39 research outputs found

    Diversity of Meiofauna from the 9°50′N East Pacific Rise across a Gradient of Hydrothermal Fluid Emissions

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    Background: We studied the meiofauna community at deep-sea hydrothermal vents along a gradient of vent fluid emissions in the axial summit trought (AST) of the East Pacific Rise 9 degrees 50'N region. The gradient ranged from extreme high temperatures, high sulfide concentrations, and low pH at sulfide chimneys to ambient deep-sea water conditions on bare basalt. We explore meiofauna diversity and abundance, and discuss its possible underlying ecological and evolutionary processes. Methodology/Principal Findings: After sampling in five physico-chemically different habitats, the meiofauna was sorted, counted and classified. Abundances were low at all sites. A total of 52 species were identified at vent habitats. The vent community was dominated by hard substrate generalists that also lived on bare basalt at ambient deep-sea temperature in the axial summit trough (AST generalists). Some vent species were restricted to a specific vent habitat (vent specialists), but others occurred over a wide range of physico-chemical conditions (vent generalists). Additionally, 35 species were only found on cold bare basalt (basalt specialists). At vent sites, species richness and diversity clearly increased with decreasing influence of vent fluid emissions from extreme flow sulfide chimney (no fauna), high flow pompei worm (S: 4-7, H-loge': 0.11-0.45), vigorous flow tubeworm (S: 8-23; H-loge': 0.44-2.00) to low flow mussel habitats (S: 28-31; H-loge': 2.34-2.60). Conclusions/Significance: Our data suggest that with increasing temperature and toxic hydrogen sulfide concentrations and increasing amplitude of variation of these factors, fewer species are able to cope with these extreme conditions. This results in less diverse communities in more extreme habitats. The finding of many species being present at sites with and without vent fluid emissions points to a non endemic deep-sea hydrothermal vent meiofaunal community. This is in contrast to a mostly endemic macrofauna but similar to what is known for meiofauna from shallow-water vents

    Dichotic integration: is it similar in the elderly and children?

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    Abstract Background Aging process is associated with central auditory changes, which may explain some understanding difficulties in elderly. It may be evaluated with the dichotic digits (DD) test, a widely used experimental paradigm for studying interhemispheric interactions. Purpose This study was performed to evaluate dichotic integration ability in the elderly and children populations by comparing it with adults who acted as reference. Research design The study design was a cross-sectional one. It was conducted in Ain Shams University, Faculty of Medicine, Demerdash Hospital, Audiology Unit, for a period of 4 years. The study comprised 75 participants divided into three groups: the adult group, the elderly group, and the pediatric group. Data collection and analysis Basic Audiological Evaluation and the DD test in the free recall condition were carried out in all participants. Results Results of this study suggest that central auditory processing concerning dichotic integration is different in children and elderly individuals when compared with adults. Moreover, there was no significant difference between elderly patients and children. The age had a direct correlation with DD test scores in children, but an inverse correlation in the elderly. Conclusion Dichotic integration as measured using the DD test is similar in the elderly and children, but in opposite directions with regard to its change with age progress

    Methods and Applications of the Audibility Index in Hearing Aid Selection and Fitting

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