Islands in the forest: effects of patch size and isolation on farmland bird species richness and community composition of farmland patches in forest landscapes

Landscape Ecology - Theory predicts that species diversity of isolated habitat patches depends on patch size and isolation. However, there are few previous studies of how patch size and isolation...     

Water re-use system for smolt production

A recirculation unit for salmon smolt production is described. The preliminary results for growth rate and viability of the fry were satisfactory.     

Sexual dimorphism of fast muscle fibre recruitment in farmed Atlantic halibut (Hippoglossus hippoglossus L.)

Commercially farmed Atlantic halibut (Hippoglossus hippoglossus) were reared at the Aga Marin's facility located on Dønna (Norway) under ambient environmental conditions in duplicate 15 × 15 × 8 m netpens (May 2004 to May 2005). Twenty fish were sampled five times over a twelve month production period during which time the average body weight increased from 1.26 to 2.08 kg (n = 100 fish). Body mass, fork length (L_F), and the number and size distributions of fast muscle fibres were determined in male and female fish. All males matured during the autumn whereas no maturation was observed in females. From the point of maturation females had superior growth performance to males and body mass and the total cross-sectional area of muscle were 1.4-fold (P < 0.05) and 1.3-fold higher (P < 0.01) respectively by May 2005. The total number of fast muscle fibres per trunk cross-section at 0.55 L_F was 24.5% higher in females (7.58 × 10⁵) than males (5.80 × 10⁵) prior to sexual maturation. In females, muscle fibre recruitment slowed with short days and low water temperatures (< 6.5 °C), but had increased to 1.01 × 10⁶ by May 2005 (P < 0.001). In contrast, there was no growth and no increase in muscle fibre number in males following the onset of maturation. The distribution of muscle fibre diameters prior to maturation in males was also significantly different between male and female fish matched for L_F. The results illustrate a sexual dimorphism of muscle fibre recruitment patterns in Atlantic halibut and highlight the adverse affects of sexual maturation in males on muscle growth.     

鳀鱼的生物量、渔业及其生物学特征

IntroductionThe Yellow Sea is characterized by a shallow continental shelf. High tides and seasonally varying mon-soons,freshwater discharge from surrounding landmasses and large amounts of sediments transported intothe sea as well as the effect of the Kuroshio current have strong effects on the environment in these areas.Productivity of an ecosystem may be measured in terms of abundance of the adult population and recruitmentof new year classes.Japanese anchovy(Engraulis jap onicus) is cons…     

The Contribution to Nitrogen Deposition and Ozone Formation in South Norway from Atmospheric Emissions Related to the Petroleum Activity in the North Sea

A photochemical puff-trajectory model (Fotoplume) has been applied to simulate emissions, atmospheric transport and chemical transformations of pollutants from offshore oil and gas production in the North Sea. The above model was used in conjunction with the European Monitoring and Evaluation Programme (EMEP) regional Lagrangian oxidant model. The Fotoplume and EMEP models were used to evaluate the effects of the atmospheric emissions from the oil and gas exploration activity in the Norwegian sector of the North Sea. Deposition of nitrogen and formation of boundary level ozone in Southern Norway due to North Sea emissions of nitrogen oxides (NO_x), carbon monoxide (CO) and volatile organic compounds (VOC) have been studied. The petroleum activity in the North Sea is calculated to contribute approximately 20% of the nitrogen deposition in the coastal areas of Norway in 1992. In addition, the models were used to estimate the AOT40 ozone exposure levels. The results indicate that emissions from British and Norwegian oil and gas exploitation sector separately contribute to less than 5% each of the AOT40 values for coniferous forests and meadows. Comparison of model calculations with experimental measurements is quite satisfactory and the models show realistic results for both the nitrogen deposition and AOT40 values.     

An evaluation of field and non-invasive genetic methods to estimate brown bear (Ursus arctos) population size

Estimates of population size and density are essential for successful management and conservation of any species. Although there are a variety of methods available for estimating abundance and density of populations, most studies rely on only one estimator and very few studies have compared and critically evaluated the adequacy and the cost of these methods. We used the brown bear (Ursus arctos) in south-central Sweden to compare the performance of three different methods of estimating population size, including methods based on conventional field data as well as on non-invasive genetic data. The method based on observations of females with cubs underestimated the true population size, as the estimates were below the number of unique genotypes determined from faecal data inside the study area. The best traditional method was based on observations of bears from a helicopter. The genetic method using the closed population MARK estimator, as recommended in a previous study, seemed to perform the best. We conclude that approximately 223 (188-282) bears were present in our 7328 km² study area during 2001 and 2002 and suggest that this hunted brown bear population has been relatively stable for about ten years. The non-invasive genetic method was less expensive than the most reliable traditional field method (a CMR method based on observations of bears from a helicopter), and preferable from an ethical point of view. We recommend that future studies using non-invasive genetic methods based on collected faecal samples should aim at collecting 2.5-3 times the number of faecal samples as the “assumed” number of animals.     

Experimental Encephalitozoonosis in the Blue Fox: Clinical and Serological Examinations of Affected Pups

Two groups of blue fox pups about 1½— 2 and 2½—3 months old, respectively, suffering from experimental encephalitozoonosis, were examined clinically and serologically. Antibodies to Encephalitozoon cuniouli were detected in all pups, the titres varying within the range 10–12,800. In addition to unspecific signs of disease the pups showed various neurological disturbances including ataxia, posterior weakness, lameness and circling behaviour, terminaiting in recumbency, paralysis or convulsions. Reduced sight or blindness was observed occasionally. Some of the pups appeared thirsty. Haematological examinations revealed pronounced leukocytosis without any conspicuous shift within the various groups of leukocytes. Biochemical examinations of serum showed significant elevated values of urea nitrogen, creatinine, and magnesium concentrations, reflecting renal dysfunction. Alanine aminotransferase was found significantly depressed in both groups. Raised levels of total protein were demonstrated due to pronounced hyperglobulinaemia. This finding, together with the common occurrence of generalized polyarteritis nodosa and proliferations of plasma cells in clinically affected pups, is probably a result of autoimmune disturbances initiated directly or indirectly by the protozoan infection.     

Serological Investigations of Leptospiral Deoxyribonucleases

Enzymoserological comparison of a selection of leptospira strains tested with sera from rabbits immunized with unpurified DNase of Leptospira interrogans, serotype canicola, indicates the production of DNase of serologically very similar properties by the serotypes canicola, autumnalis, icterohemorrhagiae and pomona. The DNase produced by serotype hyos was serologically different from the others, while the serotypes grippotyphosa and bataviae did not produce DNases at all. The method used made it possible to differentiate between leptospiral DNase and normally occurring DNases in the serum samples. Neither leptospira DNase nor specific leptospira-DNase-antibodies could be detected in dog sera with high agglutinationlysis titres after natural infection.     

An Investigation of Ovine Pneumonia in Four Herds from Central Norway: I. Prevalence of Pneumonia and Microbiological Findings

In a study of 4 sheep herds, 1 apparently healthy and 3 having respiratory problems, lesions typical of subacute or chronic pneumonia were found in 3–36 % of slaughtered lambs. Occurrence appeared to be related to certain environmental factors such as pasture, whereas moderate lungworm invasion was not found to contribute to subacute or chronic pneumonia. Relation between pneumonia and low carcass weight was established only in 1 herd.Lungs were subjected to microbiological examination. Mycoplasma ovipneumoniae was isolated from both normal and pneumonic lungs from all 4 herds. The prevalence was far higher in pneumonic (98 %) than in normal ones (28 %). Bacteria, mostly Pasteurella haemolytica, were also found in both pneumonic (49 %) and normal (18 %) lungs from all 4 herds. These results confirm the conclusions of a previous study that M. ovipneumoniae is of etiological significance in subacute or chronic pneumonia, whereas bacteria mainly occur as secondary invaders. M. ovipneumoniae appears, however, only to be a potential pathogen. Examinations for Mycoplasma arginini and virus were negative and these agents are considered to be of less significance in subacute or chronic pneumonia under Norwegian conditions.     

Pathological Lesions in Swine at Slaughter: IV. Pathological Lesions in Relation to Rearing System and Herd Size

Data from the meat inspection at a large regional abattoir in Norway was used to study the effect of different production systems and herd size on the occurrence of pathological lesions in pig carcasses. Three production systems were compared: combined production, production strictly in batches and continuous production. Only the former reared its own piglets. The data was collected in the period 1975–1977. The number of herds varied between 87 and 94, and between 26,000 and 30,000 bacon pigs were slaughtered each year. The herds were divided into three different size groups: ≤ 200, 201–400, and > 400 pigs slaughtered annually. Each year was considered separately.The study showed that the highest frequency of sound carcasses occurred in the combined production group. There was no significant difference between the two production groups rearing purchased piglets. Moreover, there was an inverse relationship between the frequency of sound carcasses and herd size, but the positive effect of the small herd was estimated to be less important than that of production system.The distribution of 16 different pathological lesions was also considered. Four lesions (pneumonia — moderate and severe —, pleurisy and scabies) were recorded at significantly different levels in the production systems all three years of recording.Analysis of the effect of herd size also showed that in the cases of moderate pneumonia and pleurisy, the small herds were at an advantage. The other lesions had a rather casual distribution among the groups.The statistical evaluation indicates however, that in cases of significant differences between the tested groups, only 20–40 % of the variation could be “explained” by our model comprizing production systems and herd size groups.