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621.
Many studies of copepod egg production have shown that food availability and temperature are major factors that influence copepod growth. However, coastal environments are complicated ecosystem and the relationships between growth of copepods and influencing factors are not always clear in nature. We conducted a study along an inner–middle–outer bay transect where variations in environmental parameters would be expected to affect the biomass and egg production rate of A. hongi from February 2001 to December 2001. In this study, we investigated the abundance and biomass with developmental stages and egg production rates of A. hongi in relation to various environmental factors. The copepod A. hongi occurred continuously throughout the year, with a peak abundance in May. In general, the variation in egg production rates showed a similar tendency with the variations in chlorophyll-a throughout the study period. This suggests that phytoplankton biomass is an important factor that affects the egg production of A. hongi. In addition, during the warm season, the egg production of A. hongi was also influenced by the ciliates abundance in the middle and outer bay. Consequently, the egg production of A. hongi is generally affected by food availability in Kyeonggi Bay. 相似文献
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A new coupled ice–ocean ecosystem model that links the pelagic and ice ecosystems was used to clarify the role of ice algae in ice-covered ocean ecosystems. The model was applied to Lake Saroma (Hokkaido, Japan) in 1992. Comparison of the model's results with observational data confirmed that the model reproduced the behavior of the ecosystem with acceptable accuracy during the period from winter to spring. The primary production of the ice algae is effectively transported into the pelagic system by means of physical releasing effects: brine convection, ice melting and freezing, and diffusion generated at the bottom of the ice. Ice algae released from the ice are rapidly exported because of their high sinking speed and the shallow depth of Lake Saroma. For this reason, the zooplankton in Lake Saroma cannot graze these released algae. However, zooplankton actively graze the ice algae living along the bottom of the ice. These results show that, before their release, ice algae play an important role as a food source for overwintering zooplankton. A sensitivity analysis revealed a positive correlation between the sinking speed of the released ice algae and the magnitude of the spring bloom by pelagic phytoplankton, and that the time when secondary production becomes active is an important factor in the linkage between these two algal populations. 相似文献
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在中国,二手车鉴定评估还缺乏科学统一的评估理论和方法。文中以重置成本法为依据,并对重置成本法进行了改进,阐述了如何利用改进的重置成本法来确定二手车价值,并进行了实例验证,证明了改进的重置成本法的有效性。 相似文献
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黑龙江省农村金融有效供给机制现状及对策 总被引:1,自引:0,他引:1
长期以来,我国农村金融改革和发展相对缓慢,成为制约农村经济发展和农民生活水平提高的重要因素。目前,城市流动性过剩愈演愈烈,资金供应非常充裕,而农村地区资金需求缺口巨大,缺乏引导资金流向农村的有效渠道。分析农村金融供给体系存在的问题,探讨建立与农村金融需求相适应的长效供给机制具有十分重要意义。 相似文献
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针对目前国内修船市场业务量萎缩的现状,为减少资源浪费,根据中海工业立新船厂的实践经验,简要阐述控制劳动力数量、租赁闲置设备、减少加班运营及考核工作效率等控制产能的方法;同时在成本控制方法方面,文章提出“周期一价格曲线”和“工程量一价格曲线”的报价方法以供业内船厂参考,期望通过报价形式的改变将部分修船成本转嫁出去,达到成本控制的目的。 相似文献