Simulation of vegetation cover on sidewalks in Denmark

Data from five 3-year experiments comparing different strategies of non-chemical weed control were analysed in order to set up a model that could be used for simulating further strategies. The treatments included different frequencies and effects of weed control using flaming, steaming and weed brushing. Each plot consisted of about 100 m of sidewalk. The amount of weed on the sidewalks was recorded several times during the 3-year period using a system of cameras mounted on a Terrain Vehicle moving on the sidewalk and post processing using image analyses of extracted images. The percentage of sidewalk covered by weed was estimated on the basis of the image analyses. The model used for describing the weed coverage comprises three components. The first component describes the growth of weeds; the second describes reduction caused by wearing and decay of weeds in the autumn and the third describes the reduction caused by weed control using weed brushing, steaming and flaming. The parameters of the model were estimated from the data for later use for simulating additional strategies.     

Salmon lice infection of wild sea trout and Arctic char in marine and freshwaters: the effects of salmon farms

The abundance of salmon lice and the physiological effects of infection were examined in two stocks of sympatric sea trout and anadromous Arctic char in northern Norway. One stock feed in a coastal area with extensive salmon farming (exposed locality), while the other feed in a region with little farming activity (unexposed locality). The results showed that the lice infection was significantly higher at the exposed locality, at which the mean intensity of infection peaked in June and July at over 100 and 200 lice larvae per fish respectively. At the exposed locality we also observed a premature return to freshwater of the most heavily infected fish. Such behaviour has previously been interpreted as a response by the fish to reduce the stress caused by the infection and/or to enhance survival. Blood samples taken from sea trout at sea at the exposed locality showed a positive correlation between intensity of parasite infection and an increase in the plasma cortisol, chloride and blood glucose concentrations, while the correlations from sea trout in freshwater were more casual. Several indices pointed towards an excessive mortality of the heaviest infected fish, and 47% of the fish caught in freshwater and 32% of those captured at sea carried lice at intensities above the level that has been shown to induce mortality in laboratory experiments. Furthermore, almost half of all fish from the exposed locality had lice intensities that would probably cause osmoregulatory imbalance. High salmon lice infections may therefore have profound negative effects upon wild populations of sea trout. At the unexposed location, the infection intensities were low, and few fish carried more than 10 lice. These are probably within the normal range of natural infection and such intensities are not expected to affect the stock negatively.     

Effects of pre-rigour filleting on quality aspects of Atlantic cod (Gadus morhua L.)

Aquaculture is promising in increasing the amount of fresh Atlantic cod available all year around. The aim of this study was to investigate the effects of pre‐rigour filleting on fillet quality of wild and farmed cod. Pre‐rigour filleting resulted in significantly less fillet gaping than in fillets produced post rigour. The pre‐rigour fillets were, however, 12–13% shorter post rigour. In spite of the significantly lower water content of the muscle 6 days post mortem, a significantly higher liquid loss was seen in the pre‐rigour group. Differences in gaping score and muscle pH were dependent on whether the fish were wild or fed. Fillet gaping increased with storage time and was particularly pronounced for well‐fed cod. Fed cod had a significantly higher hydroxyproline (Hyp) content and significantly lower amount of glycosaminoglycans (GAGs) than wild cod. The ratio between GAGs and Hyp was thus significantly lower in fed cod. A connection between connective tissue components and fillet gaping may exist. However, further investigations are required.     

Pre-rigor filleting and drip loss from fillets of farmed Atlantic cod (Gadus morhua L.)

Improved slaughtering procedures of farmed fish may provide sufficient time so that filleting can be performed pre‐rigor while the muscle pH is still high. Such filleting not only reduces fillet gaping but also lowers the transportation costs and makes fresh fillets available to the markets at an earlier stage. The aim of our work was to determine the weight reduction of the fillets due to liquid loss and to study the proteins and enzymes in the drip. After 11 days of cold storage, fillets of farmed Atlantic cod produced pre‐rigor had a weight loss of 10% and a fillet contraction of 19% while for fillets produced post‐rigor the values were 5% and 4% respectively. At the same time, approximately twice the amount of proteins had been lost from the pre‐rigor‐produced fillets. Sodium dodecyl sulphate polyacrylamide gel electrophoresis analysis showed that the proteins in the drip were similar to the sarcoplasmatic proteins extracted from the muscle. Specific analysis of proteolytic enzymes indicated that they are less stable in the expelled liquid than in the flesh during storage. The extensive loss of weight and proteins from pre‐rigor‐produced fillets during subsequent storage must be taken into account if such processing is considered for farmed cod.     

The suitability of anadromous Arctic charr as host and vector of the monogenean Gyrodactylus salaris

Abstract –  In 2000, the Atlantic salmon ( Salmo salar L.) stock in the river Signaldalselva, North Norway was found to be infected with the monogenean Gyrodactylus salaris (Malmberg). This river system has a multispecies fish community of nine species in total. Low densities of Atlantic salmon parr were found during electrofishing in October (2003) with a prevalence of 94% and a mean abundance of 848 G. salaris. This watercourse also holds a riverine stock of anadromous Arctic charr ( Salvelinus alpinus ), which is not common in Norway. Among the parr of Arctic charr, 64% were infested with an abundance of 23 parasites per fish. The most heavily infected 0+ and 1+ juvenile Arctic charr had 469 and 534 parasites, respectively, indicating that the parasites are able to reproduce on Arctic charr in the wild. There was little variation in the rates of infestation of Arctic charr along the studied stretch of the river, even in areas with very low densities of Atlantic salmon parr. The parr of anadromous Arctic charr seem to be suitable as long-term hosts for G. salaris . Moreover, a few (22%) infested adult sea-running Arctic charr were captured after ascending the river in the autumn, which shows that large fish may also act as carriers of G. salaris . However, no parasites were recorded on potential anadromous Arctic charr before descending during early spring (April 2003 and April 2004). Thus, it is still not clear whether anadromous Arctic charr are able to disperse the parasite between watercourses. So far, it is uncertain whether G. salaris may increase the mortality rates of Arctic charr and thereby be a threat to these unusual occurring riverine anadromous Arctic charr stocks.     

Relationships between breeding waterbird abundance,diversity, and clear water status after the restoration of two shallow nutrient‐rich Danish lakes

1. Breeding waterbird communities have suffered globally from the effects of anthropogenic changes in water quality (especially nutrient enrichment) in recent decades, but few studies have demonstrated the positive effects of restorative actions.
2. Annual breeding waterbird surveys in the period 1977–2005 at two restored southern Danish lake basins (combining nutrient load reduction and biomanipulation) showed an up to five‐fold increase in abundance, and considerable changes in species richness and diversity, following restoration to clear water status in both lakes.
3. Parallel surveys at a third lake, which retained clear water quality throughout, offering a form of natural ‘control', showed no such changes over the same time period.
4. Consistent relationships between breeding waterbird abundance, species richness, and diversity with measures of water clarity (Secchi disc depth, chlorophyll a, and suspended matter) suggest that water clarity mainly drives the relationship; inverse relationships between these measures and total nitrogen and phosphorus were less consistent than for water clarity.
5. The results suggest that an improvement in water clarity plays a key role in restoring breeding waterbird communities and suggest that breeding waterbirds can be indicators of the success of lake restoration projects, but more studies are needed to confirm their wider utility under a variety of conditions.

     

Hypospadias in a Friesian gelding

Objective: To report clinical signs and management of hypospadias in a horse. Study Design: Clinical report. Animal: A 6‐year‐old, Friesian gelding. Methods: Partial phallectomy was performed to resolve contact dermatitis of the pelvic limbs and abnormal behavior during urination. Subsequent urethral meatal stenosis was treated by revision. Results: Hypospadias and chordee caused altered direction of urine flow, contact dermatitis of the pelvic limbs, and abnormal behavior. Partial phallectomy and subsequent revision after meatal stenosis resolved urine direction, flow and abnormal behavior. Conclusions: Abnormalities of the urinary tract associated with hypospadias can result in urine‐induced, contact dermatitis and distress during urination, but these complications can be resolved by partial phallectomy.     

Visual Colour Shades in Pelts from Brown Mink (Mustela vison) Explained Colourimetrically

Microspectrophotometric methods were used to provide objective correlates to the visually judged colour shade (CS) of the underfur in scanbrown mink pelts. The study included 21 scanbrown mink pelts (winter coat), representing a larger group of 87 mink pelts coming from a feeding trial with experimental and control animals. The pelts were visually graded from 1 (blue-greyish) to 5 (reddish), primarily in respect of the CS (in auction classification=clarity of colour) of the underfur seen on the edge of the pelt. Prepared samples of underfur fibres showed in visual inspection a gliding change of colour from paler to darker in a proximal-distal direction and were consequently examined at three levels above the skin surface. The means of the dominant wavelengths (hues) were 589.40, 588.00 and 586.70 nm, respectively, indicating that the variation between levels was small. Investigation of the small pelt material concerned showed that CS was significantly correlated with the measured lightness (L*) and with the yellow chromaticity coordinate (b*) of the underfur samples. In this investigation it was also shown that the underfur fibres with a visually blue-greyish colour shade were relatively dark and less yellow compared with underfur fibres with a reddish colour shade. However, data and the model estimating the colour shade demonstrated that, for the material concerned, visually very reddish underfur colour shades were not found in the lightest coloured pelts.     

Determining treatment frequency for controlling weeds on traffic islands using chemical and non‐chemical weed control

Many public authorities rely on the use of non‐chemical weed control methods, due to stringent restrictions on herbicide use in urban areas. However, these methods usually require more repeated treatments than chemical weed management, resulting in increased costs of weed management. In order to investigate the efficacy of four non‐chemical weed control methods and glyphosate treatment, experiments were carried out on traffic islands in the growing seasons 2005 and 2006. Three trial sites were each divided into six treatment areas, which were either treated with glyphosate, flame, steam, hot air/flame, hot water or left untreated. The treatments were carried out at regular, predetermined intervals throughout the growing season in 2004, whereas in 2005 and 2006 how many treatments that were required to keep weed cover below a predetermined acceptance level of 2% were investigated. Percentage weed cover was measured every second week using a 75 cm × 75 cm quadrat divided into 100 squares. On the control areas, a rapid increase in weed cover was observed, whereas weed cover could be kept below 2% by 2–7 treatments per year, depending on control method. On average, the following numbers of treatments per year were required: glyphosate 2.5, hot water 3, flames 5, hot air/flames 5.5 and steam 5.5 treatments. The results demonstrate that the weed control should be adjusted to the prescribed quality for the traffic islands by regularly assessing the need for weed control. They also show that tailored treatments can reduce the number of required non‐chemical treatments per year.