Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
164
result(s) for
"University of Reading"
Sort by:
Prey and predator density‐dependent interactions under different water volumes
Predation is a critical ecological process that directly and indirectly mediates population stabilities, as well as ecosystem structure and function. The strength of interactions between predators and prey may be mediated by multiple density dependencies concerning numbers of predators and prey. In temporary wetland ecosystems in particular, fluctuating water volumes may alter predation rates through differing search space and prey encounter rates. Using a functional response approach, we examined the influence of predator and prey densities on interaction strengths of the temporary pond specialist copepod Lovenula raynerae preying on cladoceran prey, Daphnia pulex, under contrasting water volumes. Further, using a population dynamic mode-ling approach, we quantified multiple predator effects across differences in prey den-sity and water volume. Predators exhibited type II functional responses under both water volumes, with significant antagonistic multiple predator effects (i.e., antagonisms) exhibited overall. The strengths of antagonistic interactions were, however, enhanced under reduced water volumes and at intermediate prey densities. These findings indicate important biotic and abiotic contexts that mediate predator– prey dynamics, whereby multiple predator effects are contingent on both prey density and search area characteristics. In particular, reduced search areas (i.e., water volumes) under intermediate prey densities could enhance antagonisms by heightening predator– predator interference effects.
Journal Article
Connecting hydrological modelling and forecasting from global to local scales: Perspectives from an international joint virtual workshop
The unprecedented progress in ensemble hydro-meteorological modelling andforecasting on a range of temporal and spatial scales, raises a variety of newchallenges which formed the theme of the Joint Virtual Workshop, ‘Connecting global to local hydrological modelling and forecasting: challenges andscientific advances’. Held from 29 June to 1 July 2021, this workshop was coorganised by the European Centre for Medium-Range Weather Forecasts(ECMWF), the Copernicus Emergency Management (CEMS) and ClimateChange (C3S) Services, the Hydrological Ensemble Prediction EXperiment(HEPEX), and the Global Flood Partnership (GFP). This article aims to summarise the state-of-the-art presented at the workshop and provide an earlycareer perspective. Recent advances in hydrological modelling and forecasting,reflections on the use of forecasts for decision-making across scales, and meansto minimise new barriers to communication in the virtual format are also discussed. Thematic foci of the workshop included hydrological model development and skill assessment, uncertainty communication, forecasts for earlyaction, co-production of services and incorporation of local knowledge, Earthobservation, and data assimilation. Connecting hydrological services to societalneeds and local decision-making through effective communication, capacitybuilding and co-production was identified as critical. Multidisciplinary collaborations emerged as crucial to effectively bring newly developed tools topractice
Journal Article
Plant chemistry and aphid parasitoids (Hymenoptera: Braconidae): Imprinting and memory
Emerging parasitoids of aphids encounter secondary plant chemistry from cues left by the mother parasitoid at oviposition and from the plant-feeding of the host aphid. In practice, however, it is secondary plant chemistry on the surface of the aphid mummy which influences parasitoid olfactory behaviour. Offspring of Aphidius colemani reared on Myzus persicae on artificial diet did not distinguish between the odours of bean and cabbage, but showed a clear preference for cabbage odour if sinigrin had been painted on the back of the mummy. Similarly Aphidius rhopalosiphi reared on Metopolophium dirhodum on wheat preferred the odour of wheat plants grown near tomato plants to odour of wheat alone if the wheat plants on which they had been reared had been exposed to the volatiles of nearby tomato plants. Aphidius rhopalosiphi reared on M. dirhodum, and removed from the mummy before emergence, showed a preference for the odour of a different wheat cultivar if they had contacted a mummy from that cultivar, and similar results were obtained with A. colemani naturally emerged from M. persicae mummies. Aphidius colemani emerged from mummies on one crucifer were allowed to contact in sequence (for 45 min each) mummies from two different crucifers. The number of attacks made in 10 min on M. persicae was always significantly higher when aphids were feeding on the same plant as the origin of the last mummy offered, or on the second plant if aphids feeding on the third plant were not included. Chilling emerged A. colemani for 24 h at 5 deg C appeared to erase the imprint of secondary plant chemistry, and they no longer showed host plant odour preferences in the olfactometer. When the parasitoids were chilled after three successive mummy experiences, memory of the last experience appeared at least temporarily erased and preference was then shown for the chemistry of the second experience.
Journal Article
Regional phytoplankton responses to upwelling in the Arabian Gulf and northwestern Arabian Sea adjacent to the Omani coast
Phytoplankton productivity in the Arabian Gulf is strongly influenced by regional oceanographic processes, yet the specific role of upwelling remains unclear. This study addresses this gap by analyzing seasonal and lagged correlations between Chlorophyll-a (Chl-a) concentrations and Vertical velocity (Wt) during the summer monsoon period (June–September 2018). The results show that in the Iranian regions (I & II), a slight delay in phytoplankton response to upwelling was observed in early summer, with the highest correlation at lag 1 in June (r = 0.80). In contrast, Region III, located in the northwestern Arabian Sea adjacent to the Omani coast, exhibited an immediate response throughout the season, with peak correlations at lag 0 (r = 0.72 in June and 0.67 in July). Stratification and horizontal currents played distinct roles in modulating Chl-a distributions: in Iran, stratification was positively correlated with Chl-a throughout the season (r = 0.37–0.42), while currents showed a consistently negative correlation (r = -0.57 to -0.40). In region III, stratification was negatively correlated with Chl-a in June (r = -0.54), becoming positive in later months (up to r = 0.39), and currents were positively correlated throughout (r = 0.15–0.42). These regional contrasts emphasize the importance of local oceanographic context, with upwelling, stratification, and horizontal transport exerting distinct controls on phytoplankton dynamics in the Arabian Gulf and northwestern Arabian Sea.
Journal Article
A real-time feedback system stabilises the regulation of worker reproduction under various colony sizes
Social insects demonstrate adaptive behaviour for a given colony size. Remarkably, most species do this even without visual information in a dark environment. However, how they achieve this is yet unknown. Based on individual trait expression, an agent-based simulation was used to identify an explicit mechanism for understanding colony size dependent behaviour. Through repeated physical contact between the queen and individual workers, individual colony members monitor the physiological states of others, reflecting such contact information in their physiology and behaviour. Feedback between the sensing of physiological states and the corresponding behaviour patterns leads to self-organisation with colonies shifting according to their size. We showed (1) the queen can exhibit adaptive behaviour patterns for the increase in colony size while density per space remains unchanged, and (2) such physical constraints can underlie the adaptive switching of colony stages from successful patrol behaviour to unsuccessful patrol behaviour, which leads to constant ovary development (production of reproductive castes). The feedback loops embedded in the queen between the perception of internal states of the workers and behavioural patterns can explain the adaptive behaviour as a function of colony size.
Journal Article
Impact of Flavonols on Cardiometabolic Biomarkers: A Meta‐Analysis of Randomized Controlled Human Trials to Explore the Role of Inter‐Individual Variability
Several epidemiological studies have linked flavonols with decreased risk of cardiovascular disease (CVD). However, some heterogeneity in the individual physiological responses to the consumption of these compounds has been identified. This meta‐analysis aimed to study the effect of flavonol supplementation on biomarkers of CVD risk such as, blood lipids, blood pressure and plasma glucose, as well as factors affecting their inter‐individual variability. Data from 18 human randomized controlled trials were pooled and the effect was estimated using fixed or random effects meta‐analysis model and reported as difference in means (DM). Variability in the response of blood lipids to supplementation with flavonols was assessed by stratifying various population subgroups: age, sex, country, and health status. Results showed significant reductions in total cholesterol (DM = −0.10 mmol/L; 95% CI: −0.20, −0.01), LDL cholesterol (DM = −0.14 mmol/L; Nutrients 2017, 9, 117 2 of 21 95% CI: −0.21, 0.07), and triacylglycerol (DM = −0.10 mmol/L; 95% CI: −0.18, 0.03), and a significant increase in HDL cholesterol (DM = 0.05 mmol/L; 95% CI: 0.02, 0.07). A significant reduction was also observed in fasting plasma glucose (DM = −0.18 mmol/L; 95%CI: −0.29, −0.08), and in blood pressure (SBP: DM = −4.84 mmHg; 95% CI: −5.64, −4.04; DBP: DM = −3.32 mmHg; 95% CI: -4.09, -2.55). Subgroup analysis showed a more pronounced effect of flavonol intake in participants from Asian countries and in participants with diagnosed disease or dyslipidemia, compared to healthy and normal baseline values. In conclusion, flavonol consumption improved biomarkers of CVD risk, however, country of origin and health status may influence the effect of flavonol intake on blood lipid levels
Journal Article
Challenges of operational river forecasting
Skillful and timely streamflow forecasts are critically important to water managers and emergency protection services. To provide these forecasts, hydrologists must predict the behavior of complex coupled human-natural systems using incomplete and uncertain information and imperfect models. Moreover, operational predictions often integrate anecdotal information and unmodeled factors. Forecasting agencies face four key challenges: 1) making the most of available data, 2) making accurate predictions using models, 3) turning hydrometeorological forecasts into effective warnings, and 4) administering an operational service. Each challenge presents a variety of research opportunities, including the development of automated quality-control algorithms for the myriad of data used in operational streamflow forecasts, data assimilation, and ensemble forecasting techniques that allow for forecaster input, methods for using human-generated weather forecasts quantitatively, and quantification of human interference in the hydrologic cycle. Furthermore, much can be done to improve the communication of probabilistic forecasts and to design a forecasting paradigm that effectively combines increasingly sophisticated forecasting technology with subjective forecaster expertise. These areas are described in detail to share a real-world perspective and focus for ongoing research endeavors.
Journal Article
The Iso2k database: a global compilation of paleo-δ18O and δ2H records to aid understanding of Common Era climate
Reconstructions of global hydroclimate during the Common Era (CE; the past ∼2000 years) are important for providing context for current and future global environmental change. Stable isotope ratios in water are quantitative indicators of hydroclimate on regional to global scales, and these signals are encoded in a wide range of natural geologic archives. Here we present the Iso2k database, a global compilation of previously published datasets from a variety of natural archives that record the stable oxygen (δ18O) or hydrogen (δ2H) isotopic compositions of environmental waters, which reflect hydroclimate changes over the CE. The Iso2k database contains 759 isotope records from the terrestrial and marine realms, including glacier and ground ice (210); speleothems (68); corals, sclerosponges, and mollusks (143); wood (81); lake sediments and other terrestrial sediments (e.g., loess) (158); and marine sediments (99). Individual datasets have temporal resolutions ranging from sub-annual to centennial and include chronological data where available. A fundamental feature of the database is its comprehensive metadata, which will assist both experts and nonexperts in the interpretation of each record and in data synthesis. Key metadata fields have standardized vocabularies to facilitate comparisons across diverse archives and with climate-model-simulated fields. This is the first global-scale collection of water isotope proxy records from multiple types of geological and biological archives. It is suitable for evaluating hydroclimate processes through time and space using large-scale synthesis, model–data intercomparison and (paleo)data assimilation. The Iso2k database is available for download at 10.25921/57j8-vs18 (Konecky and McKay, 2020) and is also accessible via the NOAA/WDS Paleo Data landing page: https://www.ncdc.noaa.gov/paleo/study/29593 (last access: 30 July 2020).
Journal Article