洞庭湖中是否存在溯河洄游型刀鲚

利用电子探针微区分析(EPMA)技术, 分析了2018年8月采自湖南省岳阳市洞庭湖畔水产市场2尾刀鲚(Coilia nasus)干制个体的矢耳石中锶和钙微化学特征。定量线分析结果显示, 2尾样本的耳石锶钙比值(Sr/Ca×1000)波动显著, 从耳石核心到边缘可分别出现对应淡水生境的锶钙比值<3的低值区, 对应于半咸水生境的3—7高值区和再次为对应于淡水生境<3的低值区。面分布分析结果更直观显示两尾刀鲚个体的耳石从核心到边缘对应于不同盐度生境的锶含量变化图谱, 即从耳石核心到边缘可分别出现对应于淡水生境的蓝色区域, 对应长江口外半咸水生境的黄绿色区域和再次对应于淡水生境的蓝色区域。这种淡水-半咸水-淡水的生境转换显示出了上述个体的典型溯河洄游生活史“履历”。研究显示目前距长江河口约1400 km的洞庭湖中仍可能存在溯河洄游型刀鲚个体。     

基于耳石微化学的长江安徽和县江段刀鲚生境履历重建

为了解长江刀鲚(Coilia nasus)的“生境履历”, 利用电子探针微区分析技术研究了2015年5月17日在长江安徽和县江段捕获的刀鲚短颌鲚与长颌鲚类型耳石Sr和Ca微化学特征。短颌鲚的耳石Sr/Ca值变化动态为2类, 一类比值稳定在2.00左右(1.65±0.87—2.03±0.96), 反映了其纯淡水的生境履历; 另一类比值波动显著, 不仅具有对应淡水生境的低值(2.39±1.18—2.63±0.85), 还具有对应半咸水生境的高值(3.22±1.17—3.29±1.14), 显现了其江海生活的生境履历。长颌鲚耳石的Sr/Ca值均波动显著, 同时具有对应淡水生境的低值(1.35±1.07—2.37±1.04)和半咸水、海水生境的高值(3.47±1.09—8.35±1.25), 表现了其均为溯河洄游的生境履历。Sr面分析结果也与上述Sr/Ca值的结果相印证。长江安徽和县江段刀鲚资源组成复杂, 群体可由纯淡水型和江海生活型的个体共同组成。     

长江安庆江段刀鲚耳石微化学及洄游生态学意义

刀鲚(Coilia nasus)属辐鳍鱼纲、鲱形目、鳀科,是我国长江下游一种传统的名贵经济鱼类。长江安徽江段为刀鲚的主要分布区之一,但近年来由于人类活动干扰、栖息地衰退及过捕等原因,资源量急剧下降。近期发布的《国家重点保护野生动物名录》水生野生动物调整方案已拟将刀鲚列入国家二级重点野生动物保护名录。为客观了解长江安庆江段刀鲚的生境"履历"及探讨其洄游史,利用X射线电子探针微区分析技术对2008年7月捕获于长江安庆江段的10尾刀鲚(均为传统意义上的长颌鲚)进行了耳石微化学研究。结果表明:这些个体均具典型的溯河洄游习性。从耳石核心到边缘定量线分析结果表明,耳石的沉积过程中元素Sr/Ca比值波动显著,不仅有对应淡水生境的低值(3)阶段,还具有对应河口半咸水、海水生境的高值(3)阶段。这种现象亦得到了16色Sr元素面分布分析结果的印证。根据耳石淡水系数、Sr/Ca比值高低波动特征及Sr元素面分布图谱的差异性可以将这些刀鲚分为3种淡-海水生境转换生活史类型。这种现象明显地反映出长江安庆江段刀鲚的群体具有个体组成和洄游模式的多样性。     

长江口近岸水域鮻耳石的元素组成

为了解长江口近岸水域鮻耳石的元素组成特征,采用激光剥蚀电感等离子质谱法对长江口近岸水域1～6年龄的13个鮻样本的耳石进行了检测。结果表明:鮻耳石中共检测到47种元素,含量前10位的元素依次为钙(Ca)、钠(Na)、锶(Sr)、铁(Fe)、钡(Ba)、镁(Mg)、锰(Mn)、铬(Cr)、锌(Zn)和锂(Li)。其中,Ca是含量最高且最稳定的元素,占检出元素总量的98.9%。鮻耳石含量前10位的元素在雌雄间不存在显著性差异(P0.05),表明雌雄间存在相同的生活履历。基于耳石核心区Sr和Ca的含量比值,推测长江口近岸水域鮻的产卵孵化场位于潮间带淡水和半咸水水域。研究结果为长江口鮻的生境履历重建提供了基础数据和参考。     

基于耳石元素微化学的江苏吕泗近岸小黄鱼生境履历重建

利用电子显微探针元素分析技术,对江苏吕泗近岸海域小黄鱼矢耳石的Sr和Ca微化学特征进行了研究.结果表明: Sr含量在小黄鱼耳石的矢状面上呈非均匀分布,总体为核心部位高,其余部分明显降低.核心高Sr区域的Sr/Ca比值为(7.10±1.00),其余部分为(4.79±1.01),两者差异极显著.后者部分个体存在Sr含量更低的区域,Sr/Ca比值为(3.51±0.76).基于这些结果重建了吕泗近岸小黄鱼的生境履历： 它们在孵化及初期发育阶段生活在高盐度生境,随后的生长和发育过程则会洄游至盐度稍低的生境;部分个体的早期发育阶段还会选择利用更低盐度的生境.     

金枪鱼类耳石微化学研究进展

近年来,基于鱼类钙化物质中微量元素和同位素等微化学成分分析已成为分析鱼类种群结构、生活史及洄游环境史等的一种新兴手段.随着鱼类耳石微化学研究及应用的日渐成熟与完善,该手段也日益成为金枪鱼类生态学研究的良好工具.目前金枪鱼类耳石微化学的研究内容主要包括微量元素和同位素等,其中微量元素是应用研究的重点和热点,其在金枪鱼类,尤其是蓝鳍金枪鱼种群划分、出生源、洄游环境史和生活史分析等方面发挥了重要的作用.但多数研究集中在耳石锶钙比率(Sr/Ca)的变化上,且关于耳石碳氧同位素分馏与温度之间的关系尚无定论.为了开发耳石微化学的巨大价值,有必要加强对其沉积机理的研究,并采用综合研究方法从时空角度分析耳石中多种微量元素的含量及其变化.     

有明银鱼耳石显微结构和微化学研究

1998年从鸭绿江捕取有明银鱼成鱼 ,生物学测量后剖出耳石。每尾鱼 1对矢耳石中的 1个用于制片 ,显微镜下观察其显微结构 ,另 1个制片镀碳膜后 ,用扫描电子微探针测定Sr和Ca的浓度比率。Sr和Ca分析的标准样用SrSO4 和CaSO4 。 31尾鱼 (体长 116～ 15 7mm)耳石长半径 (Y)与鱼体长 (X)成线性关系 ,其方程式为Y =2 72 16X +9 2 2 92 ,r =0 9178,P <0 0 1。耳石中心和耳石原基的平均直径分别为 2 2 5 5± 2 88μm和6 95± 1 30 μm。 13尾鱼耳石上的日轮数为 30 5～ 35 4,大约在 45～ 70日轮处出现过渡轮。日轮间距 0 94～ 1 14μm ,最大间距在 190～ 2 2 0日轮处 ,最小间距出现在 2 80日轮之后。耳石中Sr、Ca浓度比例在第 5至第 7测点出现第 1个高峰 ,这与稚鱼为了越冬洄游到海中时间相吻合。第 2个高峰出现在 2 8～ 32测点 ,这与鱼产卵上溯洄游时间相符。个体发育过程中生理和生态条件的变化 ,可引起耳石中Sr、Ca比率的改变 ,但栖息水域盐度的突然改变是导致Sr、Ca比率显著增高的主导因素。     

据于矢耳石Sr/Ca值的长江日本鳗鲡迁移格局多样性分析(英文)

长江口是中国日本鳗鳗苗的主要产区和仅存的成鳗渔业水域。日本鳗自长江河口至上游金沙江近3000km干流及许多支流中都有分布,但其迁移行为却不为人了解。该文分析了2008年9～11月采自长江靖江段(31o30′N,120o42′E)的153尾银色鳗样本的生物学特征,测定了其中27尾标本的矢耳石Sr/Ca值。结果显示,153尾样本中有雌性85尾、雄性68尾,雌雄性比1:0.8。雌性由3～7(平均5.52)龄组成,平均体长(669±80)mm,体重(555±229)g,丰满度1.77±0.22,性腺指数(GSI)1.32±0.31。雄性由3～5(平均4.38)龄组成,平均体长(518±51)mm,体重(234±76)g,丰满度1.62±0.18,GSI0.21±0.11。雌性的这些生物学参数均显著大于雄性(P<0.05)。依据矢耳石线鳗标志轮平均Sr/Ca值(7.99±1.05)×10-3进行判断,有17尾(即62.96%个体)为"淡水型",10尾(即37.04%个体)为"河口型"。16尾雌性中有13尾(即81.25%)为"淡水型",3尾为"河口型"。11尾雄性中仅36.36%为"淡水型",63.64%为"河口型"。对每个生长层组的Sr/Ca值分析表明,雌雄间2龄时无显著差异,但3龄、4龄和洄游龄组都有显著或极显著的差异,预示着2龄时两者的栖息水域比较一致,但后来出现了明显栖息地分化。     

西南大西洋阿根廷滑柔鱼耳石元素组成

耳石微量元素越来越广泛地被用于头足类群体划分、洄游史等领域的研究。根据我国鱿钓船2007、2008和2010年在西南大西洋生产期间采集的阿根廷滑柔鱼样本,利用激光剥蚀电感等离子质谱法(Laser ablation inductively coupled plasma mass spectrometry,LA-ICP-MS)按不同群体、不同性别和不同生长阶段,分析了33枚阿根廷滑柔鱼耳石的元素组成及分布特性。结果表明,阿根廷滑柔鱼耳石主要由56种元素组成,含量最多的前10种元素分别为钙Ca、锶Sr、钠Na、磷P、钾K、铁Fe、镁Mg、钡Ba、硼B、镓Ga。方差分析表明(ANOVA),不同性别间Ca、Sr、Na、P、K、Fe、Mg、Ba、B、Ga都不存在显著性差异(P0.05)。冬季孵化群和秋季孵化群间耳石的Sr、Na、Mg、Ba和B存在显著性差异(P0.05),Ca、P、K、Fe和Ga则不存在显著性差异(P0.05)。耳石的核心区、后核心区、暗区和外围区等不同部位间的Na、Ba和Ga不存在显著性差异(P0.05),Ca、Sr、P、K、Fe、Mg和B则存在显著性差异(P0.05)。研究表明,Sr和Mg含量及其分布特性最适合用于研究阿根廷滑柔鱼的群体划分、洄游史等渔业生态学特性。     

西北太平洋柔鱼耳石微量元素

耳石是头足类重要的硬组织之一,其微化学被用于头足类生活史的重建、群体划分等渔业生态学领域.本文根据我国鱿钓船2007年在西北太平洋海域生产期间采集的柔鱼样本,利用激光剥蚀电感等离子质谱法(laser ablation inductively coupled plasma mass spectrometry, LA-ICP-MS)分析了18枚柔鱼耳石的微量元素组成及其分布特性.结果表明： 柔鱼耳石主要由55种元素组成,含量最多的前10位元素分别为钙(Ca)、锶(Sr)、钠(Na)、磷(P)、钾(K)、硅(Si)、镁(Mg)、硼(B)、铁(Fe)和钡(Ba).方差分析表明,不同性别间柔鱼的Ca、Sr、Na、K、Mg、Fe、Ba的含量不存在显著性差异,但P、Si和B含量差异性明显;不同孵化期的群体间Sr和Na含量存在显著性差异,Ca、P、K、Si、Mg、B、Fe和Ba不存在显著性差异;不同耳石部位的Ca、Sr、Na、P、Mg和Ba含量存在显著性差异,而K、Fe、B和Si则不存在显著性差异.研究表明微量元素Sr和Na比较适合用于研究柔鱼的群体划分、洄游史推测等渔业生态学.
     

Migration of Sakhalin taimen (<Emphasis Type="Italic">Parahucho perryi</Emphasis>): evidence of freshwater resident life history types

Sakhalin taimen (Parahucho perryi) range from the Russian Far East mainland along the Sea of Japan coast, and Sakhalin, Kuril, and Hokkaido Islands and are considered to primarily be an anadromous species. We used otolith strontium-to-calcium ratios (Sr/Ca) to determine the chronology of migration between freshwater and saltwater and identify migratory contingents of taimen collected from the Koppi River, Russia. In addition, we examined taimen from the Sarufutsu River, Japan and Tumnin River, Russia that were captured in marine waters. Transects of otolith Sr/Ca for the Sarufutsu River fish were consistent with patterns observed in anadromous salmonids. Two fish from the Tumnin River appeared to be recent migrants to saltwater and one fish was characterized by an otolith Sr/Ca transect consistent with marine migration. Using these transects as benchmarks, all Koppi River taimen were classified as freshwater residents. These findings suggest more work is needed to assess life history variability among locations and the role of freshwater productivity in controlling migratory behavior in taimen.     

Diversity of life strategies of pikepech <Emphasis Type="Italic">Sander lucioperca</Emphasis> (L.) in the Lower Volga (by the data of microelement composition of otolithes)

Strontium (Sr) and calcium (Ca) contents and Sr/Ca ratios in otoliths of pikeperch Sander lucioperca have been studied by X-ray fluorescent microanalysis. A sample of 95 specimens from the Lower Volga region are studied. The fish were obtained in a section of the Akhtuba River at a distance of 250–279 km upstream from the Caspian Sea. Some specimens in the sample have low strontium content throughout the otolith. The other fish have increased both Sr content and Sr/Ca ratios in core zones of otolith or near its outer edge: the Sr/Ca ratio is over 6.00 × 10^–3, with a maximum at 10.02 × 10^–3. The fish with a low Sr/Ca ratio live in freshwater and demonstrate a resident life history strategy. Pikeperch that have increased ratios of Sr/Ca in outer zones of otolith demonstrate a migratory life history strategy. These fish leave the freshwater of the Volga and feed in brackish water of the Northern Caspian Sea. Some migratory fish migrate to the sea as underyearlings, stay in a brackish water for 1 year or less, and then return back to fresh water for the rest of its life. The other group migrates back and forth from freshwater to the sea several times during their life. Finally, some fish leave freshwater for 1–2 years, spending this time in the Northern Caspian Sea. The conclusion is that the pikeperch stock in the Lower Volga has a complicated composition and consists of freshwater (residents and rheodromic ones) and migratory (anadromous and semianadromous) fish.     

Genetics, recruitment, and migration patterns of Arctic cisco (Coregonus autumnalis) in the Colville River, Alaska, and Mackenzie River, Canada

Arctic cisco Coregonus autumnalis have a complex anadromous life history, many aspects of which remain poorly understood. Some life history traits of Arctic cisco from the Colville River, Alaska, and Mackenzie River basin, Canada, were investigated using molecular genetics, harvest data, and otolith microchemistry. The Mackenzie hypothesis, which suggests that Arctic cisco found in Alaskan waters originate from the Mackenzie River system, was tested using 11 microsatellite loci and a single mitochondrial DNA gene. No genetic differentiation was found among sample collections from the Colville River and the Mackenzie River system using molecular markers (P > 0.19 in all comparisons). Model-based clustering methods also supported genetic admixture between sample collections from the Colville River and Mackenzie River basin. A reanalysis of recruitment patterns to Alaska, which included data from recent warm periods and suspected changes in atmospheric circulation patterns, still finds that recruitment is correlated to wind conditions. Otolith microchemistry (Sr/Ca ratios) confirmed repeated, annual movements of Arctic cisco between low-salinity habitats in winter and marine waters in summer.     

Migratory patterns of anadromous white-spotted charr Salvelinus leucomaenis in Eastern Hokkaido, Japan: The solution to a mystery?

We evaluated the migratory patterns of white-spotted charr in eastern Hokkaido, Japan using: (1) field observation of fish, (2) salinity-recording archival tags, and (3) analysis of otolith Sr and Ca concentrations. Field observations suggest that the majority of anadromous white-spotted charr outmigrate to the sea in spring (April to June) and ascend the river between late summer and autumn (August to November). Salinity records from archival tags revealed a fluctuating pattern consisting of both low and high values within a month, indicating frequent short-term movements between freshwater (including non-natal rivers) and brackish/salt water habitats. Otolith Sr:Ca ratios exhibited a sharp rise at about 40–50% of the otolith radius, which was followed by several spikes consisting of both low and high values, indicating that fish migrated between freshwater and marine environments multiple times during their life history. However, the peaks in Sr:Ca ratios were generally associated with annulus zones on the otolith, indicating that the anadromous migration was generally an annual event.     

Migratory history of the spotted flagtail, <Emphasis Type="Italic">Kuhlia marginata</Emphasis>

The spotted flagtail, Kuhlia marginata (Kuhliidae) is commonly found in streams throughout the Ryukyu Archipelago, including Okinawa Island, Japan. Although it has been suggested that they spawn at sea, little is known about their migratory history. The aim of the study was to clarify their migration history based on otolith microchemistry analysis, size composition and the gonadal development of fish collected from the Genka River on Okinawa Island. All strontium/calcium (Sr/Ca) ratios of otoliths remained high around their cores, and then dropped rapidly at some distance from the core. The estimated standard length corresponding to decreases correlated with the size of new recruits collected in the river (ca. 20 mm in standard length: SL). Multiple increases, the sign for migrations into the high saline area, were recognized intermittently around the otolith margin. As the estimated SL at these increases in the Sr/Ca ratio occurred above the minimum maturation size (female: 95.5 mm SL; male: 83.5 mm SL), such multiple increases in Sr/Ca ratios were caused by spawning migration. Therefore, we conclude that the catadromous pattern of K. marginata is as follows; this species grows in the sea during the early life stage until ca. 20 mm SL and then grow in the freshwater area until maturation, before they migrate again to the sea for spawning. Sr/Ca ratio profiles also suggested that a large number of males did not return to the freshwater area after spawning, whereas females might spawn several times during their lives around the inshore area.     

Flexible Life History Strategies of Ninespine Sticklebacks,Genus <Emphasis Type="BoldItalic">Pungitius</Emphasis>

Synopsis We studied the life histories of the ninespine sticklebacks, Pungitius pungitius and Pungitius tymensis, collected from Japanese freshwater and brackish (sea) water habitats by examining the strontium (Sr) and calcium (Ca) concentrations in their otoliths. The Sr:Ca ratios in the otoliths changed with the salinity of the habitat regardless of identification as freshwater or brackish water type based on morphological characteristics. The ninespine sticklebacks living in a freshwater environment showed consistently low Sr:Ca ratios throughout the otolith. These samples were identified as a standard freshwater type. In contrast, all freshwater-type fishes collected from the intertidal zone showed higher otolith Sr:Ca ratios than those in the standard freshwater type, and the ratios fluctuated with the growth phase. All brackish water-type fishes collected in the intertidal zone showed the highest otolith Sr:Ca ratio throughout the otolith. In the present study, besides the two representative life history types of P. pungitius, i.e., freshwater and brackish water life history types, other sticklebacks had an anadromous life history type. These findings clearly indicate that the ninespine stickleback has a flexible migration strategy with a high degree of behavioral plasticity and an ability to utilize the full range of salinity in its life history.     

Migration flexibility between freshwater and marine habitats of the pond smelt Hypomesus nipponensis

The life histories of the pond smelt Hypomesus nipponensis collected from Japanese fresh waters and brackish (sea) waters were studied by examining the strontium (Sr) and calcium (Ca) concentrations in their otoliths. The Sr:Ca ratios in the otoliths changed with the salinity of the habitat. The pond smelt living in a freshwater environment showed consistently low Sr:Ca ratios throughout the otolith, averaging 1·2–1·3 × 10⁻³. These samples were identified as a standard freshwater type. In contrast, fish collected from the intertidal zone showed higher otolith Sr:Ca ratios than those in the standard freshwater type, and the ratios fluctuated along the growth phase. In addition to the two representative life‐history types of H. nipponensis , i. e . freshwater and anadromous life‐history types, other pond smelts were found to have an estuarine resident life history‐type with no freshwater phase, indicating that the pond smelt has a flexible migration strategy with a high degree of behavioural plasticity and an ability to utilize the full range of salinity in its life history.     

Diverse migratory histories in a brackish water type of the ninespine stickleback, <Emphasis Type="Italic">Pungitius pungitius</Emphasis>

The life history in a brackish water type of the ninespine stickleback, Pungitius pungitius, was studied by examining the strontium (Sr) and calcium (Ca) concentrations in the otoliths. The fluctuating patterns of Sr/Ca ratios along the life history transect in the otoliths varied widely among fish in spite of their identification as brackish water type as estimated by morphological characteristics. More than 70% fish showed the intermediate otolith Sr/Ca ratio throughout, averaging 5.23–7.71 × 10⁻³. Besides this brackish water resident life history type of P. pungitius, other sticklebacks had anadromous (25%) and freshwater amphidromous (2.5%) life history types. These findings clearly indicate that the migration of the ninespine stickleback between fresh and sea waters is obligatory but facultative having an ability to utilize the full range of salinity in its life history.