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排序方式: 共有419条查询结果,搜索用时 15 毫秒
91.
Ane T Laugen Georg H Engelhard Rebecca Whitlock Robert Arlinghaus Dorothy J Dankel Erin S Dunlop Anne M Eikeset Katja Enberg Christian Jørgensen Shuichi Matsumura Sébastien Nusslé Davnah Urbach Loїc Baulier David S Boukal Bruno Ernande Fiona D Johnston Fabian Mollet Heidi Pardoe Nina O Therkildsen Silva Uusi‐Heikkilä Anssi Vainikka Mikko Heino Adriaan D Rijnsdorp Ulf Dieckmann 《Fish and Fisheries》2014,15(1):65-96
Managing fisheries resources to maintain healthy ecosystems is one of the main goals of the ecosystem approach to fisheries (EAF). While a number of international treaties call for the implementation of EAF, there are still gaps in the underlying methodology. One aspect that has received substantial scientific attention recently is fisheries‐induced evolution (FIE). Increasing evidence indicates that intensive fishing has the potential to exert strong directional selection on life‐history traits, behaviour, physiology, and morphology of exploited fish. Of particular concern is that reversing evolutionary responses to fishing can be much more difficult than reversing demographic or phenotypically plastic responses. Furthermore, like climate change, multiple agents cause FIE, with effects accumulating over time. Consequently, FIE may alter the utility derived from fish stocks, which in turn can modify the monetary value living aquatic resources provide to society. Quantifying and predicting the evolutionary effects of fishing is therefore important for both ecological and economic reasons. An important reason this is not happening is the lack of an appropriate assessment framework. We therefore describe the evolutionary impact assessment (EvoIA) as a structured approach for assessing the evolutionary consequences of fishing and evaluating the predicted evolutionary outcomes of alternative management options. EvoIA can contribute to EAF by clarifying how evolution may alter stock properties and ecological relations, support the precautionary approach to fisheries management by addressing a previously overlooked source of uncertainty and risk, and thus contribute to sustainable fisheries. 相似文献
92.
Our aim was to determine the effects of two secondary metabolites secreted by Trichoderma harzianum, pachybasin and emodin, on the mycoparasitic coiling behavior and cAMP content of T. harzianum. The number of T. harzianum coils around Nylon 66 fiber was increased in the presence of R. solani. The number of T. harzianum coils around R. solani hyphae and Nylon 66 fiber were significantly increased in the presence of pachybasin and emodin. The cAMP level in T. harzianum was significantly increased by close contact with R. solani and much higer cAMP level in the presence of exogenous pachybasin and emodin. A cAMP inhibitor diminished the effect of pachybasin and emodin on T. harzianum coiling around Nylon 66 fiber. The results suggest that pachybasin and emodin mediate the increase in the number of Trichoderma mycoparasitic coils via cAMP signaling. This is the first report to suggest that pachybasin and emodin play roles in the biocontrol mechanism of Trichoderma. 相似文献
93.
考虑水轮机工况变换过程中引水管道内瞬变流与机组内部暂态流动的相互影响,对管道瞬变流采用特征线法求解,机组内部暂态流动采用三维不可压缩流动的有限体积法求解,按照管道与机组连接处流量连续和水头平衡的原则,建立了管道瞬变流与机组内部三维暂态流动的耦合计算模型.并分别采用建立的耦合计算模型、电站常规过渡过程计算模型和常规三维流动计算模型对带有引水管道的水轮机甩负荷导叶关闭工况进行了仿真计算.结果表明:3种计算方法得到的机组压力、转速等宏观参数变化趋势一致,但采用耦合计算模型时,由于考虑了管道内水击压力的反射和叠加,导叶关闭过程中蜗壳进口的压力上升更高,机组内的压力脉动也更剧烈,能够更真实地反映动态过程中管道瞬变流与机组内部三维暂态流动的相互作用. 相似文献
94.
Francesco Pini Cristina Grossi Sabrina Nereo Luigi Michaud Angelina Lo Giudice Vivia Bruni Franco Baldi Renato Fani 《European Journal of Soil Biology》2007,43(5-6):368
A set of 21 Antarctic marine bacteria isolated from the Ross Sea and able to utilise diesel fuel as the sole carbon and energy source was characterised. Isolates were analysed by amplified 16S rDNA restriction analysis using the enzyme AluI, resulting in two different groups corresponding to different bacterial species. These species were assigned to the genera Rhodococcus and Alcaligenes, on the basis of 16S rDNA sequencing. This low degree of inter-specific biodiversity was parallel to a low intra-specific biodiversity, as shown by Random Amplified Polymorphic DNA analysis. Then, a 550-bp DNA fragment coding for the inner region of alkane mono-oxygenase was PCR-amplified from the genome of each strain. The phylogenetic analysis of the sequence of the putative AlkB protein coded for by the amplified DNA fragment revealed that these alkB genes were very likely inherited by horizontal gene transfer. Lastly, the analysis of the biodegradation ability of four strains revealed two different strategies of hydrocarbon uptake, mediated either by bio-surfactants and peculiar of Rhodococcus isolates, or by membrane modifications and shown by Alcaligenes isolates. In order to understand the interrelationships between hydrocarbon-degrading isolates, the dynamics of two strains, belonging to Rhodococcus and Alcaligenes, grown together in a co-culture was also followed over a seventeen days period. 相似文献
95.
96.
97.
S9606菌发酵脱毒棉籽粕饲喂蛋鸡 总被引:4,自引:0,他引:4
饲料中添加6.5%~10%的含游离棉酚为0.0101%~0.0164%的发酵脱毒棉粕,鸡的产蛋率提高0.03%~4.03%。其中添加7.66%的发酵脱毒棉粕的饲料,其经济效益最好,1000g蛋成本降低0.1732元、料蛋比由2.6287降到2.5250。试验组和对照组的鸡血清谷雨转氨酶活性、总蛋白含量、清蛋白和球蛋白的相对含量、清蛋白和球蛋白之比均差异不显著。说明饲喂脱毒棉粕的鸡,其肝脏和其他组织的功能正常、健康。 相似文献
98.
Macro‐geographical differences influenced by family‐based expression on cultured pearl grade,shape and colour in the black‐lip ‘pearl oyster’ Pinctada margaritifera: a preliminary bi‐local case study in French Polynesia 下载免费PDF全文
Chin‐Long Ky Carole Blay Vaite Aiho Philippe Cabral Gilles Le Moullac Cédrik Lo 《Aquaculture Research》2017,48(1):270-282
In French Polynesia, the aquaculture of Pinctada margaritifera is carried out in numerous grow‐out sites, located over three archipelagos (Gambier, Society and Tuamotu). To evaluate the impact of macro‐geographical effects of these growing sites on pearl quality traits, five hatcheries produced families were used as homogeneous donor oysters in an experimental graft. The molluscs were then reared in two commercial locations: Tahaa Island (Society) and Rangiroa atoll (Tuamotu). At harvest, eight pearl quality traits were recorded and compared: surface defects, lustre, grade, circles, shape categories, darkness level, body and secondary colour and visual colour categories. Overall inter‐site comparison revealed that: (1) all traits were affected by grow‐out location except for lustre and round shape, and (2) a higher mean rate of valuable pearls was produced in Rangiroa. Indeed, for pearl grade, Rangiroa showed twice as many A‐B and less reject samples than Tahaa. This was related to the number of surface defects (grade component): in Rangiroa, twice as many pearls had no defects and less pearls had up to 10 defects. Concerning pearl shape, more circled and baroque pearls were found in Tahaa (+10%). For colour variation, 10% more pearls have an attractive green overtone in Rangiroa than in Tahaa, where more grey body colour were harvested. Lustre does not seem to be affected by these two culture site (except at a family scale). This is the first time P. margaritifera donor family have been shown to vary in the quality of pearls they produce depending on their grow‐out location. 相似文献
99.
100.
F. Faranda A. Salleo G. Lo Paro A. Manganaro 《Aquaculture (Amsterdam, Netherlands)》1984,37(2):125-131
Juvenile Penaeus kerathurus (average weight = 0.64 g) were fed three different daily amounts (40%, 60% and 100% of biomass) of an unprocessed and unsupplemented diet composed of 43% anchovy, 33% shrimp head and 24% squid, whose suitability for P. kerathurus had been previously assessed. The experiment was performed with an animal density of 30/m2 at 23° C for a period of 180 days. From the results obtained, it is concluded that, of the three feeding rates employed, 100% of biomass was suitable for animals weighing 0.64–1.8 g. For animals 1.8–4.3 g a feeding rate of 60% was appropriate, while a reduction to 40% seemed satisfactory for animals over 4.3 g in this experiment. 相似文献