Microarray evidence for off target effects in tick RNA interference experiments, and the lack of strong correlation between DSRNA and antibody phenotypes in tick In vitro treatments for vaccine candidate screening

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Placing barrier-island transgression in a blue-carbon context

Backbarrier saltmarshes are considered carbon sinks; however, barrier island transgression and the associated processes of erosion and overwash are typically not included in coastal carbon budgets. Here, we present a carbon-budget model for transgressive barrier islands that includes a dynamic carbon-storage term, driven by backbarrier-marsh width, and a carbon-export term, driven by ocean and backbarrier shoreline erosion. To examine the impacts of storms, human disturbances and the backbarrier setting of a transgressive barrier island on carbon budgets and reservoirs, the model was applied to sites at Core Banks and Onslow Beach, NC, USA. Results show that shoreline erosion and burial of backbarrier marsh from washover deposition and dredge-spoil disposal temporarily transitioned each site into a net exporter (source) of carbon. The magnitude of the carbon reservoir was linked to the backbarrier setting of an island. Carbon reservoirs of study sites separated from the mainland by only backbarrier marsh (no lagoon) decreased for over a decade because carbon storage could not keep pace with erosion. With progressive narrowing of the backbarrier marsh, these barriers will begin to function more persistently as carbon sources until the reservoir is depleted at the point where the barrier welds with the mainland. Undeveloped barrier islands with wide lagoons are carbon sources briefly during erosive periods; however, at century time scales are net carbon importers (sinks) because new marsh habitat can form during barrier rollover. Human development on backbarrier saltmarsh serves to reduce the carbon storage capacity and can hasten the transition of an island from a sink to a source

Where do coastlines stabilize following rapid retreat?

We present a numerical model that shows that the transgressing upper shoreline of wave-dominated estuaries (bayhead deltas), which commonly contain populous urban and industrial centers, stabilizes, and their rate of retreat decreases at tributary junctions. The decreased rate of retreat across a tributary junction is caused by a decrease in the total accommodation, while sediment supply remains conserved. Our model predicts that bayhead deltas from smaller systems will be located closer to tributary confluences than their larger counterparts. An examination of the modern bayhead deltas in Albemarle Sound, U.S. Atlantic Coast, reveals that bayhead deltas from smaller tributaries are located closer to tributary confluences than bayhead deltas associated with larger tributaries, supporting our model prediction. Our results highlight the importance of antecedent topography created during falling sea-levels on shaping the nature of transgression during the ensuing sea-level rise. In particular, tributary junctions act as pinning points during transgression. Key Points Bayhead deltas stabilize at tributary junctions during transgression Inherited topography impacts the nature of subsequent transgressions Smaller deltas retreat at slower rates within flooded valley networks

Capacitive wire-mesh sensor measurements in oilwater flow

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.In this paper, a capacitive wire-mesh sensor was applied to investigate viscous-oil in water dispersed flow in a transparent acrylic section of 26-mm-i.d. and 12-m-length. The sensor was used to obtain in-situ volumetric phase fractions (holdup) and phase distributions in the pipe cross-section. Two mixture permittivity models from the literature, Maxwell– Garnett and Power–Law were applied to calculate the oil volumetric phase fractions in order to compare with the phase fraction measured via quick-closing valves technique (QCVs). In these models the relation is modified as function of a variable parameter. This paper presented a new attempt to find a suitable relation for holdup measurements in oil-water dispersed flows.cf201

Bayhead deltas and shorelines: Insights from modern and ancient examples

Bayhead deltas are important components of the rock record as well as modern estuaries, hosting important hydrocarbon reservoirs and many coastal cities, ports and large expanses of wetlands. Despite their significance, few studies have summarized their occurrence and sedimentary characteristics. In this paper we review the stratigraphic, sedimentary, and geomorphic characteristics of 68 modern and ancient bayhead deltas. Bayhead deltas are found in incised valleys, structural basins, fjords, interdistributary bays of larger open-ocean deltas, and other backbarrier environments. Except for within fjords, they generally prograde into shallower and more brackish waters than their open-ocean equivalents. As a result, 80% of modern, 68% of Quaternary, and 67% of ancient bayhead deltas have clinoform thicknesses of 10 m or less with 73% of modern bayhead deltas having clinoform thicknesses of 5 m or less. Additionally, 89% of modern, 81% of Quaternary, and 77% of ancient bayhead deltas examined are fluvial dominated. We distinguish true bayhead deltas from their genetically similar bayhead shorelines, which are not constructional features but sites of enhanced marsh or estuarine sedimentation near river mouths with inadequate rates of sediment delivery to form distributary channels and prograde into the estuary or lagoon. We also distinguish confined bayhead deltas found in incised valleys, structural basins, and fjords from unconfined bayhead deltas found as incipient lobes of larger delta complexes and other back-barrier lagoons. The architecture of confined bayhead deltas is largely influenced by the limited accommodation brought about by the walls of the flooded valleys in which they are located. As such, confined bayhead-delta ontogeny is controlled by many autogenic interactions within these valley walls. Both confined and unconfined bayhead deltas are sensitive to sea-level rise, climate-controlled changes in sediment flux, and tectonics. Their relatively small size, connection with the terrestrial system, and protected nature make them the ideal depositional system to record Earth history including sea-level and climate changes

Evidence of exceptional oyster-reef resilience to fluctuations in sea level

Ecosystems at the land–sea interface are vulnerable to rising sea level. Intertidal habitats must maintain their surface elevations with respect to sea level to persist via vertical growth or landward retreat, but projected rates of sea-level rise may exceed the accretion rates of many biogenic habitats. While considerable attention is focused on climate change over centennial timescales, relative sea level also fluctuates dramatically (10–30 cm) over month-to-year timescales due to interacting oceanic and atmospheric processes. To assess the response of oyster-reef (Crassostrea virginica) growth to interannual variations in mean sea level (MSL) and improve long-term forecasts of reef response to rising seas, we monitored the morphology of constructed and natural intertidal reefs over 5 years using terrestrial lidar. Timing of reef scans created distinct periods of high and low relative water level for decade-old reefs (n = 3) constructed in 1997 and 2000, young reefs (n = 11) constructed in 2011 and one natural reef (approximately 100 years old). Changes in surface elevation were related to MSL trends. Decade-old reefs achieved 2 cm/year growth, which occurred along higher elevations when MSL increased. Young reefs experienced peak growth (6.7 cm/year) at a lower elevation that coincided with a drop in MSL. The natural reef exhibited considerable loss during the low MSL of the first time step but grew substantially during higher MSL through the second time step, with growth peaking (4.3 cm/year) at MSL, reoccupying the elevations previously lost. Oyster reefs appear to be in dynamic equilibrium with short-term (month-to-year) fluctuations in sea level, evidencing notable resilience to future changes to sea level that surpasses other coastal biogenic habitat types. These growth patterns support the presence of a previously defined optimal growth zone that shifts correspondingly with changes in MSL, which can help guide oyster-reef conservation and restoration

Direct connectivity between upstream and downstream promotes rapid response of lower coastal-plain rivers to land-use change

Low-relief fluvial systems that originate in the lower coastal plain and discharge into estuaries are common along passive margins. These watersheds are thought to be disconnected from their termini by floodplains, which buffer the sediment-routing system by sequestration. Here, we present a detailed study of the Newport River, a typical lower coastal-plain system, which reveals high connectivity between watershed and delta. Connectivity is measured as the time lag between initiation of a silviculture operation, which increased landscape erosion, and when the sediment appeared at the bay-head delta. The time lag, measured from aerial photographs and sedimentation rates calculated from 210Pb- and 137Cs-activities in cores from the watershed and delta, is <3 years. Most lower coastal-plain rivers are steeper and have less floodplain accommodation available for storage than their larger counterparts that originate landward of the fall line, which promotes higher connectivity between upstream and downstream

Salt Marsh and Fringing Oyster Reef Transgression in a Shallow Temperate Estuary: Implications for Restoration, Conservation and Blue Carbon

The importance of intertidal estuarine habitats, like salt marsh and oyster reef, has been well established, as has their ubiquitous loss along our coasts with resultant forfeiture of the ecosystem services they provide. Furthering our understanding of how these habitats are evolving in the face of anthropogenic and climate driven changes will help improve management strategies. Previous work has shown that the growth and productivity of both oyster reefs and salt marshes are strongly linked to elevation in the intertidal zone (duration of aerial exposure). We build on that research by examining the growth of marsh-fringing oyster reefs at yearly to decadal time scales and examine movement of the boundary between oyster reef and salt marsh at decadal to centennial time scales. We show that the growth of marsh-fringing reefs is strongly associated to the duration of aerial exposure, with little growth occurring below mean low water and above mean sea level. Marsh-shoreline movement, in the presence or absence of fringing oyster reefs, was reconstructed using transects of sediment cores. Carbonaceous marsh sediments sampled below the modern fringing oyster reefs indicate that marsh shorelines within Back Sound, North Carolina are predominantly in a state of transgression (landward retreat), and modern oyster-reef locations were previously occupied by salt marsh within the past two centuries. Cores fronting transgressive marsh shorelines absent fringing reefs sampled thinner and less extensive carbonaceous marsh sediment than at sites with fringing reefs. This indicates that fringing reefs are preserving carbonaceous marsh sediment from total erosion as they transgress and colonize the exposed marsh shoreline making marsh sediments more resistant to erosion. The amount of marsh sediment preservation underneath the reef scales with the reef’s relief, as reefs with the greatest relief were level with the marsh platform, preserving a maximum amount of carbonaceous sediments during transgression by buffering the marsh from erosional processes. Thus, fringing oyster reefs not only have the capacity to shelter shorelines but, if located at the ideal tidal elevation, they also keep up with accelerating sea-level rise and cap carbonaceous sediments, protecting them from erosion, as reefs develop along the marsh