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1.
为研究长江口鮻矢耳石形态特征及其质量与年龄的关系,2017年2—6月从长江口水域采集鮻358尾,解剖并提取耳石324对,并对其形态学参数进行测量分析.结果表明:鮻矢耳石具有基叶和翼叶,中央听沟明显,矢耳石的大小和形状随个体生长变化明显,矢耳石由边缘规则的圆润瓜子状渐变为褊窄的叶片状,边缘波浪状突起逐渐变多.矢耳石平均密度为1.52 mg·mm-2,平均矩形趋近率为0.68,耳石长占其体长的0.021%~0.047%,耳石宽占其体长的0.009%~0.021%,耳石质量占其体质量的0.045‰~0.731‰.鮻矢耳石长(OL)、宽(OW)、质量(OM)均与体长呈显著相关,耳石宽与耳石质量函数关系式的决定系数(R^2)最高(0.928).耳石质量与体长(BL)最佳拟合方程为幂函数:OM=0.0009BL1.8737(R2=0.967);耳石质量与年龄(A)以及体长与年龄的最佳拟合方程为多项式:OM=2.9262A^2+4.8437A+2.1894(R^2=0.847);BL=-3.2248A^2+102.54A+38.373(R^2=0.858),矢耳石质量与年龄呈显著线性相关,用耳石质量与年龄关系估算的年龄与从耳石上直接读取的年龄无显著差异,矢耳石质量可以作为鉴定鮻年龄的有效辅助手段.  相似文献   

2.
利用地理信息系统工具,以最新的植被类型图为依据,在统计、建模和空间模拟区域气候因子的基础上,对内蒙古主要植被类型与气候的关系进行了分析,并获得适宜的气候范围.结果表明,内蒙古植被空间分布表现出明显的规律性.一方面,随着距离海洋的远近变化,无论是地带性植被,还是山地垂直带、沙地及低湿地植被,从东向西均反映出地带分异,水分对于这种东西向更替更为重要.另一方面,热量的差异导致纬向上的变化.此外,热量成为大兴安岭东西两麓发育的林缘草甸、草原、灌丛和低湿地等植被类型空间分布的主导因素.  相似文献   

3.
张梅英  岳玉环 《生态学杂志》1995,14(3):26-28,32
梭鱼幼鱼选择温度的研究张梅英岳玉环(中国医科大学实验动物部,沈阳110001)(吉林农业大学动物科学系,长春130118)侯文礼(东北师范大学环境科学系,长春130024)TemperatureselectionforLarvaofLizahaema...  相似文献   

4.
梭鱼幼鱼热忍受温度的研究   总被引:9,自引:2,他引:9  
自然界水体温度变化通常表现为缓慢的渐进过程,因而水生生物能长期适应并稳定地生活在其中。然而,随着热(核)电站的兴建,许多湖泊、水库、河流、沿海水域成为其冷却水源,温排水造成该水域水温升高,并不同程度地危害水生生物资源,形成热污染。国外早在50年代已开...  相似文献   

5.
  总被引:2,自引:0,他引:2  
Otoliths of male (1+ year old) Terubok, tropical shad Tenualosa toli from the Lupar River, Sarawak, were treated in different ways to assess the effect of post-capture storage on element concentrations in the otolith core and edge detected by laser-ablation inductively coupled plasma mass spectrometry (ICPMS). Five treatments were compared: rapid removal and dry storage; fish kept 5 h after capture then otoliths removed; rapid removal and stored in alcohol; fish rozen for 24 h then otoliths removed; and storage of intact head in alcohol for several weeks. Seven elements were detected at the core and edge of otoliths (Li, Na, Mg, Mn, Co, Sr, Ba). Of these, Na, Mg, Co and Ba differed among treatments, being highest in treatments where the otolith remained in the head. Variation in element measurements due to treatment effects was similar to within-otolith variation for the other elements and was least variable in the fresh treatment. The variation in concentration between the core and edge was more significant than other sources of variation (up to 100 times) for some elements. These differences were probably due to physiological factors (ontogenetic) or to yearly changes in water chemistry. The results indicate that the method of otolith storage, especially freezing whole fish, can have a small, but measurable, effect on the concentrations of Na, Mg, Co and Ba.  相似文献   

6.
    
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7.
金枪鱼类耳石微化学研究进展   总被引:3,自引:0,他引:3  
Zhu GP 《应用生态学报》2011,22(8):2211-2218
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.  相似文献   

8.
    
Juvenile sockeye salmon Oncorhynchus nerka that were reared and smolted in laboratory conditions were found to produce otolith daily increments, as well as a consistently visible marine‐entry check formed during their transition to salt water. Field‐collected O. nerka post‐smolts of an equivalent age also displayed visible checks; however, microchemistry estimates of marine‐entry date using Sr:Ca ratios differed from visual estimates by c. 9 days suggesting that microstructural and microchemical processes occur on different time scales.  相似文献   

9.
    
Two populations of pike Esox lucius have been identified on the eastern coast of Sweden, in the Baltic Sea. These live together, but separate into two different populations during the spawning season. One is an obligate freshwater spawner and the other not only reproduces in ambient Baltic salinities, but appears not to enter fresh water at all.  相似文献   

10.
采集池塘育苗的39日龄之前的梭鱼(Liza haematocheila)仔、稚、幼鱼,对其早期发育阶段体色的变化以及鳍的发生、发育进行了连续观察。初孵仔鱼体表不具黑色素,仅卵黄囊具黑色素,孵化后2日龄体表黑色素增加,鳍膜无色透明。8日龄仔鱼开始变得不透明,腹侧有黑色线状斑点。在18~19日龄仔鱼转化为稚鱼时,鱼体背部具大量雪花状黑色素颗粒,在透色光下可观察到淡黄色斑点(黄色素)。30日龄幼鱼与成鱼相似,体表具淡白色,背褐腹白。梭鱼仔鱼在早期发育阶段各鳍的发育顺序是:胸鳍→尾鳍→腹鳍→背鳍→臀鳍→第二鳍棘。初孵仔鱼,鳍褶从头部后缘向后绕过尾部,终止于卵黄囊后缘油球外侧。2日龄仔鱼具胸鳍芽,全身由鳍膜包裹,5日龄仔鱼胸鳍和尾鳍鳍膜已具有相当的运动能力,能够起到推动和维持身体平衡的作用。梭鱼鳍在早期发育过程中最明显的变化是尾鳍的生长和鳍节的发育。梭鱼仔鱼在12日龄时出现腹鳍棘芽基,15日龄时第二背鳍棘出现。17日龄,尾椎骨向上弯曲,尾鳍基本发育完成,长鳍条16根,具10节,中间几根棘条末三节二向分叉,短鳍条上下各6~8根;背鳍有鳍条11根,具5节,最外侧鳍棘具刺,基部有支鳍骨。至30日龄,梭鱼幼鱼各鳍发育完全,与成鱼相似。  相似文献   

11.
Anadromous and resident forms of pond smelt, Hypomesus nipponensis, were found to occur in sympatry in Lake Ogawara, Japan. Profiles of Sr: Ca ratios from individuals could be grouped to two patterns (1) a resident pattern with low Sr: Ca ratios from core to edge and (2) an anadromous pattern with relatively low Sr: Ca ratios near the core with abrupt increases in ratios at a location approximately 0.3mm from the core. Spawners smaller than 60mm standard length (SL) were resident, between 60 to 80mm were mixed resident and anadromous, and larger than 80mm were anadromous. Anadromous individuals first migrated after 40 to 82 days from hatching (mean±sd, 59.1±13.5d) and 14.6 to 30.9mm SL (22.2±5.3mm). There was no difference in SL between resident and anadromous individuals during age at first migration, suggesting that size may not be the mechanism for divergence of alternative life history styles.  相似文献   

12.
    
The relationship between the strontium content of the outer layers of otoliths (an indication of recent marine, estuarine or riverine habitat use) and the strontium content of roe in ripe female brown trout Salmo trutta was examined in fish collected from the Pomahaka River and the lower reaches of the Clutha River, South Island, New Zealand. A close relationship was found between the strontium content of roe and the outer layers of otoliths. This finding suggests that spawned eggs collected from redds could potentially be used to track the extent of upstream spawning migrations by anadromous brown trout.  相似文献   

13.
    
Movement is a fundamental aspect of fish ecology, and it therefore represents an important trait to monitor for the management and conservation of fish populations. This is especially true for small benthic fish, as they often inhabit part of the catchment where their movement may be restricted by alterations to river connectivity due to human activity. Still, the movement of these small benthic fish remains poorly understood, partly because of their small size and their cryptic nature. This applies to Percilia irwini, an endangered small darter native to the south-central region of Chile. Its habitat has been affected by the presence of large hydroelectric dams and is currently threatened by the construction of several others. In this study, the authors investigated movement patterns of P. irwini from populations inhabiting different parts of the Biobío catchment, with different levels of connectivity due to natural and/or human-induced features. The authors combined chronological clustering with random forest classification to reconstruct lifelong movements from multi-elemental otolith microchemistry transects. The majority of the movements detected occurred in an undisturbed part of the catchment. These were directional upstream movements occurring between capture sites from the lower and the middle reaches of the river, representing a distance of nearly 30 km, a distance much larger than previously thought. Nonetheless, in the part of the catchment where connectivity was affected by human activity, no such movements were identified. This study shows that connectivity alteration could impede naturally occurring movement and further threaten the resilience of populations of P. irwini. Furthermore, the results presented are used to discuss advantages and disadvantages of microchemistry analysis for studying movement of small benthic fish.  相似文献   

14.
Synopsis In order to determine whether the trace element composition in otolith of the Japanese eel Anguilla japonica could be used to determine its habitat use, we used laser ablation inductivity coupled plasma mass spectrometry (LA-ICPMS) to assay sectioned otoliths of both marine-resident (sea eels) and freshwater-resident (river eels) eels. A close linear relationship in the Sr:Ca ratios between EPMA (X-ray analysis with an electron microprobe) and LA-ICPMS analyses was found, suggesting that the latter technique could be used to separate the marine and freshwater life phases. Elemental signatures in the otolith outside the elver mark showed significant differences in Cr:Ca, Mn:Ca, and Ba:Ca ratios as well as Sr:Ca ratios between sea and river eels. These results indicate that the elemental compositions may reflect environmental variability between marine and fresh water masses. Thus, those elemental ratios determined by LA-ICPMS analysis seem to have the potential to help distinguish the habitat of the eel.  相似文献   

15.
    
  1. Amazonian goliath catfishes are widespread in the Amazon Basin. Recently, otolith 87Sr:86Sr analyses using laser ablation–multi-collector–inductively coupled plasma mass spectrometry (LA-MC-ICPMS) revealed a >8,000 km trans-Amazonian natal homing in Brachyplatystoma rousseauxii among fish caught and hatched in the largest Amazon River tributary, the upper Madeira basin. Although also suspected for fish in the upper Amazon, homing could not be demonstrated owing to less distinct environmental 87Sr:86Sr gradients along the Amazon mainstem. Using scanning X-ray fluorescence microscopy (SXFM), a separate study provided evidence that Se:Ca and Sr:Ca are useful markers for identifying migration into Andean headwaters and the estuarine environment.
  2. We analysed otoliths of known 87Sr:86Sr profiles using SXFM mapping to test if Sr:Ca and Se:Ca patterns could demonstrate natal homing for three fish caught in the upper Amazon, using as reference two individuals that were natal homers and two forced residents (hatched after the construction of hydroelectric dams on the Madeira River) from the upper Madeira River.
  3. As hypothesised, although the Sr isotope profiles of the upper Amazon individuals were uninformative, two of them presented similar alternating mirror patterns of Sr:Ca and Se:Ca to those of the upper Madeira natal homers, indicating migrations out of the Andean region and into the estuary area. Both were therefore natal homers from the upper Amazon.
  4. The third individual from the upper Amazon presented similar Sr:Ca and Se:Ca patterns to those of the upper Madeira residents, suggesting it was a natural resident from the upper Amazon.
  5. By combining the results of 87Sr:86Sr analyses (LA-MC-ICPMS) and Sr:Ca and Se:Ca mappings (SXFM) that are completely independent of one another, we demonstrated that B. rousseauxii also performs natal homing in the upper Amazon. Our results indicate that the life cycle of B. rousseauxii is more complex than previous literature hypothesised, with the existence of partial migration, even in absence of physical barriers. Quantifying the relative importance of these different life-history strategies will have important implications for fisheries management. Our results also lay the groundwork for conservation efforts in the context of hydropower development in the Amazon Basin and set testable hypotheses of the potential impacts of the Madeira River dams.
  相似文献   

16.
    
Otolith chemical analyses (proton-induced X-ray emission and laser ablation inductively coupled plasma mass spectrometry) were used to examine patterns of diadromy in Australian grayling Prototroctes maraena collected from three rivers in south-eastern Australia. Concentrations of Sr:Ca and Ba:Ca were measured in the sagittal otoliths of 25 fish and in water samples collected on two occasions from multiple sites within freshwater, estuarine and marine reaches of the rivers. The results provide evidence of marine residency during the juvenile phase, with high Sr:Ca and low Ba:Ca in the inner region of the otoliths that were consistent across all three rivers. This general pattern was apparent for all individuals examined, suggesting that diadromous migration may be an obligate aspect of the life history. The chemical signatures of the outer regions of the otoliths were distinct between the three rivers, whilst there was no difference in the inner regions of the otoliths. This suggests that juveniles from different rivers may reside in a relatively homogenous chemical environment, such as the sea, and populations in coastal Victorian rivers may share a common marine recruitment source.  相似文献   

17.
Temperate-zone anguillid eels use both saline (marine or brackish) and fresh waters during their continental phase, but use of fresh waters is paradoxical because on average these fishes grow more rapidly in saline than in fresh waters. Based on data from anguillid eels whose habitat-residency histories had been determined by Sr:Ca otolithometry, superiority of growth rates in saline water is much greater in American eels Anguilla rostrata in north-eastern North America (mean saline:fresh growth rate ratio 2·07) than in European Anguilla anguilla , Japanese Anguilla japonica and shortfinned Anguilla australis eels (range of mean ratios 1·12–1·14). Data from A. rostrata in the Hudson Estuary, U.S.A., and Prince Edward Island, Canada, were used to test adaptive explanations of catadromous migrations. The hypothesis that lower mortality in fresh water offsets faster growth in saline water was not supported because loss (mortality + emigration ) rates did not vary between saline and fresh zones of the Hudson Estuary. Hypotheses that anguillid eels move to fresh water to escape from larger anguillid eels in saline water or to evaluate habitat quality were not supported by size and age distributions. Catadromy in temperate-zone anguillid eels increases the diversity of occupied habitats and therefore lowers fitness variance caused by environmental fluctuations. Catadromy in temperate-zone anguillid eels could be due to natural selection for maximum geometric mean fitness which is sensitive to fitness variance. Temperate-zone catadromy might also be maladaptive, at least in local areas, due to shifts over time in selective pressures or to inability of panmictic genetic systems to adapt to local conditions.  相似文献   

18.
  总被引:1,自引:0,他引:1  
Sr : Ca ratios measured in the otoliths of sea‐caged Atlantic salmon Salmo salar showed distinct seasonal peaks that were unrelated to water temperature and somatic growth, suggesting other factors have a greater influence on strontium deposition. Atlantic salmon remained in the sea‐cages for two seasons, or equivalent to two‐seawinter fish in the wild and were subjected to seasonally varying temperatures. Water temperature appeared to be inversely related to the Sr : Ca ratios, but this relationship was statistically not significant. Furthermore, water temperature could not explain the distinct increase in the strontium during the second year. The intensity of the Sr peaks increased in the second season while average winter water temperatures were consistent between years. Additionally, strontium deposition in the otoliths was unrelated to somatic growth. Somatic growth, as evidenced by circuli spacings on the scales, was largely invariant and therefore could not explain the observed peaks. Though not explicitly measured, the data are consistent with the notion that strontium deposition is a function of maturity state in Atlantic salmon.  相似文献   

19.
    
Sagittal otoliths of Coryphaenoides rupestris (roundnose grenadier), Helicolenus dactylopterus (bluemouth) and Merluccius merluccius (European hake) were collected using a variety of handling and storage treatments and their elemental composition was examined using inductively coupled plasma mass spectrometry. Some differences between element concentrations were identified between the control and treatment groups, most notably for the element Li. For H. dactylopterus and M. merluccius , Li concentrations were significantly higher in the otoliths extracted with metal forceps and stored in paper envelopes (treatment), compared to those from the same fishes that had been extracted using plastic forceps and stored in polyethylene vials (control). Lower concentrations of Ba and Cr were found in M. merluccius otoliths extracted from fish that had been stored frozen. The presence or absence of elemental concentrations above the instrumental limits of detection was noted, but no significant differences were identified between otolith pairs for any of the treatments. The differences between otolith pairs attributable to storage and handling effects are small compared to between‐area differences.  相似文献   

20.
  总被引:4,自引:0,他引:4  
From examination of the ratios of strontium to calcium laid down as a lifetime record in the otoliths of sea trout Salmo trutta from Gotland, Baltic Sea, it was found that: (1) the shortest stream was used mostly by precociously emigrant or coastally hatched spawners; (2) longer streams had more fish that underwent normal smoltification; (3) sea-caught fish were predominantly coastally hatched (presumably near stream mouths). Furthermore, some otoliths showed no evidence of a freshwater history at all, raising the possibility of a contingent of the coastal population that does not depend on riverine spawning. The results emphasize the importance of the coastal zone as natal and early life habitat for sea trout in the Baltic, particularly with respect to a potential change to a warmer climate which may exacerbate conditions within small, ephemeral trout streams.  相似文献   

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