Dynamics of salt marsh margins are related to their 3-dimensional

The three-dimensional configuration of sedimentary landforms in intertidal environments represents a major control on regional hydrodynamics. It modulates the location and magnitude of forces exerted by tidal currents and waves on the landform itself and on engineered infrastructure such as sea walls or coastal defences. Furthermore, the effect is reflexive with the landforms representing an integrated, long-term response to the forces exerted on them. There is a strong reciprocal linkage between form and process (morphodynamics) in the coastal zone which is significantly lagged and poorly understood in the case of cohesive, vegetated sediments in the intertidal zone. A method is presented that links the geometric properties of the tidal at-saltmarsh interface to the history and potential future evolution of that interface. A novel quantitative classification scheme that is capable of separating marsh margins based on their functional form is developed and is applied to demonstrate that relationships exist between landform configuration and morphological evolution across a regional extent. This provides evidence of a spatially variable balance between self-organised and external controls on morphodynamic evolution and the first quantitative basis for a quick assessment procedure for likely future dynamism.Foreshore Assessment using Space Technology (FAST) EU 7th Framework Programme FP7-SPACE-2013-1 The Isaac Newton Trust

Will nature work with us? Erosion and flooding impacts on a UK barrier

‘Barrier island’ refers to a diverse collection of coastal landforms that often support substantial human populations, critical infrastructures, and ecosystems. Globally, many coastal barriers are experiencing climatically altered environmental forcing coupled with increasing anthropogenic pressures. This paper undertakes high resolution shoreline change analysis to reveal how Blakeney Point, a mixed sandy-gravel barrier located on the UK’s East Coast, has evolved over centennial, decadal and event timescales. We seek to establish the implications of barrier evolution, under contrasting management regimes, for present erosion and flooding hazards. Interrogating a series of alternative shoreline proxies reveals a series of interdependent behaviors. Over the 130-year period of study, Blakeney Point is shown to be rolling landward at a mean rate of 0.60 m a-1. Assuming continued landward retreat over the coming decades, future flood-generating storm events will encounter more landward shoreline positions than today. Superimposed on this trend, we observe the presence of alongshore migrating erosional hotspots which give rise to unpredictable morphologies at any given location on the spit. Finally, we find that instances of barrier setback are driven by individual storm events, which makes barrier retreat both highly variable and discontinuous in time and space. This is illustrated by the presence of overwash, particularly along stretches of the barrier that have experienced a recent shift in management regime towards a non-interventionist approach.This work was funded by the NERC/ESRC Data, Risk and Environmental Analytical Methods (DREAM) Centre, Grant/Award Number: NE/M009009/1. It is also a contribution to the NERC-funded project “Physical and Biological dynamic coastal processes and their role in coastal recovery” (BLUEcoast), Grant Award Number: NE/N015924/1

The Influence Of Particle Size And Frictional/Cohesional Shear Strength Components On UK Salt Marsh Substrate Stability

Salt marshes and tidal flats contribute valuable ecosystem services, by providing habitats, storing pollutants and reducing flood and erosion risk in the coastal hinterland. However, salt marsh areal extent is decreasing both globally and regionally (e.g. in Northwest Europe). While we know that salt marshes are retreating, this could be occurring due to biological, geochemical and geotechnical properties of the marsh and tidal flat, and/or due to changes in hydrodynamic forcing. Until now, very few studies have assessed how substrate geotechnical properties influence both the erosion processes and the erodibility of the marsh edge and tidal flat surface. Here, we compare frictional and cohesional strength components at two hydrodynamically-similar but sedimentologically-different salt marshes and tidal flats in the UK. As such, we assess how sediment composition and behavior may influence marsh resistance to hydrodynamic forcing.This work was funded by a NERC PhD studentship (LCAG/329; 2016-2020), and a Collaborative Award in Science and Engineering with the British Geological Survey (LCAG/352)

Geotechnical Properties of Salt Marsh and Tidal Flat Substrates at Tillingham, Essex, UK.

Salt marshes and, to a lesser extent, tidal flats, attenuate incoming hydrodynamic energy, thus reducing flood and erosion risk in the coastal hinterland. However, marshes are declining in aerial extent both globally and regionally (e.g. the Northwest European region). In order to comprehend why a reduction in salt marsh extent due to marsh edge erosion is occurring, we need to understand the resistance of salt marshes to incoming hydrodynamic energy. This resistance depends on marsh biological, geochemical and geotechnical properties. However, there currently exists no systematic study of marsh geotechnical properties and how these may impact both marsh edge and marsh surface erosion processes (e.g. surface removal, cliff undercutting, gravitational slumping). This has led to an oversimplification of marsh evolution models. Here, we present the initial results of a systematic study of salt marsh and tidal flat geotechnical properties (shear strength, plasticity and particle size) at Tillingham marsh, Essex, UK.Department of Geograph

The p.V37I Exclusive Genotype Of GJB2: A Genetic Risk-Indicator of Postnatal Permanent Childhood Hearing Impairment

Postnatal permanent childhood hearing impairment (PCHI) is frequent (0.25%–0.99%) and difficult to detect in the early stage, which may impede the speech, language and cognitive development of affected children. Genetic tests of common variants associated with postnatal PCHI in newborns may provide an efficient way to identify those at risk. In this study, we detected a strong association of the p.V37I exclusive genotype of GJB2 with postnatal PCHI in Chinese Hans (P = 1.4×10−10; OR 62.92, 95% CI 21.27–186.12). This common genotype in Eastern Asians was present in a substantial percentage (20%) of postnatal PCHI subjects, and its prevalence was significantly increased in normal-hearing newborns who failed at least one newborn hearing screen. Our results indicated that the p.V37I exclusive genotype of GJB2 may cause subclinical hearing impairment at birth and increases risk for postnatal PCHI. Genetic testing of GJB2 in East Asian newborns will facilitate prompt detection and intervention of postnatal PCHI

Perceptual Load-Dependent Neural Correlates of Distractor Interference Inhibition

The load theory of selective attention hypothesizes that distractor interference is suppressed after perceptual processing (i.e., in the later stage of central processing) at low perceptual load of the central task, but in the early stage of perceptual processing at high perceptual load. Consistently, studies on the neural correlates of attention have found a smaller distractor-related activation in the sensory cortex at high relative to low perceptual load. However, it is not clear whether the distractor-related activation in brain regions linked to later stages of central processing (e.g., in the frontostriatal circuits) is also smaller at high rather than low perceptual load, as might be predicted based on the load theory.We studied 24 healthy participants using functional magnetic resonance imaging (fMRI) during a visual target identification task with two perceptual loads (low vs. high). Participants showed distractor-related increases in activation in the midbrain, striatum, occipital and medial and lateral prefrontal cortices at low load, but distractor-related decreases in activation in the midbrain ventral tegmental area and substantia nigra (VTA/SN), striatum, thalamus, and extensive sensory cortices at high load.Multiple levels of central processing involving midbrain and frontostriatal circuits participate in suppressing distractor interference at either low or high perceptual load. For suppressing distractor interference, the processing of sensory inputs in both early and late stages of central processing are enhanced at low load but inhibited at high load

Identifying an indoor air exposure limit for formaldehyde considering both irritation and cancer hazards

Formaldehyde is a well-studied chemical and effects from inhalation exposures have been extensively characterized in numerous controlled studies with human volunteers, including asthmatics and other sensitive individuals, which provide a rich database on exposure concentrations that can reliably produce the symptoms of sensory irritation. Although individuals can differ in their sensitivity to odor and eye irritation, the majority of authoritative reviews of the formaldehyde literature have concluded that an air concentration of 0.3 ppm will provide protection from eye irritation for virtually everyone. A weight of evidence-based formaldehyde exposure limit of 0.1 ppm (100 ppb) is recommended as an indoor air level for all individuals for odor detection and sensory irritation. It has recently been suggested by the International Agency for Research on Cancer (IARC), the National Toxicology Program (NTP), and the US Environmental Protection Agency (US EPA) that formaldehyde is causally associated with nasopharyngeal cancer (NPC) and leukemia. This has led US EPA to conclude that irritation is not the most sensitive toxic endpoint and that carcinogenicity should dictate how to establish exposure limits for formaldehyde. In this review, a number of lines of reasoning and substantial scientific evidence are described and discussed, which leads to a conclusion that neither point of contact nor systemic effects of any type, including NPC or leukemia, are causally associated with exposure to formaldehyde. This conclusion supports the view that the equivocal epidemiology studies that suggest otherwise are almost certainly flawed by identified or yet to be unidentified confounding variables. Thus, this assessment concludes that a formaldehyde indoor air limit of 0.1 ppm should protect even particularly susceptible individuals from both irritation effects and any potential cancer hazard

THE COASTAL PROTECTION FUNCTION OF SALT MARSHES: CONSIDERING BIO-PHYSICAL COMPLEXITY

Presentation given at ASLO conference 2015 in Granada, Spain; Session organised by EU-FP7-SPACE FAST project Abstract: Coastal wetlands have provided a source of fascination for ecologists and geomorphologists alike. The study of the interplay between salt marsh vegetation growth, sedimentary processes and dynamic tidal and wave processes has led to a growing recognition of the importance of bio-physical factors determining coastal landform evolution. An increased focus on bio-physical linkages that control coastal wetland functioning can also be seen in the conservation, engineering, and policy sector, due to a rising awareness of the value of coastal wetlands due to the services they provide to society. The role of salt marshes as natural sea defences is increasingly significant in the context of ever increasing coastal population densities alongside environmental pressures (e.g. sea level rise and increasing storm frequencies arising from climate change, alongside ever increasing coastal population densities). This talk reviews how advances in field, laboratory, and numerical modeling approaches have made particular inroads into the quantification of the sea defence role of coastal wetlands. The sea defence function itself is complex and context dependent. There is now a need for improved ecologically-informed engineering solutions towards coastal defence