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.
     

中国南海西沙群岛海域鸢乌贼耳石元素组成

耳石是头足类重要的硬组织,其微化学被广泛用于头足类生活史的重建、群体划分等研究领域.本文根据中国灯光罩网渔船于2017年5—8月在中国南海西沙群岛海域采集的鸢乌贼样本,利用激光剥蚀电感耦合等离子质谱法(LA-ICP-MS)分析了20枚鸢乌贼耳石的元素组成及其分布特性.结果表明: 西沙群岛海域鸢乌贼耳石主要由55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)、硅(Si)、镁(Mg)、钾(K)、硼(B)、 铁(Fe)和钡(Ba).方差分析表明,不同性别间Ca、Sr、Na、P、Si、Mg、K、Fe、Ba和B的分布均不存在显著性差异;不同孵化群体间Ca、P、B、Fe和Ba的分布也不存在显著性差异,而Si、Sr、Mg、Na和K则差异显著;不同耳石部位间除了Ca和Fe的分布不存在群体间差异外,Sr、Na、P、K、Si、Mg、B、和Ba均存在显著性差异.表明Sr、Na、K 和 Mg可能比较适合用于鸢乌贼群体划分和生活史研究.     

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。     

白蜡虫雌成虫某些生化成分分析

分析了白蜡虫雌成虫含氮 6.3 3 4 %、蛋白质 3 9.59% (含非蛋白氮 )、脂肪 6.2 556% ,其碘价68.877。白蜡虫乙醇提取液含氮 0 .2 60 %、蛋白质 0 .656%、还原糖 3 3 %、总糖 7 0 0 % ,测定出含有 1 7种氨基酸 ,其中以His、Glu、Ala含量较高。测定了Ca、Fe、Mg、Al、Ba、Co、Mn、Sr、Zn、P元素的含量 ,其中Ca、Mg、P含量较高。微量元素较为丰富     

新疆和静县察吾呼沟口四号墓地出土人骨化学元素的含量分析

近几十年来,古代人群的食谱研究已经成为现代科技考古学的一个重要组成部分,也是当前国际科技考古学研究领域的一项前沿性课题。人类骨骼的化学元素分析为重建古代居民的食谱提供了大量信息。本文采用电感耦合等离子发射光谱仪(ICP-AES),对新疆和静县察吾呼沟口四号墓地出土人骨中的Sr、P、Zn、Ca、Cu、Mg、Fe、Ba、Mn等8种化学元素进行了测定,结果显示:察吾呼沟口四号墓地古代居民的饮食结构中以肉类食物为主,植物类食物为辅。     

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.     

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。     

南京栖霞山地区树木元素富集的初步研究

 本文用树木元素富集系数(T／S)来研究南京栖霞山铅锌多金属矿区树木—土壤系统中元素的富集特性。结果表明,树木对土壤中K、P二个元素的吸收基本与树种和开矿活动关系不大。黑松对Cr、Al,马尾松对Mn、Pb、Co、Ni、枫杨对P,刺槐对Mg、Na,Ti,栎对Zn、Ca、K、Fe、Sr、Ba、V,槐树对Cu均有最大的富集系数。黑松树龄对Co、K、Zn含量和Ca的富集系数有一定的影响。另外,Co—Ni、Sr—Ba的T／S曲线分别呈正相关,表现出这两组元素各自的地球化学共轭性。     

喀喇昆仑、昆仑山地区植物中一些元素的自然含量特征

 本文论述了喀喇昆仑、昆仑山地区87种植物12个元素含量的特征。在含量水平上>10000ppm的元素有K,Ca,800—5000ppm的元素为Na、Mg,Fe、Al,10—100ppm的元素有Ba、Sr、Ti,Mn,V与Be的含量<10ppm。大多数植物Fe、V,Sr的含量高于一般的自然含量。植物中K含量的频数分布呈正态分布,其余元素的频数分布呈对数正态分布。不同植物种元素含量差异较大,Na的变异系数最大,Ca、Mg含量的变异系数最小。同种植物在不同地点元素含量有较大差异,不同植物种差异也不同。如紫花针茅(Stipa purpurea)>垫状驼绒藜(Ceratoides compacta)>鼠麴凤毛菊(Saussurea gnaphaloides)。植物中元素含量之间的相关分析表明,Fe、Al,V,Ti之间分别达极显著相关水平。用植物中12个元素的资料,对22种植物进行分类和排序,区分出Na,K型植物和Fe,Al,V,Ba型植物。     

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。     

Allometric constraints on Sr/Ca and Ba/Ca partitioning in terrestrial mammalian trophic chains

In biological systems, strontium (Sr) and barium (Ba) are two non-essential elements, in comparison to calcium (Ca) which is essential. The Sr/Ca and Ba/Ca ratios tend to decrease in biochemical pathways which include Ca as an essential element, and these processes are termed biopurification of Ca. The quantitative pathway of the biopurification of Ca in relation to Sr and Ba between two biological reservoirs (R _n and R_{n -1}) is measured with an observed ratio (OR) expressed by the (Sr/Ca) _Rn /(Sr/Ca) _Rn-1 and (Ba/Ca) _Rn /(Ba/Ca) _Rn-1 ratios. For a mammalian organism, during the whole biopurification of Ca starting with the diet to the ultimate reservoir of Ca which is the bone, the mean values for OR_Sr and OR_Ba are 0.25 and 0.2, respectively. In this study, published Sr/Ca and Ba/Ca ratios are used for three sets of soils, plants, and bones of herbivorous and carnivorous mammals, each comprising a trophic chain, to illustrate the biopurification of Ca at the level of trophic chains. Calculated OR_Sr and OR_Ba of herbivore bones in relation to plants and of bones of carnivores in relation to bones of herbivores give OR_Sr=0.30±0.08 and OR_Ba=0.16±0.08, thus suggesting that trophic chains reflect the Sr/Ca and Ba/Ca fluxes that are prevalent at the level of a mammalian organism. The slopes of the three regression equations of log(Sr/Ca) vs. log(Ba/Ca) are similar, indicating that the process of biopurification of Ca with respect to Sr and Ba is due to biological processes and is independent of the geological settings. Modifications of the logarithmic expression of the Sr/Ca and Ba/Ca relationship allow a new formula of the biopurification process to be deduced, leading to the general equation OR_Ba=OR_Sr^1.79±0.33,where the allometric coefficient is the mean of the slopes of the three regression equations. Some recent examples are used to illustrate this new analysis of predator-prey relations between mammals. This opens up new possibilities for the utilization of Ba/Ca and Sr/Ca in addition to stable isotope ratios (¹³C and ¹⁵N) for the determination of the relative contribution of different food sources to an animals diet.     

Ontogenetic variations in Sr/Ca and Ba/Ca ratios of dental bioapatites from Bos taurus and Odocoileus virginianus

Sr/Ca and Ba/Ca ratios of bone are commonly used as biochemical indicators of trophic level in modern and fossil mammals. Concerns over the effects of diagenesis on Sr/Ca and Ba/Ca ratios of bone led archaeologists and paleontologists to favor tooth enamel, which is less prone to alteration. Sr/Ca and Ba/Ca ratios of bone, enamel, and dentin from three farm-raised steers (Bos taurus) and five wild white-tailed deer (Odocoileus virginianus) from central Missouri were compared. Our results show that changes in diet, discrimination, and growth rate during ontogeny can lead to significant differences in Sr/Ca and Ba/Ca ratios of different bioapatite types as well as significant differences within the same bioapatite forming at different times. Early- and late-forming tooth enamel can have significant differences in Sr/Ca and Ba/Ca ratios equivalent to almost one full trophic step. Although differences between early- and late-forming dentin are typically not significant, dentin Sr/Ca and Ba/Ca ratios are significantly greater than enamel values. This difference in Sr/Ca or Ba/Ca ratios between enamel and dentin from the same tooth can be greater than one full trophic step. These results have profound implications for the use of dental bioapatites in trophic level reconstructions. They highlight the importance of consistency in bioapatite selection, tooth selection, and relative location of sampling within the enamel cap. Furthermore, this expected difference in Sr/Ca and Ba/Ca ratios could be used as another means of checking for diagenetic alteration in ancient samples.     

Evaluation of the mobility and discrimination of Ca, Sr and Ba in forest ecosystems: consequence on the use of alkaline-earth element ratios as tracers of Ca

A comprehensive understanding of Ca cycling in an ecosystem is desirable because of the role of this element in tree mineral nutrition and its status as a major base cation on the soil exchange complex. The determination of the origin of Ca in forests is particularly indicated in regard of important changes linked to acid inputs and intensive logging. Natural strontium isotopes are increasingly used as tracers of Ca in forest ecosystems for qualitative and quantitative assessments. Nevertheless this method is limited to relatively simple systems with two sources of nutrients. Some recent studies coupled Sr/Ca or Sr/Ba ratios to Sr isotopic measurements in order to solve more complex systems. Such method has however associated with it some uncertainties: this approach assumed that Ca, Sr and Ba behave similarly throughout the ecosystem and does not take into account the Ca biopurification processes occurring in some tree’s organs which can alter element ratio. The present work focuses on two deciduous species covering large areas in Europe: European beech (Fagus sylvatica L.) and pedunculate oak (Quercus robur L.). In order to test the similarity of behaviour between Ca, Sr and Ba, their concentrations were measured extensively in the major compartments of two forest ecosystems. In parallel, the discrimination process inside tree organs was studied in 23 stands for beech and 10 stands for oak. We found that Sr and Ca behave similarly in all soil and tree compartments. By contrast, Ba and Ca appear to have contrasting behaviours, especially in streams, soil solution and soil exchange complex (no correlations between element concentrations). Sr/Ba and Ba/Ca ratios must therefore be used with care as tracer of Ca. The Ca biopurification is absent in roots and slight in bole wood but is large in bark, twigs and leaves. The discrimination factors (DF) between wood and leaves are characteristic of the two species studied and do not change significantly as a function of the soil Ca status (acidic or calcareous soils). Therefore, strontium–calcium DF can be used as a correction factor of the Sr/Ca ratio of leaves when this ratio is used in connection with Sr isotopic ratios. This correction allows to solve systems of tree nutrition with more than two sources of Ca.     

Analysis of otolith chemistry in Nassau grouper (Epinephelus striatus) from the Bahamas and Belize using solution-based ICP-MS

 We examined the utility of otolith minor and trace element chemistry, assayed with inductively coupled plasma mass spectrometry (ICP-MS), as a means of delineating population structure in the Nassau grouper (Epinephelus striatus). We characterized the elemental composition of otoliths collected in 1993 from three locations in Exuma Sound, Bahamas and from Glover Reef, Belize in 1995. A single location in Exuma Sound was sampled in 1994 to test temporal variability in otolith composition. Five elements (Ca, Zn, Sr, Ba and Pb) were routinely detected, at levels significantly above background, by solution-based ICP-MS. Results from analysis of variance of elemental data, expressed as a ratio to Ca, indicated that there were no significant differences among the Exuma locations for any element, but significant variability was found between Glover Reef and the pooled Exuma localities for Zn/Ca, Sr/Ca and Ba/Ca ratios. Significant inter-annual differences at one Exuma Sound location was restricted to Ba/Ca ratios. Discriminant function analysis correctly classified 86% and 95% of the Belize and pooled Exuma sites, respectively. Otoliths from Belize were characterized by low Zn/Ca and high Ba/Ca and Pb/Ca ratios compared to otoliths from fish collected in Exuma Sound. Although differences in Ba levels may be related to upwelling at Glover Reef, more data are needed to definitely link otolith composition with regional differences in water chemistry. Accepted: 15 February 1999     

The use of the Ca2(+)-sensitive intramitochondrial dehydrogenases and entrapped fura-2 to study Sr2+ and Ba2+ transport across the inner membrane of mammalian mitochondria

In extracts of rat heart mitochondria, Sr2+ mimicked the activatory effects of Ca2+ on the Ca2(+)-sensitive intramitochondrial enzymes, pyruvate dehydrogenase phosphate phosphatase, isocitrate dehydrogenase (NAD+), and 2-oxoglutarate dehydrogenase, but at about tenfold higher concentrations (effective range approximately 1-100 muM) in each case. Ba2+ had no effect on extracted phosphatase, but did mimic the effect of Ca2+ on the other two enzymes with effective concentration ranges similar to those of Sr2+; as with Ca2+ and Sr2+, effective Ba2+ ranges were slightly (2-3-fold) raised by increases in ATP/ADP. In intact uncoupled rat heart mitochondria, the effects of Sr2+ and Ba2+ on the pyruvate and 2-oxoglutarate dehydrogenases were essentially similar to their effects in extracts. In fully coupled rat heart or liver mitochondria, the effective concentration ranges of extramitochondrial Sr2+, leading to activation of the matrix enzymes, were always approximately tenfold higher than those for Ca2+ under all conditions. Ba2+ did not affect pyruvate dehydrogenase in coupled mitochondria, but was shown to activate 2-oxoglutarate dehydrogenase in heart or liver mitochondria, and also isocitrate dehydrogenase (NAD+) in the latter; effective concentration ranges for extramitochondrial Ba2+ were approximately 100-fold greater than those for Ca2+, and like those for Ca2+ and Sr2+, were affected markedly by Mg2+ and spermine (which inhibit and promote mitochondrial Ca2+ uptake, respectively) but, in contrast to Ca2+ and Sr2+, they were hardly affected at all by Na+ (which promotes mitochondrial Ca2+ egress). Ba2+ effects were also blocked by ruthenium red (an inhibitor of mitochondrial Ca2+ uptake), but not so effectively as its blockage of the effects of Sr2+ and Ca2+. Ba2+ and Sr2+ both mimicked the inhibitory effects of extramitochondrial Ca2+ on the Na+/Ca2+ exchanger, but only Sr2+ could mimic Ca2+ in exchanging for internal Ca2+ by this mechanism. Both Sr2+ and Ba2+ changed the fluorescent properties of fura-2 or indo-1 in a similar manner to Ca2+, but with higher kd values. In fura-2-loaded rat heart mitochondria, increases in matrix Sr2+ and Ba2+ and the effects of the transport effectors could be readily demonstrated.     

Otolith Sr:Ca and Ba:Ca may give inconsistent indications of estuarine habitat use for American eels (<Emphasis Type="Italic">Anguilla rostrata</Emphasis>)

Temporal patterns in otolith Sr:Ca and Ba:Ca ratio values of American eels Anguilla rostrata from two sites in western Newfoundland gave insight into the use of freshwater and saline habitats. Mean Sr:Ca and Ba:Ca values at the core zone did not differ between sites, indicative of a common oceanic origin. At the otolith edge, representing continental life, both Sr:Ca and Ba:Ca values varied between sites consistent with ambient element:Ca ratio values and salinity, with typically higher Sr:Ca and lower Ba:Ca values in saline than in fresh waters. Most eels (73%) from Muddy Hole, an estuarine site, were evaluated as estuarine residents while most (70%) eels from Castors River, a freshwater site, were evaluated as freshwater residents, with the remaining eels from each site evaluated as inter-habitat migrants. An otolith element:Ca critical value appropriate for distinguishing between fresh and saline water residence is fundamental for estimating the proportion of eel residence in freshwater and their subsequent classification into habitat residence groups. Such classification is moderately robust to the critical value selected. For inter-habitat migrants, moderate otolith Sr:Ca values between the elver check and otolith edge suggestive of estuarine residence may coincide with Ba:Ca values suggestive of freshwater residence. No general critical value for separating fresh and estuarine habitats was found for otolith Ba:Ca. Otolith Ba:Ca temporal patterns may assist the use of Sr:Ca in the evaluation of historical habitat residence and inter-habitat movement but the use of otolith Ba:Ca values should be applied cautiously for American eels and perhaps of other estuarine/freshwater migratory fishes.     

Activation of pig oocytes by intracytoplasmic injection of strontium and barium

Ovulated mouse oocytes are activated by exposure to culture medium containing Sr2+ or Ba2+ or by intracytoplasmic injection of the divalent cations. It is known that in vitro matured pig oocytes are activated by the intracytoplasmic injection of Ca2+. In this study, we examined the effect of exposure and of intracytoplasmic injection of Sr2+ or Ba2+ on in vitro matured pig oocytes (MII-oocytes). When MII-oocytes were exposed to the medium containing divalent cations, no oocytes were activated. However, in the case of oocytes that were injected with Sr2+, Ba2+ and Ca2+, at 6 h after injection, 64%, 71% and 86% of the oocytes had been released from MII-arrest, and 51%, 67% and 84% formed female pronuclei, respectively. The initial transient in intracellular Ca2+ concentration ([Ca2+]i) was measured by the Ca2+ indicator dye fluo-4 dextran. Microinjection of Sr2+, Ba2+ or Ca2+ induced a rapid elevation of [Ca2+]i. The exocytosis of cortical granules was examined by staining with fluorescein isothiocyanate (FITC)-labelled peanut agglutinin. After an injection of divalent cations, a release of cortical granules was observed in the oocytes. Maturation promoting factor (MPF) activity declined to a low level after 6 h in all the oocytes injected with divalent cations. To test their developmental ability, injected oocytes were treated with cytochalasin B and then cultured for 168 h in NCSU23 medium. After 168 h, 29% (Sr2+), 29% (Ba2+) and 51% (Ca2+) of the oocytes had developed to the blastocyst stage. These results indicate that intracytoplasmic injection of Sr2+ and Ba2+, like that of Ca2+, induces in vitro matured pig oocytes to be released from MII-arrest and leads them into a series of events related to oocyte activation.     

Spatial and temporal variations in otolith chemistry and relationships with water chemistry: a useful tool to distinguish Atlantic salmon Salmo salar parr from different natal streams

Otolith elemental (Sr:Ca, Ba:Ca, Mn:Ca, Mg:Ca and Rb:Ca) and isotopic (⁸⁷Sr:⁸⁶Sr) profiles from several annual cohorts of juvenile Atlantic salmon Salmo salar were related to the physico‐chemical characteristics (chemical signatures, flow rate, temperature and conductivity) of their natal rivers over an annual hydrological cycle. Only Sr:Ca, Ba:Ca and ⁸⁷Sr:⁸⁶Sr in otoliths were determined by their respective ratios in the ambient water. Sr:Ca ratios in stream waters fluctuated strongly on a seasonal basis, but these fluctuations, mainly driven by water flow regimes, were not recorded in the otoliths. Otolith Sr:Ca ratios remained constant during freshwater residency at a given site and were exclusively related to water Sr:Ca ratios during low flow periods. While interannual differences in otolith elemental composition among rivers were observed, this variability was minor compared to geographic variability and did not limit classification of juveniles to their natal stream. Success in discriminating fish from different sites was greatest using Sr isotopes as it remained relatively constant across years at a given location.     

Changes in Sr/Ca, Ba/Ca and 87Sr/86Sr ratios between trophic levels in two forest ecosystems in the northeastern U.S.A.

The variability and biologicalfractionation of Sr/Ca, Ba/Ca and ⁸⁷Sr/⁸⁶Srratios were studied in a soil–plant–invertebrate–bird food chain in two forested ecosystems withcontrasting calcium availability in the northeasternU.S.A. Chemical measurements were made of the soilexchange pool, leaves, caterpillars, snails, and boththe femurs and eggshells of breeding insectivorousmigratory songbirds. ⁸⁷Sr/⁸⁶Sr values weretransferred up the food chain from the soil exchangepool to leaves, caterpillars, snails and eggshellswithout modification. Adult birds were the oneexception; their ⁸⁷Sr/⁸⁶Sr values generallyreflected those of lower trophic levels at each site,but were lower and more variable, probably becausetheir strontium was derived in part from foods intropical winter habitats where lower⁸⁷Sr/⁸⁶Sr ratios are likely to predominate. Sr/Ca and Ba/Ca ratios decreased at each successive trophiclevel, supporting previous suggestions that Sr/Ca andBa/Ca ratios can be used to identify the trophic levelat which an organism is primarily feeding. The changesin Sr/Ca and Ba/Ca ratios we measured for vegetationand insects were comparable to similar measurementsmade previously (but based on single samples of eachorganism) in an alpine ecosystem. Changes in Sr/Ca andBa/Ca ratios between birds and their food have notpreviously been measured, but the values we obtainedwere similar to those for herbivorous and carnivorousmammals at similar trophic levels. Our results provideevidence that supports the use of Sr/Ca ratios in thedetermination of human paleodiets and suggests thatSr/Ca ratios may also provide a useful tool in studiesof modern food webs. Furthermore, our findings suggestthat ⁹⁰Sr from nuclear fallout will notbioaccumulate in forests and that changes in Sr/Caratios between trophic levels will need to beconsidered in some cases when using⁸⁷Sr/⁸⁶Sr as a tracer of calciumbiogeochemistry.     

Life history and age at maturity of an anadromous smelt, the eulachon Thaleichthys pacificus (Richardson)

Trace element and fork length ( L _F) frequency analyses of eulachon Thaleichthys pacificus otoliths were used to determine age at maturity and repeat spawning potential, two aspects of eulachon life history that are not known but are important for successful management of this species. The L _F-frequency analysis for ocean caught and spawning eulachon was used to estimate age at maturation. Two size classes of eulachon were caught in the ocean and spawning eulachon were consistently the largest fish indicating that spawners from mid-coast of British Columbia were 3 years old. Laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) was also used to reconstruct the Ba:Ca and Sr:Ca molar ratios deposited spatially into the otolith to estimate spawner age for five populations of eulachon. Age at maturation differed among populations examined. Based on the seasonal fluctuations in Ba:Ca molar ratios caused by seasonal upwelling of deep waters, it was determined that more southerly populations spawned at a younger age than the northern populations examined. Southern populations of eulachon, Columbia River, Washington, U.S.A., spawn after 2 years. Eulachon from the Fraser, Kemano and Skeena Rivers in British Columbia, Canada, generally mature after 3 years. Some Skeena River eulachon and most of the eulachon from the Copper River, Alaska, U.S.A., matured after 4 years. In contrast to the Ba:Ca molar ratios in the otolith, Sr:Ca molar ratios maintained a relatively flat profile over the life of the eulachon. The lack of a change in Sr:Ca ratios within the otolith, the single size class of spawners across all systems and the single age class within most populations strongly suggest that eulachon in the present study are semelparous.