排序方式： 共有27条查询结果，搜索用时 15 毫秒
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Albert A. Zijlstra Mikako Matsuura Peter R. Wood G. C. Sloan Eric Lagadec Jacco Th. van Loon M. A. T. Groenewegen M. W. Feast J. W. Menzies P. A. Whitelock J. A. D. L. Blommaert M.-R. L. Cioni H. J. Habing S. Hony C. Loup L. B. F. M. Waters 《Monthly notices of the Royal Astronomical Society》2006,370(4):1961-1978
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We investigated temporal (day‐to‐day and season) and spatial (reach) variability of drift with the aim of guiding sampling protocol for quantifying drift at the whole river or reach scale. Overall, we found aquatic drift density and biomass varied considerably seasonally (CV = 72.9, 88.1) and to a lesser extent spatially (CV = 31.3, 30.7) and from day‐to‐day (CV = 45.2, 39.4). Although spatial and day‐to‐day variation in drift density and biomass were similar, sampling logistics suggest spatial sampling would be more cost‐effective and less time consuming. Drift density and biomass estimated from top samplers was often higher than estimates from samplers near the streambed or mid‐water column. A reliable estimate of mean densities and biomass at a site may require only two samplers— a top sampler and either a middle or bottom sampler. In our study, we calculated that sampling at four sites over 1 or 4 days at one site would be required to obtain a 95% CI within 50% of the mean drift density. Eight sites over 1 or 10 days at one site would be required to achieve a 95% CI within 25% of the mean drift density. 相似文献
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Jacco Kromkamp 《新西兰海洋与淡水研究杂志》2013,47(3):457-465
The most common storage products of cyanobacteria are polyphosphate as a phosphorus storage compound, cyanophycin or phycobilin protein pigment as nitrogen storage products, and glycogen as a storage product of both carbon and energy. Nutrient uptake kinetics are regulated by the storage pools, and the patterns of regulation have a feedback effect on the amount of accumulated nutrient in the cells. Besides having a storage function the nutrient storage products are likely to act as metabolic sinks during conditions of energy stress. Regulation of storage products is especially strict in light‐limited cultures. By increasing the rate of polysaccharide formation during growth with short photoperiods, cyanobacteria are able to sustain relatively high growth rates. This effect is enhanced by keeping respiratory losses very low. 相似文献
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