Faunal response to benthic and hyporheic sedimentation varies with direction of vertical hydrological exchange

1. Sedimentation and clogging of benthic and hyporheic zone substrates is increasingly being recognised as one of the greatest threats to the ecological integrity of riverine ecosystems globally. This ex-situ study examined the influence of sedimentation (benthic and hyporheic) and pattern of hydrological exchange on the vertical distribution of the freshwater shrimp Gammarus pulex within the experimental substrates of running water mesocosms. 2. Six sediment treatments representing a continuum from a clean gravel substratum through to heavy sediment loading of both benthic and hyporheic substrates were used to examine the distribution of G. pulex in relation to the direction of hydrological exchange (downwelling, upwelling and no exchange). 3. The vertical distribution of fauna varied significantly for both sediment treatment and pattern of hydrological exchange. There was a significant interaction between the two effects indicating that the effect of sedimentation varied depending on the pattern of vertical hydrological exchange

Early warnings and missed alarms for abrupt monsoon transitions

Journal ArticlePalaeo-records from China demonstrate that the East Asian Summer Monsoon (EASM) is dominated by abrupt and large magnitude monsoon shifts on millennial timescales, switching between periods of high and weak monsoon rains. It has been hypothesized that over these timescales, the EASM exhibits two stable states with bifurcation-Type tipping points between them. Here we test this hypothesis by looking for early warning signals of past bifurcations in speleothem δ18O records from Sanbao Cave and Hulu Cave, China, spanning the penultimate glacial cycle. We find that although there are increases in both autocorrelation and variance preceding some of the monsoon transitions during this period, it is only immediately prior to the abrupt monsoon shift at the penultimate deglaciation (Termination II) that statistically significant increases are detected. To supplement our data analysis, we produce and analyse multiple model simulations that we derive from these data. We find hysteresis behaviour in our model simulations with transitions directly forced by solar insolation. However, signals of critical slowing down, which occur on the approach to a bifurcation, are only detectable in the model simulations when the change in system stability is sufficiently slow to be detected by the sampling resolution of the data set. This raises the possibility that the early warning "alarms" were missed in the speleothem data over the period 224-150 kyr and it was only at the monsoon termination that the change in the system stability was sufficiently slow to detect early warning signals

Living standards and plague in London, 1560–1665

This article uses individual records of 930,000 burials and 630,000 baptisms to reconstruct the spatial and temporal patterns of birth and death in London from 1560 to 1665, a period dominated by recurrent plague. The plagues of 1563, 1603, 1625, and 1665 appear of roughly equal magnitude, with deaths running at five to six times their usual rate, but the impact on wealthier central parishes falls markedly through time. Tracking the weekly spread of plague, we find no evidence that plague emerged first in the docks, and in many cases elevated mortality emerges first in the poor northern suburbs. Looking at the seasonal pattern of mortality, we find that the characteristic autumn spike associated with plague continued into the early 1700s. Natural increase improved as smaller crises disappeared after 1590, but fewer than half of those born survived childhood

30-year record of Himalaya mass-wasting reveals landscape perturbations by extreme events

In mountainous environments, quantifying the drivers of mass-wasting is fundamental for understanding landscape evolution and improving hazard management. Here, we quantify the magnitudes of mass-wasting caused by the Asia Summer Monsoon, extreme rainfall, and earthquakes in the Nepal Himalaya. Using a newly compiled 30-year mass-wasting inventory, we establish empirical relationships between monsoon-triggered mass-wasting and monsoon precipitation, before quantifying how other mass-wasting drivers perturb this relationship. We find that perturbations up to 5 times greater than that expected from the monsoon alone are caused by rainfall events with 5-to-30-year return periods and short-term (< 2 year) earthquake-induced landscape preconditioning. In 2015, the landscape preconditioning is strongly controlled by the topographic signature of the Gorkha earthquake, whereby high Peak Ground Accelerations coincident with high excess topography (rock volume above a landscape threshold angle) amplifies landscape damage. Furthermore, earlier earthquakes in 1934, 1988 and 2011 are not found to influence 2015 mass-wasting

Coseismic and monsoon-triggered landslide impacts on remote trekking infrastructure, Langtang Valley, Nepal

This is the author accepted manuscript. The final version is available from the Geological Society via the DOI in this recordIn 2015, the Mw 7.8 Gorkha earthquake struck Nepal, triggering thousands of landslides across the central and eastern Himalayas. These landslides had many adverse effects, including causing widespread damage to low-grade transport routes (e.g. tracks, footpaths) in rural regions that depend on tourism for survival. Langtang Valley is a glacial–periglacial landscape located 60 km north of Kathmandu. It is one of the most popular trekking regions in Nepal and has been severely affected by Gorkha earthquake-triggered and monsoon-triggered landsliding. Here, qualitative and quantitative observations from fieldwork and remote sensing are used to describe the materials and geomorphology of the landslides across Langtang Valley, and to quantify the extent to which coseismic and monsoon-triggered landslides have affected Langtang's trekking infrastructure. The dominant bedrock materials involved within Langtang landslides are found to be a range of gneisses and intruded leucogranites. In total, 64 landslides are found to have intersected trekking paths across Langtang, with coseismic and monsoon-triggered landslides having an impact on c. 3 km and 0.8 km of path respectively. It is observed that the practice of reconstructing paths through unstable landslide deposits is leaving the trekking infrastructure across Langtang increasingly vulnerable to future failure.University of PlymouthNatural Environment Research Council (NERC)Geological Societ

Defining, conceptualizing and evaluating pragmatic qualities of quantitative instruments measuring implementation determinants and outcomes: a scoping and critical review of the literature and recommendations for future research.

The pragmatic (i.e., practical) quality of quantitative implementation measures has received increased attention in the implementation science literature in recent years. Implementation measures that are judged to be pragmatic by implementation stakeholders are thought to be more likely to be applied in research and practice. Despite the need for pragmatic implementation measures, ambiguity and uncertainty regarding what constitutes a pragmatic measure remains. This study sought to identify and critically appraise the published literature to understand (i) how pragmatism is defined as a measurement construct/quality of implementation determinants and outcome instruments; (ii) how pragmatic qualities of instruments are evaluated; (iii) identify key gaps and limitations of the current evidence-base and (iv) identify recommendations for future research. We conducted a scoping review of the literature also employing methods of critical review. PubMed and PsycINFO databases, using the OVID interface, were searched for relevant articles published between January 2010 and September 2020. Articles that contained a definition and/or described characteristics of "pragmatism" as a measurement construct of quantitative implementation outcomes (as defined by Proctor's Implementation Outcomes taxonomy) and/or implementation determinants were eligible for inclusion. Nine articles met inclusion criteria. A degree of overlap in definitions and terms used to describe the pragmatic qualities of quantitative implementation determinant and outcome instruments were found. The most frequently cited descriptors of pragmatism were "not burdensome", "brief", "reliable", "valid" and "sensitive to change". 3 of the 9 included articles involved international implementation stakeholders in defining and conceptualizing pragmatism and employed specific methods to do so, including a systematic literature review, stakeholder interviews, concept mapping, and a Delphi process. All other articles defined pragmatism, with or without citing relevant literature. One article objectively assessed the pragmatic qualities, above and beyond the psychometric qualities, of implementation measures, using the Psychometric and Pragmatic Evidence Rating Scale (PAPERS). The evidence base within the implementation instrumentation literature on what pragmatism is and how it might be assessed is limited. Some of the research identified in the review provides a strong foundation to build upon, by testing its applicability in other settings (including healthcare areas and countries) and among a more diverse group of stakeholders. We discuss directions for further development of the concept of pragmatism relating to the measurement of implementation determinants and outcomes