Grass carp larval density synchronised with river discharge fluctuations in the subtropical Pearl River, China

文献类型： 外文期刊

第一作者： Zhang, Yingqiu

作者： Zhang, Yingqiu;Li, Xinhui;Li, Jie;Li, Yuefei;Zhang, Yingqiu;Li, Xinhui;Li, Jie;Li, Yuefei;Zhang, Yingqiu;Li, Xinhui;Li, Jie;Li, Yuefei;Zhang, Yingqiu;Li, Xinhui;Li, Jie;Li, Yuefei

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关键词： Ctenopharyngodon idella; environmental effects; fish larvae; river flow; wavelet coherence

期刊名称：ECOHYDROLOGY （ 影响因子：2.843； 五年影响因子：3.318 ）

ISSN： 1936-0584

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收录情况： SCI

摘要： River discharge/flow exerts fundamental driving effects on the river ecosystem and larval abundance dynamics. In the subtropical Pearl River, China, the species-specific effects of river discharge on the occurrence of grass carp larvae remain unknown. We performed cross wavelet analysis, using data on the daily density of larvae collected from 2006 to 2013 at a fixed site downstream in the Pearl River, to explore the temporal correlation between river discharge/water temperature and larval density. We further used the conditional random forest and generalised additive models to determine relevant environmental effects on their relationship. Grass carp larvae appeared from late April to early October, but mainly during June and July. River discharge, but not water temperature, showed significant coherence and in-phase relationship with larval density. For discharge in significant coherence with larval density, it ranged from 4,740 to 28,700 m(3)/s, with peak discharge from 4,900 to 30,900 m(3)/s, and the discharge fluctuation state from -16 to 10 days (where - indicates the falling stage and + the rising stage). Maximum daily temperature/water temperature, ammonia-nitrogen concentration, peak discharge and discharge contributed the most to the variations in coherence and phase relationships between discharge and larval densities over the short timescale (<32 days) and accounted for 22.4% of coherence variation, 19.7% of in-phase degrees and 15% of variation in phase lagging. These suggest that a combination of ecological regulation and water environment control would be efficient to promote the recruitment of grass carp and relevant freshwater fish species.

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