160 research outputs found

    A mixed life-cycle stage bloom of Syracosphaera bannockii (Borsetti and Cati, 1976) Cros et al. 2000 (Bay of Biscay, April 2010)

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    High concentrations (464 cells mL-1) of Syracosphaera bannockii have been identified for the first time, in the Bay of Biscay during April 2010. These high concentrations combined with coccolithophore community dominance (~87%) indicated that a bloom of S. bannockii had formed. While the bloom consisted mostly of heterococcolith coccospheres, both holococcolith coccospheres and holococcolith-heterococcolith combination coccospheres were observed. This is only the second time that combination coccospheres of S. bannockii have been observed

    Phytoplankton dynamics in contrasting early stage North Atlantic spring blooms: composition, succession, and potential drivers

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    The spring bloom is a key annual event in the phenology of pelagic ecosystems, making a major contribution to the oceanic biological carbon pump through the production and export of organic carbon. However, there is little consensus as to the main drivers of spring bloom formation, exacerbated by a lack of in situ observations of the phytoplankton community composition and its evolution during this critical period. We investigated the dynamics of the phytoplankton community structure at two contrasting sites in the Iceland and Norwegian basins during the early stage (25 March–25 April) of the 2012 North Atlantic spring bloom. The plankton composition and characteristics of the initial stages of the bloom were markedly different between the two basins. The Iceland Basin (ICB) appeared well mixed down to >400 m, yet surface chlorophyll a (0.27–2.2 mg m−3) and primary production (0.06–0.66 mmol C m−3 d−1) were elevated in the upper 100 m. Although the Norwegian Basin (NWB) had a persistently shallower mixed layer (<100 m), chlorophyll a (0.58–0.93 mg m−3) and primary production (0.08–0.15 mmol C m−3 d−1) remained lower than in the ICB, with picoplankton (<2 μm) dominating chlorophyll a biomass. The ICB phytoplankton composition appeared primarily driven by the physicochemical environment, with periodic events of increased mixing restricting further increases in biomass. In contrast, the NWB phytoplankton community was potentially limited by physicochemical and/or biological factors such as grazing. Diatoms dominated the ICB, with the genus Chaetoceros (1–166 cells mL−1) being succeeded by Pseudo-nitzschia (0.2–210 cells mL−1). However, large diatoms (>10 μm) were virtually absent (<0.5 cells mL−1) from the NWB, with only small nano-sized (<5 μm) diatoms (i.e. Minidiscus spp.) present (101–600 cells mL−1). We suggest microzooplankton grazing, potentially coupled with the lack of a seed population of bloom-forming diatoms, was restricting diatom growth in the NWB, and that large diatoms may be absent in NWB spring blooms. Despite both phytoplankton communities being in the early stages of bloom formation, different physicochemical and biological factors controlled bloom formation at the two sites. If these differences in phytoplankton composition persist, the subsequent spring blooms are likely to be significantly different in terms of biogeochemistry and trophic interactions throughout the growth season, with important implications for carbon cycling and organic matter export

    High export via small particles before the onset of the North Atlantic spring bloom

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    Sinking organic matter in the North Atlantic Ocean transfers 1-3 Gt carbon year?1 from the surface ocean to the interior. The majority of this exported material is thought to be in form of large, rapidly sinking particles that aggregate during or after the spring phytoplankton bloom. However, recent work has suggested that intermittent water column stratification resulting in the termination of deep convection can isolate phytoplankton from the euphotic zone, leading to export of small particles. We present depth profiles of large (>0.1mm equivalent spherical diameter, ESD) and small (300m depth, leading to deep mixing of particles as deep as 600m. Subsequent re-stratification could trap these particles at depth and lead to high particle fluxes at depth without the need for aggregation (‘mixed layer pump'). Overall we suggest that pre-bloom fluxes to the mesopelagic are significant, and the role of small sinking particles requires careful consideration

    High export via small particles before the onset of the North Atlantic spring bloom

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    Sinking organic matter in the North Atlantic Ocean transfers 1-3 Gt carbon year?1 from the surface ocean to the interior. The majority of this exported material is thought to be in form of large, rapidly sinking particles that aggregate during or after the spring phytoplankton bloom. However, recent work has suggested that intermittent water column stratification resulting in the termination of deep convection can isolate phytoplankton from the euphotic zone, leading to export of small particles. We present depth profiles of large (&gt;0.1mm equivalent spherical diameter, ESD) and small (&lt;0.1mm ESD) sinking particle concentrations and fluxes prior to the spring bloom at two contrasting sites in the North Atlantic (61°30N, 11°00W and 62°50N, 02°30W) derived from the Marine Snow Catcher and the Video Plankton Recorder. The downward flux of organic carbon via small particles ranged from 23-186 mg C m?2 d?1, often constituting the bulk of the total particulate organic carbon flux. We propose that these rates were driven by two different mechanisms: In the Norwegian Basin, small sinking particles likely reached the upper mesopelagic by disaggregation of larger, faster sinking particles. In the Iceland Basin, a storm deepened the mixed layer to &gt;300m depth, leading to deep mixing of particles as deep as 600m. Subsequent re-stratification could trap these particles at depth and lead to high particle fluxes at depth without the need for aggregation (‘mixed layer pump'). Overall we suggest that pre-bloom fluxes to the mesopelagic are significant, and the role of small sinking particles requires careful consideration. <br/

    PEACHâ„¢ Queensland program improved child eating behaviours and reduced BMI z-score for overweight children (pilot study)

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    Background/Aims: Parenting, Eating and Activity for Child Health (PEACH™) Queensland is a 6-month family-focussed child weight management program currently targeting 1400 Queensland children. This study aims to investigate changes in child BMI and eating behaviours during the pilot phase. Methods: From 2013 – 2014, 251 overweight children (US-CDC BMI percentile ≥ 85th) were enrolled in the pilot phase of PEACH™ Queensland, using pre-defined inclusion criteria which included having a child above a healthy weight for their age (5 – 11 years). Baseline and follow-up data were collected from parents by questionnaire and included child eating behaviours, measured by core food intake and Children’s Dietary Questionnaire (CDQ). Children attending sessions were weighed and measured by a trained facilitator. Results: Children attending sessions were 80% obese (IOTF cut-points), 60% female, with average age of 9.0 ± 1.9 years. For the subset of children with complete anthropometry (n = 69), we observed significant decreases in US-CDC z-scores for weight and BMI, 2.3 ± 0.7 to 2.2 ± 0.7 (p < 0.001) and 2.2 ± 0.5 to 2.1 ± 0.7 (p < 0.0001), respectively. This reduction in BMI z-score was accompanied by increases in the proportion meeting recommendations for serves of fruit and vegetables, and significantly lower scores for sweetened beverages and discretionary food intake as measured by CDQ. Conclusions: The PEACH™ Queensland pilot reduced child weight and BMI z-scores, and improved eating behaviours (increased fruit and vegetable intake, decreased intake of discretionary foods and sweetened beverages) although there is need for further improvement

    Neonatal jaundice in association with autism spectrum disorder and developmental disorder

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    Objective: To examine the association between neonatal jaundice and autism spectrum disorder (ASD) and non-ASD developmental disorder (DD). Study design: We analyzed data from the Study to Explore Early Development, a US multisite, case-control study conducted from 2007 to 2011. Developmental assessment classified children aged 2–5 years into: ASD (n = 636), DD (n = 777), or controls (POP; n = 926). Neonatal jaundice (n = 1054) was identified from medical records and maternal interviews. We examined associations between neonatal jaundice and ASD and DD using regression models to obtain adjusted odds ratios (aOR). Results: Our results showed interaction between gestational age and neonatal jaundice. Neonatal jaundice was associated with ASD at 35–37 weeks (aOR = 1.83, 95%CI 1.05, 3.19), but not ≥38 weeks gestation (aOR = 0.97, 95%CI 0.76, 1.24). Similar results were observed with DD. Conclusions: Further exploration of timing and severity of neonatal jaundice and ASD/DD is warranted

    Growth and mortality of coccolithophores during spring in a temperate Shelf Sea (Celtic Sea, April 2015)

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    Coccolithophores are key components of phytoplankton communities, exerting a critical impact on the global carbon cycle and the Earth’s climate through the production of coccoliths made of calcium carbonate (calcite) and bioactive gases. Microzooplankton grazing is an important mortality factor in coccolithophore blooms, however little is currently known regarding the mortality (or growth) rates within non-bloom populations. Measurements of coccolithophore calcite production (CP) and dilution experiments to determine microzooplankton (≤63 µm) grazing rates were made during a spring cruise (April 2015) at the Central Celtic Sea (CCS), shelf edge (CS2), and within an adjacent April bloom of the coccolithophore Emiliania huxleyi at station J2. CP at CCS ranged from 10.4 to 40.4 µmol C m−3 d−1 and peaked at the height of the spring phytoplankton bloom (peak chlorophyll-a concentrations ∼6 mg m−3). Cell normalised calcification rates declined from ∼1.7 to ∼0.2 pmol C cell−1 d−1, accompanied by a shift from a mixed coccolithophore species community to one dominated by the more lightly calcified species E. huxleyi and Calciopappus caudatus. At the CCS, coccolithophore abundance increased from 6 to 94 cells mL−1, with net growth rates ranging from 0.06 to 0.21 d−1 from the 4th to the 28th April. Estimates of intrinsic growth and grazing rates from dilution experiments, at the CCS ranged from 0.01 to 0.86 d−1 and from 0.01 to 1.32 d−1, respectively, which resulted in variable net growth rates during April. Microzooplankton grazers consumed 59 to >100% of daily calcite production at the CCS. Within the E. huxleyi bloom a maximum density of 1986 cells mL−1 was recorded, along with CP rates of 6000 µmol C m−3 d−1 and an intrinsic growth rate of 0.29 d−1, with ∼80% of daily calcite production being consumed. Our results show that microzooplankton can exert strong top-down control on both bloom and non-bloom coccolithophore populations, grazing over 60% of daily growth (and calcite production). The fate of consumed calcite is unclear, but may be lost either through dissolution in acidic food vacuoles, and subsequent release as CO2, or export to the seabed after incorporation into small faecal pellets. With such high microzooplankton-mediated mortality losses, the fate of grazed calcite is clearly a high priority research direction

    Maternal diabetes and hypertensive disorders in association with autism spectrum disorder

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    Previous studies have shown complications of pregnancy, often examined in aggregate, to be associated with autism spectrum disorder (ASD). Results for specific complications, such as maternal diabetes and hypertension, have not been uniformly consistent and should be investigated independently in relation to ASD in a large community-based sample. The Study to Explore Early Development (SEED), a US multisite case–control study, enrolled children born in 2003–2006 at 2–5 years of age. Children were classified into three groups based on confirmation of ASD (n = 698), non-ASD developmental delay (DD; n = 887), or controls drawn from the general population (POP; n = 979). Diagnoses of any diabetes or hypertensive disorder during pregnancy were identified from prenatal medical records and maternal self-report. Logistic regression models estimated adjusted odds ratios (aOR) and confidence intervals (CI) adjusting for maternal age, race/ethnicity, education, smoking during pregnancy, and study site. Models for hypertension were additionally adjusted for parity and plurality. Among 2,564 mothers, we identified 246 (9.6%) with any diabetes and 386 (15.1%) with any hypertension in pregnancy. After adjustment for covariates, any diabetes during pregnancy was not associated with ASD (aOR = 1.10 [95% CI 0.77, 1.56]), but any hypertension was associated with ASD (aOR = 1.69 [95% CI 1.26, 2.26]). Results were similar for DD, and any diabetes (aOR = 1.29 [95% CI 0.94, 1.78]) or any hypertension (aOR = 1.71 [95% CI 1.30, 2.25]). Some pregnancy complications, such as hypertension, may play a role in autism etiology and can possibly serve as a prompt for more vigilant ASD screening efforts. Autism Res 2019, 12: 967–975. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. Lay Summary: We studied if common complications in pregnancy are associated with autism spectrum disorder (ASD) in a large sample of mothers and children. Our results show an association between conditions marked by high blood pressure and ASD, but no association with conditions marked by high blood sugar and ASD. Associations were similar for children who had a developmental disorder that was not ASD, suggesting that this relationship may not be specific to ASD

    The epidemiology of autism spectrum disorders

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    Autism spectrum disorders (ASDs) are complex, lifelong, neurodevelopmental conditions of largely unknown cause. They are much more common than previously believed, second in frequency only to mental retardation among the serious developmental disorders. Although a heritable component has been demonstrated in ASD etiology, putative risk genes have yet to be identified. Environmental risk factors may also play a role, perhaps via complex gene-environment interactions, but no specific exposures with significant population effects are known. A number of endogenous biomarkers associated with autism risk have been investigated, and these may help identify significant biologic pathways that, in turn, will aid in the discovery of specific genes and exposures. Future epidemiologic research should focus on expanding population-based descriptive data on ASDs, exploring candidate risk factors in large well-designed studies incorporating both genetic and environmental exposure data and addressing possible etiologic heterogeneity in studies that can stratify case groups and consider alternate endophenotypes
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