In addition to playing a critical ecological and biogeochemical role, pteropods can offer a significant value as an early-indicator of anthropogenic OA. This role as a sentinel species should be developed further to consolidate their potential use within marine environmental management policy making

    Les effets de l'acidification des océans sur le potentiel de calcification et l'intégration des éléments et des isotopes dans les ptéropodes méditerranéens et les foraminifÚres

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    This study used an interdisciplinary approach to assess the effects of ocean acidification on Mediterranean pteropods and foraminifers. A comparison of museum and modern samples of two pteropod species investigated the effects of pH on shell properties. Pteropod populations were analysed using time series data. To improve future perturbation experiments, a collaborative review of pteropod culture techniques was produced. Finally, the foraminifer O. universa was cultured under decoupled pH and [CO32-] to assess the effects of changes in the carbonate chemistry on boron incorporation and isotope fractionation. Museum pteropod samples were thicker than shells from 2012 and C. inflexa shells collected in 1910 were significantly denser than those from 2012, possibly due to a pH effect. Pteropod abundances displayed an increasing trend between 1967-2003 and are influenced by inter- annual temperature changes, with no sign of the observed changes in shell properties having had negative impacts. pH was the sole parameter of the carbonate system that affected the ÎŽ11B of O. universa calcite. The B/Ca ratio decreased with decreasing [CO32-] at constant pH but did not show consistent trends at constant [CO32-] and varying pH. Instead, a close correlation of B/Ca ratios and [HCO3-] was observed suggesting that boron is controlled by the [HCO3-].Cette Ă©tude a utilisĂ© une approche interdisciplinaire pour Ă©valuer les effets de l'acidification de l'ocĂ©an sur des ptĂ©ropodes et les foraminifĂšres MĂ©diterranĂ©ennes. Une comparaison d'Ă©chantillons conservĂ©s et modernes de 2 espĂšces de ptĂ©ropodes a Ă©tĂ© rĂ©alisĂ©e pour Ă©tudier les effets du pH sur les propriĂ©tĂ©s de la coquille. Des populations de ptĂ©ropodes ont Ă©galement Ă©tĂ© analysĂ©es Ă  l'aide des donnĂ©es de sĂ©ries temporelles. Pour permettre l'amĂ©lioration de futures expĂ©riences de perturbation, une revue collaborative des techniques de culture de ptĂ©ropodes a Ă©tĂ© produite. Enfin, le foraminifĂšre O. universa a Ă©tĂ© cultivĂ© dans des conditions de pH et de [CO32-] dĂ©couplĂ©s pour Ă©valuer les effets des changements dans la chimie du carbonate sur la composition en bore et le ?11B. Les coquilles des Ă©chantillons conservĂ©s de ptĂ©ropodes Ă©taient plus Ă©paisses que celles collectĂ©es en 2012 et les coquilles de C. inflexa recueillies en 1910 Ă©taient nettement plus denses que celles de 2012, probablement en raison d'un effet de pH. Les abondances de ptĂ©ropodes ont montrĂ© une tendance croissante entre 1967-2003 et se sont rĂ©vĂ©lĂ©es ĂȘtre influencĂ©es par les changements de tempĂ©rature interannuelles, sans que des changements dans les propriĂ©tĂ©s des coquilles n'ai eu d'impacts nĂ©gatifs. Lors de la derniĂšre Ă©tude le pH Ă©tait le seul paramĂštre du systĂšme de carbonate a affecter le ?11Bde la calcite de O. universa. Le B/Ca a diminuĂ© avec la diminution du [CO23-] Ă  pH constant mais n'a pas montrĂ© de tendance cohĂ©rente avec une [CO23-] constant et un pH variable. Au lieu de cela, une Ă©troite corrĂ©lation entre les B / Ca et [HCO3-] suggĂ©rant que le bore est contrĂŽlĂ© par la [HCO3-]

    "It made him seem real": The Creation of a Socially Visible Fetus through the Discourses and Practices of Routine Fetal Ultrasound

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    This thesis investigates the various meanings produced by and interpreted from ultrasonic fetal images. Women's reflections on their ultrasounds reveal that they constructed from these fuzzy pictures specific ideas about how this baby would be incorporated into an existing family. Expanding the analysis of ultrasound experiences beyond the realm of highly personalized examinations illustrates that the (ultrasonic) fetal image has come to occupy a particular position in our national consciousness. Both in women's reflections and in the larger context, fetal images influence the ways in which women conceptualize themselves as mothers, their pregnant bodies, and their relation to their fetus still in utero. As such, ultrasound images lend themselves to interpretive manipulation as individuals and organizations struggle to control the social construction of the visual fetus. Given its role in the production of symbolically important imagery, ultrasound must be analyzed in terms of its impact on individual women's pregnancies as well as on the collective social meanings attached to pregnancy and birth
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