Fin condition and growth among rainbow trout reared at different sizes,densities and feeding frequencies in high-temperature re-circulated water

Rainbow trout were studied at different rearing densities, fish sizes and feeding frequencies so that we could evaluate the effect of these parameters on fin condition, growth and feed utilisation. In one study, two sizes of rainbow trout (18–70 g or 48–125 g), fed to near satiation at 17.7°C, were examined at two rearing densities (11–41 kg m⁻³ or 21–92 kg m⁻³). This study showed that the anal fin was healthier (P < 0.05) at low densities. In the second study rainbow trout were again fed to near satiation and grown from 50 g to 125 g in 16.4°C water, and they were fed either once daily or three times daily at two densities (18–45 kg m⁻³ or 54–124 kg m⁻³). Rainbow trout growth and feed utilisation were slightly but significantly (P < 0.05) reduced at high densities, while dorsal fin condition, surprisingly, was better (P < 0.0001) at the high densities. Possible explanations to these findings are discussed. Condition of the left pectoral fin was improved at once daily feeding (P < 0.05) compared with three feedings per day, at which fights for feed possibly are more frequent.     

Wireless indoor tracking network based on Kalman filters with an application to monitoring dairy cows

We propose an algorithm for estimating positions of devices in a sensor network using Kalman filtering techniques. The specific area of application is monitoring the movements of cows in a barn. The algorithm consists of two filters. The first filter enhances the signal-to-noise ratio of the observed signal strengths and gives interpolated values at specific timestamps. Information from the first filter is transferred to the second filter which estimates the positions. Methods for estimating the parameters of the filters are given and these provide a straightforward calibration of the system.     

Copper toxicity and chemistry in the environment: a review

Copper compounds have been widely used in industrial processes and agriculture. As a result, elevated Cu concentrations can be found in certain areas of the biosphere. To better understand the toxicity of Cu to organisms it is necessary to understand the mechanism by which Cu influences biological and chemical processes in the environment. This review will examine Cu toxicity, microbial resistance mechanisms and factors influencing Cu speciation and toxicity in the environment     

Predicting plant species richness in a managed forest

This paper describes an attempt to predict ground flora species richness under various forest management scenarios. The approach is based on a geographic information system (GIS) and uses three standard map layers of topography, soils and stands to derive environmental gradients of light, nutrients, water and disturbance. A simple floristic survey provides the data necessary to relate plant distribution with environmental variables. The potential distribution of 60 understorey plant species is modelled based on the four derived gradients. The sum of these maps, i.e., the total potential diversity, is used as a proxy for the prediction of actual species richness. The model predicts high species diversity along roads and in relatively disturbed areas and low species diversity in stands with coniferous species and in stands of old, deciduous trees (mainly beech). The overall predicted pattern of species diversity corresponds well with observations made in the forests. However, the model explained only a fraction of the variation in the data set on the plot level. Dispersal effects, demographic stochasticity and biological factors are the probable causes of this. The combination of GIS-based spatial operations and fuzzy cognitive mapping proved to be an efficient way of producing gradient maps based on standard forestry maps and expert knowledge.     

Interaction of bacteria-feeding soil flagellates and Pseudomonas spp.

Pseudomonas strains may be used as alternatives to fungicides as some of them produce secondary metabolites, which can inhibit growth of plant pathogenic fungi. Increased knowledge of non-target effects of the antagonistic bacteria on other soil organisms as well as of the survival and predation resistance of the antagonistic bacteria is necessary for risk assessment and increased performance of antagonistic bacteria as biological control agents. In the present study, we aimed to investigate the difference between Pseudomonas spp. with respect to their predation resistance to and effects on the three different and common soil flagellates Bodo caudatus, Cercomonas longicauda, and Neocercomonas jutlandica. Two antagonistic Pseudomonas: Pseudomonas fluorescens CHA0 and P. fluorescens DR54 and two positive control strains: P. fluorescens DSM 50090^T and Pseudomonas chlororaphis ATCC 43928 were studied. CHA0, which is reported to produce a range of different antibiotic substances, was inhibitory to all the tested flagellates whereas DR54, which produces viscosinamide, only inhibited the growth rate of B. caudatus. Removal of spent medium from a CHA0 culture reduced the growth inhibition of C. longicauda, although the growth rate was still lowered compared with DSM 50090^T. In contrast, removal of spent medium from a DR54 culture had minor effect on C. longicauda. The flagellate B. caudatus was far more sensitive towards the antagonistic Pseudomonas strains of the tested flagellates.