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Abstract –  Winter growth and survival of wild individually tagged juvenile Arctic charr (1+ age) from a riverine anadromous stock, were studied in a small ice-covered (∼6 months) ground water brook (temperature ∼1 °C) connected to Skibotnelva in subarctic northern Norway. The overall winter survival was estimated to be 68% from late October 2005 to early May 2006. The recaptured charr were not significantly different in initial length or weight compared with the nonrecaptured fish suggesting low size-dependent mortality. The majority (98%) of the recaptured charr showed significant increase in size, with a mean increment of 62% from their initial bodyweight and 12% of the charr parr had more than doubled their weight. The mean specific growth rate was calculated to be slightly lower (0.27) than estimated values from a growth model (∼0.35). In addition, the condition factor increased significantly during the field experiment. These results are the first individual growth data on riverine anadromous Arctic charr parr under natural winter conditions, and indicate that charr can grow relatively fast during periods with low temperature and also that ground water brooks can be good over-wintering habitat for juvenile Arctic charr. These results suggest that the winter period is perhaps a less severe bottleneck than previously recognised for the cold-adapted Arctic charr.  相似文献
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水资源是制约绿洲农业发展的关键因素,同时绿洲的农业活动也直接或间接地影响着区域水资源的循环过程,造成水资源时空分布的差异。博斯腾湖小湖区位于博斯腾湖西部,其水资源主要来源于开都河及灌区地下水的补给,研究小湖区的生态需水是协调区域生态环境与人类生产生活效益的重要环节。因此,本文基于MIKE-SHE水文模型及水量平衡公式,以2017年为研究背景,量化了不同种植结构情景下的地下水及地表水对于小湖补给量的变化情况,核算了区域年补给总量,进而讨论了绿洲农业区最适宜小湖生态需水要求的农业种植结构。结果显示:模型在验证期模拟值与观测值的平均相关系数及纳什系数分别为0.89及0.79,表明模型具有较高的可信度;水稻及油菜分别为地下水及地表水对小湖补给量最大的农业种植结构,补给量约为10.628×10^6m3及538.023×10^6m3,其中地下水对于小湖的补给量与灌溉期、灌溉定额、作物种类有着强烈的相关关系,地表水对于小湖的年补给量远远大于地下水,且与总补给量高度相关,成为小湖总补给量的决定性因素;油菜及小麦的年补给量分别为544.939×10^6m3及541.158×10^6m3,进而讨论在生态需水要求下不同种植结构所需最小的配水量,为区域水资源决策管理及协调配置提供理论支持。  相似文献
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Production of shrimp in inland ponds supplied by water from saline aquifers is a potential new aquaculture industry in Alabama. Examination of 2,527 well records of the Geological Survey of Alabama and the United States Geological Survey and samples from 35 wells revealed 238 wells with chloride concentration of 125 mg/L chloride or more in 11 counties of central and west-central Alabama. Chloride concentrations varied from 136 mg/L to 94,000 mg/L. The highest chloride concentrations were from wells in Washington, Choctaw, and Clarke Counties. However, 83% of the saline-water wells in Dallas, Hale, Greene, Marengo, Wilcox, and Sumter Counties were supplied by aquifers of the Eutaw, Gordo, McShan, and undifferentiated Eutaw-McShan formations. Water from these wells had an average and standard deviation of 1,238 ± 615 mg/L chloride. Based on the frequency of saline-water wells, the number of wells with chloride concentrations above 700 mg/L (about 2 ppt salinity), and well depths, it was concluded that Hale, Greene, Marengo, and Sumter Counties have the greatest potential for saline-water aquaculture. Contour maps for chloride concentrations and depths of wells in these four counties were prepared to better delineate this potential water source for aquaculture. There were, however, areas in Lowndes, Tuscaloosa, and Wilcox Counties with saline ground water suitable for inland aquaculture.  相似文献
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