Species-specific effects of herbivorous fishes on the establishment of the macroalga Lobophora on coral reefs

Herbivory is a key ecosystem function that influences ecosystem trajectories. However, interactions between plants and herbivores are species-specific and change throughout the plants' lifetime. On coral reefs, herbivorous fishes reduce competition between corals and macroalgae through their grazing activity, thereby regulating the ecosystem state. Grazing vulnerability of marine algae generally decreases with increasing algal size. Therefore, the removal of newly settled recruits by herbivorous fish is likely important in preventing macroalgal blooms and reducing competition with corals. We studied the grazing susceptibility of recruits of the brown macroalga Lobophora to multiple fish species through a combination of feeding observations and manipulative in situ and ex situ experiments. Further, we recorded short-term Lobophora growth patterns and adult survival over 9 wk. Lobophora recruits were more susceptible to herbivory than adults, likely owing to their smaller size. However, recruit mortality was driven by only 3 of the studied species: Acanthurus nigrofuscus, Scarus niger and Chlorurus spilurus, whereas other common herbivores did not remove any Lobophora recruits. Our data also suggest variable growth and recruitment among months. These findings point to a possible increase in grazing resistance with age for Lobophora. As such, a decrease in grazing pressure by key fish species controlling Lobophora recruits could permit Lobophora to establish more grazingtolerant adult populations

Towards an Achievable Performance for the Loop Nests

Numerous code optimization techniques, including loop nest optimizations, have been developed over the last four decades. Loop optimization techniques transform loop nests to improve the performance of the code on a target architecture, including exposing parallelism. Finding and evaluating an optimal, semantic-preserving sequence of transformations is a complex problem. The sequence is guided using heuristics and/or analytical models and there is no way of knowing how close it gets to optimal performance or if there is any headroom for improvement. This paper makes two contributions. First, it uses a comparative analysis of loop optimizations/transformations across multiple compilers to determine how much headroom may exist for each compiler. And second, it presents an approach to characterize the loop nests based on their hardware performance counter values and a Machine Learning approach that predicts which compiler will generate the fastest code for a loop nest. The prediction is made for both auto-vectorized, serial compilation and for auto-parallelization. The results show that the headroom for state-of-the-art compilers ranges from 1.10x to 1.42x for the serial code and from 1.30x to 1.71x for the auto-parallelized code. These results are based on the Machine Learning predictions.Comment: Accepted at the 31st International Workshop on Languages and Compilers for Parallel Computing (LCPC 2018

Quantification of uncertainties in fossil leaf aleoaltimetry: does leaf size matter?

The utility of multivariate foliar physiognomy, specifically the Climate Leaf Analysis Multivariate Program (CLAMP), to yield reliable estimates of enthalpy and hence paleoelevation has been demonstrated by comparison with other proxies, yet concerns have arisen regarding uncertainties arising from 1) apparent ambiguities in the scoring regime and 2) the way leaf size is scored. Regarding 1) scoring ambiguities are examined by reporting on scoring tests with novice users and inter-laboratory comparisons. The uncertainties were found to be less than those arising from the statistical methodology underpinning CLAMP. In respect of 2) the effect of removing all size data both from modern test sites and fossil data was tested. Specifically the effect of removing leaf size data from the 15 Ma Namling data set from south central Tibet, was investigated. Removal of all size data from modern sites demonstrated that size data contributes little to estimates of MAT (Mean Annual Temperature) and enthalpy. Similarly the removal of leaf size information from the Namling data set alone, but with calibration unchanged, and from both the Namling site and calibration sites, this time with recalibration, still yield paleoelevation estimates that have been independently matched by oxygen isotope techniques. Moreover the removal of all leaf size information results in only small increases in uncertainty (± 52 m)

The Production of Hospitable Space: Commercial Propositions and Consumer Co-Creation in a Bar Operation

This paper examines the processes through which a commercial bar is transformed into a hospitable space. Drawing on a study of a venue patronized by lesbian, gay, bisexual and transsexual/transgender consumers, it considers how social and commercial forms of hospitality are mobilized. The paper argues that hospitable space has an ideological, normative and situational dimension. More specifically, it suggests the bar’s operation is tied to a set of ideological conceptions, which become the potential basis of association and disassociation among consumers. It examines the forces and processes that shape who participates in the production and consumption of hospitality and how. Finally, it considers the situational, emergent nature of hospitality and the discontinuous production of hospitable space. Rather than focusing exclusively on host-guest or provider-customer relations, which dominates existing work on hospitality, the paper examines how consumers’ perceptions, actions and interactions shape the production of hospitality. By doing so the paper offers an alternative approach to understanding queer spaces, bar operation as well as hospitality

Refining CLAMP - investigations towards improving the Climate Leaf Analysis Multivariate Program

CLAMP (Climate Leaf Analysis Multivariate Program) has been used for the past 17 years to estimate palaeoclimatic conditions. The reliability and applicability of this method, based on leaf physiognomic characters of fossil woody dicots, has been widely discussed over the same period. The present study focuses on some technical aspects of CLAMP, mainly on its robustness in the context of the theoretical unimodal requirements of Canonical Correspondence Analysis, and introduces “correction coefficients” for these aspects of the statistical approach as a new way of interpreting and improving on CLAMP estimates. This tool was tested on datasets derived from 17 European fossil floras ranging in age from the Late Oligocene to the Pliocene. Additionally, an objective statistical method for the selection of the best-suited modern vegetation dataset from 144 site (Physg3br) or 173 (Physg3ar) extant biotopes is proposed

Investigating generalizability of results from a randomized controlled trial of the management of chronic widespread pain : the MUSICIAN study

The MUSICIAN trial was supported by an award from Arthritis Research UK, Chesterfield, UK. Grant number: 17292. Ethical approval for the study was granted by Cheshire NHS Research Ethics Committee; reference number: 07/Q1506/61. All participants provided written consent.Peer reviewedPublisher PD

Autonomous in situ calibration of ion‐sensitive field effect transistor pH sensors

Ion‐sensitive field effect transistor‐based pH sensors have been shown to perform well in high frequency and long‐term ocean sampling regimes. The Honeywell Durafet is widely used due to its stability, fast response, and characterization over a large range of oceanic conditions. However, potentiometric pH monitoring is inherently complicated by the fact that the sensors require careful calibration. Offsets in calibration coefficients have been observed when comparing laboratory to field‐based calibrations and prior work has led to the recommendation that an in situ calibration be performed based on comparison to discrete samples. Here, we describe our work toward a self‐calibration apparatus integrated into a SeapHOx pH, dissolved oxygen, and CTD sensor package. This Self‐Calibrating SeapHOx is capable of autonomously recording calibration values from a high quality, traceable, primary reference standard: equimolar tris buffer. The Self‐Calibrating SeapHOx\u27s functionality was demonstrated in a 6‐d test in a seawater tank at Scripps Institution of Oceanography (La Jolla, California, U.S.A.) and was successfully deployed for 2 weeks on a shallow, coral reef flat (Lizard Island, Australia). During the latter deployment, the tris‐based self‐calibration using 15 on‐board samples exhibited superior reproducibility to the standard spectrophotometric pH‐based calibration using \u3e 100 discrete samples. Standard deviations of calibration pH using tris ranged from 0.002 to 0.005 whereas they ranged from 0.006 to 0.009 for the standard spectrophotometric pH‐based method; the two independent calibration methods resulted in a mean pH difference of 0.008. We anticipate that the Self‐Calibrating SeapHOx will be capable of autonomously providing climate quality pH data, directly linked to a primary seawater pH standard, and with improvements over standard calibration techniques

Unexpected role of communities colonizing dead coral substrate in the calcification of coral reefs

Global and local anthropogenic stressors such as climate change, acidification, overfishing, and pollution are expected to shift the benthic community composition of coral reefs from dominance by calcifying organisms to dominance by non-calcifying algae. These changes could reduce the ability of coral reef ecosystems to maintain positive net calcium carbonate accretion. However, relationships between community composition and calcification rates remain unclear. We performed field experiments to quantify the metabolic rates of the two most dominant coral reef substrate types, live coral and dead coral substrate colonized by a mixed algal assemblage, using a novel underwater respirometer. Our results revealed that calcification rates in the daytime were similar for the live coral and dead coral substrate communities. However, in the dark, while live corals continued to calcify at slower rates, the dead coral substrate communities exhibited carbonate dissolution. Daytime net photosynthesis of the dead coral substrate communities was up to five times as much as for live corals, which we hypothesize may have created favorable conditions for the precipitation of carbonate minerals. We conclude that: (1) calcification from dead coral substrate communities can contribute to coral reef community calcification during the day, and (2) dead coral substrate communities can also contribute to carbonate mineral dissolution at night, decreasing ecosystem calcification over a diel cycle. This provides evidence that reefs could shift from slow, long-term accretion of calcium carbonate to a state where large daily cycling of calcium carbonate occurs, but with little or no long-term accumulation of the carbonate minerals needed to sustain the reef against erosional forces

Assessing North American Forest Disturbance from the Landsat Archive

Forest disturbances are thought to play a major role in controlling land-atmosphere fluxes of carbon. Under the auspices of the North American Carbon Program, the LEDAPS (Landsat Ecosystem Disturbance Adaptive Processing System) and NACP-FIA projects have been analyzing the Landsat satellite record to assess rates of forest disturbance across North America. In the LEDAPS project, wall-to-wall Landsat imagery for the period 1975-2000 has been converted to surface reflectance and analyzed for decadal losses (disturbance) or gains (regrowth) in biomass using a spectral "disturbance index". The NACP-FIA project relies on a geographic sample of dense Landsat image time series, allowing both disturbance rates and recovery trends to be characterized. Preliminary results for the 1990's indicate high rates of harvest within the southeastern US, Eastern Canada, and the Pacific Northwest, with spatially averaged (approx.50x50 km) turnover periods as low as 25-40 years. Lower rates of disturbance are found in the Rockies and Northeastern US