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

Yingqiu Zhang,Xinhui Li,Jie Li,Yuefei Li

Published 2021 in Ecohydrology

ABSTRACT

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 m3/s, with peak discharge from 4,900 to 30,900 m3/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.

PUBLICATION RECORD

  • Publication year

    2021

  • Venue

    Ecohydrology

  • Publication date

    2021-09-03

  • Fields of study

    Biology, Environmental Science

  • Identifiers
    DOI 10.1002/eco.2355
  • External record

    Open on Semantic Scholar

  • Source metadata

    Semantic Scholar

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