Habitat use of the tapertail anchovy(Coilia mystus Linnaeus, 1758) from the Oujiang River Estuary and the Zhujiang(Pearl) River Estuary was studied by examining the environmental signatures of Sr and Ca in otoliths us...Habitat use of the tapertail anchovy(Coilia mystus Linnaeus, 1758) from the Oujiang River Estuary and the Zhujiang(Pearl) River Estuary was studied by examining the environmental signatures of Sr and Ca in otoliths using electron probe microanalysis. Individuals from the Oujiang River had higher and varied Sr:Ca ratios(expressed as(Sr:Ca)×1 000, 3.83–13.0 average) in the otolith core regions, suggesting that they were born in brackish or sea waters, and that a freshwater habitat might not be necessary for egg hatching and larval growth.While, individuals from the Zhujiang River had lower Sr:Ca ratios(0.39–2.51 average) in the core regions,suggesting a freshwater origin. After hatching, anchovies from the Zhujiang River migrate downstream to the river estuary close to brackish water. Our results demonstrated varied habitat use for spawning during stages of early life history between the two populations, and suggested that such variations are promoting diversity of life history strategies of this species.展开更多
The Oujiang River Estuary(ORE)is a macrotidal estuary with drastic variation of river discharge and large tidal range.Numerical simulations based on the unstructured grid,Finite-Volume,primitive equation Community Oce...The Oujiang River Estuary(ORE)is a macrotidal estuary with drastic variation of river discharge and large tidal range.Numerical simulations based on the unstructured grid,Finite-Volume,primitive equation Community Ocean Model(FVCOM)are conducted to investigate the intratidal and intertidal variations of salinity with an extremely upstream river boundary and large computational domain.The dynamic equation of potential energy anomaly is adopted to evaluate the stratification and mixing processes from model results.Meanwhile,the stability of estuarine stratification on different timescales and its spatial variation are studied using estuarine Richardson number and stratification parameter.The critical values of tidal range and river discharge that determine the stratification state are obtained.The critical values exhibit distinct spatial difference.The north branch of the ORE exhibits well-mixed conditions when the tidal range exceeds 3.8,4.0 and 4.6m at upper inlet,middle segment and the river mouth,respectively.When river discharge is below 280 m^3/s or exceeds 510 m^3/s,the upper part of the north branch is well-mixed sustainably.Near the river mouth,river discharge of 280 m^3/s is a rough critical value that separates well-mixed and stratified states.It is also concluded that periodic stratification exists in the North Channel.The lower estuary appears to be partially stratified at early ebb or early flood tide,and well-mixed in other tidal stages.The stratification only develops during early ebb in the upper segment.The enhancement of stratification is mainly caused by longitudinal advection and lateral velocity shear,while turbulent mixing and longitudinal tidal strain are the main factors of stratification attenuation.展开更多
A 3D, time-dependent, baroclinic, hydrodynamic and salinity model was implemented and applied to the Oujiang River estuarine system in the East China Sea. The model was driven by the forcing of tidal elevations along ...A 3D, time-dependent, baroclinic, hydrodynamic and salinity model was implemented and applied to the Oujiang River estuarine system in the East China Sea. The model was driven by the forcing of tidal elevations along the open boundaries and freshwater inflows from the Oujiang River. The bottom friction coefficient and vertical eddy viscosity were adjusted to complete model calibration and verification in simulations. It is demonstrated that the model is capable of reproducing observed temporal variability in the water surface elevation and longitudinal velocity, presenting skill coefficient higher than 0,82. This model was then used to investigate the influence of freshwater discharge on residual current and salinity intrusion under different freshwater inflow conditions in the Oujiang River estuary. The model results reveal that the river channel presents a two-layer structure with flood currents near the bottom and ebb currents at the top layer in the region of seawater influenced on north shore under high river flow condition. The river discharge is a major factor affecting the salinity stratification in the estuarine system, The water exchange is mainly driven by the tidal forcing at the estuary mouth, except under high river flow conditions when the freshwater extends its influence from the river＇s head to its mouth.展开更多
基金The China Central Governmental Research Institutional Basic Special Research Project from Public Welfare Fund under contract No.2016PT01the Open Project for Key Laboratory of South China Sea Fishery Research Exploitation&Utilization of Ministry of Agriculture under contract No.FREU2015-07+2 种基金the Central Public-interest Scientific Institution Based Research Fund,Freshwater Fisheries Research Center,CAFS under contract No.2017JBFR02the National Natural Science Foundation of China under contract No.31602159the Natural Science Foundation of Jiangsu Province,China under contract No.BK20160204
文摘Habitat use of the tapertail anchovy(Coilia mystus Linnaeus, 1758) from the Oujiang River Estuary and the Zhujiang(Pearl) River Estuary was studied by examining the environmental signatures of Sr and Ca in otoliths using electron probe microanalysis. Individuals from the Oujiang River had higher and varied Sr:Ca ratios(expressed as(Sr:Ca)×1 000, 3.83–13.0 average) in the otolith core regions, suggesting that they were born in brackish or sea waters, and that a freshwater habitat might not be necessary for egg hatching and larval growth.While, individuals from the Zhujiang River had lower Sr:Ca ratios(0.39–2.51 average) in the core regions,suggesting a freshwater origin. After hatching, anchovies from the Zhujiang River migrate downstream to the river estuary close to brackish water. Our results demonstrated varied habitat use for spawning during stages of early life history between the two populations, and suggested that such variations are promoting diversity of life history strategies of this species.
基金The National Key Research and Development Program of China under contract No.2016YFC1401802
文摘The Oujiang River Estuary(ORE)is a macrotidal estuary with drastic variation of river discharge and large tidal range.Numerical simulations based on the unstructured grid,Finite-Volume,primitive equation Community Ocean Model(FVCOM)are conducted to investigate the intratidal and intertidal variations of salinity with an extremely upstream river boundary and large computational domain.The dynamic equation of potential energy anomaly is adopted to evaluate the stratification and mixing processes from model results.Meanwhile,the stability of estuarine stratification on different timescales and its spatial variation are studied using estuarine Richardson number and stratification parameter.The critical values of tidal range and river discharge that determine the stratification state are obtained.The critical values exhibit distinct spatial difference.The north branch of the ORE exhibits well-mixed conditions when the tidal range exceeds 3.8,4.0 and 4.6m at upper inlet,middle segment and the river mouth,respectively.When river discharge is below 280 m^3/s or exceeds 510 m^3/s,the upper part of the north branch is well-mixed sustainably.Near the river mouth,river discharge of 280 m^3/s is a rough critical value that separates well-mixed and stratified states.It is also concluded that periodic stratification exists in the North Channel.The lower estuary appears to be partially stratified at early ebb or early flood tide,and well-mixed in other tidal stages.The stratification only develops during early ebb in the upper segment.The enhancement of stratification is mainly caused by longitudinal advection and lateral velocity shear,while turbulent mixing and longitudinal tidal strain are the main factors of stratification attenuation.
基金financially supported by the National Natural Science Foundation of China(Grant No.50339010)the National Key Technology R & D Program of China(Grant No.2012BAB03B01)State water pollution control and management of Special Science and Technology Project(Grant No.2009zx07210-10)
文摘A 3D, time-dependent, baroclinic, hydrodynamic and salinity model was implemented and applied to the Oujiang River estuarine system in the East China Sea. The model was driven by the forcing of tidal elevations along the open boundaries and freshwater inflows from the Oujiang River. The bottom friction coefficient and vertical eddy viscosity were adjusted to complete model calibration and verification in simulations. It is demonstrated that the model is capable of reproducing observed temporal variability in the water surface elevation and longitudinal velocity, presenting skill coefficient higher than 0,82. This model was then used to investigate the influence of freshwater discharge on residual current and salinity intrusion under different freshwater inflow conditions in the Oujiang River estuary. The model results reveal that the river channel presents a two-layer structure with flood currents near the bottom and ebb currents at the top layer in the region of seawater influenced on north shore under high river flow condition. The river discharge is a major factor affecting the salinity stratification in the estuarine system, The water exchange is mainly driven by the tidal forcing at the estuary mouth, except under high river flow conditions when the freshwater extends its influence from the river＇s head to its mouth.
