Predation effects upon the behaviour and ecology of Scottish Gasterosteus aculeatus L. populations

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The epidemiology and population ecology of Argulus spp. : Infections in UK stillwater trout fisheries

Argulus spp. are branchiuran crustaceans, the majority of which are ectoparasites of fish. In the UK three freshwater species have been recorded: A. foliaceus, A. japonicus and A. coregoni. Argulus spp. have been reported to cause mortality in stillwater trout fisheries, but little data is currently available as to the problems they cause or ways to control them. This study was carried out within the broad aims of the sponsors, which were as follows: a) To review of the current perception of the extent and severity of Argulus spp. infections in UK Stillwater trout fisheries, and identification of the methods currently employed for controlling these infections. b) To review and increase the knowledge of the biology and ecology of Arglilus spp. in relation to these systems. c) To assess the prospects for novel control and management strategies to reduce economic loss. A cross-sectional, questionnaire-based study of 69 randomly selected stillwater trout fisheries showed that Arglilus spp. infections may cause economic loss, through a reduction in the number of anglers attending a fishery. Argulus spp. are perceived to reduce the feeding and therefore catchability of trout. This, in combination with the resulting reduction in condition and aesthetic appeal of fish is believed to reduce angler numbers. In year 2000, 29% of stillwater trout fisheries in the UK suffered a problem infection. Argulus spp. were widely distributed throughout the UK, although problem infections appeared more common in central and southern England and Wales. A. foliaceus was the most common species being found in all but one of the infected study waters. The cross-sectional study identified three factors associated with problem Argulus spp. infections. Presence of an algal bloom / high turbidity, and slow stock turnovers were both associated with an increased risk ofa problem infections, and a drop in water level was associated with a reduced risk of a problem infection. A longitudinal study of the population ecology of A. foliaceus in five trout fisheries of varying management intensity was conducted to identify correlations between risk factors and increase our knowledge of the population dynamics of A. foliaceus. The study also investigated the effects of temperature and identified key points in the life-cycle of Argulus spp. around which interventions could be targeted. Low water clarity and high temperatures were significantly correlated with a high abundance of A. foliaceus. Low water clarity was also associated with reduced stock turnover and would suggest that high numbers of A. foliaceus alone may not affect the catch. The abundance of A. foliacells is greatest towards the end of summer and drops to low levels over winter. The first and second cohorts of the season hatch, in May and June respectively, from eggs that have over-wintered. These cohorts became adult and stal1ed laying eggs in July and August. The over-wintering of hatched stages of A .. J()!iaceus is dependent on a slow winter stock turnover of fish and the presence of reservoir hosts. If these stages over-winter they lay eggs at the end of April that hatch in July. A cohort then hatches every month until September, giving a total of 5 cohorts hatching in a year. The cohorts hatching in July and August lay eggs that over-winter, and the September cohort over-winters as hatched stages. Field studies also elucidated valuable information on the egg laying habits of A. foliacell.\', determining that egg laying occurred between April and September, before stopping over the winter month. Depth of egg laying was found to increase as the season progressed, and was found to occur deeper in clear water than turbid water. Laboratory experiments were used to study the effects of illuminated & darkened conditions, different host species and temperature on the infection success and survival of the parasite. Infection success was high under all conditions. Subsequent survival was similar in all of the experiments, but the likelihood of the parasite reaching adult size was greatest at temperatures of 20°C. Experiments also showed that the metanauplii of A. foliaceus could not survive without a host for more than 3 days. This project has successfully identified the problem posed by Argulus spp. infections to UK stillwater trout fisheries and determined the extent and severity of such problem infections. Several risk factors associated with problem infections were identified and studies were carried out in relation to the parasites population ecology. This work has greatly increased our understanding of the factors controlling A. foliaceus populations, and has led to the development of a series of management recommendations and opened avenues for further research

Environmental valuation and benefit-cost analysis in U.K. policy

This paper presents an evaluation of the use of environmental valuation – techniques to assign monetary values to environmental impacts of policies and projects, especially nonmarket impacts – in U.K. policy. In doing so, we seek to contribute to the debate, more generally, of the use and influence of benefit-cost analysis (BCA) in national policy processes such as Impact Assessment. Specifically, our contribution in this paper is two-fold. First, we identify a number of trends that have characterized U.K. policy use of environmental valuation over the past two or so decades. While this has notably involved development of “sharable values” allowing more widespread uptake, it also seems that different branches of government have developed different traditions of use adding nuance to what, on the face of it, is otherwise a shared endeavor. Second, we evaluate the extent to which the use of environmental valuation can be said to have influenced policy decisions and the degree to which this is embedded by evolving policy processes. As such, we discuss two areas of environmental policy – water quality improvements and natural capital – which have entailed either substantial use of environmental valuation either in determining specific policy and investment project options or where this has helped shape the broader policy agenda. Our evaluation is not exhaustive; nor do our findings suggest that environmental valuation and BCA are necessarily the dominant driver of decisions, as we discuss. However, in recognizing this, we argue it is also important to consider a number of established or evolving cultural and legal institutional processes which broadly appear to support our assessment of such cases

Soil nitrate reducing processes drivers, mechanisms for spatial variation, and significance for nitrous oxide production

The microbial processes of denitrification and dissimilatory nitrate reduction to ammonium (DNRA) are two important nitrate reducing mechanisms in soil, which are responsible for the loss of nitrate (NO− 3 ) and production of the potent greenhouse gas, nitrous oxide (N2O). A number of factors are known to control these processes, including O2 concentrations and moisture content, N, C, pH, and the size and community structure of nitrate reducing organisms responsible for the processes. There is an increasing understanding associated with many of these controls on flux through the nitrogen cycle in soil systems. However, there remains uncertainty about how the nitrate reducing communities are linked to environmental variables and the flux of products from these processes. The high spatial variability of environmental controls and microbial communities across small sub centimeter areas of soil may prove to be critical in determining why an understanding of the links between biotic and abiotic controls has proved elusive. This spatial effect is often overlooked as a driver of nitrate reducing processes. An increased knowledge of the effects of spatial heterogeneity in soil on nitrate reduction processes will be fundamental in understanding the drivers, location, and potential for N2O production from soils

A Relational Database for the Discovery of Genes Encoding Amino Acid Biosynthetic Enzymes in Pathogenic Fungi

Fungal phytopathogens continue to cause major economic impact, either directly, through crop losses, or due to the costs of fungicide application. Attempts to understand these organisms are hampered by a lack of fungal genome sequence data. A need exists, however, to develop specific bioinformatics tools to collate and analyse the sequence data that currently is available. A web-accessible gene discovery database (http://cogeme.ex.ac.uk/biosynthesis.html) was developed as a demonstration tool for the analysis of metabolic and signal transduction pathways in pathogenic fungi using incomplete gene inventories. Using Bayesian probability to analyse the currently available gene information from pathogenic fungi, we provide evidence that the obligate pathogen Blumeria graminis possesses all amino acid biosynthetic pathways found in free-living fungi, such as Saccharomyces cerevisiae. Phylogenetic analysis was also used to deduce a gene history of succinate-semialdehyde dehydrogenase, an enzyme in the glutamate and lysine biosynthesis pathways. The database provides a tool and methodology to researchers to direct experimentation towards predicting pathway conservation in pathogenic microorganisms

The Submillimeter Polarization Spectrum of M17

We present 450 {\mu}m polarimetric observations of the M17 molecular cloud obtained with the SHARP polarimeter at the Caltech Submillimeter Observatory. Across the observed region, the magnetic field orientation is consistent with previous submillimeter and far-infrared polarization measurements. Our observations are centered on a region of the molecular cloud that has been compressed by stellar winds from a cluster of OB stars. We have compared these new data with previous 350 {\mu}m polarimetry and find an anti-correlation between the 450 to 350 {\mu}m polarization magnitude ratio and the ratio of 21 cm to 450 {\mu}m intensity. The polarization ratio is lower near the east end of the studied region where the cloud is exposed to stellar winds and radiation. At the west end of the region, the polarization ratio is higher. We interpret the varying polarization spectrum as evidence supporting the radiative alignment torque (RAT) model for grain alignment, implying higher alignment efficiency in the region that is exposed to a higher anisotropic radiation field.Comment: 24 pages, 10 figure

RpfC (Rv1884) atomic structure shows high structural conservation within the resuscitation promoting factor catalytic domain

We report the first structure of the catalytic domain of RpfC (Rv1884), one of theresuscitation-promoting factors (RPFs) from Mycobacterium tuberculosis. The structure was solved using molecular replacement, once the space group had been correctly identified as twinned P21 rather than the apparent C2221 by searching for anomalous scattering sites in P1. The structure displays a very high degree of structural conservation with the structures of the catalytic domains of RpfB (Rv1009) and RpfE (Rv2450) already published. This structural conservation highlights the importance of the versatile domain composition of the RPF family