Impacts of signal crayfish on stream fishes

Invasive species cause biodiversity and economic loss globally. Invasive crayfish have a wide range of effects as a result of their high densities and biomass, feeding at multiple trophic levels, aggressive competition for shelter and ecosystem engineering. In Britain, the invasive signal crayfish Pacifastacus leniusculus has displaced the native white-clawed crayfish Austropotamobius pallipes from much of its former range and occupied previously crayfishfree habitats. Signal crayfish could affect fish populations by preying upon eggs, juvenile and adult fish and competing for food and shelter. This thesis assesses the extent to which signal crayfish can affect densities of the commercially important brown trout Salmo trutta, and a species of benthic fish of conservation concern, the European bullhead Cottus gobio, in upland streams. This thesis also investigates the extent to which signal crayfish predation could affect salmonid egg survival through a combination of controlled field and laboratory experiments. Electric fishing was used to estimate fish densities from tributaries of the upper River Tees, north east England. Model selection was then used to determine which factors most affected bullhead and 0+ (less than one year old) brown trout densities. Signal crayfish density was negatively related to both bullhead density and the density of 0+ brown trout. Substrate composition and flow variables and were also selected as predictors of 0+ brown trout and bullhead densities. Small (10-16.2 mm carapace length (CL)) crayfish and fine material apparently reduced buried sea trout S. trutta egg survival in controlled field experiments. However, in laboratory studies, only larger crayfish were found to significantly reduce the survival of salmon S. salar eggs, and this reduction only affected eggs on the surface of the gravel and not buried eggs. These results suggest that signal crayfish pose a threat to both salmonid and bullhead populations, and that, where possible, the sites chosen for reintroduction or habitat enhancement for salmonids and sculpins should be free of invasive crayfish. Evidence for signal crayfish predation upon buried salmonid eggs remains equivocal, although this study provides definite evidence that large signal crayfish will prey upon exposed Atlantic salmon eggs. Both egg predation, and other mechanisms by which signal crayfish may affect salmonid and bullhead populations, are worthy of further investigation. Structural equation models should be used to further investigate relationships between the densities of a range of fish and crayfish species

Long‐term research reveals multiple relationships between the abundance and impacts of a non‐native species

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147876/1/lno11029.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147876/2/lno11029_am.pd

Dissolved organic carbon uptake in streams: A review and assessment of reach‐scale measurements

Quantifying the role that freshwater ecosystems play in the global carbon cycle requires accurate measurement and scaling of dissolved organic carbon (DOC) removal in river networks. We reviewed reach‐scale measurements of DOC uptake from experimental additions of simple organic compounds or leachates to inform development of aquatic DOC models that operate at the river network, regional, or continental scale. Median DOC uptake velocity (vf) across all measurements was 2.28 mm min−1. Measurements using simple compound additions resulted in faster vf (2.94 mm min−1) than additions of leachates (1.11 mm min−1). We also reviewed published data of DOC bioavailability for ambient stream water and leaf leachate DOC from laboratory experiments. We used these data to calculate and apply a correction factor to leaf leachate uptake velocity to estimate ambient stream water DOC uptake rates at the reach scale. Using this approach, we estimated a median ambient stream DOC vf of 0.26 mm min−1. Applying these DOC vf values (0.26, 1.11, 2.28, and 2.94 mm min−1) in a river network inverse model in seven watersheds revealed that our estimated ambient DOC vf value is plausible at the network scale and 27 to 45% of DOC input was removed. Applying the median measured simple compound or leachate vf in whole river networks would require unjustifiably high terrestrial DOC inputs to match observed DOC concentrations at the basin mouth. To improve the understanding and importance of DOC uptake in fluvial systems, we recommend using a multiscale approach coupling laboratory assays, with reach‐scale measurements, and modeling

BODIPY-based conjugated polymers for broadband light sensing and harvesting applications

The synthesis of novel low band-gap polymers has significantly improved light sensing and harvesting in polymer-fullerene devices. Here the synthesis of two low band-gap polymers based on the 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene core (BODIPY), and either bis(3,4-ethylenedioxythiophene) (bis-EDOT) or its all-sulfur analogue bis(3,4-ethylenedithiathiophene) (bis-EDTT) are described. The polymers demonstrate ambipolar charge transport and are shown to be suitable for broadband light sensing and solar energy harvesting in solution-processable polymer-fullerene devices

Scottish Labour Market Trends [June 2017]

Despite apparently very little growth in the overall economy, Scotland’s labour market continues to hold up remarkably well. Over the year to the 3-months January to March 2017, unemployment in Scotland fell 48,000 whilst employment levels rose 41,000. The current rates of employment and unemployment are close to the best on record. Indeed, since 1992 – when the labour force survey was first published – only in the early summer of 2008 has Scotland’s unemployment rate been lower than the current rate of 4.4% Levels of underemployment – that is people in work but who would prefer to work longer hours – have also fallen back towards pre-recession levels. Scotland’s youth unemployment rate continues to outperform all other parts of the UK and compares favourably internationally. However, as we highlighted in our last report, the headline figures do hide some challenges. Firstly, the type of employment being created appears to be less secure in many instances. For example, since the financial crisis there has been a rise in part-time employment (up around 9% since 2007). Within the part-time figures, there has been a 60% increase in the number of people who say the reason they are working part-time is that they cannot find a full-time job. Self-employment has also risen – up around 25% since 2007. Indeed, nearly ¾ of the growth in Scottish employment over the last year was in the form of self-employment. Secondly, there has been a further rise in economic inactivity – that is people not actively seeking work – of 15,000 over the last year. Thirdly, the general news on the Scottish economy remains disappointing. With little or no growth in output, but rising levels of employment, productivity takes the hit. In 2016, productivity as measured by output per hour worked in Scotland fell 1.5%. Weak productivity levels will make it difficult for businesses to find new resources to support sustained wage increases. With inflation now at 2.6% and forecast to go higher over the next few months, the prospects for household incomes continues to look weak. This issue includes an analysis of trade union membership in Scotland and the UK in 2016, by Patricia Findlay and Stuart McIntyre

CIPD Good Work Index 2021 : UK Working Lives Survey

The CIPD Good Work Index is an annual benchmark of good work or job quality in the UK. It measures a wide range of aspects of job quality, including employment essentials, such as pay and contracts, the day-to-day realities of work as experienced by workers themselves, and the impacts on people’s health and wellbeing. This survey report is based on the fourth annual UK Working Lives survey, which draws on a representative sample of UK workers. The CIPD Good Work Index measures a wide range of aspects of job quality, including employment essentials, such as pay and contracts, the day-to-day realities of work as experienced by workers themselves, and the impacts on people’s health and wellbeing. This year’s survey was conducted nearly 12 months on from the start of the COVID-19 pandemic and gives a snapshot of the experiences of workers during this time. Since the last full annual survey, the global economy has experienced its greatest shock in over a generation. Alongside a major contraction in economic activity, the COVID-19 crisis has ushered in an unprecedented policy response. Cumulatively, the UK Government’s furlough scheme – the Coronavirus Job Retention Scheme (CJRS) – has supported over 11 million jobs since its launch in March 2020. This survey offers important insights into workers’ experiences during this crisis – including those on furlough and those working from home. The report also examines the extent to which the experiences of those deemed to be key workers during this crisis has differed from that of the general workforce

Factors affecting ammonium uptake in streams - an inter-biome perspective

The Lotic Intersite Nitrogen experiment (LINX) was a coordinated study of the relationships between North American biomes and factors governing ammonium uptake in streams. Our objective was to relate inter-biome variability of ammonium uptake to physical, chemical and biological processes. 2. Data were collected from 11 streams ranging from arctic to tropical and from desert to rainforest. Measurements at each site included physical, hydraulic and chemical characteristics, biological parameters, whole-stream metabolism and ammonium uptake. Ammonium uptake was measured by injection of \u275~-ammonium and downstream measurements of 15N-ammonium concentration. 3. We found no general, statistically significant relationships that explained the variability in ammonium uptake among sites. However, this approach does not account for the multiple mechanisms of ammonium uptake in streams. When we estimated biological demand for inorganic nitrogen based on our measurements of in-stream metabolism, we found good correspondence between calculated nitrogen demand and measured assimilative nitrogen uptake. 4. Nitrogen uptake varied little among sites, reflecting metabolic compensation in streams in a variety of distinctly different biomes (autotrophic production is high where allochthonous inputs are relatively low and vice versa). 5. Both autotrophic and heterotrophic metabolism require nitrogen and these biotic processes dominate inorganic nitrogen retention in streams. Factors that affect the relative balance of autotrophic and heterotrophic metabolism indirectly control inorganic nitrogen uptake

Nitrate removal in stream ecosystems measured by 15N addition experiments: Denitrification

We measured denitrification rates using a field 15NO3− tracer-addition approach in a large, cross-site study of nitrate uptake in reference, agricultural, and suburban-urban streams. We measured denitrification rates in 49 of 72 streams studied. Uptake length due to denitrification (SWdenn) ranged from 89 m to 184 km (median of 9050 m) and there were no significant differences among regions or land-use categories, likely because of the wide range of conditions within each region and land use. N2 production rates far exceeded N2O production rates in all streams. The fraction of total NO3− removal from water due to denitrification ranged from 0.5% to 100% among streams (median of 16%), and was related to NH4+ concentration and ecosystem respiration rate (ER). Multivariate approaches showed that the most important factors controlling SWden were specific discharge (discharge / width) and NO3− concentration (positive effects), and ER and transient storage zones (negative effects). The relationship between areal denitrification rate (Uden) and NO3− concentration indicated a partial saturation effect. A power function with an exponent of 0.5 described this relationship better than a Michaelis-Menten equation. Although Uden increased with increasing NO3− concentration, the efficiency of NO3− removal from water via denitrification declined, resulting in a smaller proportion of streamwater NO3− load removed over a given length of stream. Regional differences in stream denitrification rates were small relative to the proximate factors of NO3− concentration and ecosystem respiration rate, and land use was an important but indirect control on denitrification in streams, primarily via its effect on NO3− concentration

Hantavirus infection in type I interferon receptor-deficient (A129) mice.

Type I interferon receptor knockout mice (strain A129) were assessed as a disease model of hantavirus infection. A range of infection routes (intramuscular, intraperitoneal and intranasal) were assessed using minimally passaged Seoul virus (strain Humber). Dissemination of virus to the spleen, kidney and lung was observed at 5 days after intramuscular and intraperitoneal challenge, which was resolved by day 14. In contrast, intranasal challenge of A129 mice demonstrated virus tropism to the lung, which was maintained to day 14 post-challenge. These data support the use of the A129 mouse model for future infection studies and the in vivo evaluation of interventions