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首页> 外文期刊>Journal of Applied Ichthyology >Hydrological and water chemical factors in the Yichang reach of the Yangtze River pre- and post-impoundment of the Three Gorges Reservoir: consequences for the Chinese sturgeon Acipenser sinensis spawning population (a perspective)
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Hydrological and water chemical factors in the Yichang reach of the Yangtze River pre- and post-impoundment of the Three Gorges Reservoir: consequences for the Chinese sturgeon Acipenser sinensis spawning population (a perspective)

机译：长江三峡水库蓄水前后宜昌河段的水文和水化学因素：对中华st中华A产卵种群的影响（观点）

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摘要

In order to understand the downstream hydrological and water chemical status after impoundment of the Three Gorges Reservoir (TGR) and to assess the impact of changes on the spawning of Chinese Sturgeon, we assessed hydrological factors (water temperature, water level, water discharge and sediment concentration), and some water chemical factors (dissolved oxygen and ammonia-N) at the Yichang spawning reach during pre- and post-impoundment periods. In addition, hydro-acoustic survey on the occurrence and distribution of Chinese sturgeon were undertaken and investigations on sturgeon-egg-eating predatory fishes were conducted to evaluate the spawning occurrence date of the Chinese sturgeon during autumn between 1997 and 2008. The main subject of interest is whether changes in spawning ground conditions occurred in pre- and post impoundment periods, from 1998 to 2008. After impoundment of TGR, when spawning occurred, many environmental factors decreased from pre-impoundment levels: sediment concentration (down 96.30%), water discharge (down 33.44%), flow velocity (down 12.20%) and water level (down 4.52%). Judging from the annual cycle, annual mean ammonia-N decreased by 50.9%, annual mean dissolved oxygen concentration also decreased by 9.6%. However, some factors increased: monthly average water temperature (increase 7.5% to a mean of 18.7 degrees C) in every Nov after impoundment. The analysis showed that the number of days with suitable water temperature for Chinese sturgeon spawning between Oct and Nov varied according to the highest impoundment level of the TGR. The annual natural spawning activity showed that there were two spawning periods each year from 1997 to 2002 (pre-impoundment period) with the exception of 1998, but there was only one spawning period each year from 2003 to 2008 (post-impoundment period). There was annual average 369 adults in 1998-2002, and there was annual average 231 adults in 2004-2008. There was annual spawning magnitude 3547.5 ten thousand eggs in 1997, and there was only 193.5 ten thousand eggs in 2008. The date for the beginning of spawning was delayed gradually by the impoundment of TGR. The later spawning periods may relate to a change in original water temperature rhythm in the Yichang spawning reach and reaching the upper limit of the spawning temperature in the fall after 2003 may also be the key to regulate occurrence of reproduction and its intensity.
机译：为了了解三峡水库（TGR）蓄水后的下游水文和水化学状况，并评估变化对中华urge产卵的影响，我们评估了水文因素（水温，水位，排水量和沉积物）围产期前后宜昌产卵期的一些水化学因素（溶解氧和氨氮）。此外，对中华st的发生和分布进行了水声调查，并进行了以食st鱼为食的掠食性鱼类的调查，以评估中华st在1997年至2008年秋季的产卵日期。有趣的是，在1998年至2008年的蓄水前后，产卵场条件是否发生了变化。TGR蓄水后，产卵时，许多环境因素都比蓄水前水平降低了：沉积物浓度（下降了96.30％），水流量（下降33.44％），流速（下降12.20％）和水位（下降4.52％）。从年循环来看，年平均氨氮下降了50.9％，年平均溶解氧浓度也下降了9.6％。但是，一些因素增加了：蓄水后的每个十一月，月平均水温（升高7.5％，至平均18.7摄氏度）。分析表明，在十月至十一月之间，适合中华temperature产卵的水温天数根据TGR的最高蓄水量而变化。年度自然产卵活动表明，除1998年外，1997年至2002年（蓄水前期）每年有两个产卵期，但2003年至2008年（蓄水后期）每年只有一个产卵期。 1998年至2002年，年平均369名成年人，2004年至2008年，年平均231名成年人。 1997年的年产卵量为3547.5个万卵，而2008年只有193.5个万卵。产卵开始的时间由于TGR的蓄积而逐渐推迟。后期的产卵期可能与宜昌产卵期原始水温节律的变化有关，在2003年以后的秋季达到产卵温度的上限也可能是调节繁殖发生及其强度的关键。

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