Dispersal Dynamics in a Wind-Driven Benthic System

Bedload and water column traps were used with simultaneous wind and water velocity measurements to study postlarval macrofaunal dispersal dynamics in Manukau Harbour, New Zealand. A 12-fold range in mean wind condition resulted in large differences in water flow (12-fold), sediment flux (285-fold), and trap collection of total number of individuals (95-fold), number of the dominant infaunal organism (84-fold for the bivalve Macomona liliana), and number of species (4-fold). There were very strong, positive relationships among wind condition, water velocity, sediment flux, and postlarval dispersal, especially in the bedload. Local density in the ambient sediment was not a good predictor of dispersal. Results indicate that postlarval dispersal may influence benthic abundance pat- terns over a range of spatial scales

Experimenting with ecosystem interaction networks in search of threshold potentials in real-world marine ecosystems

Thresholds profoundly affect our understanding and management of ecosystem dynamics, but we have yet to develop practical techniques to assess the risk that thresholds will be crossed. Combining ecological knowledge of critical system interdependencies with a large-scale experiment, we tested for breaks in the ecosystem interaction network to identify threshold potential in real-world ecosystem dynamics. Our experiment with the bivalves Macomona liliana and Austrovenus stutchburyi on marine sandflats in New Zealand demonstrated that reductions in incident sunlight changed the interaction network between sediment biogeochemical fluxes, productivity, and macrofauna. By demonstrating loss of positive feedbacks and changes in the architecture of the network, we provide mechanistic evidence that stressors lead to break points in dynamics, which theory predicts predispose a system to a critical transition

The iBRA (implant breast reconstruction evaluation) study: protocol for a prospective multi-centre cohort study to inform the feasibility, design and conduct of a pragmatic randomised clinical trial comparing new techniques of implant-based breast reconstruction.

BACKGROUND: Implant-based breast reconstruction (IBBR) is the most commonly performed reconstructive procedure in the UK. The introduction of techniques to augment the subpectoral pocket has revolutionised the procedure, but there is a lack of high-quality outcome data to describe the safety or effectiveness of these techniques. Randomised controlled trials (RCTs) are the best way of comparing treatments, but surgical RCTs are challenging. The iBRA (implant breast reconstruction evaluation) study aims to determine the feasibility, design and conduct of a pragmatic RCT to examine the effectiveness of approaches to IBBR. METHODS/DESIGN: The iBRA study is a trainee-led research collaborative project with four phases:Phase 1 - a national practice questionnaire (NPQ) to survey current practicePhase 2 - a multi-centre prospective cohort study of patients undergoing IBBR to evaluate the clinical and patient-reported outcomesPhase 3- an IBBR-RCT acceptability survey and qualitative work to explore patients' and surgeons' views of proposed trial designs and candidate outcomes.Phase 4 - phases 1 to 3 will inform the design and conduct of the future RCT All centres offering IBBR will be encouraged to participate by the breast and plastic surgical professional associations (Association of Breast Surgery and British Association of Plastic Reconstructive and Aesthetic Surgeons). Data collected will inform the feasibility of undertaking an RCT by defining current practice and exploring issues surrounding recruitment, selection of comparator arms, choice of primary outcome, sample size, selection criteria, trial conduct, methods of data collection and feasibility of using the trainee collaborative model to recruit patients and collect data. DISCUSSION: The preliminary work undertaken within the iBRA study will determine the feasibility, design and conduct of a definitive RCT in IBBR. It will work with the trainee collaborative to build capacity by creating an infrastructure of research-active breast and plastic surgeons which will facilitate future high-quality research that will ultimately improve outcomes for all women seeking reconstructive surgery. TRIAL REGISTRATION: ISRCTN37664281

Organism-sediment interactions govern post-hypoxia recovery of ecosystem functioning

Hypoxia represents one of the major causes of biodiversity and ecosystem functioning loss for coastal waters. Since eutrophication-induced hypoxic events are becoming increasingly frequent and intense, understanding the response of ecosystems to hypoxia is of primary importance to understand and predict the stability of ecosystem functioning. Such ecological stability may greatly depend on the recovery patterns of communities and the return time of the system properties associated to these patterns. Here, we have examined how the reassembly of a benthic community contributed to the recovery of ecosystem functioning following experimentally-induced hypoxia in a tidal flat. We demonstrate that organism-sediment interactions that depend on organism size and relate to mobility traits and sediment reworking capacities are generally more important than recovering species richness to set the return time of the measured sediment processes and properties. Specifically, increasing macrofauna bioturbation potential during community reassembly significantly contributed to the recovery of sediment processes and properties such as denitrification, bedload sediment transport, primary production and deep pore water ammonium concentration. Such bioturbation potential was due to the replacement of the small-sized organisms that recolonised at early stages by large-sized bioturbating organisms, which had a disproportionately stronger influence on sediment. This study suggests that the complete recovery of organism-sediment interactions is a necessary condition for ecosystem functioning recovery, and that such process requires long periods after disturbance due to the slow growth of juveniles into adult stages involved in these interactions. Consequently, repeated episodes of disturbance at intervals smaller than the time needed for the system to fully recover organism-sediment interactions may greatly impair the resilience of ecosystem functioning.

The impact of trench defects in InGaN/GaN light emitting diodes and implications for the "green gap" problem

The impact of trench defects in blue InGaN/GaN light emitting diodes (LEDs) has been investigated. Two mechanisms responsible for the structural degradation of the multiple quantum well (MQW) active region were identified. It was found that during the growth of the p-type GaN capping layer, loss of part of the active region enclosed within a trench defect occurred, affecting the top-most QWs in the MQW stack. Indium platelets and voids were also found to form preferentially at the bottom of the MQW stack. The presence of high densities of trench defects in the LEDs was found to relate to a significant reduction in photoluminescence and electroluminescence emission efficiency, for a range of excitation power densities and drive currents. This reduction in emission efficiency was attributed to an increase in the density of non-radiative recombination centres within the MQW stack, believed to be associated with the stacking mismatch boundaries which form part of the sub-surface structure of the trench defects. Investigation of the surface of green-emitting QW structures found a two decade increase in the density of trench defects, compared to its blue-emitting counterpart, suggesting that the efficiency of green-emitting LEDs may be strongly affected by the presence of these defects. Our results are therefore consistent with a model that the “green gap” problem might relate to localized strain relaxation occurring through defects.This is the accepted manuscript version. The final version is available from AIP at http://scitation.aip.org/content/aip/journal/apl/105/11/10.1063/1.4896279?showFTTab=true&containerItemId=content/aip/journal/apl

Effects of Polyester Microfibers on Microphytobenthos and Sediment-Dwelling Infauna

Microfibers often dominate sediment microplastic samples, but little is known about their ecological effects on benthic organisms and functions. Polyethylene terephthalate) (PET) microfibers were added to 36 sediment chambers at six concentrations (0-0.5 g kg-1 sediment) to assess the effects on microphytobenthos (MPB), a key deposit-feeding bivalve, Macomona liliana, and sediment nutrient pools. MPB photosynthesis was promoted in 18 chambers through a 12 h light/dark cycle. Another 18 chambers were maintained under dark conditions to inhibit photosynthesis. After 35 days of MPB growth and stabilization, four M. liliana were added to each chamber for a further 40 days. MPB biomass and composition were examined alongside M. liliana biochemical and behavioral properties and porewater dissolved inorganic nutrient concentrations. Increasing microfibers resulted in lower MPB biomass, fewer diatom-associated fatty acids (FAs), and an increase in cyanobacteria. The changes in MPB coincided with up to 75% lower energy reserves and reduced burrowing activity in M. liliana. In the light, nitrate + nitrate (NOx) was significantly elevated and related to M. liliana and MPB biochemical properties. Ammoniu (NH4+) concentrations increased but were variable in both the light and the dark. Our results suggest that increasing microfiber concentrations influence the interactions between M. liliana and MPB and affect biogeochemical processing in coastal marine sediments

Tipping Points in Coastal Ecosystems

Change can happen fast in our coastal ecosystems and we often do not know what has been lost until it’s too late. Once ecological ‘tipping points’ are passed, it is difficult to reverse the state of the ecosystem.1 Often these changes creep up on us because they are caused by the cumulative impact of multiple stressors. These changes in ecosystems mean we can lose important ecosystem functions that underpin many of the things we value about out coastal ecosystems. One of the key challenges of ecosystem-based management (EBM) is therefore to identify what combination of stressors are likely to cause threshold changes and what parts of the ecosystem are most likely to be affected. A multi-institutional team of scientists from across New Zealand is conducting the science to assess the risk of passing these ‘tipping points’ in estuaries before they happen

An international effort towards developing standards for best practices in analysis, interpretation and reporting of clinical genome sequencing results in the CLARITY Challenge

BACKGROUND: There is tremendous potential for genome sequencing to improve clinical diagnosis and care once it becomes routinely accessible, but this will require formalizing research methods into clinical best practices in the areas of sequence data generation, analysis, interpretation and reporting. The CLARITY Challenge was designed to spur convergence in methods for diagnosing genetic disease starting from clinical case history and genome sequencing data. DNA samples were obtained from three families with heritable genetic disorders and genomic sequence data was donated by sequencing platform vendors. The challenge was to analyze and interpret these data with the goals of identifying disease causing variants and reporting the findings in a clinically useful format. Participating contestant groups were solicited broadly, and an independent panel of judges evaluated their performance. RESULTS: A total of 30 international groups were engaged. The entries reveal a general convergence of practices on most elements of the analysis and interpretation process. However, even given this commonality of approach, only two groups identified the consensus candidate variants in all disease cases, demonstrating a need for consistent fine-tuning of the generally accepted methods. There was greater diversity of the final clinical report content and in the patient consenting process, demonstrating that these areas require additional exploration and standardization. CONCLUSIONS: The CLARITY Challenge provides a comprehensive assessment of current practices for using genome sequencing to diagnose and report genetic diseases. There is remarkable convergence in bioinformatic techniques, but medical interpretation and reporting are areas that require further development by many groups

Impacts of a novel shellfishing gear on macrobenthos in a marine protected area: pump-scoop dredging in Poole Harbour, UK

Understanding the impact of bottom-fishing gears at various scales and intensities on habitats and species is necessary to inform management. In Poole Harbour, UK, a multiple use marine protected area, fishermen utilise a unique “pump-scoop” dredge to harvest the introduced Manila clam Ruditapes philippinarum. Managers need to balance the socio-economic benefits of the fishery with ecological concerns across the region, which has required a revision of by-laws that include both spatial and temporal measures. Within an operational fishery, we used a Before-After-Control-Impact sampling design to assess the impacts of pump-scoop dredging on benthic physical characteristics and community structure in an area where there was no dredging, an area newly opened to dredging and an area subject to high levels of historic dredging. A sampling grid was used in each area to best capture any fishing effort in the newly opened area. Core samples were taken to a depth of 30 cm within intertidal mudflats. A significant loss of fine sediments was observed in the site subject to high intensity dredging and a significant change in community structure also occurred in both dredged sites throughout the study period. In the newly opened site this was characterised by a relative increase in species richness, including increased abundance of annelid worms, notably Hediste diversicolor and Aphelochaeta marioni and a decline in the abundance of the bivalve mollusc Abra tenuis. These changes, albeit relatively small, are attributed to physical disturbance as a direct result of pump-scoop dredging, although no difference in the classification of the biotope of the site was observed. This is of particular interest to managers monitoring site condition within areas under the new bylaws as the Manila clam is spreading to other protected estuaries in the region

Nicaragua Block Press

Friends In Action International (FIA), our project partner, is assisting the Rama people of Nicaragua in relocating from an overpopulated island to the mainland. Our team has developed a manual press for the Rama people to produce compressed earth blocks from local materials for construction of their homes. After testing an initial prototype of the press in Nicaragua it was determined that the press needed more durability. After testing two presses with welded chambers manufactured by E&E Metal Fab Inc., further modifications were required such as welding chamber skirts, adding a lid handle, and applying rust prevention coating. Once both presses reached a workable state, the team made blocks using different mixtures to determine the composition for the highest strength. Blocks were tested for water absorption and for strength in compression, and met published standards for compressed earth blocks (CEB). The team also developed a user manual complete with manufacturing instructions, operating procedures, maintenance suggestions, and exploded subassembly views. Lastly, our team has drafted a one-page user guide for quick reference on-site and will deliver everything to FIA at the end of the semester.https://mosaic.messiah.edu/engr2020/1002/thumbnail.jp