Global prediction of planktic foraminiferal fluxes from hydrographic and productivity data

International audienceUnderstanding and quantifying the seasonal and spatial distribution of planktic foraminiferal fluxes reflected in sedimentary assemblages is key to interpret foraminifera-based proxies in paleoceanography. Towards this goal we present an empirical model to predict foraminiferal fluxes on a global scale. A compilation of planktic foraminiferal flux and export production data from globally distributed sediment traps together with environmental data of sea-surface temperature and mixed-layer depth from online databases is used to calibrate the model that calculates monthly foraminiferal fluxes for the 18 most common species. The calibrated model is then forced with a global data set of hydrographic and productivity data to predict monthly foraminiferal fluxes worldwide. The predictive skills of the model are assessed by comparing the model output with planktic foraminiferal assemblages from globally distributed surface sediments as well as with measured foraminiferal fluxes of sediment traps not included in the calibration data set. Many general distribution patterns of foraminiferal species recognized from the model output compare favorably with observations from coretops or sediment traps, even though the model still produces problematic results in some places. Among others, meridional gradients in species richness and diversity, increased relative abundances of Neogloboquadrina pachyderma (dex.) in upwelling areas, and peak abundances of Globigerinella siphonifera in oligotrophic subtropical gyres show good agreement between model and coretops. Absolute foraminiferal fluxes are significantly underestimated in most cases, while seasonal variations can be reproduced for some species. Interannual differences in foraminiferal fluxes are not reflected by the model which might partly be due to a lack of actual environmental data for the calibration and model experiments. The limited predictive skills of the model suggest that additional parameters should be considered. Export production should probably be replaced by a more realistic representation of food availability for planktic foraminifera. This could be achieved by adding a dynamic component to the model and linking it to an ecosystem model

Environmental Predictors of Diversity in Recent Planktonic Foraminifera as Recorded in Marine Sediments

© 2016 Fenton et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. [4.0 license]. The attached file is the published version of the article

Predicting Individual Differences in Reading and Spelling Skill With Artificial Script–Based Letter–Speech Sound Training

In this study, we examined the learning of letter-speech sound correspondences within an artificial script and performed an experimental analysis of letter-speech sound learning among dyslexic and normal readers vis-à-vis phonological awareness, rapid automatized naming, reading, and spelling. Participants were provided with 20 min of training aimed at learning eight new basic letter-speech sound correspondences, followed by a short assessment of mastery of the correspondences and word-reading ability in this unfamiliar script. Our results demonstrated that brief training is moderately successful in differentiating dyslexic readers from normal readers in their ability to learn letter-speech sound correspondences. The normal readers outperformed the dyslexic readers for accuracy and speed on a letter-speech sound matching task, as well as on a word-reading task containing familiar words written in the artificial orthography. Importantly, the new artificial script-related measures were related to phonological awareness and rapid automatized naming and made a unique contribution in predicting individual differences in reading and spelling ability. Our results are consistent with the view that a fundamental letter-speech sound learning deficit is a key factor in dyslexia

A Randomized Controlled Trial on The Beneficial Effects of Training Letter-Speech Sound Integration on Reading Fluency in Children with Dyslexia.

A recent account of dyslexia assumes that a failure to develop automated letter-speech sound integration might be responsible for the observed lack of reading fluency. This study uses a pre-test-training-post-test design to evaluate the effects of a training program based on letter-speech sound associations with a special focus on gains in reading fluency. A sample of 44 children with dyslexia and 23 typical readers, aged 8 to 9, was recruited. Children with dyslexia were randomly allocated to either the training program group (n = 23) or a waiting-list control group (n = 21). The training intensively focused on letter-speech sound mapping and consisted of 34 individual sessions of 45 minutes over a five month period. The children with dyslexia showed substantial reading gains for the main word reading and spelling measures after training, improving at a faster rate than typical readers and waiting-list controls. The results are interpreted within the conceptual framework assuming a multisensory integration deficit as the most proximal cause of dysfluent reading in dyslexia.ISRCTN register ISRCTN12783279