瓯江口海域春秋季鱼类多样性及群落结构研究

根据2013年5月(春)、2013年10月(秋)在温州瓯江口海域进行渔业资源定点拖网调查获得的鱼类数据,利用渔获率作为数量分布的指标,对瓯江口海域的鱼类生态类群和鱼类种类组成、优势种、物种数目空间分布及多样性和鱼类群落结构进行了分析。结果显示:两次调查共鉴定鱼类66种,隶属12目37科51属,其中暖温性鱼类29种,占44%,暖水性鱼类37种,占66%,种类季节间变化较为稳定,优势种季节更替明显,春季优势种有银鲳Pampus argenteus、花鲈Lateolabrax japonicus、日本鳀Engraulis japonicus、棕腹刺鲀Gastrophysus spadiceus 4种,而秋季为花鲈、斑鰶Konosirus punctatus、龙头鱼Harpodon nehereus 3种;种类数平面分布结果显示,种类数春季沿岸区域高,秋季岛礁区域高,生物多样性春季高于秋季;多样性指数与种类数平面分布结果相似,均为江口外部海域高于内部,近岸和岛礁处高于中部,地形、台湾暖流和瓯江淡水团对其分布影响较大;春、秋季鱼类群落结构差异不大,种级和属级之间具有相似性。     

瓯江口树排沙湿地不同生境大型底栖动物群落多样性研究

为了解瓯江口树排沙湿地不同生境大型底栖动物群落多样性,于2014年10月至2015年6月对红树林、互花米草及光滩3种生境开展大型底栖动物调查。共鉴定出大型底栖动物48种,隶属于5纲15目31科40属。大型底栖动物年平均栖息密度和生物量,红树林生境最高,互花米草生境次之,光滩生境最低。采用物种多样性指数和G-F多样性指数分析不同生境大型底栖动物群落多样性,发现红树林生境大型底栖动物的多样性高于互花米草生境和光滩生境。单因素方差分析表明:物种数、栖息密度、生物量及物种多样性季节间差异不显著,而物种数、Shannon-Wiener多样性指数与Margalef物种丰富度指数生境间差异显著。人工恢复红树林有助于提高大型底栖动物群落的多样性。     

2015年春、秋季瓯江口鱼卵和仔稚鱼生态分布

为了解瓯江口海域鱼卵和仔稚鱼的生态分布现状,分别于2015年4月和10月在该海域开展生态调查。春、秋两季共采集到鱼卵42粒,仔稚鱼295尾;共鉴定出鱼卵和仔稚鱼16种,分别隶属于8目14科15属,其中鲈形目种类最多。春季鱼卵、仔稚鱼物种数和丰度均远高于秋季。春季鱼卵优势种为斑鰶Konosirus punctatus,秋季为舌鳎属未定种Cynoglossus sp.;春季仔稚鱼优势种为鮻Liza haematocheila、花鲈Lateolabrax japonicus和矛尾鰕虎鱼Chaeturichthys stigmatias,秋季为侧带小公鱼属未定种Stolephorus sp.。瓯江口海域春季鱼卵和仔稚鱼的丰度高值区均位于大门岛周围,该海域应在海洋生态红线划定时予以考虑,秋季则相对分散在较外侧海域。春季仔稚鱼数量分布与盐度和营养盐有极显著相关性。与20世纪90年代初相比,该海域的鱼卵、仔稚鱼物种及数量均在发生变化,数量略呈下降趋势。与浙江近岸其他海域相比,瓯江口海域的鱼卵、仔稚鱼数量偏低。     

筑坝工程对瓯江口及其邻近水域浮游动物群落的影响研究

瓯江口因人工筑坝等原因而形成了以"灵昆岛-灵霓海堤-霓屿岛-状元岙岛-洞头岛"一线为界的南北水域环境差异。为研究瓯江口及其邻近水域的浮游动物生态特征并分析人类活动对其造成的影响,于2009年11月和2010年1月对瓯江口及邻近水域浮游动物进行了调查研究(以浅水I型浮游生物网采集样品),比较了南北水域浮游动物的优势种组成、丰度和次级生产力的差异及其主要影响因素。结果表明:11月,南北水域浮游动物优势种具有明显差异,南部水域暖水种的种类数和丰度高于北部;1月,南北水域优势种无显著差异,主要为广温广盐种。2次调查中,北部水域浮游动物总丰度均高于南部。研究水域浮游动物的次级生产力总体上呈现北高南低的趋势。分析认为,由于人工堤坝、桥梁等近岸海洋工程建筑对海洋地理环境的影响,已导致南北水域浮游动物的优势种组成、丰度和次级生产力分布呈现显著差异。     

基于耳石中锶和钙元素分析破解日本六角川和筑后川河口水域刀鲚的生境履历

为了解日本有明海沿岸六角川和筑后川河口水域鳀科鲚属鱼类刀鲚（Coilia nasus）的洄游特征和生境履历,利用电子探针微区分析（EPMA）技术,对采于两水域刀鲚的矢耳石进行了锶（Sr）元素含量的X射线强度面分布及耳石最长轴锶钙元素比值（Sr:Ca）的定量线分析。结果发现10尾六角川刀鲚（LJC）中的7尾以及15尾筑后川刀鲚（ZHC）耳石核心区域的Sr:Ca比值≤ 3,显示出这些个体在淡水生境出生并早期生活于淡水的履历。紧邻核心区域随后的生长阶段,Sr面分布图谱显示出了多样对应于含量水平差异的不同颜色同心环轮变化样式,Sr:Ca比值的波动亦可相应地分成1-6个差异极其显著的阶段,显示出这些个体在随后生活史阶段中极富变化的生境转换状况。另外3尾六角川刀鲚耳石核心的Sr:Ca比值较高（3-6.7）,对应于半咸水生境;但在核心区域之外,Sr:Ca比值则高低变化不一,显示出这些六角川刀鲚个体在河口半咸水生境孵化的特征。本研究表明,二维Sr元素含量面分布图谱和基于耳石最长轴的Sr:Ca比值完全可以作为重建日本有明海沿岸各河口水域刀鲚生境履历的有效工具。     

基于耳石微化学的南海北部海域两种枪乌贼洄游路线初步研究

根据2016年5月于南海北部采集的中国枪乌贼（Uroteuthis chinensis）和剑尖枪乌贼（U.edulis）样本,分析其不同时期耳石微量元素的差异,推测两种枪乌贼类可能的洄游路线。研究结果表明,选取的枪乌贼样本均孵化于2015年10月-2016年2月,其中主要分布于11-12月。中国枪乌贼耳石Sr/Ca随着月份推移呈现出先降低后回升的趋势;剑尖枪乌贼耳石Sr/Ca在不同月份间有更多的变化,稚鱼期的Sr/Ca为最低;中国枪乌贼耳石的Ba/Ca值随着生长而下降,成鱼期迅速上升,剑尖枪乌贼耳石Ba/Ca由仔鱼期后开始逐渐下降,至成鱼期逐步回升。根据耳石Ba/Ca与水深关系确定了不同生长时期对应的水层,随后将对应水层的平均温度与Sr/Ca建立关系,发现除1月孵化的中国枪乌贼外其耳石Sr/Ca与水温均呈正相关,而剑尖枪乌贼耳石Sr/Ca与水温均呈负相关。根据上述结果,最后推测两种枪乌贼的洄游方式均在大陆架范围内进行南北定向洄游。     

刀鲚、凤鲚和湖鲚矢耳石的形态学比较研究

选取凤鲚(Coilia mystus)、湖鲚(Coilia nasus taihuensis)以及采自崇明、黄海和瓯江口3个水域的刀鲚(Coilia hasps)的矢耳石为对象,描述了这些鱼类耳石的形态特征,并进一步使用基于12组形态数据的框架测量进行了种间和种内比较和判别分析.结果表明耳石形态的差异种间较种内更为明显...     

利用耳石日轮研究珠江口棘头梅童鱼的产卵期及生长

测记耳石生长轮纹数量,依据耳石日轮对采自珠江口的棘头梅童鱼(Collichthys lucidus)的日龄进行了鉴定、并据此研究了其产卵期和生长特性.棘头梅童鱼的产卵期为12月至次年的7月,主要集中在2、4、5月,产卵高峰出现在5月,占样本总数的27.27%;其次为2月,占18.18%.用直线、幂函数和指数函数关系对棘头梅童鱼的生长特性进行回归分析,体长范围为29.8～104.0 mm的棘头梅童鱼的体长与体重关系为幂函数关系,体重生长为匀速生长;体长随日龄的生长关系以幂函数模型符合程度较好,体重与日龄的生长关系则符合指数关系和幂函数关系.研究结果表明,利用耳石日龄来推算棘头梅童鱼的产卵期是可行的,并可用于研究一定体长范围内鱼的生长.     

南海东北部和珠江口沉积物的~(57)Fe穆斯堡尔谱学研究

应用57Fe穆斯堡尔诺学的方法对南海东北部和珠江口沉积物进行了Fe的价态及相对组成的研究，讨论了环境变化对南海东北部沉积物Fe的价态的影响；研究了珠江口沉积物Fe2＋／Fe3＋的比值和溶解态Fe含量与盐度的关系。     

基于高精度海洋动力模型的珠江口羽状流季节和年际变化规律研究

基于高精度海洋动力模型FVCOM (finite-volume community ocean model), 模拟分析了1999—2010年珠江口羽状流的季节和年际变化规律, 并结合经验正交函数(empirical orthogonal function, EOF)分析探讨了影响珠江口羽状流扩展变化的主要动力因子。采用模拟时段内的现场观测数据对多年模拟结果进行验证, 结果表明模型具有较高的精度, 能够较好地模拟珠江口羽状流的扩展变化规律。模拟结果显示, 珠江口羽状流存在显著的季节变化。夏季, 受大径流和西南风的影响, 羽状流的扩展呈现双向特征, 即粤西沿岸扩展和粤东离岸扩展同时存在, 扩展范围最大; 冬季, 径流衰减为最小值, 风场转变为强烈的东北风, 羽状流被紧紧挤压在西岸, 形成狭窄的条带状, 扩展范围最小; 春、秋两季属于过渡季节, 羽状流扩展情况类似, 均表现为沿岸向粤西扩展。年际变化层面, 夏季羽状流的年际变化最为显著, 呈现粤东扩展占优型、近似对称型和粤西扩展占优型三种形态; 春季羽状流的年际变化次之, 羽状流的差异主要体现在珠江口和粤西海域; 秋、冬两季羽状流的年际变化较小, 尤以冬季最小。EOF分析的第一模态可以解释整体变化的91.2%, 反映了径流量对珠江口羽状流的影响; 第二模态可以解释整体变化的4.1%, 反映了盛行风对珠江口羽状流的影响。     

2015年7月珠江口逆温现象的观测与分析

根据珠江口2015年7月6日至17日航次的CTD（conductivity, temperature, and depth）观测结果,分析得到：珠江口附近海域存在海水的垂向逆温现象,逆温差平均值为0.42 oC,上界深度在1 m-6 m间,下界深度在3 m-10 m间,逆温层平均厚度约为4 m。根据时空分布差异的不同,逆温现象可区分为以下三种情况：（1）在狮子洋、太平水道和蕉门水道的出口汇集处,存在温、盐差异的不同水体的交互过程中,由于潮汐和径流的作用所形成的水平流场差异导致了垂向温度的逆转现象。（2）在珠江口西侧的盐度锋面区域附近,第一航段观测期间锋面内侧低盐水团的温度低于锋面外侧高盐水团约2 oC,此时可观测到逆温现象;但在同一区域的第二航段观测期间由于河口内表层水温的上升,导致了逆温现象消失。该区域盐度锋面附近的两个水团在锋面位置附近发生叠置,冲淡水覆盖于海水之上,两个水团的温、盐差异是温度逆转现象的主因。（3）香港西南侧的上升流区域与盐度锋面的相互作用导致了该区域逆温现象的产生。     

Otolith microchemical evidence revealing multiple spawning site origination of the anadromous tapertail anchovy (Coilia nasus) in the Changjiang (Yangtze) River Estuary

The estuarine tapertail anchovy(Coilia nasus) is a high-value commercial fish. Estimating the spawning site or hatchery origin and habitat is essential for its conservation. This study aimed to determine the habitat use and life history characteristics of C. nasus from the Changjiang River Estuary. We investigated the environmental signatures of strontium(Sr) and calcium(Ca) in the otoliths of the collected specimens using electron probe microanalysis; additionally, we examined their gonadal mat...     

Contrasts between estuarine and river systems in near-bed turbulent flows in the Zhujiang (Pearl River) Estuary, China

A bottom-mounted instrumental tripod was deployed in the tidally energetic Zhujiang (Pearl River) Estuary to examine the contrasting properties of the bottom boundary layer (BBL) flows between estuarine and tide-affected river systems. Three aspects of the BBL flows were investigated to understand the mechanism of the turbulence responses to the large-scale ambient forcing: the flow structures (profile, anisotropy, and spectra), shearing strains and stresses, and the balance of turbulent kinetic energy (TKE). Single log-law profiles and turbulence anisotropy predominated in the two systems, but the non-log regime and stronger anisotropy occurred more frequently at the slack tide in the estuary. The ADV-based turbulence intensities and shearing strains both exceeded their low-frequency counterparts (frictional velocities and mean shears) derived from the logarithmic law. On the contrary, the ADV-based Reynolds stresses were smaller than the log profile-derived bottom stresses, so the hypothesis of a constant stress layer cannot be well satisfied, especially in the river. The bandwidth of the inertial subrange in the river was of one decade larger than in the estuary. The balance between shear production and viscous dissipation was better achieved in the straight river. This first-order balance was significantly broken in the estuary and in the meandering river, by non-shear production/dissipation due to wave-induced fluctuations or salinity/sediment stratification. All these disparities between two systems in turbulence properties are essentially controlled by the anisotropy induced by the large-scale processes such as secondary currents, density stratification. In conclusion, the acceleration of unsteady flows determines the profile structure of the BBL flow, and turbulence anisotropy results in the invalidation of the phenomenological relations such as the constant stress hypothesis and the first-order TKE balance.     

珠江口最大浑浊带的形成与季节变化

应用Delft3D研究了珠江口最大浑浊带的分布以及影响因素。盐度和悬沙浓度的垂向分布揭示出最大浑浊带范围的变化。最大浑浊带在干季的悬沙浓度比湿季更大,而其中心位置与湿季相比向上游移动10 km。最大浑浊带的形成受到潮汐、径流和地形的综合影响,而沉积物的再悬浮和垂向环流为影响最大浑浊带的主要因素。     

Habitat use by the European eel Anguilla anguilla in Irish waters

The apparent use of marine and freshwater habitats by European eel Anguilla anguilla was examined by analyzing the strontium (Sr) and calcium (Ca) concentrations in otoliths of the eels collected from Irish coastal and fresh waters. The age and growth of eels were also examined using their otolith annuli. The sizes and ages of the female eels were greater than those of the males. The somatic growth rates ranged from 15 to 62 mm/year, which is typical for Ireland and other European countries. Analyses of Sr:Ca ratios along a life history transect in each otolith showed peaks (maximum more than 25 × 10⁻³) between the core and elver mark corresponding to the period of their leptocephalus and early glass eel stages in the ocean. Outside the elver mark, the Sr:Ca ratios indicated that eels had remained in different habitats that included freshwater (average Sr:Ca ratios, 0.98–1.78 × 10⁻³) and areas with relatively high salinities (average Sr:Ca ratios, 6.73–8.89 × 10⁻³). Some individuals showed clear evidence of shifts from sea to fresh waters. These findings suggest that Irish eels have the same behavioral plasticity regarding whether or not to enter freshwater or remain in marine environments as has been recently documented in this species and several other temperate anguillid species. However, patterns of habitat use in Irish waters were somewhat different than those previously reported for other habitats.     

珠江口黑鲷海捕群体与不同养殖群体的形态差异比较

为探明珠江口黑鲷海捕苗种与人工繁殖苗种间的形态差异,作者采用3种多元统计分析和方差分析方法,对采集自珠江口两岸的海捕黑鲷(Acanthopagrusschlegelii)苗种与2个繁殖场的人工繁殖苗种进行形态差异比较,比较了不同样品组的外部形态特征差异。可量性状主成分分析结果表明,前2项主成分的累计贡献率为89.90%,聚类分析结果表明汕头苗场(ST)样品组与另外3个样品组距离最远,判别分析结果同样显示以对该样品组判别准确率最高;可数性状单因素方差分析结果表明,样品组间背鳍鳍条数、鳃耙数、椎骨数存在显著性差异(P0.05)。主成分分析、聚类分析、判别分析和单因素方差分析从不同角度反映了样品组间的形态差异,各分析方法获得结论基本类似,相互印证。该研究结果显示,采集自不同繁殖场的黑鲷苗种与珠江口海域野生苗种存在一定的形态差异,但没有证据显示这种差异已导致黑鲷野生和养殖群体间明显的形态分化。     

基于MODIS数据的珠江口悬沙扩散形态对风和径流的响应

Cloud-free moderate-resolution imaging spectroradiometer(MODIS) images of the Zhujiang(Pearl) River Estuary(ZRE) taken between 2002 and 2012 are retrieved and used to study the spatial and temporal patterns of suspended sediment concentrations(SSCs) across the estuary under runoff, wind, and tropical storm conditions.Five typical dispersal patterns of suspended sediments in the estuary are defined: Case I shows generally low SSCs under low dynamics; Case Ⅱ shows a river-dominant dispersal pattern of suspended sediments from the outlets,particularly from Modaomen, Jiaomen, Hengmen, and others; Case Ⅲ shows wind-dominant dispersal of high SSCs derived from the west shoal and southwesterly transport under a strong NE wind; Case IV is the combination of relatively large runoff and wind; and Case V is caused by a strong tropical storm with high river discharge and wind, which is characterized by the high SSCs across the entire estuary that are transported eastward by winddriven and buoyancy currents outside the estuary. Runoff is a dominant factor that controls seasonal and annual SSC variations in the ZRE, with the area of high SSCs being largest in the summer and smallest in the spring. The correlation coefficients between the monthly averaged river-suspended sediment discharge and the area of the high SSCs are approximately 0.6. The wind power over the west shoal increases with a wind speed, which induces more sediment resuspension and shows a close relationship between the wind speed and high SSC area.     

Chemometric study of spatial variations of environmental and ecological characteristics in the Zhujiang River (Pearl River) Estuary and adjacent waters

Chemometric approach based on principal component analysis (PCA) was utilized to examine the spatial variances of environmental and ecological characteristics in the Zhujiang River (Pearl River) Estuary and adjacent waters (ZREAW) in the South China Sea. The PCA result shows that the ZREAW can be divided into different zones according to the principal components and geographical locations of the study stations, and indicates that there are distinct regional variances on environmental features and the corresponding phytoplankton biomass and community structures among different areas. The spatial distribution of ecological features was implied to be influenced by various degrees of the different water resources, such as the Pearl River discharges, the coastal current and the oceanic water from the South China Sea. The variation of the biomass maximum zone and the complex impacts on the spatial distributions of phytoplankton biomass and production were also evaluated.