基于投喂法的牙鲆耳石锶标记

本研究首次采用投喂标记饲料的方法,对牙鲆(Paralichthys olivaceus)耳石锶(Sr)标记进行研究。实验组设置1、8、64 g/kg (SrCl_2·6H_2O/饲料) 3个梯度,无SrCl_2·6H_2O添加饲料为对照组,投喂标记饲料10 d,再养殖30 d后采样。利用EPMA对样本的矢耳石进行线性定量和面分析,检测耳石Sr标记效果。结果显示,8、64 g/kg实验组耳石均出现Sr标记。8 g/kg组耳石Sr标记峰值为对照组的2倍,64g/kg组耳石Sr标记峰值较对照组分别高6倍和18倍,Sr标记峰值随着标记饲料浓度增加而增大。对各梯度组生长研究发现,1、8g/kg梯度组全长分别为(11.11±1.32)cm和(10.88±1.07) cm,差异不显著(P0.05),1、8 g/kg梯度组与0、64 g/kg梯度组全长差异显著(P0.05),说明摄食适量Sr元素,可促进鱼体生长。标记期间,各梯度组均未出现实验鱼死亡,表明Sr元素对牙鲆安全无毒。本研究为海水鱼类耳石元素指纹标记探索了新的标记途径,为科学进行牙鲆增殖放流效果评估积累了参考资料。     

耳石锶标记识别鮻放流群体的可行性研究

为探究耳石锶(Sr;)标记技术在鮻(Liza haematocheila)增殖放流群体识别的可行性,以体长5 cm左右的鮻幼鱼为研究对象,将其养殖海水中Sr;的质量浓度分别调至50、100、200和400 mg/L,以自然海水(Sr;质量浓度为7.9 mg/L)为对照组,人为改变鮻幼鱼生存环境中Sr;的质量浓度标记48 h。同时开展双环标记实验(在鮻3 cm幼鱼时进行Sr;质量浓度200 mg/L海水96 h标记,待其长至5 cm幼鱼时进行Sr;质量浓度100 mg/L海水48 h标记)。实验结果显示,Sr;质量浓度50;00 mg/L的海水48 h标记的鮻耳石Sr/Ca比均出现一个显著的上升阶段且面分析出现明显的"高Sr;标记环"。综合本研究结果和标记效率,推荐采用Sr;质量浓度为50 mg/L的海水进行鮻耳石Sr;标记。双环标记实验鮻耳石Sr;元素面分布结果出现层次分明的双环,且双环标记组鮻耳石2条不同标记环的线性分析结果与其相对应的单环标记组基本一致,这表明通过Sr;标记次数来进行不同放流群体识别是可行的。     

太湖及洪泽湖太湖新银鱼耳石元素微化学比较研究

利用元素电子显微探针分析技术,对南太湖(白雀乡水域)、北太湖(吴塘门至乌龟山水域)以及洪泽湖(老子山水域)的太湖新银鱼(Neosalanx taihuensis)的矢耳石进行了元素微化学(如锶及钙元素分布、积累、浓度比等)特征的比较研究。元素定量线分析和面分布分析结果均直观而明显地表明,北太湖太湖新银鱼的个体可以分为两种类型,一类耳石具高锶钙比(21.41?0.50,N=4),另一类耳石具低锶钙(1.64?0.12,N=5);南太湖个体耳石的锶钙比值居中(3.12?0.07,N=10);而洪泽湖个体耳石的锶钙比普遍偏高(5.42?0.32,N=9)。这些组别间锶钙比值的差异均显著(P<0.05)。此外,洪泽湖个体耳石标本有高锶环的存在,而太湖个体耳石中锶的分布水平较均一化。上述结果显示,一方面太湖和洪泽湖太湖新银鱼耳石微化学类型差异明显;另一方面太湖不同水域太湖新银鱼的微化学类型亦不尽相同;反映出耳石微化学特征具有可以用来区别太湖新银鱼不同地理资源群体的潜力。     

国内外对鱼类耳石日轮的研究和应用

人类对鱼类耳石日轮的研究开始于七十年代初。到目前为止，国内外许多学者对多种海水、淡水鱼类的耳石日轮进行了研究。本文简要介绍了这方面的研究结果，其中包括耳石日轮的结构，日轮的形成与环境之间的关系，日轮研究在其它领域中的应用，以及目前该研究工作存在的问题。     

Lifelong population connectivity between large rivers and their tributaries: A case study of shovelnose sturgeon from the Mississippi and Wisconsin rivers

Fishes that depend on large‐river habitats have declined in many regions due to human alteration of both mainstems and tributaries. Conserving these species is often complicated by their dependence on long‐distance movements to complete their life cycle, but the location of key habitats is difficult to assess across multiple life history stages. Movement of large‐river fishes between mainstems and major tributaries is commonly observed, but the role of these exchanges at the population level is uncertain. We used shovelnose sturgeon (Scaphirhynchus platorynchus) as a case study for assessing the lifelong spatial ecology of large‐river fishes. Fin ray microchemistry data indicate that shovelnose sturgeon from the Mississippi and Wisconsin rivers represent a unified population that relies on connections among multiple large‐river habitats throughout life history. The tributary serves as an important spawning area, but fin ray chemistry data suggest larvae subsequently drift downstream to nursery habitats in the mainstem; an assertion that is supported by extensive field survey data. Our analyses underscore the lifelong importance of connections within river networks for maintaining viable populations of this, and likely other large‐river species that have been documented to use tributary habitats. These findings support a metapopulation perspective on species that depend on large‐river habitats, many of which are now highly altered and fragmented. For shovelnose sturgeon and species with similar life history, protecting or restoring linkages between mainstem rivers and their tributaries should be a conservation priority.     

An otolith microchemistry study of possible relationships between the origins of leptocephali of European eels in the Sargasso Sea and the continental destinations and relative migration success of glass eels

Martin J, Daverat F, Pécheyran C, Als TD, Feunteun E, Réveillac E. An otolith microchemistry study of possible relationships between the origins of leptocephali of European eels in the Sargasso Sea and the continental destinations and relative migration success of glass eels.
Ecology of Freshwater Fish 2010: 19: 627–637. © 2010 John Wiley & Sons A/S Abstract – Little is known about the extent to which Atlantic eels coming from different European rivers converge on the same spawning site. Our aim was to evaluate the spatial homogeneity of eel spawning area(s) with an otolith microchemistry approach. This work compared the elemental signatures of otolith’s core region of Anguilla anguilla leptocephali caught in the Sargasso Sea in 2007 with those of glass eels and elvers sampled in European estuaries during 2006, 2008 and 2009. Using laser ablation inductively coupled plasma mass spectrometry, the same annular ablation trajectory along the first feeding mark was applied on otoliths of glass eels, elvers and leptocephali. The concentrations of thirteen isotopes in the otoliths of glass eels/elvers did not vary among three annual cohorts collected in eleven European locations. However, otolith elemental fingerprints of leptocephali differed significantly from glass eels otolith’s signature. Although the mechanisms that regulate the differences in trace element signatures among leptocephali and glass eels/elvers are unknown, we propose that the sampled glass eels/elvers were born in a spawning site or region where favourable transport and/or feeding conditions occurred. Conversely, the leptocephali may have been sampled in a less favourable region in the Sargasso Sea, with a low probability of reaching continental growth areas.     

Colonisation tactics of three temperate catadromous species,eel Anguilla anguilla,mullet Liza ramada and flounder Plathychtys flesus,revealed by Bayesian multielemental otolith microchemistry approach

Daverat F, Martin J, Fablet R, Pécheyran C. Colonisation tactics of three temperate catadromous species, eel Anguilla anguilla, mullet Liza ramada and flounder Plathychtys flesus, revealed by Bayesian multielemental otolith microchemistry approach.
Ecology of Freshwater Fish 2011: 20: 42–51. © 2010 John Wiley & Sons A/S Abstract – The colonisation of Gironde (SW France) river catchment by juvenile, eel, Anguilla anguilla, flounder Platychtys flesus and thinlipp mullet Liza ramada was investigated comparatively using Sr:Ca and Ba:Ca composition of otolith. The relation between Sr, Ba and habitat was investigated based on Sr and Ba water composition sampled each month along the estuary‐river gradient. A total of 50 mullets, 30 eels and 47 flounders were collected in the Gironde river catchment. Analysis was performed with a Femtosecond LA‐ICPMS along a trajectory from the core to the edge. Sr and Ba water concentrations discriminated three habitats within the Gironde system, the lower estuary, the upper estuary and the freshwater sites. A signal processing method based on Gaussian hidden Markov models was applied to the multielemental life‐history data. The linear model used to allocate a Gironde habitat to coupled Sr, Ca values was parameterised with seasonal patterns and magnitude of Sr and Ba water values in the different habitats. The results showed that the three species used three different habitats and they had a large diversity of habitat use patterns with resident and nomadic tactics. Resident tactics were less frequent than nomadic tactics that suggested individual fish used two or more habitats. Mullet used a wider range of habitats in the lower part of the estuary than eel and flounder and switched habitats more frequently. Flounders tended to colonise initially freshwater, and then estuarine habitats later in life while mullets used the entire range of available catchment habitats throughout their life.     

Parr dispersal between streams via a marine environment: A novel mechanism behind straying for anadromous brown trout?

Otolith Sr:Ca profiles demonstrated that juvenile anadromous brown trout (ABT) Salmo trutta may descend to the brackish waters of the Baltic Sea from their natal streams as parr or fry and then migrate into non‐natal streams before transforming into smolt. To our knowledge, no such published documentation exists for ABT. The ecological significance of this life‐history strategy is presently not clear. However, stream shifting through the marine environment should to be considered with regard to stock management and the assessment and restoration of salmonid populations and their potential habitats.     

李花芽形态分化的研究

从外部形态、内部组织和营养物质的动态变化等方面对李花芽分化进行了综合研究,结果表明：李花芽形态分化的过程可划分为：未分化期、花原基分化期、萼片原基分化期、花瓣原基分化期、雄蕊和雌蕊原基分化期及雄蕊和雌蕊结构分化期等6期;细胞分裂快、合成作用旺盛的原基中,蛋白质含量高,淀粉粒则分布在原分生组织衍生的组织内。