Acidity status of surface waters in Massachusetts

The Massachusetts Acid Rain Monitoring project surveyed 80.5% of the state's 5294 named water bodies between 1983 and 1985. PH and acid neutralizing capacity (ANC) were measured monthly the first 14 mo and semi-annually afterwards. Sample collection and analysis were performed by volunteers. The majority of surface waters in Massachusetts were found to be sensitive to possible long term acidification, with 63% exhibiting ANC less than 200 μeq L^?1 and 22% with ANC less than 40 μeq L^?1. Seasonal patterns in ANC were observed, the median ANC being 384 μeq L^?1 in summer/fall and 134 μeq L^?1 in winter/spring. Geographical differences were also found across the state: the streams and lakes with lowest pH and ANC were located in the southeastern and north-central parts of the state, while the most alkaline surface waters were found in the western-most part of the state, which is the only area of the state with significant limestone deposits.     

Resilience, experimentation, and scale mismatches in social-ecological landscapes

Growing a resilient landscape depends heavily on finding an appropriate match between the scales of demands on ecosystems by human societies and the scales at which ecosystems are capable of meeting these demands. While the dynamics of environmental change and ecosystem service provision form the basis of many landscape ecology studies, enhancing landscape resilience is, in many ways, a problem of establishing relevant institutions that act at appropriate scales to modify and moderate demand for ecosystem services and the resulting exploitation of ecosystems. It is also of central importance for landscape sustainability that institutions are flexible enough to adapt to changes in the external environment. The model provided by natural ecosystems suggests that it is only by encouraging and testing a diversity of approaches that we will be able to build landscapes that are resilient to future change. We advocate an approach to landscape planning that involves growing learning institutions on the one hand, and on the other, developing solutions to current problems through deliberate experimentation coupled with social learning processes.     

Segmental tracheal dysplasia in a mixed breed dog

A 6-month-old, spayed female, mixed breed dog was referred for respiratory difficulty. Radiographic and bronchoscopic evaluations showed tracheal narrowing from the thoracic inlet to its bifurcation. Under anesthesia, the trachea ruptured and the dog died. Microscopic evaluation revealed underlying segmental tracheal and bronchial cartilaginous malformation (dysplasia).     

The quantitation of turbinate atrophy in pigs to measure the severity of induced atrophic rhinitis.

The two-fold purpose of this study was to establish a useful image analysis technique for quantitation of turbinate atrophy and to determine an optimum bacterial dose for inducing atrophic rhinitis (AR). Two morphometric analysis methods were compared to determine a turbinate area ratio (TAR) and a turbinate perimeter ratio (TPR); the ratios of turbinate area to total nostril area and of turbinate perimeter to total nostril perimeter, respectively. Our first image analysis method differed from Collins et al (1) in that we used direct image capture (digitalization) via a video camera and a Macintosh microcomputer, rather than photographs and a digitizer tablet. The tracing techniques were the same as those used by Collins et al. The second morphometric method was modified from the first by exclusion of dorsal turbinate when tracing the nostril area and directly tracing only the ventral turbinate to get a turbinate measurement without subtracting. Area and perimeter ratios, for both methods, were compared to conventional visual snout scores, ventral measurements, and to each other. The results of the two image analysis methods correlated well, both with each other and with the visual scores. Doses of Pasteurella multocida (Pm) at a constant level, and Bordetella bronchiseptica (Bb) at various concentrations, were administered to 36 Hampshire-Duroc F1 SPF pigs to determine the best dose and frequency for inducing AR. Although the dose selection may have been somewhat affected by the pre-existing presence of Bb, the optimal dose per naris in this study was 2 mL Bb at 10(7) cfu/mL combined with 2 mL Pm at 10(9) cfu/mL inoculum. The frequency of administration (1 x or 2 x) did not greatly affect results. Turbinate area ratio was the best tool for quantitating gross morphological turbinate changes associated with atrophic rhinitis in this study. Our simplified modification of Collins et al image analysis method (exclusion of dorsal turbinates and direct measurement of ventral turbinates) correlated well with visual scores, and, when compared to Collins et al method, required less data manipulation and labour.     

大豆粕在杂食性淡水鱼类饲料中的应用(续)

(接上期) 四、原料替代 大豆粕具有蛋白质含量较高、氨基酸组合互补性相对合理的特点,人们传统上将其与鱼粉比较来加以评估,而鱼粉一般被认为是对水产动物营养价值最高的蛋白质原料.由于鱼粉较为昂贵,而且随着水产养殖业的不断发展,鱼粉有限的可获性已引起人们的关注,因此对合适的鱼粉替代物的评估已成为一项长期、优先的研究任务(Hardy,1999).