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Several indices were examined to assess the physical condition of wrasse stocked on Atlantic salmon, Salmo salar, farms as cleaner fish, and included examination of eye condition, snout erosion, skin hemorrhaging, and erosion and splitting of dorsal, pectoral, anal and caudal fins. Baseline values were determined for five wrasse species: goldsinny, Ctenolabrus rupestris; rock cook, Centrolabrus exoletus; corkwing, Crenilabrus melops; cuckoo, Labrus mixtus; and ballan, Labrus bergylta, held in a farm environment for 3 mo prior to transfer to salmon farms. The caudal fin was most affected by injury. The fin erosion index (FEI) was low in all species and below 0.6. The fin splitting index (FSI) was the most prominent index and was significantly higher in the caudal fin (FSI > 2) compared with other fins (FSI < 0.5), and also significantly higher in corkwing and rock cook compared with the other wrasse species. The FEI and FSI were also calculated for a group of ballan wrasse before stocking on a seawater farm, during the first winter and upon harvesting. There were no significant differences in the scores of fin erosion and fin splitting in any of the samples, although the indices were marginally poorer in winter. 相似文献
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利用木麻黄营造沿海沙地防护林,不仅符合适地适树的造林原则,而且也是保护和恢复全省海防林带生态工程的有效途径之一.因此持续性发展木麻黄沿海防护林、苗木品种和造林技术至关重要.文章介绍了木麻黄沿海防护林造林技术,并对以后的造林工作提出了一些建议. 相似文献
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Heavy metals such as cadmium (Cd) enter the ecosystem chiefly as the result of human activities. Nowadays the heavy‐metal pollution of the soil is causing ever greater problems, exacerbated by the fact that the heavy metals accumulated in plants may, either directly or indirectly, find their way into animals and human beings. Maize is one of the world's most important crops, ranking third after wheat and rice, so the changes induced by one of the most toxic heavy metals, Cd, in maize plants is a cause of some concern. This review discusses not only the toxic symptoms caused by Cd stress, but also the tolerance mechanisms activated in the plants. Cadmium induces a number of physiological changes, such as growth inhibition, changes in the water and ion metabolism, the inhibition of photosynthesis, changes in enzyme activities, and the formation of free radicals. The synthesis and compartmentalization of phytochelatins is induced shortly after the initiation of Cd stress, while other defense mechanisms also play an important role. 相似文献
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Forest loss with accompanying urbanization is often permanent as forests are replaced by impervious concrete structures or surfaces. The remaining forest patches are usually isolated and too small to maintain viable populations of forest-dependent wildlife species. Consistent with the species-area function (S = cAz), extirpation of species should follow forest loss. However, this has rarely ever been tested in the urban landscape. We determined whether the observed number of forest-dependent bird extirpations occurring after forest loss matches that predicted by the species-area function in Vancouver (study area ∼126.7 km2), British Columbia, Canada. Prior to European settlement in 1859, Vancouver was covered completely by coastal western hemlock forest. Based on published historical maps of forest cover and present Landsat imagery of Vancouver, we estimated that approximately 87% of the forest area in Vancouver has been converted to urban development. Using the species-area function, we then predicted that approximately 14 bird species closely associated with lowland forest should have been extirpated. This figure is significantly greater than the three bird species known to have been extirpated in Vancouver. When we constrained the comparison to bird species closely associated with lowland forest and restricted in their distribution in British Columbia, we found a close match between the observed and predicted number of extirpations, suggesting that bird species closely associated with lowland forest and restricted in their geographic distribution are most prone to extirpation as a result of forest loss. Given that urban areas are situated in productive habitats with inherently high species richness, it is important that local land-use plans incorporate the conservation of habitat fragments from the onset and place particular emphasis on the regionally restricted forest-dependent species. 相似文献
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由于新疆牧业灌区无电供应,水源无法过滤,实现滴灌工程难,目前采用地面灌溉。地形坡度大、灌水量多、大量水土流失。灌区下游排水不畅,洼地沼泽化面积剧增,地下水位上升导致土壤盐碱化,弃田面积逐渐扩大、种植面积萎缩。为了解决上述问题,充分利用地形落差,研制了自压滴灌工程过滤装置。同时渠道进水流量、调水池的调节流量、集水桶流量及系统流量之间建立了平衡关系。用实例说明不同地形落差与自压滴灌工程系统流量及过滤装置尺寸的计算过程。解决了自压滴灌工程水源的过滤、排沙、冲沙及自行冲洗等问题。为无电牧业灌区实现节水灌溉技术提供依据。 相似文献
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Korbinian Pieper Tibor Schuster Olivier Levionnois Ulrike Matis Alessandra Bergadano 《Veterinary journal (London, England : 1997)》2011,187(3):335-341
To assess the antinociceptive efficacy of transdermal (TD) buprenorphine (B) in dogs, a prospective, positive-controlled experimental study was performed in 10 healthy Beagles. In an open label crossover design, the dogs initially received intravenous B (IVB, 0.02 mg kg?1) as a positive control, followed by TDB (52.5 μg h?1) 4 months later. Blood was collected at regular intervals for determination of the plasma concentrations of B ([B]) and its metabolite norbuprenorphine. The antinociceptive efficacy was assessed using thermal and mechanical models of nociception. The peak concentration [B] was 1.54 ng mL?1 (±1.98) 60 h after TDB application, although three dogs had no measurable [B] after TDB. Maximum thermal threshold (TT) was 52.6 °C (±0.48) at 1 h after IVB administration and 51.63 °C (±1.01) 72 h after TDB application. The significant increase in TT indicated that effective antinociception was achieved beyond 36 h after the application of TDB, lasting until patch removal. There was hysteresis between [B] and the antinociceptive effect. 相似文献
10.
Maintaining connectivity among local populations in a fragmented landscape is crucial for the survival of many species. For
isolated habitat patches, stochastic fluctuations and reduced gene flow can lead to high risk of extinction. The connectivity
of the landscape is especially crucial for the carabid species living in the fragmented forests of the Bereg plain (NE Hungary
and W Ukraine) because a highway will be constructed through the plain. Our purpose is to (1) evaluate the impacts of three
possible highway tracks, (2) suggest a solution that is realistic with less impact on connectivity than other plans and (3)
discuss how to decrease the disadvantageous effects of each track. Our results, based on a network analysis of landscape graph
of patches and ecological corridors, indicate that the intended highway could have deleterious consequences on forest-living
carabids. Relatively simple actions, like the establishment of stepping stones, could compensate for the loss of habitat connectivity
and promote the survival of carabids, or minor modifications in one possible track could diminish its adverse effects. While
many other studies would be needed for a comprehensive assessment of the biotic impact of the highway, we provide an example
on the usefulness of network analysis for land use management.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献