13 research outputs found

    Data for: Impact of bottom water currents on benthic foraminiferal assemblages in a cold-water coral environment: the Moira Mounds (NE Atlantic)

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    Annex 1: Discussed grain size analysis parameters (mean, sorting, skewness, kurtosis) for surface samples from the downslope Moira Mounds.Annex 2: Quantitative foraminiferal data of the living and dead assemblages from the downslope Moira Mounds - surface samples, combining all fractions (63-125 µm, 125-250 µm and >250 µm).Annex 3: Quantitative foraminiferal data of the living and dead assemblages from the downslope Moira Mounds - surface samples, for all fractions taken separately (63-125 µm, 125-250 µm and >250 µm).Annex 4: Living/Dead ratios for surface benthic foraminiferal assemblages from the downslope Moira Mounds combining all fractions (63-125 µm, 125-250 µm and >250 µm)

    Data for: Impact of bottom water currents on benthic foraminiferal assemblages in a cold-water coral environment: the Moira Mounds (NE Atlantic)

    No full text
    Annex 1: Discussed grain size analysis parameters (mean, sorting, skewness, kurtosis) for surface samples from the downslope Moira Mounds.Annex 2: Quantitative foraminiferal data of the living and dead assemblages from the downslope Moira Mounds - surface samples, combining all fractions (63-125 µm, 125-250 µm and >250 µm).Annex 3: Quantitative foraminiferal data of the living and dead assemblages from the downslope Moira Mounds - surface samples, for all fractions taken separately (63-125 µm, 125-250 µm and >250 µm).Annex 4: Living/Dead ratios for surface benthic foraminiferal assemblages from the downslope Moira Mounds combining all fractions (63-125 µm, 125-250 µm and >250 µm).THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

    Deep-sea response to interglacial-glacial variability on the South Australian margin over the last 94 ka

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    The continuous record offered by deep-sea sediments has been extensively used to constrain shifting continental and oceanographic conditions. Yet, past fluctuations in deep-sea benthic conditions and bottom-currents are in numerous parts of the globe scarcely documented, one such example being the South Australian margin. Indeed, though variations in surface water masses and continental aeolian dust and river outflow are well documented in the area, little is known about benthic environments and their dynamics during the last interglacial-glacial cycle. We focus here on benthic foraminiferal assemblages sampled from a sediment core recovered at 2420 m depth from a small plateau south of Kangaroo Island within the underwater Murray Canyons Group (South Australian margin). Benthic foraminiferal assemblages show a distinct separation between interglacial and glacial periods over the last 94 ka, and indicate that the benthic environment was well-ventilated and oligotrophic during glacial periods, whilst being rather marked by reduced oxygenation associated to higher food input during the Holocene and Marine Isotope Stage 5a-c. We demonstrate that autochtonous deep-sea benthic foraminiferal communities neither respond to changes in the Murray River's discharges, nor do they follow variations in aeolian dust input from South Australia. Instead, the deep-sea and the terrestrial realm appear decoupled. Moreover, our observations suggest that bottom-water slope currents were stronger during the Holocene and Marine Isotope Stage 5a-c. We propose that this strengthening was triggered by an intensification of the poleward-circulating deep eastern boundary current transporting carbon-rich Indian Deep Water. In contrast, glacial seafloor conditions, especially during the Last Glacial Maximum, may reflect a greater influence and a shoaling of oxygen-rich Antarctic Bottom Water of South Australia. This bottom-water shift would follow the northward displacement of the Subtropical and Subantarctic Fronts and coincide with a withering influence of the Leeuwin Current within surface waters

    Distribution of benthic foraminiferal assemblages in the transitional environment of the Djerba lagoon (Tunisia)

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    The eastern edge of the Djerba Island represents an important tourist pole. However, studies describing the environmental processes affecting this Island are scarce. Although never studied before, the peculiar Djerba lagoon is well known by the local population and by tourists. In July 2014, surface sediment and seawater samples were collected in this lagoon to measure grain size, organic matter content and living foraminiferal assemblages to describe environmental conditions. Seawater samples were also collected and the concentration of 17 chemical elements were measured by ICP-OES. The results show that a salinity gradient along the studied transect clearly impacts seagrass distribution, creating different environmental conditions inside the Djerba lagoon. Biotic and abiotic parameters reflect a transitional environment from hypersaline to normal marine conditions. Living benthic foraminifera show an adaptation to changing conditions within the different parts of the lagoon. In particular, the presence of Ammonia spp. and Haynesina depressula correlates with hypersaline waters, whilst Brizalina striatula characterizes the parts of the lagoon colonized by seagrass. Epifaunal species, such as Rosalina vilardeboana and Amphistegina spp. colonize hard substrata present at the transition between the lagoon and the open sea

    Changes in northeast Atlantic hydrology during Termination 1: Insights from Celtic margin's benthic foraminifera

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    International audienceUsing benthic foraminiferal-based proxies in sediments from the Celtic margin, we provide a well-dated record across the last deglaciation of the Channel River dynamics and its potential impact on the hydrology of intermediate water masses along the European margin. Our results describe three main periods: 1) During the Last Glacial Maximum, and before ∼21 ka BP, the predominance of meso-oligotrophic species suggests well oxygenated water masses. After ∼21 ka BP, increasing proportions of eutrophic species related to enhanced riverine supply occurs concomitantly with early warming in Greenland air-temperatures; 2) A thick laminated deposit, occurring during a 1500-years long period of seasonal melting of the European Ice Sheet (EIS), is associated with early Heinrich Stadial 1 period (∼18.2–16.7 ka BP). The benthic proxies describe low salinity episodes, cold temperatures, severe dysoxia and eutrophic conditions on the sea floor, perhaps evidence for cascading of turbid meltwaters; 3) During late HS1 (∼16.7–14.7 ka BP), conditions on the Celtic margin's seafloor changed drastically and faunas indicate oligotrophic conditions as a result of the ceasing of EIS meltwater discharges. While surface waters were cold due to Laurentide Ice Sheet (LIS) icebergs releases, increasing benthic Mg/Ca ratios reveal a progressive warming of intermediate water masses whereas oxygen proxies indicate overall well oxygenated conditions. In addition to the well known effect of EIS meltwaters on surface waters in the Celtic margin, our benthic record documents a pronounced impact on intermediate water depths during HS1, which coincided with major AMOC disruptions.</p

    Staggered cold-water coral mound build-up on an Alboran ridge during the last deglacial (East Melilla Mound Field, western Mediterranean)

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    International audienceThe start-up, build-up and demise of cold-water coral mounds are governed by environmental changes at global, regional and local scales. Whilst the formation of cold-water coral mounds across the globe is widely documented to follow interglacial-glacial cycles, less is known about their response to local environmental fluctuations during short time intervals. This study investigates the local variations in coral mound build-up along Brittlestar Ridge I (East Melilla Coral Province, Southeast Alboran Sea) by comparing three on-mound gravity cores collected ∼1 km apart, together with five previously described on-mound records, along a longitudinal transect on the ridge crest. Radiocarbon foraminiferal dating associated to U-series coral dating allowed to correlate the different records and to estimate mound aggradation rates, whilst grain-size analysis provided information on bottom current velocities. Prior to a rapid period of coral mound build-up initiated at ∼14.75 ka BP, the three cores present an occurrence of cm-thick bryozoan-dominated intervals nearly entirely consisting of the erect cheleistome Buskea dichotoma. Offsets between benthic foraminiferal and coral ages suggest that older dead allochtonous benthic foraminifera are possibly eroded from neighbouring settings, transported and deposited within the coral framework. In contrast, younger benthic foraminifera would develop on dead coral framework during periods of reef stagnation. The comparison of all cores indicates that mound build-up along the ridge did not follow the same timing during the last ∼16 kyr and that mound aggradation was marked by a staggered dynamic. Both local differences in bottom current velocities and patchiness of other key environmental actors (e.g. substrate availability) are suspected to drive the observed staggered mound build-up. Cold-water coral mound build-up shows important differences during Greenland Interstadial 1 (i.e. the Bølling-Allerød) and the Holocene, hence exemplifying how local environmental variability may overprint global and regional climate variability over short time periods

    Breast-conserving surgery with or without radiotherapy in women with ductal carcinoma in situ: a meta-analysis of randomized trials

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    <p>Abstract</p> <p>Background</p> <p>To investigate whether Radiation therapy (RT) should follow breast conserving surgery in women with ductal carcinoma in situ from breast cancer (DCIS) with objective of decreased mortality, invasive or non invasive recurrence, distant metastases and contralateral breast cancer rates. We have done a meta-analysis of these results to give a more balanced view of the total evidence and to increase statistical precision.</p> <p>Methods</p> <p>A meta-analysis of randomized controlled trials (RCT) was performed comparing RT treatment for DCIS of breast cancer to observation. The MEDLINE, EMBASE, CANCERLIT, Cochrane Library databases, Trial registers, bibliographic databases, and recent issues of relevant journals were searched. Relevant reports were reviewed by two reviewers independently and the references from these reports were searched for additional trials, using guidelines set by QUOROM statement criteria.</p> <p>Results</p> <p>The reviewers identified four large RCTs, yielding 3665 patients. Pooled results from this four randomized trials of adjuvant radiotherapy showed a significant reduction of invasive and DCIS ipsilateral breast cancer with odds ratio (OR) of 0.40 (95% CI 0.33 – 0.60, p < 0.00001) and 0.40 (95% CI 0.31 – 0.53, p < 0.00001), respectively. There was not difference in distant metastases (OR = 1.04, 95% CI 0.57–1.91, p = 0.38) and death rates (OR = 1.08, 95%CI 0.65 – 1.78, p = 0.45) between the two arms. There was more contralateral breast cancer after adjuvant RT (66/1711 = 3.85%) versus observation (49/1954 = 2.5%). The likelihood of contralateral breast cancer was 1.53-fold higher (95% CI 1.05 – 2.24, p = 0.03) in radiotherapy arms.</p> <p>Conclusion</p> <p>The conclusion from our meta-analysis is that the addition of radiation therapy to lumpectomy results in an approximately 60% reduction in breast cancer recurrence, no benefit for survival or distant metastases compared to excision alone. Patients with high-grade DCIS lesions and positive margins benefited most from the addition of radiation therapy. It is not yet clear which patients can be successfully treated with lumpectomy alone; until further prospective studies answer this question, radiation should be recommended after lumpectomy for all patients without contraindications.</p
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