Migration patterns and habitat use of the tapertail anchovy Coilia mystus in the Oujiang River Estuary and the Zhujiang River Estuary, China

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.

Characteristics of Heavy Minerals and Quantitative Provenance Identification of Sediments from the Muddy Area Outside the Oujiang Estuary Since 5.8 kyr

The heavy mineral compositions of the sediments in core D04 with a length of 20.2 m from the muddy area outside the Oujiang Estuary along the coast of Zhejiang-Fujian Provinces have been analyzed. Core D04 can be divided into three units: DU1(0–7.4 m), DU2(7.4–11.4 m) and DU3(11.4–20.2 m). The results showed that the heavy minerals are authigenic pyrite(65.6%)– hornblende(16.0%) – epidote(4.6%) assemblages. The core sediments are mainly composed of clayey silt, which belongs to the clinoform deposit formed since 5.8 kyr, indicating a weak hydrodynamic environment. The deposition rates changed in the trend of high-low-high upward. Quantitative analysis shows that the core sediments were mainly from the suspended sediments of the Changjiang(Yangtze) River, accounting for 79.2%, with only 10.0% from Oujiang, and 10.8% from other provenance. The Oujiang-derived sediments were gradually increased from the bottom unit DU3(3.1%) to the top unit DU1(17.8%), but the Changjiang-derived sediments were gradually decreased. The source changes are closely related to the development of Yangtze River Delta and Wenzhou Bay, climate changes and human activities. During the period of 2.1–3.7 kyr, the sediment supply was greatly reduced due to the poor reclamation capacity of the river basins, resulting in a low deposition rate. Since 2 kyr, the enhancement of human activities in the Yangtze River Basin and the Oujiang River Basin led to more soils to be eroded and transported to the study area. Due to the short distance of the site of core D04 from the Oujiang River mouth, the study area received more Oujiang-derived sediments when upper unit(DU1) deposited than the lower units(DU2 and DU3).

A numerical study on salinity stratification at the Oujiang River Estuary, China

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.

Modeling Residual Circulation and Stratification in Oujiang River Estuary

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.

Three-dimensional tidal current numerical model of the Oujiang Estuary

The characteristics of three-dimensional （3-D） tidal current in the Oujiang Estuary are investigated according to in situ observations. The Oujiang Estuary has features of irregular coastline, complex topography, many islands, moveable boundary, and submerged dyke, therefore, σ 3-D numerical model oil an unstructured triangular grid has been degeloped. The σ coordinate transforination, the moveable boundary and submerged dyke treatment techniques were employed in the model so it is suitable for the tidal simulations in the Oujing Estuary with submerged dyke and moveable boundary problems. The model is evaluated with the in situ data, and the results show that the calculated water elevations at 19 stations and currents at 19 profiler stations are in good agreement with measured data both in magnitude and phase. This numerical model is applied to the 3-D tidal circulation simulations of experiments in stopping flow transport through the South Branch of the Oujiang Estuary, and the feasibility to cutoff the flow in the South Branch of the Oujiang Estuary is demonstrated by numerical simulation experiments. The developed numerical model simulated the 3-D tidal current circulations in complicated coastal and estuarine waters very well.

Monitoring and Evaluation of Environmental Quality of the Waters near the Oujiang River Estuary in Wenzou

Based on the monitoring results of environmental quality of the waters near the Oujiang River estuary from 2010 to 2017,the present situation of environmental quality of the waters was analyzed and evaluated.The results showed that pH,DO,COD Mn ,petroleum,and heavy metal (Cu,Pb,Zn,Cd,Hg,As and Cr) content in the waters near the Oujiang River estuary did not exceed the second-class standard of Seawater Quality Standard (GB 3097-1997),while both inorganic nitrogen and reactive phosphate in the waters greatly exceeded the second-class standard.The water quality near the Oujiang River estuary was in an eutrophic state.In terms of sediment quality,the standard index of most evaluation factors except for Cu was smaller than 1,meeting the demands of sediment quality for environmental protection.

NUMERICAL STUDY ON SALINITY STRATIFICATION IN THE OUJIANG RIVER ESTUARY

The variations of current, salt intrusion and vertical stratification under different conditions of river flow and wind in the Oujiang River Estuary （ORE） were investigated in this article using the Environmental Fluid Dynamics Code （EFDC）. The model was verified against water level variation, velocity, and salinity variations in June 2005. The simulation results agreed well with measured data. Six sensitivity tests were conducted for different conditions of river flow and wind specified in the model. Model results show that salinity intrudes further upstream under scenarios with low flow and downriver local wind conditions. In contrast, the responses of salinity stratification to different environmental forcing functions were different in different portions of the estuary. Salinity stratification was enhanced under high flow condition. Model results also show that wind is not crucial to the salt intrusion and salinity stratification in the ORE.

瓯江口海域鱼类早期资源群落结构及优势种相关性分析

为掌握瓯江口海域鱼类早期资源现状及其与主要环境因子之间的关系,基于2021年春季(5月)、夏季(8月)和秋季(11月)对瓯江口海域内25个站位的表层水平拖网数据和温度、盐度及pH等基础水文调查数据,对该海域鱼卵、仔稚鱼的物种优势度、生物多样性和群落结构特征等进行分析,同时探讨优势种侧带小公鱼属鱼类(Stolephorus spp.)资源分布与环境因子之间的关系。结果表明:3个航次调查共采集鱼卵8427粒,仔稚鱼40365尾,共鉴定49种,隶属于12目23科39属,以鲈形目(Perciformes)为主要类群,在发育阶段上以前弯曲期仔鱼居多,按照生态类型划分主要以海洋性与河口性鱼类为主。调查海域内不同季节采获鱼卵、仔稚鱼的种类、数量和密度有所差异,平均密度在0.07—4.72粒(尾)/m^(3),春季最高分别为34种、38083粒(尾)和4.72粒(尾)/m^(3)。在空间分布上,鱼卵沿着瓯江口由内向外呈递增趋势,而仔稚鱼则呈递减趋势。同时各季节鱼卵、仔稚鱼生物多样性的差异性较为显著,春季的多样性指数(H’)和均匀度指数(J’)均为最高,丰富度指数(D)最高值出现在夏季。调查海域内各季节鱼卵、仔稚鱼的优势种组成差异较大,除共有优势种侧带小公鱼属鱼类外,春季、夏季和秋季航次的主要优势种分别为虾虎鱼科鱼类(Gobiidae spp.)、凤鲚(Coilia mystus Linnaeus)和舌鳎属鱼类(Cynoglossus sp.1)。利用相对重要性指数IRI计算物种优势度,结果显示侧带小公鱼属鱼类的优势度在所有航次中均为最高,通过分析其与环境因子的关系,发现与盐度的相关性最高(P<0.01),与温度相关性最低(P<0.05)。经与历史资料对比,推测春季北龙岛附近海域是鱼类重要的产卵场,高温高盐弱碱的水文环境更有利于侧带小公鱼属鱼类的生长和繁育,这为瓯江口海域鱼类资源养护管理和渔业生态环境的保护提供了参考依据。

瓯江口海域浮游动物群落结构与环境因子的相关性分析

为探究瓯江口海域浮游动物群落结构与环境因子的相关性,分别于2021年3月(冬季)、5月(春季)、8月(夏季)、11月(秋季)对瓯江口海域的浮游动物及海水温度、盐度、叶绿素a浓度等环境因子进行了4个航次的调查。结果显示,本次调查共鉴定出浮游动物78种,其中包括16种浮游幼虫,隶属于8门14大类,夏季物种数最丰富(47种),冬季物种数最低(23种),优势种(Y≥0.02)有17种,其中桡足类占8种,如中华哲水蚤(Calanus sinicus)、中华华哲水蚤(Sinocalanus sinensis)、太平洋纺锤水蚤(Acartia pacifica)和背针胸刺水蚤(Centropages dorsispinatus)等。浮游动物的年平均丰度为(162.95±310.96)ind./m^(3),年平均生物量为(118.85±62.80)mg/m^(3),存在明显的季节变化差异,春季丰度和生物量最高,秋季最低;冬季丰度比夏季高,生物量低于夏季。浮游动物Shannon-Wiener多样性指数(H')、Pielou均匀度指数(J')和浮游动物Margalef丰富度指数(D)年平均值分别为1.500±0.702、0.656±0.270和2.301±1.087。Spearman相关性分析和典范对应分析结果表明,海水温度、盐度、叶绿素a浓度和浮游植物丰度是影响瓯江口海域浮游动物优势丰度的重要环境因素。这为瓯江口环境季节变化对浮游动物的影响研究提供科学参考依据,为瓯江口生物资源的可持续发展提供基础资料和理论依据。

基于鱼类完整性指数的瓯江口水域生态系统健康评价

评价瓯江口水域生态健康状况,为该水域渔业资源保护和恢复提供科学依据。2021年5月和8月对瓯江口进行渔业资源调查,共采集到鱼类59种,隶属10目23科,较2007年历史资料减少了22种,新增9种。针对瓯江口鱼类种群结构及特征,选取鱼类总种类数、数量密度、重量密度、重量多样性指数、中上层鱼类比例、底层鱼类比例、石首鱼科鱼类比例、暖水性鱼类比例、底栖生物食性、鱼类比例、游泳动物食性鱼类比例、产浮性卵鱼类比例等11个指标构建了瓯江口鱼类完整性指数(F-IBI)评价体系。根据2021年渔业资源调查数据,参考历史资料确定评价标准,评价瓯江口水域健康状况。结果表明,在瓯江口18个采样点中,鱼类完整性健康等级为“较好”的有3个,“一般”的有10个,“较差”的有5个。与2007年相比,瓯江口鱼类生物完整性整体呈下降趋势,过度捕捞、大规模围填海等人类活动可能是造成该现象的重要因素。

非直接选育对瓯江彩鲤形态性状的影响

在鱼类育种中,体质量通常是直接选育的目标性状,形态性状因与体质量的相关性而受到非直接选育的影响。为探讨非直接选育对形态性状的影响,以体质量和体色为目标性状、经过11代闭锁群体继代选育的5种体色瓯江彩鲤(“全红”“大花”“麻花”“粉玉”和“粉花”)选育系以及其奠基群体为材料,进行了与奠基群体形态性状相关的分析研究。单因素方差分析发现,在25个形态比例性状中,5个选育系有16~21个性状与奠基群体存在显著差异(P<0.05)。差异倍数分析显示,2个性状在所有选育系中上调明显,1个性状则下调明显。主成分分析显示,5个体色选育系均能与奠基群体明显区分开来;聚类分析发现,奠基群体的所有个体单独聚为一支,与5个选育系距离较远;判别分析指出,选育系与奠基群体间的判别准确率达100%。但以上分析均显示,5个选育系之间不能有效区分,相互间的形态差异较小。分析结果表明,非直接选育已对瓯江彩鲤的形态性状产生了较明显的影响。

温州瓯江口春、秋季主要游泳动物生态位及其分化

根据2020年秋季(11月)和2021年春季(3月)在温州瓯江口附近海域两次渔业资源调查的数据,利用相对重要性指数(IRI)、生态位宽度(Bi)、生态位重叠(Oik)和冗余分析(RDA)等方法,分析主要游泳动物的生态位及其分化。结果表明:温州瓯江口海域游泳动物物种丰富,春季优势种数目高于秋季,其中秋季口虾蛄(Oratosquilla oratoria)的相对重要性指数最高。两季主要游泳动物的生态位宽度(Bi)变化范围为1.20~7.53,广生态位种(Bi≥6)包括两季的日本蟳(Charybdis japonica)、秋季的棘头梅童鱼(Collichthys lucidus)和三疣梭子蟹(Portunus trituberculatus)和春季的脊尾白虾(Palaemon carinicauda);中生态位种(3<Bi<6)包括秋季的龙头鱼(Harpadon nehereus)、口虾蛄(Oratosquilla oratoria)和春季的花鲈(Lateolabrax japonicus)等;窄生态位种(0<Bi≤3)包括秋季的刀鲚(Coilia nasus)、春季的口虾蛄等。两季的生态位重叠变化范围为0.03~0.96,种对间生态位重叠总体差异性较大,其主要受不同物种的食性、栖息环境及捕食关系影响。RDA主要从环境因子影响物种分布和解释种对间生态位重叠不合理现象两个角度体现生态位分化。

温州市瓯江过江通道规划建设问题与对策研究

随着温州瓯江两岸城市建设和社会经济的发展,两岸交流日益密切,过江需求不断增加,原有的过江通道数量少、布局不合理、两岸衔接不畅、交通拥堵等问题逐渐凸显出来。加快完善跨瓯江通道系统、完善两岸道路交通互联互通,是温州坚持市域一体发展,打造现代化拥江滨海花园城市的重要内容。围绕瓯江两岸过江通道现状、需求和规划进行研究梳理,结合相关案例进行总结,提出过江通道规划建设策略及工作举措。

绿道助力共同富裕发展研究——以丽水市大花园瓯江绿道为例

本文通过对丽水市大花园瓯江绿道的调查研究,全面总结出丽水市在绿道建设与发展过程中的特色做法和主要成效,并通过剖析其现实存在的连通性不高、产业融合结构单一、品牌文化作用发挥不足等问题,从加强系统规划、促进产业融合、深化品牌文化宣传提出具体对策,以期进一步推动绿道促进共同富裕的发展。

基于“3S”技术的瓯江流域生态系统健康评价

流域尺度的生态系统健康对区域经济与可持续发展具有重要意义,中小尺度的健康评价并不能完全反映流域尺度下的生态系统健康问题。结合《河湖健康评估技术导则》,基于“3S”技术构建流域尺度下生态系统健康评价指标体系并对瓯江流域开展生态系统健康性评价。评价结果表明:瓯江流域总体处于健康和亚健康状态。其中,宣平溪、小溪等流域健康状况较好,生态系统结构和功能较完善;浮云溪、好溪等流域健康状况相对较差。流域内生态系统健康胁迫因子以河湖纵向连通性为主。结合现场调研,对评价结果进行验证,发现浮云溪和好溪流域人类活动强度较大,植被覆盖率较低,生态系统健康状况较差,基于“3S”技术的流域尺度健康评价方法具有良好的评价效果。

瓯江口春季营养盐、浮游植物和浮游动物的分布

研究2007年4月瓯江口海域(27°38′～28°02′N、120°50′～121°14′E)浮游生物空间分布特征,分析这一分布特征与营养盐和其他水文要素之间的联系。结果表明,悬浮物浓度、DIP和DIN分布特征均是近河口最高,由近河口向外数量逐渐减少。在灵昆岛南侧和东南侧近口门水域,是DIP和DIN的高值中心,但该水域高浓度悬沙使水体透光率较低,不利于浮游植物生长。在口门外侧海域,悬沙浓度已经明显降低,因而是浮游植物高密度区域。浮游植物和浮游动物丰度分布趋势基本相同,由内海向外海数量逐渐递减;其中,大型浮游动物丰度和浮游植物丰度,小型浮游动物丰度和浮游植物丰度之间显著地呈线性正相关关系。这一特征的形成,主要由瓯江口营养盐和悬浮物分布特征决定,浮游动物与浮游植物空间分布的一致性,很好地反映出浮游动物对浮游植物有效的下行控制,从而使水域生态系统在此季节保持稳定。

三水系中华绒螯蟹幼蟹形态判别程序的建立和使用

以中华绒螯蟹幼蟹为研究对象 ,每只幼蟹分别测量 30个形态性状参数 ,用聚类分析和逐步判别两种方法进行综合处理和比较分析。 (1)聚类分析结果表明 :长江、瓯江幼蟹形态相近 ,而辽河幼蟹与上述两者的形态差异较大 ;(2 )用逐步判别筛选出的 14个形态参数的判别分析表明 :三个种群间的形态差异极显著 (P <0 .0 1) ,判别准确率为 :81.4%～ 88.4% (P1)和 82 .5 %～ 91.4% (P2 ) ,判别效果依次为辽河蟹 >瓯江蟹 >长江蟹 ,平均拟合概率为 85 .5 % ;(3)进一步用上述 14个形态参数中对判别分析贡献较大的 9个形态参数作判别分析 ,构建了种群判别公式 ,平均拟合概率虽降至 80 .4% ,但可减少测定和计算工作量的 36 % 。

瓯江口海域夏、秋季口足目和十足目虾类分布特征

采用2007年6月和9月瓯江口海域2个航次的渔业资源调查资料,研究瓯江口海域甲壳动物口足目(Hoplocarida)和十足目(Decapoda)中虾类的资源密度、种类组成和物种多样性等分布,探讨优势种、地形地貌、水团、温度和盐度等因素变化对这些分布的影响。结果表明,在2次拖网调查中,共鉴定口足目2种和虾类17种。口虾蛄(Oratosquilla oratoria)和哈氏仿对虾(Parapenaeopsis hardwickii)是6月的关键种,口虾蛄是9月的关键种。6月和9月2类优势甲壳动物平均质量密度分别为41.14kg/km2和32.36kg/km2,尾数密度为18.41×103ind/km2和10.66×103ind/km2。质量密度与尾数密度分布趋势一致,即调查水域东部高于西部,南部高于北部。6月,种间分布较均匀,物种数多,多样性指数值(H′)较高;9月,在群岛外侧,由于口虾蛄在质量密度上形成单一优势种,导致质量多样性指数下降;但在尾数密度上,种间分布较均匀,尾数多样性指数值明显高于质量多样性指数值。无论是在6月还是9月,高密度区均出现在瓯江口洞头群岛外侧,特别是东南部受台湾暖流影响的海域。瓯江北口外的冲淡水水团是形成瓯江口北侧口足目和十足目虾类密度、种数和多样性低的重要原因。研究结果表明,瓯江冲淡水势力的季节变化是影响瓯江口海域口足目和虾类种类和多样性分布的主要水文因素。

瓯江口水文泥沙特征分析

在大量实测资料的基础上,对瓯江口海区的地貌特征、河道径流特征、河道输沙特征、潮汐特征、潮流特征、余流特征、波浪特征、含沙量特征、泥沙来源、盐度特征、悬沙粒径和底质粒径特征、瓯江南北口的分流和分沙特征、中水道和北水道的分流和分沙特征进行了分析,根据实测资料分析得到了瓯江口挟沙力公式,得到了平衡水深公式,为瓯江河口的工程开发建设和科学研究提供了基础资料。主要研究成果表明:(1)瓯江口的潮汐属正规半日潮类型,平均潮差在4 m以上,属强潮河口;(2)潮流属正规浅海半日潮流类型,呈往复流动,潮流动力强;(3)瓯江为少沙河流,多年平均年悬移质输沙量为205.1万t;(4)瓯江南北口的平均涨潮分流比为21%和79%,落潮平均分流比为26%和74%;(5)瓯江南北口的平均涨潮分沙比为20%和80%,落潮平均分流沙比为22%和78%。

多源卫星降水数据在瓯江流域的适用性分析

为利用卫星降水数据开展流域水文模拟预报,基于瓯江流域内94个雨量站1998~2013年逐日降雨量数据,分析了多源卫星降水数据（TMPA、RT、CMORPH和PERSIANN）在该地区的适用性。结果表明,PERSIANN数据精度最低,其次为CMORPH和RT,TMPA数据精度最高,其中PERSIANN和CMORPH数据低估了实际降水量,而RT和TMPA略高估了降水量;梅汛期和非汛期的精度高于台汛期,月时间尺度降水量的精度高于日时间尺度。各卫星降水数据中,TMPA和RT数据在中雨级别下精度最高,对小雨和大雨级别的降水分别存在低估和高估现象,而PERSIANN和CMORPH数据对所有量级下的降水均存在低估现象;随着雨量的增加,卫星降水的误报率均有不同程度的增加。