Social, economic and cultural perspectives of European inland fisheries: review of the EIFAC symposium on fisheries and society

The contributions presented at the EIFAC Symposium on Fisheries and Society in 2000 are reviewed. There have been considerable advances in many sectors of inland fisheries over the past decade. Nowadays the value of inland fisheries to society is generally better understood and increasingly recognized. However, it was recognized that the allocation of fishery resources and their management could still be made more effective through more extensive application of the recent approaches and techniques discussed during the Symposium and reviewed in the paper.     

Evaluation of two N cycle models for the prediction of N mineralization from grassland soils in the UK

Abstract. The ability of two nitrogen cycle models, of contrasting complexity, to predict N mineralization from a range of grassland soils in the UK, was evaluated. These were NCYCLE, a simple mass balance model of the N cycle in UK grasslands, and CENTURY, a more complex model simulating long-term C, N, P & S dynamics in grassland ecosystems. The models were tested using field measurements of net N mineralization from a range of grassland soils (differing in soil type, history & management practice), obtained over a 2 year period using a soil core incubation technique. This method was considered to measure the total net release of mineral N from the soil organic matter over a specified time, including N which may have been recycled several times. NCYCLE consistently under-estimated mineralization rates at all sites. By contrast, there was some correlation between CENTURY predictions of net N mineralization and field measurements. This may have reflected the different abilities of the two models to simulate N recycling. Neither model, however, was able to predict adequately the effect of cultivation and reseeding on net N mineralization.     

Factors Affecting the use of Dreissena polymorpha as a Bioindicator: the PCB Pollution in Lake Como (N. Italy)

The aim of this study was to assess the PCB pollutionof the South-Western branch of Lake Como by using thezebra mussel (Dreissena polymorpha) as abioindicator since its recent reintroduction. Someenvironmental and physiological variables influencingaccumulation processes of organochlorine compounds inDreissena were investigated because climaticfactors may affect life cycle, reproductive stage andage. PCB levels were highest in the soft tissues ofDreissena close to the industrialized area ofComo (2298 ng g^-1 of lipids) and slowly decrease goingnorth, reaching approximately half this value at theclosing section of the lake branch. Nonetheless, thePCB concentrations are well below the dangerous levelsfor the aquatic environment.     

COMPUTED TOMOGRAPHIC IMAGING OF INFILTRATIVE LIPOMA IN 22 DOGS

Twenty two dogs with an infiltrative lipoma had computed tomographic (CT) images acquired to evaluate the extent of local disease. Ten dogs had undergone at least one cytoreductive surgical procedure (range = 1-3; median = 2) prior to imaging. Twenty dogs had measurable disease on CT images; 2 dogs had diffuse disease at a previous surgical site that could not be measured. Tumor volume (n = 20) ranged from 20 to 5,632 cm3 (median = 345 cm3; mean = 996 cm3). None of the dogs had evidence of bone involvement on the CT images; 2 of the 22 dogs had tumors that did not come into direct contact with osseous structures. All dogs with measurable disease had evidence of a fat opacity mass with variable degrees of muscle infiltration. Eleven of 22 dogs were given intravenous contrast medium prior to image acquisition and there was not evidence of enhancement of the infiltrative lipoma in any dog. Based on CT images, tumors were classified as well-defined in 9 dogs, moderately well-defined in 4, not well-defined in 3 and a mix of well-defined and not well-defined in 6 dogs. Tumors tended to be less well-defined in regions where the infiltrative lipoma interdigitated with normal body fat. It appears CT imaging allows adequate discrimination of tumor with the caveat that differentiation of normal fat from infiltrative lipoma can be problematic.     

Detection of chlamydial antibody by fetal serology--an aid to the diagnosis of ovine abortion.

Two serological tests (indirect immunofluorescence and enzyme-linked immunosorbent assay) were developed for the detection of fetal antibody to Chlamydia psittaci. Fetal blood and thoracic fluid from 126 field cases of suspected ovine chlamydial abortion were examined using both tests. Placenta and fetal tissues (lung, liver, and kidney) from the same animals were also examined by the following conventional diagnostic methods: isolation in McCoy cells, detection of chlamydial lipopolysaccharide (LPS), modified Ziehl-Nielsen staining, and direct fluorescent antibody staining of chlamydia in frozen cryostat sections. Seventy cases were positive by fetal serology, and of these, 68 were also positive by isolation and/or LPS detection. The remaining 56 cases had negative fetal serology, and of these, 39 were positive by isolation and/or LPS detection. Results indicate that fetal serology, although less sensitive than either isolation in McCoy cells or detection of chlamydial LPS antigen, may be of particular use when placenta is not available.     

Sinnesphysiologische Untersuchungen an Schmetterlingsraupen und ihre praktische Bedeutung

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Literarische Berichte

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