590 research outputs found

    Constraints on Near-Ridge Magmatism Using \u3csup\u3e40\u3c/sup\u3eAr/\u3csup\u3e39\u3c/sup\u3eAr Geochronology of Enriched MORB from the 8°20\u27 N Seamount Chain

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    Our understanding of the spatial-temporal-compositional relationships between off-axis magmatism and mid-ocean ridge spreading centers is limited. Determining the 40Ar/39Ar ages of mid-ocean ridge basalt (MORB) lavas erupting near mid-ocean ridges (MOR) has been a challenge due to the characteristically low K2O contents in incompatible element-depleted normal MORB (NMORB). High-precision 40Ar/39Ar geochronology is used here to determine ages of young, basaltic lavas erupted along the 8°20\u27 N seamount chain west of the East Pacific Rise (EPR) axis that have a range of incompatible element enrichments (EMORB) suitable for 40Ar/39Ar geochronology (e.g., K2O contents \u3e 0.3 wt%). 40Ar/39Ar ages were determined in 29 well-characterized basalts sampled using HOV Alvin and dredging. Detailed geochronology and geochemical analyses provide important constraints on the timing, distribution, and origins of lavas that constructed this extensive volcanic lineament relative to magmatism beneath the adjacent EPR axis. Seamount eruption ages are up to ∌1.6 Ma younger than the underlying lithosphere, supporting a model of prolonged off-axis magmatism for at least 2 Myrs at distances as great as ∌90 km from the ridge axis. Increasing geochemical heterogeneity with eruption distance reflects the diminishing effect of sub-ridge melt focusing. The range of geochemically distinct lavas erupted at given distances from the ridge highlights the dynamic nature of the near-ridge magmatic environment over Myr timescales. Linear ridge-like (EPR-parallel) morphotectonic features erupt the youngest and most incompatible element-enriched lavas of the entire seamount chain, indicating there is a recent change in the influence of mantle heterogeneity and off-axis melt metasomatism on the near-ridge lithospheric mantle. Changes in seamount morphologies are attributed to counter-clockwise rotation and southward migration of the nearby Siqueiros transform over the last few million years

    The sensitivity of seabird populations to density-dependence, environmental stochasticity and anthropogenic mortality

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    The balance between economic growth and wildlife conservation is a priority for many governments. Enhancing realism in assessment of population‐level impacts of anthropogenic mortality can help achieve this balance. Population Viability Analysis (PVA) is commonly applied to investigate population vulnerability, but outcomes of PVA are sensitive to formulations of density‐dependence, environmental stochasticity and life history. Current practice in marine assessments is to use precautionary models that assume no compensation from density‐dependence or rescue‐effects via “re‐seeding” from other colonies. However, if we could empirically quantify regulatory population processes, the responses of populations to additional anthropogenic mortality may be assessed with more realism in PVA. Using Bayesian state‐space models fitted to population time series from three sympatric seabird populations, selected for varied life histories, we inferred the extent to which their dynamics are driven by environmental stochasticity and density‐dependence. Based on these inferences, we conducted an exhaustive PVA across credible parameterizations for intrinsic and extrinsic population regulation, simulated as a closed and re‐seeded system. Scenarios of anthropogenic mortality, along a sliding scale of precaution, were applied both proportionally and as a fixed quota using Potential Biological Removal (PBR). Baseline results from fitting revealed clear environmental regulation in two of our three species. Crucially, we found that for our empirically derived, realistic model parameterizations there are risks of decline to real populations even under very precautionary mortality scenarios. We find that PBR is dubious in application as a sustainable tool for population assessment when we account for regulation. Closed versus re‐seeded models showed a large divergence in outcomes, with sharper declines in closed simulations. Fixed‐quota mortality typically induced greater population declines comparative to proportional mortality, subject to regulation and re‐seeding. Synthesis and applications. Practitioners using arbitrary formulations of population regulation risk over‐precaution (economic constraint) or under‐precaution (endangering populations). The demands of increased economic development and preservation of wildlife require that methodologies apply techniques that confer reality and rigour to assessment. The current practice of employing models lacking density‐dependence and empirical environmental information imposes limitations in the efficacy of estimating impacts. Here, we provide a method to quantify the conditions that predominantly regulate a population and exacerbate the risk of decline from anthropogenic mortality. It is in the interests of both developers and conservationists to apply methods in population impact assessments that capture realism in the processes driving population dynamics

    Effects of sea temperature and stratification changes on seabird breeding success

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    As apex predators in marine ecosystems, seabirds may primarily experience climate change impacts indirectly, via changes to their food webs. Observed seabird population declines have been linked to climate-driven oceanographic and food web changes. However, relationships have often been derived from relatively few colonies and consider only sea surface temperature (SST), so important drivers, and spatial variation in drivers, could remain undetected. Further, explicit climate change projections have rarely been made, so longer-term risks remain unclear. Here, we use tracking data to estimate foraging areas for eleven black-legged kittiwake (Rissa tridactyla) colonies in the UK and Ireland, thus reducing reliance on single colonies and allowing calculation of colony-specific oceanographic conditions. We use mixed models to consider how SST, the potential energy anomaly (indicating density stratification strength) and the timing of seasonal stratification influence kittiwake productivity. Across all colonies, higher breeding success was associated with weaker stratification before breeding and lower SSTs during the breeding season. Eight colonies with sufficient data were modelled individually: higher productivity was associated with later stratification at three colonies, weaker stratification at two, and lower SSTs at one, whilst two colonies showed no significant relationships. Hence, key drivers of productivity varied among colonies. Climate change projections, made using fitted models, indicated that breeding success could decline by 21 – 43% between 1961-90 and 2070-99. Climate change therefore poses a longer-term threat to kittiwakes, but as this will be mediated via availability of key prey species, other marine apex predators could also face similar threats

    Identification of candidate pelagic marine protected areas through a seabird seasonal-, multispecific- and extinction risk-based approach

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    With increasing pressure on the oceans from environmental change, there has been a global call for improved protection of marine ecosystems through the implementation of marine protected areas (MPAs). Here, we used species distribution modelling (SDM) of tracking data from 14 seabird species to identify key marine areas in the southwest Atlantic Ocean, valuing areas based on seabird species occurrence, seasonality and extinction risk. We also compared overlaps between the outputs generated by the SDM and layers representing important human threats (fishing intensity, ship density, plastic and oil pollution, ocean acidification), and calculated loss in conservation value using fishing and ship density as cost layers. The key marine areas were located on the southern Patagonian Shelf, overlapping extensively with areas of high fishing activity, and did not change seasonally, while seasonal areas were located off south and southeast Brazil and overlapped with areas of high plastic pollution and ocean acidification. Non-seasonal key areas were located off northeast Brazil on an area of high biodiversity, and with relatively low human impacts. We found support for the use of seasonal areas depending on the seabird assemblage used, because there was a loss in conservation value for the seasonal compared to the non-seasonal approach when using ‘cost’ layers. Our approach, accounting for seasonal changes in seabird assemblages and their risk of extinction, identified additional candidate areas for incorporation in the network of pelagic MPAs

    "Obesity" and "Clinical Obesity" Men's understandings of obesity and its relation to the risk of diabetes: A qualitative study

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    <p>Abstract</p> <p>Background</p> <p>The 2007 Wanless report highlights the ever increasing problem of obesity and the consequent health problems. Obesity is a significant cause of diabetes. An increasing evidence base suggests that in terms of reducing diabetes and CVD risk, it is better to be "fit and fat" than unfit and of normal weight. There has been very little previous research into the understandings that men in the general population hold about the issues of weight, exercise and health; we therefore undertook this study in order to inform the process of health promotion and diabetes prevention in this group.</p> <p>Methods</p> <p>A qualitative study in North East England General Practice using a purposive sample of men aged 25 and 45 years (selection process designed to include 'normal', 'overweight' and 'obese' men). One to one audio-recorded semi structured interviews focused on: overweight and obesity, diet, physical activity and diabetes. Transcripts were initially analysed using framework analysis. Emerging themes interlinked.</p> <p>Results</p> <p>The men in this study (n = 17) understand the word obesity differently from the clinical definition; "obesity" was used as a description of those with fat in a central distribution, and understandings of the term commonly take into account fitness as well as weight. Men in their late 30s and early 40s described becoming more aware of health issues. Knowledge of what constitutes a 'healthy lifestyle' was generally good, but men described difficulty acting upon this knowledge for various reasons e.g. increasing responsibilities at home and at work. Knowledge of diabetes and the link between obesity and diabetes was poor.</p> <p>Conclusion</p> <p>Men in this study had a complex understanding of the interlinked importance of weight and fitness in relation to health. Obesity is understood as a description of people with centrally distributed fat, in association with low fitness levels. There is a need to increase understanding of the causes and consequences of diabetes. Discussion of increased health awareness by men round the age of 40 may indicate a window of opportunity to intervene at this time.</p

    A translational framework for public health research

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    &lt;p&gt;&lt;b&gt;Background&lt;/b&gt;&lt;/p&gt; &lt;p&gt;The paradigm of translational medicine that underpins frameworks such as the Cooksey report on the funding of health research does not adequately reflect the complex reality of the public health environment. We therefore outline a translational framework for public health research.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Discussion&lt;/b&gt;&lt;/p&gt; &lt;p&gt;Our framework redefines the objective of translation from that of institutionalising effective interventions to that of improving population health by influencing both individual and collective determinants of health. It incorporates epidemiological perspectives with those of the social sciences, recognising that many types of research may contribute to the shaping of policy, practice and future research. It also identifies a pivotal role for evidence synthesis and the importance of non-linear and intersectoral interfaces with the public realm.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Summary&lt;/b&gt;&lt;/p&gt; &lt;p&gt;We propose a research agenda to advance the field and argue that resources for 'applied' or 'translational' public health research should be deployed across the framework, not reserved for 'dissemination' or 'implementation'.&lt;/p&gt

    Gender differences in behavioral regulation in four societies: The United States, Taiwan, South Korea, and China

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    The current study investigates gender differences in behavioral regulation in four societies: the United States, Taiwan, South Korea, and China. Directly assessed individual behavioral regulation (Head–Toes–Knees–Shoulders, HTKS), teacher-rated classroom behavioral regulation (Child Behavior Rating Scale, CBRS) and a battery of school readiness assessments (mathematics, vocabulary, and early literacy) were used with 814 young children (ages 3–6 years). Results showed that girls in the United States had significantly higher individual behavioral regulation than boys, but there were no significant gender differences in any Asian societies. In contrast, teachers in Taiwan, South Korea, as well as the United States rated girls as significantly higher than boys on classroom behavioral regulation. In addition, for both genders, individual and classroom behavioral regulation were related to many aspects of school readiness in all societies for girls and boys. Universal and culturally specific findings and their implications are discussed

    A Geochemical Record of Late- Holocene Hurricane Events From the Florida Everglades

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    A 5.25- m sediment core SRM- 1 and 45 surface samples from mangrove forests at the Shark River Estuary in the Everglades National Park, Florida, were examined by using X- ray fluorescence and carbon isotopic analyses to study the history of intense hurricane landfall during the Late- Holocene. Significance testing of the surface samples in relation to storm deposits from Hurricane Wilma suggests that elemental concentration of Sr and Cl and the ratio of Cl/Br are the most sensitive indicators for major hurricane events in our study area. The geochemical data sets of core SRM- 1 identified five active periods of intense hurricane activities during the last 3,500 years at ~3,400- 3,000, ~2,200- 1,500, ~1,000- 800, ~600- 300, and ~150 calibrated years before present to present. This is the longest paleohurricane record to date from South Florida. Our results are consistent with the view that intense hurricane activities in South Florida were modulated by Intertropical Convergence Zone (ITCZ) movements, El Niño/Southern Oscillation (ENSO) activities, and North Atlantic Oscillation (NAO) strength. This study contributes to the methodological advancement in paleotempestological studies by demonstrating that geochemical signals, particularly signals of saltwater intrusions, can be preserved in the sediment profiles on millennial time- scale and measured by X- ray fluorescence techniques, thereby enabling more storm records to be produced from otherwise suboptimal sand- limited coastal systems such as the Florida Everglades. More work needs to be done to explore the use of geochemical and stable isotopic analyses in detecting storm signals from sand- limited coastal environments.Plain Language SummaryThis study uses geochemical analyses to detect intense hurricanes that made landfall near the southwest coast of the Florida Everglades from sediment profiles. The geochemical data sets identified five active periods of intense hurricane activities during the last 3,500 years at ~3,400- 3,000, ~2,200- 1,500, ~1,000- 800, ~600- 300, and ~150 years ago. Results from this study agree with previous studies that intense hurricane activities in the western Atlantic Basin were controlled by the position of ITCZ, ENSO activities, and NAO strength.Key PointsThis study demonstrates the use of XRF analysis in detecting major hurricane events in sand- limited coastal systemsFive active hurricane periods were identified at ~3,400- 3,000, ~2,200- 1,500, ~1,000- 800, ~600- 300, and ~150 cal yr BP to presentThis study suggests that intense hurricane activities in the western Atlantic Basin were modulated by ITCZ, ENSO, and NAO activitiesPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156482/2/wrcr24787_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156482/1/wrcr24787.pd
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